b'16 Carnegie Science|Fall 2019Uncovering a Trio of Planets, One Possibly HabitableTwo members of the team, Johanna Teske (left) and Jeffrey Crane, are working on the Planet Finder Spectrograph at Carnegies Las Campanas Observatory. Image courtesy Carnegie Institution for ScienceF ollowing up on the discovery of a small planet byTo confirm the planets presence, the discovery team, which was NASAs Transiting Exoplanet Survey Satellite (TESS),led by Rafael Luque of the Institute of Astrophysics of the Canary ground-based observations revealed two additionalIslands on Tenerife, used additional data from ground-based nearby planets, one of which is far enough from itsobservatories, which revealed two additional, non-transiting planets.star to be potentially habitable. An internationalIn a way, these planets were hiding in measurements made at team including several Carnegie astronomers andnumerous observatories over many years, Luque said. It took TESS instrumentation specialists announced these findings into point us to an interesting star where we could uncover them. Astronomy & Astrophysics These additional worlds were found by using the radial velocity .The newly found exoplanets orbit a star named GJ 357, anmethod of exoplanet detection. This method takes advantage of the M-type dwarf thats about one-third of the Suns mass and locatedfact that the planets gravity affects the star, creating tiny wobbles in 31 light-years away in the Hydra constellation. In February, TESSthe stars orbit; these wobbles are detectible using instruments, such cameras caught the star dimming slightly every 3.9 days,as the Planet Finder Spectrograph (PFS) on one of the Magellan revealing the presence of an exoplanet passing across in front andtelescopes at Carnegies Las Campanas Observatory in Chile.dimming its light every orbit. Because it is a nearby M dwarf, which we know often host These transits belong to GJ 357 b, a planet about 80% moresmall planets, the PFS team started monitoring this star in 2016, massive than Earth and about 22% larger in size. It orbits 11 timesexplained Carnegies Johanna Teske. As soon as we saw that TESS closer to its star than Mercury does our Sun. This gives it anhad indeed detected a small transiting planet, we accelerated our equilibrium temperature of around 490F (254C), leading the teamPFS observing campaign.to call it a hot Earth. These conditions make it one of the bestTESSs goal of determining the masses of 50 small planets exoplanets discovered for research on exoplanet atmosphericnecessitates collaborations with ground-based observatories like compositions. Las Campanas since planet mass is not a parameter that TESS measures.'