Science papers where I am co-author …
Borkovits T; Albrecht S; Rappaport S; Nelson L; Vanderburg A; Gary B L; Tan T G; Justesen A B; Kristiansen M H; Jacobs T L; LaCourse D; Ngo H; Wallack N; Ruane G; Mawet D; Howell S B; Tronsgaard R
In: Monthly Notices of the Royal Astronomical Society, 2018, ISSN: 0035-8711, 1365-2966, (arXiv: 1805.09693).
We have discovered a doubly eclipsing, bound, quadruple star system in the field of K2 Campaign 7. EPIC 219217635 is a stellar image with $Kp = 12.7$ that contains an eclipsing binary (`EB') with $P_A = 3.59470$ d and a second EB with $P_B = 0.61825$ d. We have obtained followup radial-velocity (`RV') spectroscopy observations, adaptive optics imaging, as well as ground-based photometric observations. From our analysis of all the observations, we derive good estimates for a number of the system parameters. We conclude that (1) both binaries are bound in a quadruple star system; (2) a linear trend to the RV curve of binary A is found over a 2-year interval, corresponding to an acceleration, $textbackslashdot textbackslashgamma = 0.0024 textbackslashpm 0.0007$ cm s$textasciicircum-2$; (3) small irregular variations are seen in the eclipse-timing variations (`ETVs') detected over the same interval; (4) the orbital separation of the quadruple system is probably in the range of 8-25 AU; and (5) the orbital planes of the two binaries must be inclined with respect to each other by at least 25$textasciicircumtextbackslashcirc$. In addition, we find that binary B is evolved, and the cooler and currently less massive star has transferred much of its envelope to the currently more massive star. We have also demonstrated that the system is sufficiently bright that the eclipses can be followed using small ground-based telescopes, and that this system may be profitably studied over the next decade when the outer orbit of the quadruple is expected to manifest itself in the ETV and/or RV curves.
Shvartzvald Y; Yee J C; Skowron J; Lee C; Udalski A; Novati S C; Bozza V; Beichman C A; Bryden G; Carey S; Gaudi B S; Henderson C B; Zhu W; Bachelet E; Bolt G; Christie G; Maoz D; Natusch T; Pogge R W; Street R A; Tan T; Tsapras Y; Pietrukowicz P; Soszyński I; Szymański M K; Mróz P; Poleski R; Kozłowski S; Ulaczyk K; Pawlak M; Rybicki K A; Iwanek P; Albrow M D; Cha S; Chung S; Gould A; Han C; Hwang K; Jung Y K; Kim D; Kim H; Kim S; Lee D; Lee Y; Park B; Ryu Y; Shin I; Zang W; Dominik M; Helling C; Hundertmark M; Jørgensen U G; Longa-Peña P; Lowry S; Sajadian S; Burgdorf M J; Campbell-White J; Ciceri S; Evans D F; Fujii Y I; Hinse T C; Rahvar S; Rabus M; Skottfelt J; Snodgrass C; Southworth J
In: arXiv:1805.08778 [astro-ph], 2018, (arXiv: 1805.08778).
The kinematics of isolated brown dwarfs in the Galaxy, beyond the solar neighborhood, is virtually unknown. Microlensing has the potential to probe this hidden population, as it can measure both the mass and five of the six phase-space coordinates (all except the radial velocity) even of a dark isolated lens. However, the measurements of both the microlens parallax and finite-source effects are needed in order to recover the full information. Here, we combine $Spitzer$ satellite parallax measurement with the ground-based light curve, which exhibits strong finite-source effects, of event OGLE-2017-BLG-0896. We find that the lens is a $textbackslashsim$19$M_J$ isolated brown dwarf. This is the lowest isolated-object mass measurement to date, only slightly above the common definition of a free-floating planet. The brown dwarf is located at $textbackslashsim$4 kpc toward the Galactic bulge, but with proper motion in the opposite direction of disk stars, possibly moving in the Galactic plane. While it is possibly a halo brown dwarf, it might also represent a different, unknown population.
Sarkis P; Henning T; Hartman J D; Bakos G Á; Brahm R; Jordán A; Bayliss D; Mancini L; Espinoza N; Rabus M; Csubry Z; Bhatti W; Penev K; Zhou G; Bento J; Tan T G; Arriagada P; Butler R P; Crane J D; Shectman S; Tinney C G; Wright D J; Addison B; Durkan S; Suc V; Buchhave L A; de Val-Borro M; Lázár J; Papp I; Sári P
In: arXiv:1805.05925 [astro-ph], 2018, (arXiv: 1805.05925).
We report the first discovery of a multi-planetary system by the HATSouth network, HATS-59b,c, a planetary system with an inner transiting hot Jupiter and an outer cold massive giant planet, which was detected via radial velocity. The inner transiting planet, HATS-59b, is on an eccentric orbit with $e = 0.129textbackslashpm0.049$, orbiting a $V=13.951textbackslashpm0.030$ mag solar-like star ($M_* = 1.038textbackslashpm0.039 M_textbackslashodot$, and $R_* = 1.036textbackslashpm0.067 R_textbackslashodot$) with a period of $5.416077textbackslashpm0.000017$ days. The outer companion, HATS-59c is on a circular orbit with $ m textbackslashsin i = 12.8textbackslashpm1.1 M_textbackslashmathrmJ$, and a period of $1422textbackslashpm14$ days. The inner planet has a mass of $0.806textbackslashpm0.069 M_textbackslashmathrmJ$ and a radius of $1.126textbackslashpm0.077 M_textbackslashmathrmJ$, yielding a density of $0.70textbackslashpm0.16 textbackslashrm gtextbackslash,cmtextasciicircum-3$. Unlike most of the planetary systems that include only a single hot Jupiter, HATS-59b,c includes, in addition to the transiting hot Jupiter, a massive outer companion. The architecture of this system is valuable for understanding planet migration.
Bennett D P; Udalski A; Bond I A; Suzuki D; Ryu Y; Abe F; Barry R K; Bhattacharya A; Donachie M; Fukui A; Hirao Y; Kawasaki K; Kondo I; Koshimoto N; Li M C A; Matsubara Y; Miyazaki S; Muraki Y; Nagakane M; Ohnishi K; Ranc C; Rattenbury N J; Suematsu H; Sumi T; Tristram P J; Yonehara A; Szymański M K; Soszyński I; Wyrzykowski Ł; Ulaczyk K; Poleski R; Kozłowski S; Pietrukowicz P; Skowron J; Shvartzvald Y; Maoz D; Kaspi S; Friedmann M; Batista V; DePoy D; Dong S; Gaudi B S; Gould A; Pogge C H R W; Tan T; Yee J C
In: arXiv:1806.06106 [astro-ph], 2018, (arXiv: 1806.06106).
We present the analysis of planetary microlensing event MOA-2011-BLG-291, which has a mass ratio of $q=(3.8textbackslashpm0.7)textbackslashtimes10textasciicircum-4$ and a source star that is redder (or brighter) than the bulge main sequence. This event is located at a low Galactic latitude in the survey area that is currently planned for NASA's WFIRST exoplanet microlensing survey. This unusual color for a microlensed source star implies that we cannot assume that the source star is in the Galactic bulge. The favored interpretation is that the source star is a lower main sequence star at a distance of $D_S=4.9textbackslashpm1.3textbackslash,$kpc in the Galactic disk. However, the source could also be a turn-off star on the far side of the bulge or a sub-giant in the far side of the Galactic disk if it experiences significantly more reddening than the bulge red clump stars. However, these possibilities have only a small effect on our mass estimates for the host star and planet. We find host star and planet masses of $M_textbackslashrm host =0.15textasciicircum+0.27_-0.10M_textbackslashodot$ and $m_p=18textasciicircum+34_-12M_textbackslashoplus$ from a Bayesian analysis with a standard Galactic model under the assumption that the planet hosting probability does not depend on the host mass or distance. However, if we attempt to measure the host and planet masses with host star brightness measurements from high angular resolution follow-up imaging, the implied masses will be sensitive to the host star distance. The WFIRST exoplanet microlensing survey is expected to use this method to determine the masses for many of the planetary systems that it discovers, so this issue has important design implications for the WFIRST exoplanet microlensing survey.
Hartman J D; Bakos G A; Bayliss D; Bento J; Bhatti W; Brahm R; Csubry Z; Espinoza N; Henning T; Jordán A; Mancini L; Penev K; Rabus M; Sarkis P; Suc V; de Val-Borro M; Zhou G; Addison B; Arriagada P; Butler R P; Crane J; Durkan S; Shectman S; Tan T G; Thompson I; Tinney C G; Wright D J; Lázár J; Papp I; Sári P
HATS-60b - HATS-69b: Ten Transiting Planets From HATSouth (Journal Article)
In: arXiv:1809.01048 [astro-ph], 2018, (arXiv: 1809.01048).
We report the discovery of ten transiting extrasolar planets by the HATSouth survey. The planets range in mass from the Super-Neptune HATS-62b, with $M_p textless 0.191 M_J$, to the Super-Jupiter HATS-66b, with $M_p = 5.47 M_J$, and in size from the Saturn HATS-69b, with $R_p = 0.94 R_J$, to the inflated Jupiter HATS-67b, with $R_p = 1.69 R_J$. The planets have orbital periods between 1.6092 days (HATS-67b) and 7.8180 days (HATS-61b). The hosts are dwarf stars with masses ranging from $0.89 M_textbackslashodot$ (HATS-69) to $1.56 M_textbackslashodot$ (HATS-64), and have apparent magnitudes between $V = 12.276 textbackslashpm 0.020$ mag (HATS-68) and $V = 14.095 textbackslashpm 0.030$ mag (HATS-66). The Super-Neptune HATS-62b is the least massive planet discovered to date with a radius larger than Jupiter. Based largely on the Gaia DR2 distances and broad-band photometry, we identify three systems (HATS-62, -64, and -65) as having possible unresolved binary star companions. We discuss in detail our methods for incorporating the Gaia DR2 observations into our modeling of the system parameters, and into our blend analysis procedures.
Ment K; Dittmann J A; Astudillo-Defru N; Charbonneau D; Irwin J; Bonfils X; Murgas F; Almenara J; Forveille T; Agol E; Ballard S; Berta-Thompson Z K; Bouchy F; Cloutier R; Delfosse X; Doyon R; Dressing C D; Esquerdo G A; Haywood R D; Kipping D M; Latham D W; Lovis C; Newton E R; Pepe F; Rodriguez J E; Santos N C; Tan T; Udry S; Winters J G; Wünsche A
In: arXiv:1808.00485 [astro-ph], 2018, (arXiv: 1808.00485).
LHS 1140 is a nearby mid-M dwarf known to host a temperate rocky super-Earth (LHS 1140 b) on a 24.737-day orbit. Based on photometric observations by MEarth and Spitzer as well as Doppler spectroscopy from HARPS, we report the discovery of an additional transiting rocky companion (LHS 1140 c) with a mass of $1.81textbackslashpm0.39textasciitildetextbackslashrm M_Earth$ and a radius of $1.282textbackslashpm0.024textasciitildetextbackslashrm R_Earth$ on a tighter, 3.77795-day orbit. We also obtain more precise estimates of the mass and radius of LHS 1140 b to be $6.98textbackslashpm0.98textasciitildetextbackslashrm M_Earth$ and $1.727textbackslashpm0.032textasciitildetextbackslashrm R_Earth$. The mean densities of planets b and c are $7.5textbackslashpm1.0textasciitildetextbackslashrmg/cmtextasciicircum3$ and $4.7textbackslashpm1.1textasciitildetextbackslashrmg/cmtextasciicircum3$, respectively, both consistent with the Earth's ratio of iron to magnesium silicate. The orbital eccentricities of LHS 1140 b and c are consistent with circular orbits and constrained to be below 0.06 and 0.31, respectively, with 90% confidence. Because the orbits of the two planets are co-planar and because we know from previous analyses of Kepler data that compact systems of small planets orbiting M dwarfs are commonplace, a search for more transiting planets in the LHS 1140 system could be fruitful. LHS 1140 c is one of the few known nearby terrestrial planets whose atmosphere could be studied with the upcoming James Webb Space Telescope.
Borkovits T; Rappaport S; Kaye T; Isaacson H; Vanderburg A; Howard A W; Kristiansen M H; Omohundro M R; Schwengeler H M; Terentev I A; Shporer A; Relles H; Villanueva Jr. S; Tan T G; Colón K D; Blex J; Haas M; Cochran W; Endl M
In: arXiv:1809.04366 [astro-ph], 2018, (arXiv: 1809.04366).
