(Proposal ID) S15B-163

(PI) Masuda, Kento

(Proposal Title)
Unveiling the True Nature of the Evaporating Planet Candidates

(Abstract)
KIC-12557548 and KOI-2700, short-period (<1day) transiting systems found by 
the {Kepler} spacecraft, are known to host the planet candidates possibly 
experiencing significant atmospheric evaporation. Our proposal aims to confirm 
or refute these candidates with the radial velocity (RV) observation over the 
whole orbital phase. So far, the peculiar shape of their transit light curves 
and the significant transit depth variation have been interpreted to arise 
from the comet-like dust tail being ejected from the Mercury-sized rocky core, 
and hence intensively studied at multiple wavelengths to probe the building 
blocks of rocky exoplanets. However, we find that the above peculiar features 
can also be explained by a system of totally different architecture, where a 
Jupiter-sized companion on a highly eccentric orbit grazes the host star near 
its periastron. If this is actually the case, our targets may be the 
progenitors of hot Jupiters, which are on its way of tidal migration.  
This "eccentric Jupiter" scenario induces very different stellar RV variation 
than in the evaporation scenario, and so the two scenarios can be clearly 
distinguished from our proposed RV observations. The feasibility of achieving 
our goal is already established by the previous observation using Keck/HIRES 
as well as our previous work.