BD+49 828b, HD 95127b & HD 216536b: Three Giant ExoPlanets Orbting Red Giants

Three red giants with substellar-mass companions

Authors:

Niedzielski et al

Abstract:

We present three giant stars from the ongoing Penn State-Toru\'n Planet Search with the Hobby-Eberly Telescope, which exhibit radial velocity variations that point to a presence of planetary --mass companions around them. BD+49 828 is a M=1.52±0.22 M⊙ K0 giant with a msini=1.6+0.4−0.2 MJ minimum mass companion in a=4.2+0.32−0.2 AU (2590+300−180d), e=0.35+0.24−0.10 orbit. HD 95127, a logL/L⊙=2.28±0.38, R=20±9 R⊙, M=1.20±0.22 M⊙ K0 giant has a msini=5.01+0.61−0.44 MJ minimum mass companion in a=1.28+0.01−0.01 AU (482+5−5d), e=0.11+0.15−0.06 orbit. Finally, HD 216536, is a M=1.36±0.38 M⊙ K0 giant with a msini=1.47+0.20−0.12 MJ minimum mass companion in a=0.609+0.002−0.002 AU (148.6+0.7−0.7d), e=0.38+0.12−0.10 orbit. Both, HD 95127 b and HD 216536 b in their compact orbits, are very close to the engulfment zone and hence prone to ingestion in the near future. BD+49 828 b is among the longest period planets detected with the radial velocity technique until now and it will remain unaffected by stellar evolution up to a very late stage of its host. We discuss general properties of planetary systems around evolved stars and planet survivability using existing data on exoplanets in more detail.