Using Campaign 15 data from the K2 mission, we have discovered a triply-eclipsing triple star system: EPIC 249432662. The inner eclipsing binary system has a period of 8.23 days, with shallow $textbackslashsim$3% eclipses. During the entire 80-day campaign, there is also a single eclipse event of a third-body in the system that reaches a depth of nearly 50% and has a total duration of 1.7 days, longer than for any previously known third-body eclipse involving unevolved stars. The binary eclipses exhibit clear eclipse timing variations. A combination of photodynamical modeling of the lightcurve, as well as seven follow-up radial velocity measurements, has led to a prediction of the subsequent eclipses of the third star with a period of 188 days. A campaign of follow-up ground-based photometry was able to capture the subsequent pair of third-body events as well as two further 8-day eclipses. A combined photo-spectro-dynamical analysis then leads to the determination of many of the system parameters. The 8-day binary consists of a pair of M stars, while most of the system light is from a K star around which the pair of M stars orbits.
Mentel R T; Kenworthy M A; Cameron D A; Scott E L; Mellon S N; Hudec R; Birkby J L; Mamajek E E; Schrimpf A; Reichart D E; Haislip J B; Kouprianov V V; Hambsch F -J; Tan T -G; Hills K; Grindlay J E
In: Astronomy & Astrophysics, vol. 619, pp. A157, 2018, ISSN: 0004-6361, 1432-0746, (arXiv: 1810.05171).
Context. The 16 Myr old star 1SWASP J140747.93-394542.6 (V1400 Cen) underwent a series of complex eclipses in May 2007, interpreted as the transit of a giant Hill sphere filling debris ring system around a secondary companion, J1407b. No other eclipses have since been detected, although other measurements have constrained but not uniquely determined the orbital period of J1407b. Finding another eclipse towards J1407 will help determine the orbital period of the system, the geometry of the proposed ring system and enable planning of further observations to characterize the material within these putative rings. Aims. We carry out a search for other eclipses in photometric data of J1407 with the aim of constraining the orbital period of J1407b. Methods. We present photometry from archival photographic plates from the Harvard DASCH survey, and Bamberg and Sonneberg Observatories, in order to place additional constraints on the orbital period of J1407b by searching for other dimming and eclipse events. Using a visual inspection of all 387 plates and a period-folding algorithm we performed a search for other eclipses in these data sets. Results. We find no other deep eclipses in the data spanning from 1890 to 1990, nor in recent time-series photometry from 2012-2018. Conclusions. We rule out a large fraction of putative orbital periods for J1407b from 5 to 20 years. These limits are still marginally consistent with a large Hill sphere filling ring system surrounding a brown dwarf companion in a bound elliptical orbit about J1407. Issues with the stability of any rings combined with the lack of detection of another eclipse, suggests that J1407b may not be bound to J1407.
Espinoza N; Hartman J D; Bakos G Á; Henning T; Bayliss D; Bento J; Bhatti W; Brahm R; Csubry Z; Suc V; Jordán A; Mancini L; Tan T G; Penev K; Rabus M; Sarkis P; de Val-Borro M; Durkan S; Lazar J; Papp I; Sari P
In: arXiv:1812.07668 [astro-ph], 2018, (arXiv: 1812.07668).
We report the discovery by the HATSouth project of 5 new transiting hot Jupiters (HATS-54b through HATS-58Ab). HATS-54b, HATS-55b and HATS-58Ab are prototypical short period ($P = 2.5-4.2$ days, $R_ptextbackslashsim1.1-1.2$ $R_J$) hot-Jupiters that span effective temperatures from 1350 K to 1750 K, putting them in the proposed region of maximum radius inflation efficiency. The HATS-58 system is composed of two stars, HATS-58A and HATS-58B, which are detected thanks to Gaia DR2 data and which we account for in the joint modelling of the available data --- with this, we are led to conclude that the hot jupiter orbits the brighter HATS-58A star. HATS-57b is a short-period (2.35-day) massive (3.15 $M_J$) 1.14 $R_J$, dense ($2.65textbackslashpm0.21$ g cm$textasciicircum-3$) hot-Jupiter, orbiting a very active star ($2textbackslash%$ peak-to-peak flux variability). Finally, HATS-56b is a short period (4.32-day) highly inflated hot-Jupiter (1.7 $R_J$, 0.6 $M_J$), which is an excellent target for future atmospheric follow-up, especially considering the relatively bright nature ($V=11.6$) of its F dwarf host star. This latter exoplanet has another very interesting feature: the radial velocities show a significant quadratic trend. If we interpret this quadratic trend as arising from the pull of an additional planet in the system, we obtain a period of $P_c = 815textasciicircum+253_-143$ days for the possible planet HATS-56c, and a minimum mass of $M_ctextbackslashsin i_c = 5.11 textbackslashpm 0.94$ $M_J$. The candidate planet HATS-56c would have a zero-albedo equilibrium temperature of $T_textbackslashtextrmeq=332textbackslashpm 50$ K, and thus would be orbiting close to the habitable zone of HATS-56. Further radial-velocity follow-up, especially over the next two years, is needed to confirm the nature of HATS-56c.
McLeod K K; Rodriguez J E; Oelkers R J; Collins K A; Bieryla A; Fulton B J; Stassun K G; Gaudi B S; Penev K; Stevens D J; Colón K D; Pepper J; Narita N; Tsuguru R; Fukui A; Reed P A; Tirrell B; Visgaitis T; Kielkopf J F; Cohen D H; Jensen E L N; Gregorio J; Baştürk Ö; Oberst T E; Melton C; Kempton E M -R; Baldridge A; Zhao Y S; Zambelli R; Latham D W; Esquerdo G A; Berlind P; Calkins M L; Howard A W; Isaacson H; Weiss L M; Beatty T G; Eastman J D; Penny M T; Siverd R J; Lund M B; Labadie-Bartz J; Zhao G; Curtis I A; Joner M D; Manner M; Relles H; Scarpetta G; Stephens D C; Stockdale C; Tan T G; DePoy D L; Marshall J L; Pogge R W; Trueblood M; Trueblood P
KELT-18b: Puffy Planet, Hot Host, Probably Perturbed (Journal Article)
In: arXiv:1702.01657 [astro-ph], 2017, (arXiv: 1702.01657).
We report the discovery of KELT-18b, a transiting hot Jupiter in a 2.87d orbit around the bright (V=10.1), hot, F4V star BD+60 1538 (TYC 3865-1173-1). We present follow-up photometry, spectroscopy, and adaptive optics imaging that allow a detailed characterization of the system. Our preferred model fits yield a host stellar temperature of 6670+/-120 K and a mass of 1.524+/-0.069 Msun, situating it as one of only a handful of known transiting planets with hosts that are as hot, massive, and bright. The planet has a mass of 1.18+/-0.11 Mjup, a radius of 1.57+/-0.04 Rjup, and a density of 0.377+/-0.040 g/cmtextasciicircum3, making it one of the most inflated planets known around a hot star. We argue that KELT-18b's high temperature, low surface gravity, and hot, bright host make it an excellent candidate for observations aimed at atmospheric characterization. We also present evidence for a bound stellar companion at a projected separation of textasciitilde1100 AU, and speculate that it may have contributed to the strong misalignment we suspect between KELT-18's spin axis and its planet's orbital axis. The inferior conjunction time is 2457542.524998 +/-0.000416 (BJD_TDB) and the orbital period is 2.8717510 +/- 0.0000029 days. We encourage Rossiter-McLaughlin measurements in the near future to confirm the suspected spin-orbit misalignment of this system.
Dittmann J A; Irwin J M; Charbonneau D; Bonfils X; Astudillo-Defru N; Haywood R D; Berta-Thompson Z K; Newton E R; Rodriguez J E; Winters J G; Tan T; Almenara J; Bouchy F; Delfosse X; Forveille T; Lovis C; Murgas F; Pepe F; Santos N C; Udry S; Wünsche A; Esquerdo G A; Latham D W; Dressing C D
A temperate rocky super-Earth transiting a nearby cool star (Journal Article)
In: Nature, vol. 544, no. 7650, pp. 333–336, 2017, ISSN: 0028-0836, 1476-4687, (arXiv: 1704.05556).
M dwarf stars, which have masses less than 60 per cent that of the Sun, make up 75 per cent of the population of the stars in the Galaxy . The atmospheres of orbiting Earth-sized planets are observationally accessible via transmission spectroscopy when the planets pass in front of these stars [2,3]. Statistical results suggest that the nearest transiting Earth-sized planet in the liquid-water, habitable zone of an M dwarf star is probably around 10.5 parsecs away . A temperate planet has been discovered orbiting Proxima Centauri, the closest M dwarf , but it probably does not transit and its true mass is unknown. Seven Earth-sized planets transit the very low-mass star TRAPPIST-1, which is 12 parsecs away [6,7], but their masses and, particularly, their densities are poorly constrained. Here we report observations of LHS 1140b, a planet with a radius of 1.4 Earth radii transiting a small, cool star (LHS 1140) 12 parsecs away. We measure the mass of the planet to be 6.6 times that of Earth, consistent with a rocky bulk composition. LHS 1140b receives an insolation of 0.46 times that of Earth, placing it within the liquid-water, habitable zone . With 90 per cent confidence, we place an upper limit on the orbital eccentricity of 0.29. The circular orbit is unlikely to be the result of tides and therefore was probably present at formation. Given its large surface gravity and cool insolation, the planet may have retained its atmosphere despite the greater luminosity (compared to the present-day) of its host star in its youth [9,10]. Because LHS 1140 is nearby, telescopes currently under construction might be able to search for specific atmospheric gases in the future [2,3].
Temple L Y; Hellier C; Albrow M D; Anderson D R; Bayliss D; Beatty T G; Bieryla A; Brown D J A; Cargile P A; Cameron A C; Collins K A; Colón K D; Curtis I A; D'Ago G; Delrez L; Eastman J; Gaudi B S; Gillon M; Gregorio J; James D; Jehin E; Joner M D; Kielkopf J F; Kuhn R B; Labadie-Bartz J; Latham D W; Lendl M; Lund M B; Malpas A L; Maxted P F L; Myers G; Oberst T E; Pepe F; Pepper J; Pollacco D; Queloz D; Rodriguez J E; Ségransan D; Siverd R J; Smalley B; Stassun K G; Stevens D J; Stockdale C; Tan T G; Triaud A H M J; Udry S; Villanueva Jr S; West R G; Zhou G
In: arXiv:1704.07771 [astro-ph], 2017, (arXiv: 1704.07771).
We report the joint WASP/KELT discovery of WASP-167b/KELT-13b, a transiting hot Jupiter with a 2.02-d orbit around a $V$ = 10.5, F1V star with [Fe/H] = 0.1 $textbackslashpm$ 0.1. The 1.5 R$_textbackslashrm Jup$ planet was confirmed by Doppler tomography of the stellar line profiles during transit. We place a limit of $textless$ 8 M$_textbackslashrm Jup$ on its mass. The planet is in a retrograde orbit with a sky-projected spin-orbit angle of $textbackslashlambda = -165textasciicircumtextbackslashcirc textbackslashpm 5textasciicircumtextbackslashcirc$. This is in agreement with the known tendency for orbits around hotter stars to be more likely to be misaligned. WASP-167/KELT-13 is one of the few systems where the stellar rotation period is less than the planetary orbital period. We find evidence of non-radial stellar pulsations in the host star, making it a $textbackslashdelta$-Scuti or $textbackslashgamma$-Dor variable. The similarity to WASP-33, a previously known hot-Jupiter host with pulsations, adds to the suggestion that close-in planets might be able to excite stellar pulsations.
Bayliss D; Hartman J D; Zhou G; Bakos G Á; Vanderburg A; Bento J; Mancini L; Ciceri S; Brahm R; Jordán A; Espinoza N; Rabus M; Tan T G; Penev K; Bhatti W; de Val-Borro M; Suc V; Csubry Z; Henning T; Sarkis P; Lázár J; Papp I; Sári P
In: arXiv:1706.03858 [astro-ph], 2017, (arXiv: 1706.03858).
We report on the result of a campaign to monitor 25 HATSouth candidates using the K2 space telescope during Campaign 7 of the K2 mission. We discover HATS-36b (EPIC 215969174b), a hot Jupiter with a mass of 2.79$textbackslashpm$0.40 M$_J$ and a radius of 1.263$textbackslashpm$0.045 R$_J$ which transits a solar-type G0V star (V=14.386) in a 4.1752d period. We also refine the properties of three previously discovered HATSouth transiting planets (HATS-9b, HATS-11b, and HATS-12b) and search the K2 data for TTVs and additional transiting planets in these systems. In addition we also report on a further three systems that remain as Jupiter-radius transiting exoplanet candidates. These candidates do not have determined masses, however pass all of our other vetting observations. Finally we report on the 18 candidates which we are now able to classify as eclipsing binary or blended eclipsing binary systems based on a combination of the HATSouth data, the K2 data, and follow-up ground-based photometry and spectroscopy. These range in periods from 0.7 days to 16.7 days, and down to 1.5 mmag in eclipse depths. Our results show the power of combining ground-based imaging and spectroscopy with higher precision space-based photometry, and serve as an illustration as to what will be possible when combining ground-based observations with TESS data.
