High-precision radial velocities for HD 221416

HD 221416 b (HIP 116158, TOI-197) is a bright (V=8.2 mag), spectroscopically classified subgiant that oscillates with an average frequency of about 430 {mu}Hz and displays a clear signature of mixed modes. The oscillation amplitude confirms that the redder TESS bandpass compared to Kepler has a small effect on the oscillations, supporting the expected yield of thousands of solar-like oscillators with TESS 2 minute cadence observations.

Asteroseismic modeling yields a robust determination of the host star radius (R_*_=2.943+/-0.064 R_{sun}_), mass (M_*_=1.212+/-0.074 M_{sun}_), and age (4.9+/-1.1 Gyr), and demonstrates that it has just started ascending the red-giant branch. Combining asteroseismology with transit modeling and radial-velocity observations, we show that the planet is a "hot Saturn" (R_p_=9.17+/-0.33 R_{Earth}_) with an orbital period of ~14.3 days, irradiance of F=343+/-24 F_{Earth}_, and moderate mass (M_p_=60.5+/-5.7 M_{Earth}_) and density ({rho}_p_=0.431+/-0.062 g/cm^3^).