TESS Giants Transiting Giants V -- Two hot Jupiters orbiting red-giant hosts

Abstract

In this work we present the discovery and confirmation of two hot Jupiters orbiting red-giant stars, TOI-4377 b and TOI-4551 b, observed by TESS in the southern ecliptic hemisphere and later followed-up with radial-velocity (RV) observations. For TOI-4377 b we report a mass of $0.957_{-0.087}^{+0.089}{M}_{\mathrm{J}}$ and a inflated radius of $1.348\pm 0.081R_{\mathrm{J}}$ orbiting an evolved intermediate-mass star ($1.36{\mathrm{M}}_{\odot }$, $3.52{\mathrm{R}}_{\odot }$; TIC 394918211) on a period of of $4.378$ days. For TOI-4551 b we report a mass of $1.49\pm 0.13M_{\mathrm{J}}$ and a radius that is not obviously inflated of $1.058_{-0.062}^{+0.110}{R}_{\mathrm{J}}$, also orbiting an evolved intermediate-mass star ($1.31{\mathrm{M}}_{\odot }$, $3.55{\mathrm{R}}_{\odot }$; TIC 204650483) on a period of $9.956$ days. We place both planets in context of known systems with hot Jupiters orbiting evolved hosts, and note that both planets follow the observed trend of the known stellar incident flux-planetary radius relation observed for these short-period giants. Additionally, we produce planetary interior models to estimate the heating efficiency with which stellar incident flux is deposited in the planet's interior, estimating values of $1.91\pm 0.48\%$ and $2.19\pm 0.45\%$ for TOI-4377 b and TOI-4551 b respectively. These values are in line with the known population of hot Jupiters, including hot Jupiters orbiting main sequence hosts, which suggests that the radii of our planets have reinflated in step with their parent star's brightening as they evolved into the post-main-sequence. Finally, we evaluate the potential to observe orbital decay in both systems.

14 pages with 8 figures and 6 tables. Accepted for publication in the Monthly Notices of the Royal Astronomical Society

References in corpus (33)

• The Gaia mission
• Modules for Experiments in Stellar Astrophysics (MESA)
• The Transiting Exoplanet Survey Satellite
• Basic physical parameters of a selected sample of evolved stars
• The first WASP public data release
• A New Planet Around an M Dwarf: Revealing a Correlation Between Exoplanets and Stellar Mass
• The connection between stellar granulation and oscillation as seen by the Kepler mission
• Precise Radial Velocities of Giant Stars VII. Occurrence Rate of Giant Extrasolar Planets as a Function of Mass and Metallicity
• Transit Least Squares: Optimized transit detection algorithm to search for periodic transits of small planets
• Hot Jupiters and Cool Stars
• exoplanet: Gradient-based probabilistic inference for exoplanet data & other astronomical time series
• The Orbit of WASP-12b is Decaying
• The asteroseismic potential of TESS: exoplanet-host stars
• Determining stellar parameters of asteroseismic targets: going beyond the use of scaling relations
• On the Occurrence Rate of Hot Jupiters in Different Stellar Environments
• SWEET-Cat 2.0: The Cat just got SWEETer; Higher quality spectra and precise parallaxes from GAIA eDR3
• A Hot Saturn Orbiting An Oscillating Late Subgiant Discovered by TESS
• Kepler-432: a red giant interacting with one of its two long period giant planets
• Radial Velocity Observations and Light Curve Noise Modeling Confirm That Kepler-91b is a Giant Planet Orbiting a Giant Star
• Seeing double with K2: Testing re-inflation with two remarkably similar planets around red giant branch stars
• Giant planet occurrence within 0.2 AU of low-luminosity red giant branch stars with K2
• Prospects for Galactic and stellar astrophysics with asteroseismology of giant stars in the $TESS$ Continuous Viewing Zones and beyond
• Slow Cooling and Fast Reinflation for Hot Jupiters
• TESS Delivers Five New Hot Giant Planets Orbiting Bright Stars from the Full Frame Images
• TESS Giants Transiting Giants II: The hottest Jupiters orbiting evolved stars
• The Curious Case of KOI 4: Confirming Kepler's First Exoplanet
• The Pan-Pacific Planet Search. VIII. Complete results and the occurrence rate of planets around low-luminosity giants
• $\text{TESS}$ Giants Transiting Giants I: A Non-inflated Hot Jupiter Orbiting a Massive Subgiant
• CORALIE radial-velocity search for companions around evolved stars (CASCADES). I. Sample definition and first results: Three new planets orbiting giant stars
• TESS Giants Transiting Giants III: An eccentric warm Jupiter supports a period-eccentricity relation for giant planets transiting evolved stars
• Occurrence rate of hot Jupiters orbiting red giant stars
• Discovery of an inflated hot Jupiter around a slightly evolved star TOI-1789
• Detection and characterization of planets orbiting oscillating red-giant stars with NASA's TESS mission

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