Gaudi B S; Stassun K G; Collins K A; Beatty T G; Zhou G; Latham D W; Bieryla A; Eastman J D; Siverd R J; Crepp J R; Gonzales E J; Stevens D J; Buchhave L A; Pepper J; Johnson M C; Colon K D; Jensen E L N; Rodriguez J E; Bozza V; Novati S C; D’Ago G; Dumont M T; Ellis T; Gaillard C; Jang-Condell H; Kasper D H; Fukui A; Gregorio J; Ito A; Kielkopf J F; Manner M; Matt K; Narita N; Oberst T E; Reed P A; Scarpetta G; Stephens D C; Yeigh R R; Zambelli R; Fulton B J; Howard A W; James D J; Penny M; Bayliss D; Curtis I A; DePoy D L; Esquerdo G A; Gould A; Joner M D; Kuhn R B; Labadie-Bartz J; Lund M B; Marshall J L; McLeod K K; Pogge R W; Relles H; Stockdale C; Tan T G; Trueblood M; Trueblood P
In: Nature, vol. advance online publication, 2017, ISSN: 0028-0836.
The amount of ultraviolet irradiation and ablation experienced by a planet depends strongly on the temperature of its host star. Of the thousands of extrasolar planets now known, only six have been found that transit hot, A-type stars (with temperatures of 7,300–10,000 kelvin), and no planets are known to transit the even hotter B-type stars. For example, WASP-33 is an A-type star with a temperature of about 7,430 kelvin, which hosts the hottest known transiting planet, WASP-33b (ref. 1); the planet is itself as hot as a red dwarf star of type M (ref. 2). WASP-33b displays a large heat differential between its dayside and nightside, and is highly inflated–traits that have been linked to high insolation. However, even at the temperature of its dayside, its atmosphere probably resembles the molecule-dominated atmospheres of other planets and, given the level of ultraviolet irradiation it experiences, its atmosphere is unlikely to be substantially ablated over the lifetime of its star. Here we report observations of the bright star HD 195689 (also known as KELT-9), which reveal a close-in (orbital period of about 1.48 days) transiting giant planet, KELT-9b. At approximately 10,170 kelvin, the host star is at the dividing line between stars of type A and B, and we measure the dayside temperature of KELT-9b to be about 4,600 kelvin. This is as hot as stars of stellar type K4 (ref. 5). The molecules in K stars are entirely dissociated, and so the primary sources of opacity in the dayside atmosphere of KELT-9b are probably atomic metals. Furthermore, KELT-9b receives 700 times more extreme-ultraviolet radiation (that is, with wavelengths shorter than 91.2 nanometres) than WASP-33b, leading to a predicted range of mass-loss rates that could leave the planet largely stripped of its envelope during the main-sequence lifetime of the host star.
Siverd R J; Collins K A; Zhou G; Gaudi B S; Stassun K G; Johnson M C; Quinn S N; Bieryla A; Latham D W; Ciardi D R; Rodriguez J E; Penev K; Pinsonneault M; Pepper J; Eastman J D; Relles H; Kielkopf J F; Gregorio J; Oberst T E; Aldi G F; Esquerdo G A; Calkins M L; Berlind P; Dressing C; Patel R; Stevens D J; Beatty T G; Lund M B; Labadie-Bartz J; Kuhn R B; Colon K D; James D; Yao X; Jensen E L N; Cohen D H; McLeod K K; Penny M T; Joner M D; Stephens D C; Villanueva Jr. S; Zambelli R; Stockdale C; Evans P; Tan T; Curtis I A; Reed P A; Trueblood M; Trueblood P
In: arXiv:1709.07010 [astro-ph], 2017, (arXiv: 1709.07010).
We present the discovery of the giant planet KELT-19Ab, which transits the moderately bright ($V textbackslashsim 9.9$) A8V star TYC 764-1494-1. We confirm the planetary nature of the companion via a combination of low-precision radial velocities, which limit the mass to $M_textbackslashrm P textless 4.1textbackslash,M_textbackslashrm J$ ($3textbackslashsigma$), and a clear Doppler tomography signal, which indicates a retrograde projected spin-orbit misalignment of $textbackslashlambda = -179.7textasciicircum+3.7_-3.8$ degrees. Global modeling indicates that the $T_textbackslashrm eff =7500 textbackslashpm 110textbackslash,textbackslashrm K$ host star has $M_* = 1.62textasciicircum+0.25_-0.20textbackslash,M_textbackslashodot$ and $R_* = 1.83 textbackslashpm 0.10textbackslash,R_textbackslashodot$. The planet has a radius of $R_textbackslashrm P=1.91 textbackslashpm 0.11textbackslash,R_textbackslashrm J$ and receives a stellar insolation flux of $textbackslashsim 3.2textbackslashtimes 10textasciicircum9textbackslash,textbackslashrmtextbackslash,ergtextbackslash,stextasciicircum-1textbackslash,cmtextasciicircum-2$, leading to an inferred equilibrium temperature of $T_textbackslashrm eq textbackslashsim 1935textbackslash,textbackslashrm K$ assuming zero albedo and complete heat redistribution. With a $vtextbackslashsinI_*=84.8textbackslashpm 2.0textbackslash,textbackslashrm kmtextbackslash,stextasciicircum-1$, the host star is rapidly-rotating. Interestingly, its $vtextbackslashsinI_*$ is relatively low compared to other stars with similar effective temperatures, and it appears to be enhanced in metallic species such as strontium but deficient in others such as calcium, suggesting that it is likely an Am star. KELT-19A would be the first definitive detection of an Am host of a transiting planet of which we are aware. Adaptive optics observations of the system reveal the existence of a companion with late G9V/early K1V spectral type at a projected separation of $textbackslashapprox 160textbackslash, textbackslashmathrmAU$. Radial velocity measurements indicate that this companion is bound. Most Am stars are known to have stellar companions, which are often invoked to explain the relatively slow rotation of the primary. In this case, the stellar companion is unlikely to have caused the tidal braking of the primary.
Johnson M C; Rodriguez J E; Zhou G; Gonzales E J; Cargile P A; Crepp J R; Penev K; Stassun K G; Gaudi B S; Colón K D; Stevens D J; Strassmeier K G; Ilyin I; Collins K A; Kielkopf J F; Oberst T E; Maritch L; Reed P A; Gregorio J; Bozza V; Novati S C; D'Ago G; Scarpetta G; Zambelli R; Latham D W; Bieryla A; Cochran W D; Endl M; Tayar J; Serenelli A; Aguirre V S; Clarke S P; Martinez M; Spencer M; Trump J; Joner M D; Bugg A G; Hintz E G; Stephens D C; Arredondo A; Benzaid A; Yazdi S; McLeod K K; Jensen E L N; Hancock D A; Sorber R L; Kasper D H; Jang-Condell H; Beatty T G; Carroll T; Eastman J; James D; Kuhn R B; Labadie-Bartz J; Lund M B; Mallonn M; Pepper J; Siverd R J; Yao X; Cohen D H; Curtis I A; DePoy D L; Fulton B J; Penny M T; Relles H; Stockdale C; Tan T; Villanueva Jr S
In: arXiv:1712.03241 [astro-ph], 2017, (arXiv: 1712.03241).
We present the discovery of KELT-21b, a hot Jupiter transiting the $V=10.5$ A8V star HD 332124. The planet has an orbital period of $P=3.6127647textbackslashpm0.0000033$ days and a radius of $1.586_-0.040textasciicircum+0.039$ $R_J$. We set an upper limit on the planetary mass of $M_Ptextless3.91$ $M_J$ at $3textbackslashsigma$ confidence. We confirmed the planetary nature of the transiting companion using this mass limit and Doppler tomographic observations to verify that the companion transits HD 332124. These data also demonstrate that the planetary orbit is well-aligned with the stellar spin, with a sky-projected spin-orbit misalignment of $textbackslashlambda=-5.6_-1.9textasciicircum+1.7 textbackslashcirc$. The star has $T_textbackslashmathrmeff=7598_-84textasciicircum+81$ K, $M_*=1.458_-0.028textasciicircum+0.029$ $M_textbackslashodot$, $R_*=1.638textbackslashpm0.034$ $R_textbackslashodot$, and $vtextbackslashsin I_*=146$ km s$textasciicircum-1$, the highest projected rotation velocity of any star known to host a transiting hot Jupiter. The star also appears to be somewhat metal-poor and $textbackslashalpha$-enhanced, with [Fe/H]$=-0.405_-0.033textasciicircum+0.032$ and [$textbackslashalpha$/Fe]$=0.145 textbackslashpm 0.053$; these abundances are unusual, but not extraordinary, for a young star with thin-disk kinematics like KELT-21. High-resolution imaging observations revealed the presence of a pair of stellar companions to KELT-21, located at a separation of 1.2" and with a combined contrast of $textbackslashDelta K_S=6.39 textbackslashpm 0.06$ with respect to the primary. Although these companions are most likely physically associated with KELT-21, we cannot confirm this with our current data. If associated, the candidate companions KELT-21 B and C would each have masses of $textbackslashsim0.12$ $M_textbackslashodot$, a projected mutual separation of $textbackslashsim20$ AU, and a projected separation of $textbackslashsim500$ AU from KELT-21. KELT-21b may be one of only a handful of known transiting planets in hierarchical triple stellar systems.
Henning T; Mancini L; Sarkis P; Bakos G A; Hartman J D; Bayliss D; Bento J; Bhatti W; Brahm R; Ciceri S; Csubry Z; de Val-Borro M; Espinoza N; Fulton B J; Howard A W; Isaacson H T; Jordan A; Marcy G W; Penev K; Rabus M; Suc V; Tan T G; Tinney C G; Wright D J; Zhou G; Durkan S; Lazar J; Papp I; Sari P
In: arXiv:1712.04324 [astro-ph], 2017, (arXiv: 1712.04324).
We report the discovery of four close-in transiting exoplanets, HATS-50 through HATS-53, discovered using the HATSouth three-continent network of homogeneous and automated telescopes. These new exoplanets belong to the class of hot Jupiters and orbit G-type dwarf stars, with brightness in the range V=12.5-14.0 mag. While HATS-53 has many physical characteristics similar to the Sun, the other three stars appear to be metal rich, larger and more massive. Three of the new exoplanets, namely HATS-50, HATS-51 and HATS-53, have low density and similar orbital period. Instead, HATS-52 is more dense and has a shorter orbital period. It also receives an intensive radiation from its parent star and, consequently, presents a high equilibrium temperature. HATS-50 shows a marginal additional transit feature consistent with an ultra-short period hot super Neptune, which will be able to be confirmed with TESS photometry.
Messina S; Santallo R; Tan T G; Elliott P; Feiden G A; Buccino A; Mauas P; Petrucci R; Jofre' E
In: arXiv:1612.04597 [astro-ph], 2016, (arXiv: 1612.04597).
There are a variety of different techniques available to estimate the ages of pre-main-sequence stars. Components of physical pairs, thanks to their strict coevality and the mass difference, such as the binary system analysed in this paper, are best suited to test the effectiveness of these different techniques. We consider the system WW Psa + TX Psa whose membership of the 25-Myr beta Pictoris association has been well established by earlier works. We investigate which age dating technique provides the best agreement between the age of the system and that of the association. We have photometrically monitored WW Psa and TX Psa and measured their rotation periods as P = 2.37d and P = 1.086d, respectively. We have retrieved from the literature their Li equivalent widths and measured their effective temperatures and luminosities. We investigate whether the ages of these stars derived using three independent techniques are consistent with the age of the beta Pictoris association. We find that the rotation periods and the Li contents of both stars are consistent with the distribution of other bona fide members of the cluster. On the contrary, the isochronal fitting provides similar ages for both stars, but a factor of about four younger than the quoted age of the association, or about 30% younger when the effects of magnetic fields are included. We explore the origin of the discrepant age inferred from isochronal fitting, including the possibilities that either the two components may be unresolved binaries or that the basic stellar parameters of both components are altered by enhanced magnetic activity. The latter is found to be the more reasonable cause, suggesting that age estimates based on the Li content is more reliable than isochronal fitting for pre-main-sequence stars with pronounced magnetic activity.
Messina S; Millward M; Buccino A; Zhang L; Medhi B J; Jofre' E; Petrucci R; Pi Q; Hambsch F -J; Kehusmaa P; Harlingten C; Artemenko S; Curtis I; Hentunen V -P; Malo L; Mauas P; Monard B; Serrano M M; Naves R; Santallo R; Savuskin A; Tan T G
In: Astronomy & Astrophysics, 2016, ISSN: 0004-6361, 1432-0746, (arXiv: 1612.04591).
