Exoplanets and Stellar Physics

Abstract:

Abstract Based on recently-taken and archival HARPS, FEROS, and HIRES radial velocities (RVs), we present evidence for a new planet orbiting the first ascent red giant star HD 33142 (with an improved mass estimate of M1.52 ± 0.03 M ⊙ ), already known to host two planets. We confirm the Jovian-mass planets HD 33142b and c, with periods of P b = 330.0 − 0.4 + 0.4 days and P c = 810.2 − 4.2 + 3.8 days and minimum dynamical masses of m b sin i = 1.26 − 0.05 + 0.05 M Jup and m c sin i = 0.89 − 0.05 + 0.06 M Jup , respectively. Furthermore, our periodogram analysis of the precise RVs shows strong evidence for a short-period Doppler signal in the residuals of a two-planet Keplerian fit, which we interpret as a third, Saturn-mass planet with m d sin i = 0.20 − 0.03 + 0.02 M Jup in a close-in orbit with an orbital period of P d = 89.9 − 0.1 + 0.1 days. We study the dynamical behavior of the three-planet system configuration with an N -body integration scheme, finding it to be long-term stable with the planets alternating between low and moderate eccentricity episodes. We also perform N -body simulations, including stellar evolution and second-order dynamical effects such as planet–stellar tides and stellar mass loss on the way to the white dwarf phase. We find that planets HD 33142b, c, and d are likely to be engulfed near the tip of the red giant branch phase due to tidal migration. These results make the HD 33142 system an essential b.