Old, Rich, and Eccentric: Two Jovian Planets Orbiting Evolved Metal-Rich Stars

We present radial velocity measurements of two stars observed as part of the Lick Subgiants Planet Search and the Keck N2K survey. Variations in the radial velocities of both stars reveal the presence of Jupiter-mass exoplanets in highly eccentric orbits. HD 16175 is a G0 subgiant from the Lick Subgiants Planet Search, orbited by a planet having a minimum mass of 4.4 M_Jup, in an eccentric (e = 0.59), 2.71 yr orbit. HD 96167 is a G5 subgiant from the N2K (“Next 2000”) program at Keck Observatory, orbited by a planet having a minimum mass of 0.68 M_Jup, in an eccentric (e = 0.71), 1.366 yr orbit. Both stars are relatively massive (M_star = 1.3 M_sun) and are very metal rich ([Fe/H] > +0.3). We describe our methods for measuring the stars’ radial velocity variations and photometric stability.

💡 Research Summary

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The paper reports the discovery of two Jovian planets orbiting metal‑rich, evolved subgiant stars, based on high‑precision radial‑velocity (RV) measurements obtained by the Lick Subgiants Planet Search and the Keck N2K survey. The target stars, HD 16175 (spectral type G0 IV) and HD 96167 (G5 IV), were selected because they are relatively massive (≈ 1.3 M☉) and exhibit high metallicities (