We intended to compile the most complete catalog of bona fide members and candidate members of the beta Pictoris association, and to measure their rotation periods and basic properties from our own observations, public archives, and exploring the literature. We carried out a multi-observatories campaign to get our own photometric time series and collected all archived public photometric data time series for the stars in our catalog. Each time series was analyzed with the Lomb-Scargle and CLEAN periodograms to search for the stellar rotation periods. We complemented the measured rotational properties with detailed information on multiplicity, membership, and projected rotational velocity available in the literature and discussed star by star. We measured the rotation periods of 112 out of 117 among bona fide members and candidate members of the beta Pictoris association and, whenever possible, we also measured the luminosity, radius, and inclination of the stellar rotation axis. This represents to date the largest catalog of rotation periods of any young loose stellar association. We provided an extensive catalog of rotation periods together with other relevant basic properties useful to explore a number of open issues, such as the causes of spread of rotation periods among coeval stars, evolution of angular momentum, and lithium-rotation connection.
Stevens D J; Collins K A; Gaudi B S; Beatty T G; Siverd R J; Bieryla A; Fulton B J; Crepp J R; Gonzales E J; Coker C T; Penev K; Stassun K G; Jensen E L N; Howard A W; Latham D W; Rodriguez J E; Zambelli R; Bozza V; Reed P A; Gregorio J; Buchhave L A; Penny M T; Pepper J; Berlind P; Novati S C; Calkins M L; D'Ago G; Eastman J D; Bayliss D; Colón K D; Curtis I A; DePoy D L; Esquerdo G A; Gould A; Joner M D; Kielkopf J F; Labadie-Bartz J; Lund M B; Manner M; Marshall J L; McLeod K K; Oberst T E; Pogge R W; Scarpetta G; Stephens D C; Stockdale C; Tan T G; Trueblood M; Trueblood P
In: arXiv:1608.04714 [astro-ph], 2016, (arXiv: 1608.04714).
We report the discovery of KELT-12b, a highly inflated Jupiter-mass planet transiting a mildly evolved host star. We identified the initial transit signal in the KELT-North survey data and established the planetary nature of the companion through precise follow-up photometry, high-resolution spectroscopy, precise radial velocity measurements, and high-resolution adaptive optics imaging. Our preferred best-fit model indicates that the $V = 10.64$ host, TYC 2619-1057-1, has $T_textbackslashrm eff = 6278 textbackslashpm 51$ K, $textbackslashlogg_textbackslashstar = 3.89textasciicircum+0.054_-0.051$, and [Fe/H] = $0.19textasciicircum+0.083_-0.085$, with an inferred mass $M_textbackslashstar = 1.59textasciicircum+0.071_-0.091 M_textbackslashodot$ and radius $R_textbackslashstar = 2.37 textbackslashpm 0.18 R_textbackslashodot$. The planetary companion has $M_textbackslashrm P = 0.95 textbackslashpm 0.14 M_textbackslashrm J$, $R_textbackslashrm P = 1.79textasciicircum+0.18_-0.17 R_textbackslashrm J$, $textbackslashlogg_textbackslashrm P = 2.87textasciicircum+0.097_-0.098$, and density $textbackslashrho_textbackslashrm P = 0.21textasciicircum+0.075_-0.054$ g cm$textasciicircum-3$, making it one of the most inflated giant planets known. The time of inferior conjunction in $textbackslashrm BJD_TDB$ is $2457088.692055 textbackslashpm 0.0009$ and the period is $P = 5.0316144 textbackslashpm 0.0000306$ days. Despite the relatively large separation of $textbackslashsim0.07$ AU implied by its $textbackslashsim 5.03$-day orbital period, KELT-12b receives significant flux of $2.93textasciicircum+0.33_-0.30 textbackslashtimes 10textasciicircum9$ erg s$textasciicircum-1$ cm$textasciicircum-2$ from its host. We compare the radii and insolations of transiting gas-giant planets around hot ($T_textbackslashrm eff textbackslashgeq 6250$ K) and cool stars, noting that the observed paucity of known transiting giants around hot stars with low insolation is likely due to selection effects. We underscore the significance of long-term ground-based monitoring of hot stars and space-based targeting of hot stars with the Transiting Exoplanet Survey Satellite (TESS) to search for inflated giants in longer-period orbits.
Zhou G; Rodriguez J E; Collins K A; Beatty T; Oberst T; Heintz T M; Stassun K G; Latham D W; Kuhn R B; Bieryla A; Lund M B; Labadie-Bartz J; Siverd R J; Stevens D J; Gaudi B S; Pepper J; Buchhave L A; Eastman J; Colón K; Cargile P; James D; Gregorio J; Reed P A; Jensen E L N; Cohen D H; McLeod K K; Tan T G; Zambelli R; Bayliss D; Bento J; Esquerdo G A; Berlind P; Calkins M L; Blancato K; Manner M; Samulski C; Stockdale C; Nelson P; Stephens D; Curtis I; Kielkopf J; Fulton B J; DePoy D L; Marshall J L; Pogge R; Gould A; Trueblood M; Trueblood P
In: The Astronomical Journal, vol. 152, no. 5, pp. 136, 2016, ISSN: 1538-3881, (arXiv: 1607.03512).
We present the discovery of a hot-Jupiter transiting the V=9.23 mag main-sequence A-star KELT-17 (BD+14 1881). KELT-17b is a 1.31 -0.29/+0.28 Mj, 1.525 -0.060/+0.065 Rj hot-Jupiter in a 3.08 day period orbit misaligned at -115.9 +/- 4.1 deg to the rotation axis of the star. The planet is confirmed via both the detection of the radial velocity orbit, and the Doppler tomographic detection of the shadow of the planet over two transits. The nature of the spin-orbit misaligned transit geometry allows us to place a constraint on the level of differential rotation in the host star; we find that KELT-17 is consistent with both rigid-body rotation and solar differential rotation rates (alpha textless 0.30 at 2 sigma significance). KELT-17 is only the fourth A-star with a confirmed transiting planet, and with a mass of 1.635 -0.061/+0.066 Msun, effective temperature of 7454 +/- 49 K, and projected rotational velocity v sin I_* = 44.2 -1.3/+1.5 km/s; it is amongst the most massive, hottest, and most rapidly rotating of known planet hosts.
Pepper J; Rodriguez J E; Collins K A; Johnson J A; Fulton B J; Howard A W; Beatty T; Stassun K G; Isaacson H; Colón K; Lund M B; Kuhn R B; Siverd R J; Gaudi B S; Tan T G; Curtis I; Stockdale C; Mawet D; Bottom M; James D; Zhou G; Bayliss D; Cargile P; Bieryla A; Penev K; Latham D W; Labadie-Bartz J; Kielkopf J; Eastman J D; Oberst T E; Jensen E L N; Nelson P; Sliski D H; Wittenmyer R A; McCrady N; Wright J T; Relles H M
In: arXiv:1607.01755 [astro-ph], 2016, (arXiv: 1607.01755).
We report the discovery of a transiting exoplanet, KELT-11b, orbiting the bright ($V=8.0$) subgiant HD 93396. A global analysis of the system shows that the host star is an evolved subgiant star with $T_textbackslashrm eff = 5370textbackslashpm51$ K, $M_* = 1.438_-0.052textasciicircum+0.061 M_textbackslashodot$, $R_* = 2.72_-0.17textasciicircum+0.21 R_textbackslashodot$, log $g_*= 3.727_-0.046textasciicircum+0.040$, and [Fe/H]$ = 0.180textbackslashpm0.075$. The planet is a low-mass gas giant in a $P = 4.736529textbackslashpm0.00006$ day orbit, with $M_P = 0.195textbackslashpm0.018 M_J$, $R_P= 1.37_-0.12textasciicircum+0.15 R_J$, $textbackslashrho_P = 0.093_-0.024textasciicircum+0.028$ g cm$textasciicircum-3$, surface gravity log $g_P = 2.407_-0.086textasciicircum+0.080$, and equilibrium temperature $T_eq = 1712_-46textasciicircum+51$ K. KELT-11 is the brightest known transiting exoplanet host in the southern hemisphere by more than a magnitude, and is the 6th brightest transit host to date. The planet is one of the most inflated planets known, with an exceptionally large atmospheric scale height (2763 km), and an associated size of the expected atmospheric transmission signal of 5.6%. These attributes make the KELT-11 system a valuable target for follow-up and atmospheric characterization, and it promises to become one of the benchmark systems for the study of inflated exoplanets.
Bhatti W; Bakos G Á; Hartman J D; Zhou G; Penev K; Bayliss D; Jordán A; Brahm R; Espinoza N; Rabus M; Mancini L; de Val-Borro M; Bento J; Ciceri S; Csubry Z; Henning T; Schmidt B; Arriagada P; Butler R P; Crane J; Shectman S; Thompson I; Tan T G; Suc V; Lázár J; Papp I; Sári P
In: arXiv:1607.00322 [astro-ph], 2016, (arXiv: 1607.00322).
We report the discovery by the HATSouth exoplanet survey of three hot-Saturn transiting exoplanets: HATS-19b, HATS-20b, and HATS-21b. The planet host HATS-19 is a slightly evolved V = 13.0 G0 star with [Fe/H] = 0.240, a mass of 1.303 Msun, and a radius of 1.75 Rsun. HATS-19b is in an eccentric orbit (e = 0.30) around this star with an orbital period of 4.5697 days and has a mass of 0.427 Mjup and a highly inflated radius of 1.66 Rjup. The planet HATS-20b has a Saturn-like mass and radius of 0.273 Mjup and 0.776 Rjup respectively. It orbits the V = 13.8 G9V star HATS-20 (Ms = 0.910 Msun; Rs = 0.892 Rsun) with a period of 3.7993 days. Finally, HATS-21 is a V = 12.2 G4V star with [Fe/H] = 0.300, a mass of 1.080 Msun, and a radius of 1.021 Rsun. Its accompanying planet HATS-21b has a 3.5544-day orbital period, a mass of 0.332 Mjup, and a moderately inflated radius of 1.123 Rjup. With the addition of these three very different planets to the growing sample of hot-Saturns, we re-examine the relations between the observed giant planet radii, stellar irradiation, and host metallicity. We find a significant positive correlation between planet equilibrium temperature and radius, and a weak negative correlation between host metallicity and radius. To assess the relative influence of various physical parameters on observed planet radii, we train and fit models using Random Forest regression. We find that for hot-Saturns (0.1 textless Mp textless 0.5 Mjup), the planetary mass and equilibrium temperature play dominant roles in determining radii. For hot-Jupiters (0.5 textless Mp textless 2.0 Mjup), the most important parameter is equilibrium temperature alone. Finally, for irradiated higher-mass planets (Mp textgreater 2.0 Mjup), we find that equilibrium temperature dominates in influence, with smaller contributions from planet mass and host metallicity.
de Val-Borro M; Bakos G Á; Brahm R; Hartman J D; Espinoza N; Penev K; Ciceri S; Jordán A; Bhatti W; Csubry Z; Bayliss D; Bento J; Zhou G; Rabus M; Mancini L; Henning T; Schmidt B; Tan T G; Tinney C G; Wright D J; Kedziora-Chudczer L; Bailey J; Suc V; Durkan S; Lázár J; Papp I; Sári P
In: The Astronomical Journal, vol. 152, no. 6, pp. 161, 2016, ISSN: 1538-3881, (arXiv: 1607.00006).
We report the discovery of five new transiting hot Jupiter planets discovered by the HATSouth survey: HATS-31b through HATS-35b. These planets orbit moderately bright stars with V magnitudes within the range 11.9-14.4mag while the planets span a range of masses 0.88-1.22MJ, and have somewhat inflated radii between 1.23-1.64RJ.These planets can be classified as typical hot Jupiters, with HATS-31b and HATS-35b being moderately inflated gas giant planets with radii of $1.64 textbackslashpm 0.22$ RJ and 1.464+0.069-0.044RJ, respectively, that can be used to constrain inflation mechanisms. All five systems present a higher Bayesian evidence for a fixed circular orbit model than for an eccentric orbit. The orbital periods range from $1.8209993 textbackslashpm 0.0000016$ day for HATS-35b) to $3.377960 textbackslashpm 0.000012$ day for HATS-31b. Additionally, HATS-35b orbits a relatively young F star with an age of $2.13 textbackslashpm 0.51$ Gyr. We discuss the analysis to derive the properties of these systems and compare them in the context of the sample of well characterized transiting hot Jupiters known to date.
