TESS Giants Transiting Giants. VI. Newly Discovered Hot Jupiters Provide Evidence for Efficient Obliquity Damping after the Main Sequence

Abstract

The degree of alignment between a star's spin axis and the orbital plane of its planets (the stellar obliquity) is related to interesting and poorly understood processes that occur during planet formation and evolution. Hot Jupiters orbiting hot stars ($\gtrsim$6250 K) display a wide range of obliquities, while similar planets orbiting cool stars are preferentially aligned. Tidal dissipation is expected to be more rapid in stars with thick convective envelopes, potentially explaining this trend. Evolved stars provide an opportunity to test the damping hypothesis, particularly stars that were hot on the main sequence and have since cooled and developed deep convective envelopes. We present the first systematic study of the obliquities of hot Jupiters orbiting subgiants that recently developed convective envelopes using Rossiter-McLaughlin observations. Our sample includes two newly discovered systems in the Giants Transiting Giants Survey (TOI-6029 b, TOI-4379 b). We find that the orbits of hot Jupiters orbiting subgiants that have cooled below $\sim$6250 K are aligned or nearly aligned with the spin-axis of their host stars, indicating rapid tidal realignment after the emergence of a stellar convective envelope. We place an upper limit for the timescale of realignment for hot Jupiters orbiting subgiants at $\sim$500 Myr. Comparison with a simplified tidal evolution model shows that obliquity damping needs to be $\sim$4 orders of magnitude more efficient than orbital period decay to damp the obliquity without destroying the planet, which is consistent with recent predictions for tidal dissipation from inertial waves excited by hot Jupiters on misaligned orbits.

arXiv comment22 pages, 14 figures, 3 tables

References in corpus (62)

• Astropy: A Community Python Package for Astronomy
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• Modules for Experiments in Stellar Astrophysics (MESA)
• Gaia Data Release 3: Summary of the content and survey properties
• The Transiting Exoplanet Survey Satellite
• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• Modules for Experiments in Stellar Astrophysics (MESA): Binaries, Pulsations, and Explosions
• MESA Isochrones and Stellar Tracks (MIST). I: Solar-Scaled Models
• Modules for Experiments in Stellar Astrophysics (MESA): Convective Boundaries, Element Diffusion, and Massive Star Explosions
• MESA Isochrones and Stellar Tracks (MIST) 0: Methods for the construction of stellar isochrones
• Modules for Experiments in Stellar Astrophysics (MESA): Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation
• Shrinking binary and planetary orbits by Kozai cycles with tidal friction
• Las Cumbres Observatory Global Telescope Network
• Kepler Presearch Data Conditioning II - A Bayesian Approach to Systematic Error Correction
• The Revised TESS Input Catalog and Candidate Target List
• Dynamical Outcomes of Planet-Planet Scattering
• astroquery: An Astronomical Web-Querying Package in Python
• Kepler Presearch Data Conditioning I - Architecture and Algorithms for Error Correction in Kepler Light Curves
• Hot Stars with Hot Jupiters Have High Obliquities
• AstroImageJ: Image Processing and Photometric Extraction for Ultra-Precise Astronomical Light Curves
• AstroImageJ: Image Processing and Photometric Extraction for Ultra-Precise Astronomical Light Curves (Expanded Edition)
• Origins of Hot Jupiters
• Homogeneous studies of transiting extrasolar planets. IV. Thirty systems with space-based light curves
• Spectrum radial velocity analyser (SERVAL). High-precision radial velocities and two alternative spectral indicators
• Weakened magnetic braking as the origin of anomalously rapid rotation in old field stars
• The California Planet Survey I. Four New Giant Exoplanets
• Tidal dissipation in rotating solar-type stars
• Initial Characteristics of Kepler Long Cadence Data For Detecting Transiting Planets
• Kepler Data Validation I -- Architecture, Diagnostic Tests, and Data Products for Vetting Transiting Planet Candidates
• Precision Stellar Characterization of FGKM Stars using an Empirical Spectral Library
• On Galactic density modeling in the presence of dust extinction
• Kepler Data Validation II -- Transit Model Fitting and Multiple-Planet Search
• Real-time processing of the imaging data from the network of Las Cumbres Observatory Telescopes using BANZAI
• HAT-P-7: A Retrograde or Polar Orbit, and a Third Body
• VIP: Vortex Image Processing package for high-contrast direct imaging
• Radius determination of solar-type stars using asteroseismology: What to expect from the Kepler mission
• Tidal Dissipation in Planet-Hosting Stars: Damping of Spin-Orbit Misalignment and Survival of Hot Jupiters
• The Orbit of WASP-12b is Decaying
• Departure from the constant-period ephemeris for the transiting exoplanet WASP-12 b
• Magnetospheric Truncation, Tidal Inspiral, and the Creation of Short and Ultra-Short Period Planets
• The Rossiter-McLaughlin effect in Exoplanet Research
• A Preponderance of Perpendicular Planets
• Two Transiting Earth-size Planets Near Resonance Orbiting a Nearby Cool Star
• Forward Modeling of the Kepler Stellar Rotation Period Distribution: Interpreting Periods from Mixed and Biased Stellar Populations
• Origins of Hot Jupiters from the Stellar Obliquity Distribution
• Asteroseismic inference on the spin-orbit misalignment and stellar parameters of HAT-P-7
• Orbital Decay of Short-Period Exoplanets via Tidal Resonance Locking
• On the Tidal Dissipation of Obliquity
• The Possible Tidal Demise of Kepler's First Planetary System
• TESS Giants Transiting Giants II: The hottest Jupiters orbiting evolved stars
• The TESS-Keck Survey: Science Goals and Target Selection
• TKS III: A Stellar Obliquity Measurement of TOI-1726 c
• The Curious Case of KOI 4: Confirming Kepler's First Exoplanet
• WASP-71b: a bloated hot Jupiter in a 2.9-day, prograde orbit around an evolved F8 star
• $\text{TESS}$ Giants Transiting Giants I: A Non-inflated Hot Jupiter Orbiting a Massive Subgiant
• On a Possible Solution to the Tidal Realignment Problem for Hot Jupiters
• TOI-2046b, TOI-1181b and TOI-1516b, three new hot Jupiters from \textit{TESS}: planets orbiting a young star, a subgiant and a normal star
• Predicting Granulation "Flicker" and Radial Velocity "Jitter" from Spectroscopic Observables
• Constraining Tidal Quality Factor using Spin Period in Eclipsing Binaries
• TESS Giants Transiting Giants III: An eccentric warm Jupiter supports a period-eccentricity relation for giant planets transiting evolved stars
• TESS Giants Transiting Giants V -- Two hot Jupiters orbiting red-giant hosts

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