CORALIE radial-velocity search for companions around evolved stars (CASCADES). III. A new Jupiter host-star: in-depth analysis of HD 29399 using TESS data
Context. Increasing the number of detected exoplanets is far from
anecdotal, especially for long-period planets that require a
long duration of observation. More detections imply a better
understanding of the statistical properties of exoplanet
populations, and detailed modelling of their host stars also
enables thorough discussions of star-planet interactions and
orbital evolution of planetary systems. \Aims: In
the context of the discovery of a new planetary system, we aim
to perform a complete study of HD 29399 and its companion by
means of radial-velocity measurements, seismic characterisation
of the host-star, and modelling of the orbital evolution of the
system. \Methods: High-resolution spectra of HD
29399 were acquired with the CORALIE spectrograph mounted on the
1.2-m Swiss telescope located at La Silla Observatory (Chile) as
part of the CASCADES survey. We used the moments of the cross-
correlation function profile as well as the photometric
variability of the star as diagnostics to distinguish between
stellar and planetary-induced signals. To model the host star we
combined forward modelling with global and local minimisation
approaches and inversion techniques. We also studied the orbital
history of the system under the effects of both dynamical and
equilibrium tides. \Results: We present the
detection of a long-period giant planet. Combining these
measurements with photometric observations by TESS, we are able
to thoroughly model the host star and study the orbital
evolution of the system. We derive stellar and planetary masses
of 1.17 ± 0.10 M_⊙ and
1.59 ± 0.08 M_Jup, respectively, and an age
for the system of 6.2 Gyr. We show that neither dynamical nor
equilibrium tides have been able to affect the orbital evolution
of the planet. Moreover, no engulfment is predicted for the
future evolution of the system.
\on observations collected with
the CORALIE echelle spectrograph on the 1.2-m Euler Swiss
telescope at La Silla Observatory, ESO, Chile.