Shvartzvald Y; Li Z; Udalski A; Gould A; Sumi T; Street R A; Novati S C; Hundertmark M; Bozza V; Beichman C; Bryden G; Carey S; Drummond J; Fausnaugh M; Gaudi B S; Henderson C B; Tan T G; Wibking B; Pogge R W; Yee J C; Zhu W; Tsapras Y; Bachelet E; Dominik M; Bramich D M; Cassan A; Jaimes R F; Horne K; Ranc C; Schmidt R; Snodgrass C; Wambsganss J; Steele I A; Menzies J; Mao S; Poleski R; Pawlak M; Szymański M K; Skowron J; Mróz P; Kozłowski S; Wyrzykowski Ł; Pietrukowicz P; Soszyński I; Ulaczyk K; Abe F; Asakura Y; Barry R K; Bennett D P; Bhattacharya A; Bond I A; Freeman M; Hirao Y; Itow Y; Koshimoto N; Li M C A; Ling C H; Masuda K; Fukui A; Matsubara Y; Muraki Y; Nagakane M; Nishioka T; Ohnishi K; Oyokawa H; Rattenbury N J; Saito T; Sharan A; Sullivan D J; Suzuki D; Tristram P J; Yonehara A; Jørgensen U G; Burgdorf M J; Ciceri S; D'Ago G; Evans D F; Hinse T C; Kains N; Kerins E; Korhonen H; Mancini L; Popovas A; Rabus M; Rahvar S; Scarpetta G; Skottfelt J; Southworth J; Peixinho N; Verma P; Sbarufatti B; Kennea J A; Gehrels N
In: The Astrophysical Journal, vol. 831, no. 2, pp. 183, 2016, ISSN: 1538-4357, (arXiv: 1606.02292).
Simultaneous observations of microlensing events from multiple locations allow for the breaking of degeneracies between the physical properties of the lensing system, specifically by exploring different regions of the lens plane and by directly measuring the "microlens parallax". We report the discovery of a 30-55$M_J$ brown dwarf orbiting a K dwarf in microlensing event OGLE-2015-BLG-1319. The system is located at a distance of $textbackslashsim$5 kpc toward the Galactic bulge. The event was observed by several ground-based groups as well as by $Spitzer$ and $Swift$, allowing the measurement of the physical properties. However, the event is still subject to an 8-fold degeneracy, in particular the well-known close-wide degeneracy, and thus the projected separation between the two lens components is either $textbackslashsim$0.25 AU or $textbackslashsim$45 AU. This is the first microlensing event observed by $Swift$, with the UVOT camera. We study the region of microlensing parameter space to which $Swift$ is sensitive, finding that while for this event $Swift$ could not measure the microlens parallax with respect to ground-based observations, it can be important for other events. Specifically, for detecting nearby brown dwarfs and free-floating planets in high magnification events.
Espinoza N; Bayliss D; Hartman J D; Bakos G Á; Jordán A; Zhou G; Mancini L; Brahm R; Ciceri S; Bhatti W; Csubry Z; Rabus M; Penev K; Bento J; de Val-Borro M; Henning T; Schmidt B; Suc V; Wright D J; Tinney C G; Tan T G; Noyes R
In: The Astronomical Journal, vol. 152, no. 4, pp. 108, 2016, ISSN: 1538-3881, (arXiv: 1606.00023).
We report six new inflated hot Jupiters (HATS-25b through HATS-30b) discovered using the HATSouth global network of automated telescopes. The planets orbit stars with $V$ magnitudes in the range $textbackslashsim 12-14$ and have masses in the largely populated $0.5M_J-0.7M_J$ region of parameter space but span a wide variety of radii, from $1.17R_J$ to $1.75 R_J$. HATS-25b, HATS-28b, HATS-29b and HATS-30b are typical inflated hot Jupiters ($R_p = 1.17-1.26R_J$) orbiting G-type stars in short period ($P=3.2-4.6$ days) orbits. However, HATS-26b ($R_p = 1.75R_J$, $P = 3.3024$ days) and HATS-27b ($R_p=1.50R_J$, $P=4.6370$ days) stand out as highly inflated planets orbiting slightly evolved F stars just after and in the turn-off points, respectively, which are among the least dense hot Jupiters, with densities of $0.153$ g cm$textasciicircum-3$ and $0.180$ g cm$textasciicircum-3$, respectively. All the presented exoplanets but HATS-27b are good targets for future atmospheric characterization studies, while HATS-27b is a prime target for Rossiter-McLaughlin monitoring in order to determine its spin-orbit alignment given the brightness ($V = 12.8$) and stellar rotational velocity ($v textbackslashsin i textbackslashapprox 9.3$ km/s) of the host star. These discoveries significantly increase the number of inflated hot Jupiters known, contributing to our understanding of the mechanism(s) responsible for hot Jupiter inflation.
Zhou G; Kedziora-Chudczer L; Bailey J; Marshall J P; Bayliss D D R; Stockade C; Nelson P; Tan T G; Rodriguez J E; Tinney C G; Dragomir D; Colon K; Shporer A; Bento J; Sefako R; Horne K; Cochran W
In: Monthly Notices of the Royal Astronomical Society, vol. 463, no. 4, pp. 4422–4432, 2016, ISSN: 0035-8711, 1365-2966, (arXiv: 1604.07405).
We present multi-wavelength photometric monitoring of WD 1145+017, a white dwarf exhibiting periodic dimming events interpreted to be the transits of orbiting, disintegrating planetesimals. Our observations include the first set of near-infrared light curves for the object, obtained on multiple nights over the span of one month, and recorded multiple transit events with depths varying between textasciitilde20 to 50 per cent. Simultaneous near-infrared and optical observations of the deepest and longest duration transit event were obtained on two epochs with the Anglo-Australian Telescope and three optical facilities, over the wavelength range of 0.5 to 1.2 microns. These observations revealed no measurable difference in transit depths for multiple photometric pass bands, allowing us to place a 2 sigma lower limit of 0.8 microns on the grain size in the putative transiting debris cloud. This conclusion is consistent with the spectral energy distribution of the system, which can be fit with an optically thin debris disc with minimum particle sizes of 10 +5/-3 microns.
Rabus M; Jordán A; Hartman J D; Bakos G Á; Espinoza N; Brahm R; Penev K; Ciceri S; Zhou G; Bayliss D; Mancini L; Bhatti W; de Val-Borro M; Csbury Z; Sato B; Tan T -G; Henning T; Schmidt B; Bento J; Suc V; Noyes R; Lázár J; Papp I; Sári P
In: The Astronomical Journal, vol. 152, no. 4, pp. 88, 2016, ISSN: 1538-3881, (arXiv: 1603.02894).
We report the discovery of two transiting extrasolar planets from the HATSouth survey. HATS-11, a V=14.1 G0-star shows a periodic 12.9 mmag dip in its light curve every 3.6192 days and a radial velocity variation consistent with a Keplerian orbit. HATS-11 has a mass of 1.000 $textbackslashpm$ 0.060 M$_textbackslashodot$, a radius of 1.444 $textbackslashpm$ 0.057 M$_textbackslashodot$ and an effective temperature of 6060 $textbackslashpm$ 150 K, while its companion is a 0.85 $textbackslashpm$ 0.12 M$_J$, 1.510 $textbackslashpm$ 0.078 R$_J$ planet in a circular orbit. HATS-12 shows a periodic 5.1 mmag flux decrease every 3.1428 days and Keplerian RV variations around a V=12.8 F-star. HATS-12 has a mass of 1.489 $textbackslashpm$ 0.071 M$_textbackslashodot$, a radius of 2.21 $textbackslashpm$ 0.21 R$_textbackslashodot$, and an effective temperature of 6408 $textbackslashpm$ 75 K. For HATS-12, our measurements indicate that this is a 2.38 $textbackslashpm$ 0.11 M$_J$, 1.35 $textbackslashpm$ 0.17 R$_J$ planet in a circular orbit. Both host stars show sub-solar metallicity of -0.390 $textbackslashpm$ 0.060 dex and -0.100 $textbackslashpm$ 0.040 dex, respectively and are (slightly) evolved stars. In fact, HATS-11 is amongst the most metal-poor and, HATS-12 is amongst the most evolved stars hosting a hot Jupiter planet. Importantly, HATS-11 and HATS-12 have been observed in long cadence by Kepler as part of K2 campaign 7 (EPIC216414930 and EPIC218131080 respectively).
Poleski R; Zhu W; Christie G W; Udalski A; Gould A; Bachelet E; Skottfelt J; Novati S C; Szymański M K; Soszyński I; Pietrzyński G; Wyrzykowski Ł; Ulaczyk K; Pietrukowicz P; Kozłowski S; Skowron J; Mróz P; Pawlak M; Beichman C; Bryden G; Carey S; Fausnaugh M; Gaudi B S; Henderson C B; Pogge R W; Shvartzvald Y; Wibking B; Yee J C; Beatty T G; Eastman J D; Drummond J; Friedmann M; Henderson M; Johnson J A; Kaspi S; Maoz D; McCormick J; McCrady N; Natusch T; Ngan H; Porritt I; Relles H M; Sliski D H; Tan T -G; Wittenmyer R A; Wright J T; Street R A; Tsapras Y; Bramich D M; Horne K; Snodgrass C; Steele I A; Menzies J; Jaimes R F; Wambsganss J; Schmidt R; Cassan A; Ranc C; Mao S; Bozza V; Dominik M; Hundertmark M P G; Jørgensen U G; Andersen M I; Burgdorf M J; Ciceri S; D'Ago G; Evans D F; Gu S -H; Hinse T C; Kains N; Kerins E; Korhonen H; Kuffmeier M; Mancini L; Popovas A; Rabus M; Rahvar S; Rasmussen R T; Southworth G S J; Surdej J; Unda-Sanzana E; Verma P; von Essen C; Wang Y -B; Wertz O
In: The Astrophysical Journal, vol. 823, no. 1, pp. 63, 2016, ISSN: 1538-4357, (arXiv: 1512.08520).
The microlensing event OGLE-2015-BLG-0448 was observed by Spitzer and lay within the tidal radius of the globular cluster NGC 6558. The event had moderate magnification and was intensively observed, hence it had the potential to probe the distribution of planets in globular clusters. We measure the proper motion of NGC 6558 ($textbackslashmu_textbackslashrm cl$(N,E) = (+0.36+-0.10, +1.42+-0.10) mas/yr) as well as the source and show that the lens is not a cluster member. Even though this particular event does not probe the distribution of planets in globular clusters, other potential cluster lens events can be verified using our methodology. Additionally, we find that microlens parallax measured using OGLE photometry is consistent with the value found based on the light curve displacement between Earth and Spitzer.
Ciceri S; Mancini L; Henning T; Bakos G Á; Penev K; Brahm R; Zhou G; Hartman J D; Bayliss D; Jordán A; Csubry Z; de Val-Borro M; Bhatti W; Rabus M; Espinoza N; Suc V; Schmidt B; Noyes R; Howard A W; Fulton B J; Isaacson H; Marcy G W; Butler R P; Arriagada P; Crane J; Shectman S; Thompson I; Tan T G; Lázár J; Papp I; Sari P
In: Publications of the Astronomical Society of the Pacific, vol. 128, no. 965, pp. 074401, 2016, ISSN: 0004-6280, 1538-3873, (arXiv: 1511.06305).
We report the discovery of HATS-15 b and HATS-16 b, two massive transiting extrasolar planets orbiting evolved ($textbackslashsim 10$ Gyr) main-sequence stars. The planet HATS-15 b, which is hosted by a G9V star ($V=14.8$ mag), is a hot Jupiter with mass of $2.17textbackslashpm0.15textbackslash, M_textbackslashmathrmJ$ and radius of $1.105textbackslashpm0.0.040textbackslash, R_textbackslashmathrmJ$, and completes its orbit in nearly 1.7 days. HATS-16 b is a very massive hot Jupiter with mass of $3.27textbackslashpm0.19textbackslash, M_textbackslashmathrmJ$ and radius of $1.30textbackslashpm0.15textbackslash, R_textbackslashmathrmJ$; it orbits around its G3 V parent star ($V=13.8$ mag) in $textbackslashsim2.7$ days. HATS-16 is slightly active and shows a periodic photometric modulation, implying a rotational period of 12 days which is unexpectedly short given its isochronal age. This fast rotation might be the result of the tidal interaction between the star and its planet.
Brahm R; Jordán A; Bakos G Á; Penev K; Espinoza N; Rabus M; Hartman J D; Bayliss D; Ciceri S; Zhou G; Mancini L; Tan T G; de Val-Borro M; Bhatti W; Csubry Z; Bento J; Henning T; Schmidt B; Suc V; Lázár J; Papp I; Sári P
In: The Astronomical Journal, vol. 151, no. 4, pp. 89, 2016, ISSN: 1538-3881, (arXiv: 1510.05758).
We report the discovery of HATS-17b, the first transiting warm Jupiter of the HATSouth network. HATS-17b transits its bright (V=12.4) G-type (M$_textbackslashstar$=1.131 $textbackslashpm$ 0.030 M$_textbackslashodot$, R$_textbackslashstar$=1.091$textasciicircum+0.070_-0.046$ R$_textbackslashstar$) metal-rich ([Fe/H]=+0.3 dex) host star in a circular orbit with a period of P=16.2546 days. HATS-17b has a very compact radius of 0.777 $textbackslashpm$ 0.056 R$_J$ given its Jupiter-like mass of 1.338 $textbackslashpm$ 0.065 M$_J$. Up to 50% of the mass of HATS-17b may be composed of heavy elements in order to explain its high density with current models of planetary structure. HATS-17b is the longest period transiting planet discovered to date by a ground-based photometric survey, and is one of the brightest transiting warm Jupiter systems known. The brightness of HATS-17b will allow detailed follow-up observations to characterize the orbital geometry of the system and the atmosphere of the planet.
