Discoveries

PEST was built to find planets.  The easiest to find are hot Jupiters, but the most interesting are Earths.  PEST has helped find both kinds.

Here are a few key examples;

LHS 1140b, a super-Earth in the Habitable Zone

An artist’s impression of the rocky exoplanet, LHS 1140b passing in front of its host, a small faint red star. Depicted in blue is the atmosphere the planet may have retained.
Credit: M. Weiss/CfA

LHS 1140b is now among the top candidates in the search for life.  It’s rocky rather than gaseous – we’ve measured both mass and radius.  The amount of heat it receives from its star is of about the same order as Earth, so it may have liquid water.  It’s nearby, only about 40 light years away, and bright enough so telescopes now being built may be able to test its atmosphere for signs of life.  The star is relatively placid.  Many small red stars are active, flaring and blasting any nearby planet with radiation that blows away any atmosphere.

 

HATS-6b, a warm Saturn

Artist’s impression of HATS-6b transiting its star. Image Credit: ANU

 

HATS-6b is a bit cooler and a bit less massive than a hot Jupiter and comes with a twist.  It is about the same radius as Jupiter, but with only a third of Jupiter’s mass.  Its year is just 3.3 Earth days long.  At just 0.04 AU from its star, it has a mean temperature of 440 °C.  This seems hot, but this close to a star surely it must be a lot hotter?  Therein lies the twist.  The host star, HATS-6, is a red dwarf, much smaller and cooler than the Sun.  With mass and radius just over half that of our Sun, its surface temperature is only 3770K, compared to the Sun’s 5772K.

This actually is awkward, because we don’t expect large planets to form around small stars.  The planet probably formed further away from the star and then migrated inwards, but current theories don’t explain this well.

OGLE-2013-BLG-0341: An Earth-like planet around one member of a double star system

OGLE-2013-BLG-0341: Image Credit: C Han, Chungbuk National University, Korea.

From this planet you’d see two suns.  One much closer and so brighter than the other.  But both stars are red dwarfs so OGLE-2013-BLG-0341LBb, to give it’s full name, is too cold to support liquid water and therefore life.  Here’s good article on this discovery.

 

Full list of PEST planet co-discoveries:

No.NameMasspP
/days
RadpDist
/lyrs
Masss
/Msun
VmagDepth
/mmag
Remarks
1.OGLE-2012-
BLG-0026Lb
0.11 MJ3011N/A133000.82--Two planet system, beyond 'snow line'
2.OGLE-2012-
BLG-0026Lc
0.68 MJ4018N/A133000.82--Two planet system, beyond 'snow line'
3.OGLE-2012-
BLG-0358Lb
1.85 MJ1998N/A57400.022-Host is a brown dwarf
4.HATS-4b1.32 MJ2.521.02 RJ13701.013.12.8A Dense Hot-Jupiter.
5.MOA-2013-
BLG-220Lb
0.19 MJ957N/A<66000.05--Host is possibly a brown dwarf, but parameters uncertain.
6.OGLE-2013
-BLG-0341LBb
~2 ME640N/A~30000.13-First Earth-like planet found around a binary star
system.
7.HATS-6b0.32 MJ3.330.998 RJ5630.5715.232.3Warm Saturn orbiting a dwarf star.
8.HATS-9b
0.84 MJ1.921.065 RJ20301.0313.35.3Compact hot Jupiter. 
9.HATS-10b
0.53 MJ3.310.97 RJ16201.1013.18.2Compact hot Jupiter
10.HATS-13b
0.543 MJ3.041.212 RJ15500.9613.919.6Inflated hot Jupiter
11.HATS-14b1.071 MJ2.771.039 RJ16700.9713.813.1~ Jupiter mass and radius much closer to its host star.
12.OGLE-2012-
BLG-0563Lb
0.39 MJN/AN/A43000.34--Planet around an M-dwarf star, beyond the 'snow line'.
13.KELT-10b0.68 MJ4.171.40 RJ5971.1110.714.2Highly inflated sub-Jupiter mass planet transiting a relatively bright star.
14.KELT-14b1.2 MJ1.711.52 RJ6561.1811.013.1An inflated Jupiter mass planet.  Independent discovery of WASP-122b.
15.KELT-15b0.91 MJ3.331.44 RJ9491.1811.210.0Inflated Jupiter mass planet.
16.HATS-17b1.34 MJ16.250.78 RJ11101.1312.45.3Compact warm Jupiter. Longest period transiting planet discovered to date by a ground based survey.
17.HATS-15b2.17 MJ1.751.11 RJ22500.8714.815.1High-mass hot Jupiter.  High mass planet orbiting unusually close to its star.
18.HATS-11b0.85 MJ3.621.51 RJ29601.0014.112.9Hot Jupiter.  Very metal-poor star.
19.HATS-12b2.38 MJ3.141.35 RJ32001.4912.85.1Hot Jupiter.  The transit depth is 5 mmag - the 3rd shallowest ground-based planet discovery to date.
20.HATS-27b0.53 MJ4.631.50 RJ27401.4212.88.0Among the most inflated of Hot Jupiters discovered. 
21.HATS-20b0.27 MJ3.800.78 RJ14800.9113.88.1Dense Saturn-like mass planet.
22.HATS-32b0.92 MJ2.811.25 RJ27401.1014.413.7Typical Hot Jupiter.
23.HATS-34b0.94 MJ2.111.43 RJ17400.9613.822.5Typical Hot Jupiter.
24.KELT-11b0.20 MJ4.741.37 RJ3201.448.02.7Brightest known transiting exoplanet host in the southern hemisphere Shallowest transit depth a planet discovered by a ground-based survey.
25.KELT-17b1.31 MJ3.081.53 RJ6851.649.39.1Amongst the most massive, hottest, and most rapidly rotating of known planet hosts.
26.LHS 1140b6.6 ME24.741.43 RE410.1514.25.0Super-Earth in habitable zone. May be best prospect so far to search for life-signature atmospheric gases.
27.WASP-167b/KELT-13b< 8 MJ2.021.51 RJ12401.5210.58.2A giant planet in retrograde (i.e. contrary to stellar spin) and mis-aligned orbit.
28.HATS-36b2.79 MJ4.181.26 RJ31901.1414.418Typical Hot Jupiter.

I have included only those planets for which PEST actually made observations (as opposed to instances where I did not contribute observations but was a co-author of the discovery paper).

ME = Earth masses
MJ = Jupiter masses
RE = Earth radii
RJ = Jupiter radii