Rodriguez J E; Colon K D; Stassun K G; Wright D; Cargile P A; Bayliss D; Pepper J; Collins K A; Kuhn R B; Lund M B; Siverd R J; Zhou G; Gaudi B S; Tinney C G; Penev K; Tan T G; Stockdale C; Curtis I A; James D; Udry S; Segransan D; Bieryla A; Latham D W; Beatty T G; Eastman J D; Myers G; Bartz J; Bento J; Jensen E L N; Oberst T E; Stevens D J
In: The Astronomical Journal, vol. 151, no. 6, pp. 138, 2016, ISSN: 1538-3881, (arXiv: 1509.08953).
We report the discovery of KELT-14b and KELT-15b, two hot Jupiters from the KELT-South survey. KELT-14b, an independent discovery of the recently announced WASP-122b, is an inflated Jupiter mass planet that orbits a $textbackslashsim5.0textasciicircum+0.3_-0.7$ Gyr, $V$ = 11.0, G2 star that is near the main sequence turnoff. The host star, KELT-14 (TYC 7638-981-1), has an inferred mass $M_*$=$1.18_-0.07textasciicircum+0.05$$M_textbackslashodot$ and radius $R_*$=$1.37textbackslashpm-0.08$$R_textbackslashodot$, and has $T_eff$=$5802_-92textasciicircum+95$K, $textbackslashlogg_*$=$4.23_-0.04textasciicircum+0.05$ and =$0.33textbackslashpm0.09$. The planet orbits with a period of $1.7100588 textbackslashpm 0.0000025$ days ($T_0$=2457091.02863$textbackslashpm$0.00047) and has a radius R$_p$=$1.52_-0.11textasciicircum+0.12$$R_J$ and mass M$_p$=$1.196textbackslashpm0.072$$M_J$, and the eccentricity is consistent with zero. KELT-15b is another inflated Jupiter mass planet that orbits a $textbackslashsim$ $4.6textasciicircum+0.5_-0.4$ Gyr, $V$ = 11.2, G0 star (TYC 8146-86-1) that is near the "blue hook" stage of evolution prior to the Hertzsprung gap, and has an inferred mass $M_*$=$1.181_-0.050textasciicircum+0.051$$M_textbackslashodot$ and radius $R_*$=$1.48_-0.04textasciicircum+0.09$$R_textbackslashodot$, and $T_eff$=$6003_-52textasciicircum+56$K, $textbackslashlogg_*$=$4.17_-0.04textasciicircum+0.02$ and [Fe/H]=$0.05textbackslashpm0.03$. The planet orbits on a period of $3.329441 textbackslashpm 0.000016$ days ($T_0$ = 2457029.1663$textbackslashpm$0.0073) and has a radius R$_p$=$1.443_-0.057textasciicircum+0.11$$R_J$ and mass M$_p$=$0.91_-0.22textasciicircum+0.21$$M_J$ and an eccentricity consistent with zero. KELT-14b has the second largest expected emission signal in the K-band for known transiting planets brighter than $Ktextless10.5$. Both KELT-14b and KELT-15b are predicted to have large enough emission signals that their secondary eclipses should be detectable using ground-based observatories.
Kuhn R B; Rodriguez J E; Collins K A; Lund M B; Siverd R J; Colón K D; Pepper J; Stassun K G; Cargile P A; James D J; Penev K; Zhou G; Bayliss D; Tan T G; Curtis I A; Udry S; Segransan D; Mawet D; Soutter J; Hart R; Carter B; Gaudi B S; Myers G; Beatty T G; Eastman J D; Reichart D E; Haislip J B; Kielkopf J; Bieryla A; Latham D W; Jensen E L N; Oberst T E; Stevens D J
In: Monthly Notices of the Royal Astronomical Society, vol. 459, no. 4, pp. 4281–4298, 2016, ISSN: 0035-8711, 1365-2966, (arXiv: 1509.02323).
We report the discovery of KELT-10b, the first transiting exoplanet discovered using the KELT-South telescope. KELT-10b is a highly inflated sub-Jupiter mass planet transiting a relatively bright $V = 10.7$ star (TYC 8378-64-1), with T$_eff$ = $5948textbackslashpm74$ K, $textbackslashlogg$ = $4.319_-0.030textasciicircum+0.020$ and [Fe/H] = $0.09_-0.10textasciicircum+0.11$, an inferred mass M$_*$ = $1.112_-0.061textasciicircum+0.055$ M$_textbackslashodot$ and radius R$_*$ = $1.209_-0.035textasciicircum+0.047$ R$_textbackslashodot$. The planet has a radius R$_P$ = $1.399_-0.049textasciicircum+0.069$ R$_J$ and mass M$_P$ = $0.679_-0.038textasciicircum+0.039$ M$_J$. The planet has an eccentricity consistent with zero and a semi-major axis $a$ = $0.05250_-0.00097textasciicircum+0.00086$ AU. The best fitting linear ephemeris is $T_0$ = 2457066.72045$textbackslashpm$0.00027 BJD$_TDB$ and P = 4.1662739$textbackslashpm$0.0000063 days. This planet joins a group of highly inflated transiting exoplanets with a radius much larger and a mass much less than those of Jupiter. The planet, which boasts deep transits of 1.4%, has a relatively high equilibrium temperature of T$_eq$ = $1377_-23textasciicircum+28$ K, assuming zero albedo and perfect heat redistribution. KELT-10b receives an estimated insolation of $0.817_-0.054textasciicircum+0.068$ $textbackslashtimes$ 10$textasciicircum9$ erg s$textasciicircum-1$ cm$textasciicircum-2$, which places it far above the insolation threshold above which hot Jupiters exhibit increasing amounts of radius inflation. Evolutionary analysis of the host star suggests that KELT-10b is unlikely to survive beyond the current subgiant phase, due to a concomitant in-spiral of the planet over the next $textbackslashsim$1 Gyr. The planet transits a relatively bright star and exhibits the third largest transit depth of all transiting exoplanets with V $textless$ 11 in the southern hemisphere, making it a promising candidate for future atmospheric characterization studies.
Fukui A; Gould A; Sumi T; Bennett D P; Bond I A; Han C; Suzuki D; Beaulieu J -P; Batista V; Udalski A; Street R A; Tsapras Y; Hundertmark M; Abe F; Bhattacharya A; Freeman M; Itow Y; Ling C H; Koshimoto N; Masuda K; Matsubara Y; Muraki Y; Ohnishi K; Philpott L C; Rattenbury N; Saito T; Sullivan D J; Tristram P J; Yonehara A; Choi J -Y; Christie G W; DePoy D L; Dong S; Drummond J; Gaudi B S; Hwang K -H; Kavka A; Lee C U; McCormick J; Natusch T; Ngan H; Park H; Pogge R W; Shin I -G; Tan T -G; Yee J C; Szymański M K; Pietrzyński G; Soszyński I; Poleski R; Kozłowski S; Pietrukowicz P; Ulaczyk K; Bramich Ł W D M; Browne P; Dominik M; Horne K; Ipatov S; Kains N; Snodgrass C; Steele I A
In: The Astrophysical Journal, vol. 809, no. 1, pp. 74, 2015, ISSN: 1538-4357, (arXiv: 1506.08850).
We report the discovery of a microlensing exoplanet OGLE-2012-BLG-0563Lb with the planet-star mass ratio textasciitilde1 x 10textasciicircum-3. Intensive photometric observations of a high-magnification microlensing event allow us to detect a clear signal of the planet. Although no parallax signal is detected in the light curve, we instead succeed at detecting the flux from the host star in high-resolution JHK'-band images obtained by the Subaru/AO188 and IRCS instruments, allowing us to constrain the absolute physical parameters of the planetary system. With the help of a spectroscopic information about the source star obtained during the high-magnification state by Bensby et al., we find that the lens system is located at 1.3textasciicircum+0.6_-0.8 kpc from us, and consists of an M dwarf (0.34textasciicircum+0.12_-0.20 M_sun) orbited by a Saturn-mass planet (0.39textasciicircum+0.14_-0.23 M_Jup) at the projected separation of 0.74textasciicircum+0.26_-0.42 AU (close model) or 4.3textasciicircum+1.5_-2.5 AU (wide model). The probability of contamination in the host star's flux, which would reduce the masses by a factor of up to three, is estimated to be 17%. This possibility can be tested by future high-resolution imaging. We also estimate the (J-Ks) and (H-Ks) colors of the host star, which are marginally consistent with a low metallicity mid-to-early M dwarf, although further observations are required for the metallicity to be conclusive. This is the fifth sub-Jupiter-mass (0.2textlessm_p/M_Juptextless1) microlensing planet around an M dwarf with the mass well constrained. The relatively rich harvest of sub-Jupiters around M dwarfs is contrasted with a possible paucity of textasciitilde1--2 Jupiter-mass planets around the same type of star, which can be explained by the planetary formation process in the core-accretion scheme.
Reddy V; Vokrouhlický D; Bottke W F; Pravec P; Sanchez J A; Gary B L; Klima R; Cloutis E A; Galád A; Guan T T; Hornoch K; Izawa M R M; Kušnirák P; Corre L L; Mann P; Moskovitz N; Skiff B; Vraštil J
In: Icarus, vol. 252, pp. 129–143, 2015, ISSN: 00191035, (arXiv: 1502.05006).
We explored the statistical and compositional link between Chelyabinsk meteoroid and potentially hazardous asteroid (86039) 1999 NC43 to investigate their proposed relation proposed by Borovitextbackslashčka et al. (2013). Using detailed computation we confirm that the orbit of the Chelyabinsk impactor is anomalously close to 1999 NC43. We find about (1-3) x 10-4 likelihood of that to happen by chance. Taking the standpoint that the Chelyabinsk impactor indeed separated from 1999 NC43 by a cratering or rotational fission event, we run a forward probability calculation, which is an independent statistical test. However, we find this scenario is unlikely at the about (10-3 -10-2) level. We also verified compositional link between Chelyabinska and 1999NC43. Mineralogical analysis of Chelyabinsk (LL chondrite) and (8) Flora (the largest member of the presumed LL chondrite parent family) shows that their olivine and pyroxene chemistries are similar to LL chondrites. Similar analysis of 1999 NC43 shows that its olivine and pyroxene chemistries are more similar to L chondrites than LL chondrites (like Chelyabinsk). We also took photometric observations of 1999 NC43 over 54 nights during two apparitions (2000, 2014). The lightcurve of 1999 NC43 resembles simulated lightcurves of tumblers in Short-Axis Mode with the mean wobbling angle 20-30 deg. While, a mechanism of the non-principal axis rotation excitation is unclear, we can rule out the formation of asteroid in disruption of its parent body as a plausible cause, as it is unlikely that the rotation of an asteroid fragment from catastrophic disruption would be nearly completely halted. Considering all these facts, we find the proposed link between the Chelyabinsk meteoroid and the asteroid 1999 NC43 to be unlikely.
Mancini L; Hartman J D; Penev K; Bakos G A; Brahm R; Ciceri S; Henning T; Csubry Z; Bayliss D; Zhou G; Rabus M; de Val-Borro M; Espinoza N; Jordan A; Suc V; Bhatti W; Schmidt B; Sato B; Tan T G; Wright D J; Tinney C G; Addison B C; Noyes R W; Lazar J; Papp I; Sari P
In: Astronomy & Astrophysics, vol. 580, pp. A63, 2015, ISSN: 0004-6361, 1432-0746, (arXiv: 1503.03469).
We report the discovery of HATS-13b and HATS-14b, two hot-Jupiter transiting planets discovered by the HATSouth survey. The host stars are quite similar to each other (HATS-13: V = 13.9 mag, M* = 0.96 Msun, R* = 0.89 Rsun
Brahm R; Jordán A; Hartman J D; Bakos G Á; Bayliss D; Penev K; Zhou G; Ciceri S; Rabus M; Espinoza N; Mancini L; de Val-Borro M; Bhatti W; Sato B; Tan T G; Csubry Z; Buchhave L; Henning T; Schmidt B; Suc V; Noyes R W; Papp I; Lázár J; Sári P
In: The Astronomical Journal, vol. 150, no. 1, pp. 33, 2015, ISSN: 1538-3881, (arXiv: 1503.00062).
We report the discovery of two transiting extrasolar planets by the HATSouth survey. HATS-9b orbits an old (10.8 $textbackslashpm$ 1.5 Gyr) V=13.3 G dwarf star, with a period P = 1.9153 d. The host star has a mass of 1.03 M$_textbackslashodot$, radius of 1.503 R$_textbackslashodot$ and effective temperature 5366 $textbackslashpm$ 70 K. The planetary companion has a mass of 0.837 M$_J$, and radius of 1.065 R$_J$ yielding a mean density of 0.85 g cm$textasciicircum-3$ . HATS-10b orbits a V=13.1 G dwarf star, with a period P = 3.3128 d. The host star has a mass of 1.1 M$_textbackslashodot$, radius of 1.11 R$_textbackslashodot$ and effective temperature 5880 $textbackslashpm$ 120 K. The planetary companion has a mass of 0.53 M$_J$, and radius of 0.97 R$_J$ yielding a mean density of 0.7 g cm$textasciicircum-3$ . Both planets are compact in comparison with planets receiving similar irradiation from their host stars, and lie in the nominal coordinates of Field 7 of K2 but only HATS-9b falls on working silicon. Future characterisation of HATS-9b with the exquisite photometric precision of the Kepler telescope may provide measurements of its reflected light signature.
Freeman M; Philpott L C; Abe F; Albrow M D; Bennett D P; Bond I A; Botzler C S; Bray J C; Cherrie J M; Christie G W; Dionnet Z; Gould A; Han C; Heyrovsky D; McCormick J M; Moorhouse D M; Muraki Y; Natusch T; Rattenbury N J; Skowron J; Sumi T; Suzuki D; Tan T -G; Tristram P J; Yock P C M
In: The Astrophysical Journal, vol. 799, no. 2, pp. 181, 2015, ISSN: 1538-4357, (arXiv: 1412.1546).
Recently Sumi et al. (2011) reported evidence for a large population of planetary-mass objects (PMOs) that are either unbound or orbit host stars in orbits textgreater 10 AU. Their result was deduced from the statistical distribution of durations of gravitational microlensing events observed by the MOA collaboration during 2006 and 2007. Here we study the feasibility of measuring the mass of an individual PMO through microlensing by examining a particular event, MOA-2011-BLG-274. This event was unusual as the duration was short, the magnification high, the source-size effect large and the angular Einstein radius small. Also, it was intensively monitored from widely separated locations under clear skies at low air masses. Choi et al. (2012) concluded that the lens of the event may have been a PMO but they did not attempt a measurement of its mass. We report here a re-analysis of the event using re-reduced data. We confirm the results of Choi et al. and attempt a measurement of the mass and distance of the lens using the terrestrial parallax effect. Evidence for terrestrial parallax is found at a 3 sigma level of confidence. The best fit to the data yields the mass and distance of the lens as 0.80 +/- 0.30 M_J and 0.80 +/- 0.25 kpc respectively. We exclude a host star to the lens out to a separation textasciitilde 40 AU. Drawing on our analysis of MOA-2011-BLG-274 we propose observational strategies for future microlensing surveys to yield sharper results on PMOs including those down to super-Earth mass.
Hartman J D; Bayliss D; Brahm R; Bakos G Á; Mancini L; Jordán A; Penev K; Rabus M; Zhou G; Butler R P; Espinoza N; de Val-Borro M; Bhatti W; Csubry Z; Ciceri S; Henning T; Schmidt B; Arriagada P; Shectman S; Crane J; Thompson I; Suc V; Csák B; Tan T G; Noyes R W; Lázár J; Papp I; Sári P
In: The Astronomical Journal, vol. 149, no. 5, pp. 166, 2015, ISSN: 1538-3881, (arXiv: 1408.1758).
We report the discovery by the HATSouth survey of HATS-6b, an extrasolar planet transiting a V=15.2 mag
Gould A; Udalski A; Shin I -G; Porritt I; Skowron J; Han C; Yee J C; Kozłowski S; Choi J -Y; Poleski R; Wyrzykowski Ł; Ulaczyk K; Pietrukowicz P; Mróz P; Szymański M K; Kubiak M; Soszyński I; Pietrzyński G; Gaudi B S; Christie G W; Drummond J; McCormick J; Natusch T; Ngan H; Tan T -G; Albrow M; DePoy D L; Hwang K -H; Jung Y K; Lee C -U; Park H; Pogge R W; Abe F; Bennett D P; Bond I A; Botzler C S; Freeman M; Fukui A; Fukunaga D; Itow Y; Koshimoto N; Larsen P; Ling C H; Masuda K; Matsubara Y; Muraki Y; Namba S; Ohnishi K; Philpott L; Rattenbury N J; Saito T; Sullivan D J; Sumi T; Suzuki D; Tristram P J; Tsurumi N; Wada K; Yamai N; Yock P C M; Yonehara A; Shvartzvald Y; Maoz D; Kaspi S; Friedmann M
In: Science, vol. 345, no. 6192, pp. 46–49, 2014, ISSN: 0036-8075, 1095-9203, (arXiv: 1407.1115).
We detect a cold, terrestrial planet in a binary-star system using gravitational microlensing. The planet has low mass (2 Earth masses) and lies projected at $a_textbackslashperp,ph$ textasciitilde 0.8 astronomical units (AU) from its host star, similar to the Earth-Sun distance. However, the planet temperature is much lower, Ttextless60 Kelvin, because the host star is only 0.10--0.15 solar masses and therefore more than 400 times less luminous than the Sun. The host is itself orbiting a slightly more massive companion with projected separation $a_textbackslashperp,ch=$10--15 AU. Straightforward modification of current microlensing search strategies could increase their sensitivity to planets in binary systems. With more detections, such binary-star/planetary systems could place constraints on models of planet formation and evolution. This detection is consistent with such systems being very common.
Henderson C B; Park H; Sumi T; Udalski A; Gould A; Tsapras Y; Han C; Gaudi B S; Bozza V; Abe F; Bennett D P; Bond I A; Botzler C S; Freeman M; Fukui A; Fukunaga D; Itow Y; Koshimoto N; Ling C H; Masuda K; Matsubara Y; Muraki Y; Namba S; Ohnishi K; Rattenbury N J; Saito T; Sullivan D J; Suzuki D; Sweatman W L; Tristram P J; Tsurumi N; Wada K; Yamai N; Yock P C M; Yonehara A; Szymański M K; Kubiak M; Pietrzyński G; Soszyński I; Skowron J; Kozłowski S; Poleski R; Ulaczyk K; Wyrzykowski Ł; Pietrukowicz P; Almeida L A; Bos M; Choi J -Y; Christie G W; Depoy D L; Dong S; Friedmann M; Hwang K -H; Jablonski F; Jung Y K; Kaspi S; Lee C -U; Maoz D; McCormick J; Moorhouse D; Natusch T; Ngan H; Pogge R W; Shin I -G; Shvartzvald Y; Tan T -G; Thornley G; Yee J C; Allan A; Bramich D M; Browne P; Dominik M; Horne K; Hundertmark M; Jaimes R F; Kains N; Snodgrass C; Steele I A; Street R A
In: The Astrophysical Journal, vol. 794, no. 1, pp. 71, 2014, ISSN: 1538-4357, (arXiv: 1403.3092).
The mass of the lenses giving rise to Galactic microlensing events can be constrained by measuring the relative lens-source proper motion and lens flux. The flux of the lens can be separated from that of the source, companions to the source, and unrelated nearby stars with high-resolution images taken when the lens and source are spatially resolved. For typical ground-based adaptive optics (AO) or space-based observations, this requires either inordinately long time baselines or high relative proper motions. We provide a list of microlensing events toward the Galactic Bulge with high relative lens-source proper motion that are therefore good candidates for constraining the lens mass with future high-resolution imaging. We investigate all events from 2004 -- 2013 that display detectable finite-source effects, a feature that allows us to measure the proper motion. In total, we present 20 events with mu textgreatertextasciitilde 8 mas/yr. Of these, 14 were culled from previous analyses while 6 are new, including OGLE-2004-BLG-368, MOA-2005-BLG-36, OGLE-2012-BLG-0211, OGLE-2012-BLG-0456, MOA-2012-BLG-532, and MOA-2013-BLG-029. In textlesstextasciitilde12 years the lens and source of each event will be sufficiently separated for ground-based telescopes with AO systems or space telescopes to resolve each component and further characterize the lens system. Furthermore, for the most recent events, comparison of the lens flux estimates from images taken immediately to those estimated from images taken when the lens and source are resolved can be used to empirically check the robustness of the single-epoch method currently being used to estimate lens masses for many events.
Yee J C; Han C; Gould A; Skowron J; Bond I A; Udalski A; Hundertmark M; Monard L A G; Porritt I; Nelson P; Bozza V; Albrow M D; Choi J -Y; Christie G W; DePoy D L; Gaudi B S; Hwang K -H; Jung Y K; Lee C -U; McCormick J; Natusch T; Ngan H; Park H; Pogge R W; Shin I -G; Tan T -G; Abe F; Bennett D P; Botzler C S; Freeman M; Fukui A; Fukunaga D; Itow Y; Koshimoto N; Larsen P; Ling C H; Masuda K; Matsubara Y; Muraki Y; Namba S; Ohnishi K; Philpott L; Rattenbury N J; Saito T; Sullivan D J; Sumi T; Sweatman W L; Suzuki D; Tristram P J; Tsurumi N; Wada K; Yamai N; Yock P C M; Yonehara A; Szymański M K; Ulaczyk K; Kozłowski S; Poleski R; Wyrzykowski Ł; Kubiak M; Pietrukowicz P; Pietrzyński G; Soszyński I; Bramich D M; Browne P; Jaimes R F; Horne K; Ipatov S; Kains N; Snodgrass C; Steele I A; Street R; Tsapras Y
MOA-2013-BLG-220Lb: Massive Planetary Companion to Galactic-Disk Host (Journal Article)
In: The Astrophysical Journal, vol. 790, no. 1, pp. 14, 2014, ISSN: 0004-637X, 1538-4357, (arXiv: 1403.2134).
We report the discovery of MOA-2013-BLG-220Lb, which has a super-Jupiter mass ratio $q=3.01textbackslashpm 0.02textbackslashtimes 10textasciicircum-3$ relative to its host. The proper motion, $textbackslashmu=12.5textbackslashpm 1textbackslash, textbackslashrm mastextbackslash,textbackslashrm yrtextasciicircum-1$, is one of the highest for microlensing planets yet discovered, implying that it will be possible to separately resolve the host within $textbackslashsim 7$ years. Two separate lines of evidence imply that the planet and host are in the Galactic disk. The planet could have been detected and characterized purely with follow-up data, which has important implications for microlensing surveys, both current and into the LSST era.
Jordán A; Brahm R; Bakos G Á; Bayliss D; Penev K; Hartman J D; Zhou G; Mancini L; Mohler-Fischer M; Ciceri S; Sato B; Csubry Z; Rabus M; Suc V; Espinoza N; Bhatti W; de Val-Borro M; Buchhave L; Csák B; Henning T; Schmidt B; Tan T G; Noyes R W; Béky B; Butler R P; Shectman S; Crane J; Thompson I; Williams A; Martin R; Contreras C; Lázár J; Papp I; Sári P
HATS-4b: A Dense Hot-Jupiter Transiting a Super Metal-Rich G Star (Journal Article)
In: The Astronomical Journal, vol. 148, no. 2, pp. 29, 2014, ISSN: 0004-6256, 1538-3881, (arXiv: 1402.6546).
We report the discovery by the HATSouth survey of HATS-4b, an extrasolar planet transiting a V=13.46 mag G star. HATS-4b has a period of P = 2.5167 d, mass of Mp = 1.32 Mj, radius of Rp = 1.02 Rj and density of rho_p = 1.55 +- 0.16 g/cmtextasciicircum3 textasciitilde 1.24 rhoj. The host star has a mass of 1.00 Msun, a radius of 0.92 Rsun and a very high metallicity [Fe/H]= 0.43 +- 0.08. HATS-4b is among the densest known planets with masses between 1-2 Mj and is thus likely to have a significant content of heavy elements of the order of 75 Mearth. In this paper we present the data reduction, radial velocity measurement and stellar classification techniques adopted by the HATSouth survey for the CORALIE spectrograph. We also detail a technique to estimate simultaneously vsini and macroturbulence using high resolution spectra.
Zhou G; Bayliss D; Hartman J D; Bakos G Á; Penev K; Csubry Z; Tan T G; Jordán A; Mancini L; Rabus M; Brahm R; Espinoza N; Mohler-Fischer M; Ciceri S; Suc V; Csák B; Henning T; Schmidt B
In: Monthly Notices of the Royal Astronomical Society, vol. 437, no. 3, pp. 2831–2844, 2014, ISSN: 0035-8711, 1365-2966, (arXiv: 1310.7591).
We report the discovery of four transiting F-M binary systems with companions between 0.1-0.2 Msun in mass by the HATSouth survey. These systems have been characterised via a global analysis of the HATSouth discovery data, combined with high-resolution radial velocities and accurate transit photometry observations. We determined the masses and radii of the component stars using a combination of two methods: isochrone fitting of spectroscopic primary star parameters, and equating spectroscopic primary star rotation velocity with spin-orbit synchronisation. These new very low mass companions are HATS550-016B (0.110 -0.006/+0.005 Msun, 0.147 -0.004/+0.003 Rsun), HATS551-019B (0.17 -0.01/+0.01 Msun, 0.18 -0.01/+0.01 Rsun), HATS551-021B (0.132 -0.005/+0.014 Msun, 0.154 -0.008/+0.006 Rsun), HATS553-001B (0.20 -0.02/+0.01 Msun, 0.22 -0.01/+0.01 Rsun). We examine our sample in the context of the radius anomaly for fully-convective low mass stars. Combining our sample with the 13 other well-studied very low mass stars, we find a tentative 5% systematic deviation between the measured radii and theoretical isochrone models.
Tsapras Y; Choi J -Y; Street R A; Han C; Bozza V; Gould A; Dominik M; Beaulieu J -P; Udalski A; Jørgensen U G; Sumi T; Bramich D M; Browne P; Horne K; Hundertmark M; Ipatov S; Kains N; Snodgrass C; Steele I A; Alsubai K A; Andersen J M; Novati S C; Damerdji Y; Diehl C; Elyiv A; Giannini E; Hardis S; Harpsøe K; Hinse T C; Juncher D; Kerins E; Korhonen H; Liebig C; Mancini L; Mathiasen M; Penny M T; Rabus M; Rahvar S; Scarpetta G; Skottfelt J; Southworth J; Surdej J; Tregloan-Reed J; Vilela C; Wambsganss J; Skowron J; Poleski R; Kozłowski S; Wyrzykowski Ł; Szymański M K; Kubiak M; Pietrukowicz P; Pietrzyński G; Soszyński I; Ulaczyk K; Albrow M D; Bachelet E; Barry R; Batista V; Bhattacharya A; Brillant S; Caldwell J A R; Cassan A; Cole A; Corrales E; Coutures C; Dieters S; Prester D D; Donatowicz J; Fouqué P; Greenhill J; Kane S R; Kubas D; Marquette J -B; Menzies J; P`ere C; Pollard K R; Wouters D; Christie G; DePoy D L; Dong S; Drummond J; Gaudi B S; Henderson C B; Hwang K H; Jung Y K; Kavka A; Koo J -R; Lee C -U; Maoz D; Monard L A G; Natusch T; Ngan H; Park H; Pogge R W; Porritt I; Shin I -G; Shvartzvald Y; Tan T G; Yee J C; Abe F; Bennett D P; Bond I A; Botzler C S; Freeman M; Fukui A; Fukunaga D; Itow Y; Koshimoto N; Ling C H; Masuda K; Matsubara Y; Muraki Y; Namba S; Ohnishi K; Rattenbury N J; Saito T; Sullivan D J; Sweatman W L; Suzuki D; Tristram P J; Tsurumi N; Wada K; Yamai N; Yonehara P C M Y A
In: The Astrophysical Journal, vol. 782, no. 1, pp. 48, 2014, ISSN: 0004-637X, 1538-4357, (arXiv: 1310.2428).
We present a detailed analysis of survey and follow-up observations of microlensing event OGLE-2012-BLG-0406 based on data obtained from 10 different observatories. Intensive coverage of the lightcurve, especially the perturbation part, allowed us to accurately measure the parallax effect and lens orbital motion. Combining our measurement of the lens parallax with the angular Einstein radius determined from finite-source effects, we estimate the physical parameters of the lens system. We find that the event was caused by a $2.73textbackslashpm 0.43textbackslash M_textbackslashrm J$ planet orbiting a $0.44textbackslashpm 0.07textbackslash M_textbackslashodot$ early M-type star. The distance to the lens is $4.97textbackslashpm 0.29$textbackslash kpc and the projected separation between the host star and its planet at the time of the event is $3.45textbackslashpm 0.26$ AU. We find that the additional coverage provided by follow-up observations, especially during the planetary perturbation, leads to a more accurate determination of the physical parameters of the lens.
Martin J C; Hambsch F; Margutti R; Tan T; Curtis I; Soderberg A
In: The Astronomical Journal, vol. 149, no. 1, pp. 9, 2014, ISSN: 1538-3881, (arXiv: 1308.3682).
The supernova impostor SN 2009ip has re-brightened several times since its initial discovery in August 2009. During its last outburst in late September 2012 it reached a peak brightness of m$_v$ $textbackslashsim$ 13.5 (M$_v$ brighter than -18) causing some to speculate that it had undergone a terminal core-collapse supernova. Relatively high-cadence multi-wavelength photometry of the post-peak decline revealed bumps in brightness infrequently observed in other Type IIn supernovae. These bumps occurred synchronously in all UV and optical bands with amplitudes of 0.1 -- 0.4 mag at intervals of 10 -- 30 days. Episodic continuum brightening and dimming in the UV and optical with these characteristics is not easilly explained within the context of models that have been proposed for the late September 2012 outburst of SN 2009ip. We also present evidence that the post peak fluctuations in brightness occur at regular intervals and raise more questions about their origin.
Gary B L; Tan T G; Curtis I; Tristram P J; Fukui A
Searching for White Dwarf Exoplanets: WD 2359-434 Case Study (Journal Article)
In: Society for Astronomical Sciences Annual Symposium, vol. 32, pp. 71–78, 2013.
The white dwarf WD 2359-434 was found to vary with a period of 2.695022 ± 0.000014 hours and semiamplitude of 0.00480 ± 0.00023
magnitude. One explanation for the variation is a starspot with a 3.8-degree radius (assuming 500 K cooler than the surroundings) at latitude of textasciitilde 27 degrees and a star rotation axis inclination of textasciitilde 30 degrees. The brightness variation was very close to sinusoidal, and there were no changes in amplitude, period or phase during the 1.1 years of observations. This permitted consideration of an alternative
explanation: a Jupiter-size exoplanet that reflects the white dwarf's light in amounts that vary with orbital position. Follow-up observations are suggested for distinguishing between these two interpretations.
Han C; Jung Y K; Udalski A; Sumi T; Gaudi B S; Gould A; Bennett D P; Tsapras Y; Szymański M K; Kubiak M; Pietrzyński G; Soszyński I; Skowron J; Kozłowski S; Poleski R; Ulaczyk K; Wyrzykowski Ł; Pietrukowicz P; Abe F; Bond I A; Botzler C S; Chote P; Freeman M; Fukui A; Furusawa K; Harris P; Itow Y; Ling C H; Masuda K; Matsubara Y; Muraki Y; Ohnishi K; Rattenbury N J; Saito T; Sullivan D J; Sweatman W L; Suzuki D; Tristram P J; Wada K; Yock P C M; Batista V; Christie G; Choi J -Y; DePoy D L; Dong S; Hwang K -H; Kavka A; Lee C -U; Monard L A G; Natusch T; Ngan H; Park H; Pogge R W; Porritt I; Shin I -G; Tan T G; Yee J C; Alsubai K A; Bozza V; Bramich D M; Browne P; Dominik M; Horne K; Hundertmark M; Ipatov S; Kains N; Liebig C; Snodgrass C; Steele I A; Street R A
In: The Astrophysical Journal, vol. 778, no. 1, pp. 38, 2013, ISSN: 0004-637X, 1538-4357, (arXiv: 1307.6335).
Observations of accretion disks around young brown dwarfs have led to the speculation that they may form planetary systems similar to normal stars. While there have been several detections of planetary-mass objects around brown dwarfs (2MASS 1207-3932 and 2MASS 0441-2301), these companions have relatively large mass ratios and projected separations, suggesting that they formed in a manner analogous to stellar binaries. We present the discovery of a planetary-mass object orbiting a field brown dwarf via gravitational microlensing, OGLE-2012-BLG-0358Lb. The system is a low secondary/primary mass ratio (0.080 +- 0.001), relatively tightly-separated (textasciitilde0.87 AU) binary composed of a planetary-mass object with 1.9 +- 0.2 Jupiter masses orbiting a brown dwarf with a mass 0.022 M_Sun. The relatively small mass ratio and separation suggest that the companion may have formed in a protoplanetary disk around the brown dwarf host, in a manner analogous to planets.
Mancini L; Ciceri S; Chen G; Tregloan-Reed J; Fortney J J; Southworth J; Tan T G; Burgdorf M; Novati S C; Dominik M; Fang X -S; Finet F; Gerner T; Hardis S; Hinse T C; Jorgensen U G; Liebig C; Nikolov N; Ricci D; Schaefer S; Schoenebeck F; Skottfelt J; Wertz O; Alsubai K A; Bozza V; Browne P; Dodds P; Gu S -H; Harpsoe K; Henning T; Hundertmark M; Jessen-Hansen J; Kains N; Kerins E; Kjeldsen H; Lund M N; Lundkvist M; Madhusudhan N; Mathiasen M; Penny M T; Proft S; Rahvar S; Sahu K; Scarpetta G; Snodgrass C; Surdej J
In: Monthly Notices of the Royal Astronomical Society, vol. 436, no. 1, pp. 2–18, 2013, ISSN: 0035-8711, 1365-2966, (arXiv: 1306.6384).
We present new ground-based, multi-colour, broad-band photometric measurements of the physical parameters, transmission and emission spectra of the transiting extrasolar planet WASP-19b. The measurements are based on observations of 8 transits and four occultations using the 1.5m Danish Telescope, 14 transits at the PEST observatory, and 1 transit observed simultaneously through four optical and three near-infrared filters, using the GROND instrument on the ESO 2.2m telescope. We use these new data to measure refined physical parameters for the system. We find the planet to be more bloated and the system to be twice as old as initially thought. We also used published and archived datasets to study the transit timings, which do not depart from a linear ephemeris. We detected an anomaly in the GROND transit light curve which is compatible with a spot on the photosphere of the parent star. The starspot position, size, spot contrast and temperature were established. Using our new and published measurements, we assembled the planet's transmission spectrum over the 370-2350 nm wavelength range and its emission spectrum over the 750-8000 nm range. By comparing these data to theoretical models we investigated the theoretically-predicted variation of the apparent radius of WASP-19b as a function of wavelength and studied the composition and thermal structure of its atmosphere. We conclude that: there is no evidence for strong optical absorbers at low pressure, supporting the common idea that the planet's atmosphere lacks a dayside inversion; the temperature of the planet is not homogenized, because the high warming of its dayside causes the planet to be more efficient in re-radiating than redistributing energy to the night side; the planet seems to be outside of any current classification scheme.
Pastorello A; Cappellaro E; Inserra C; Smartt S J; Pignata G; Benetti S; Valenti S; Fraser M; Takats K; Benitez S; Botticella M T; Brimacombe J; Bufano F; Cellier-Holzem F; Costado M T; Cupani G; Curtis I; Elias-Rosa N; Ergon M; Fynbo J P U; Hambsch F -J; Hamuy M; Harutyunyan A; Ivarson K M; Kankare E; Martin J C; Kotak R; LaCluyze A P; Maguire K; Mattila S; Maza J; McCrum M; Miluzio M; Norgaard-Nielsen H U; Nysewander M C; Ochner P; Pan Y -C; Pumo M L; Reichart D E; Tan T G; Taubenberger S; Tomasella L; Turatto M; Wright D
In: The Astrophysical Journal, vol. 767, no. 1, pp. 1, 2013, ISSN: 0004-637X, 1538-4357, (arXiv: 1210.3568).
We report the results of a 3 year-long dedicated monitoring campaign of a restless Luminous Blue Variable (LBV) in NGC 7259. The object, named SN 2009ip, was observed photometrically and spectroscopically in the optical and near-infrared domains. We monitored a number of erupting episodes in the past few years, and increased the density of our observations during eruptive episodes. In this paper we present the full historical data set from 2009-2012 with multi-wavelength dense coverage of the two high luminosity events between August - September 2012. We construct bolometric light curves and measure the total luminosities of these eruptive or explosive events. We label them the 2012a event (lasting textasciitilde50 days) with a peak of 3x10textasciicircum41 erg/s, and the 2012b event (14 day rise time, still ongoing) with a peak of 8x10textasciicircum42 erg/s. The latter event reached an absolute R-band magnitude of about -18, comparable to that of a core-collapse supernova (SN). Our historical monitoring has detected high-velocity spectral features (textasciitilde13000 km/s) in September 2011, one year before the current SN-like event. This implies that the detection of such high velocity outflows cannot, conclusively, point to a core-collapse SN origin. We suggest that the initial peak in the 2012a event was unlikely to be due to a faint core-collapse SN. We propose that the high intrinsic luminosity of the latest peak, the variability history of SN 2009ip, and the detection of broad spectral lines indicative of high-velocity ejecta are consistent with a pulsational pair-instability event, and that the star may have survived the last outburst. The question of the survival of the LBV progenitor star and its future fate remain open issues, only to be answered with future monitoring of this historically unique explosion.