NEID Rossiter-McLaughlin Measurement of TOI-1268b: A Young Warm Saturn Aligned with Its Cool Host Star

Abstract

Close-in gas giants present a surprising range of stellar obliquity, the angle between a planet's orbital axis and its host star's spin axis. It is unclear whether the obliquities reflect the planets' dynamical history (e.g., aligned for in situ formation or disk migration versus misaligned for high-eccentricity tidal migration) or whether other mechanisms (e.g., primordial misalignment or planet-star interactions) are more important in sculpting the obliquity distribution. Here we present the stellar obliquity measurement of TOI-1268 (TIC-142394656, $V_{\mathrm{mag}}\sim 10.9$), a young K-type dwarf hosting an 8.2-day period, Saturn-sized planet. TOI-1268's lithium abundance and rotation period suggest the system age between the ages of Pleiades cluster ($\sim 120$ Myr) and Praesepe cluster ($\sim 670$ Myr). Using the newly commissioned NEID spectrograph, we constrain the stellar obliquity of TOI-1268 via the Rossiter-McLaughlin (RM) effect from both radial velocity (RV) and Doppler Tomography (DT) signals. The 3$\sigma$ upper bounds of the projected stellar obliquity $|\lambda |$ from both models are below 60${}^{\circ }$. The large host star separation ($a/R_{\star }\sim 17$), combined with the system's young age, makes it unlikely that the planet has realigned its host star. The stellar obliquity measurement of TOI-1268 probes the architecture of a young gas giant beyond the reach of tidal realignment ($a/R_{\star }\gtrsim 10$) and reveals an aligned or slightly misaligned system.

14 pages, 6 figures, 1 table, accepted for publication in ApJL; see independent work by Subjak et al. for RV follow-up of TOI-1268

References in corpus (29)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• The NumPy array: a structure for efficient numerical computation
• The Transiting Exoplanet Survey Satellite
• Gaia Early Data Release 3: The astrometric solution
• EXOFAST: A fast exoplanetary fitting suite in IDL
• Spectrum radial velocity analyser (SERVAL). High-precision radial velocities and two alternative spectral indicators
• Three regimes of extrasolar planets inferred from host star metallicities
• A spin-down clock for cool stars from observations of a 2.5-billion-year-old cluster
• exoplanet: Gradient-based probabilistic inference for exoplanet data & other astronomical time series
• Hot Jupiters from Coplanar High-eccentricity Migration
• Analytic Planetary Transit Light Curves and Derivatives for Stars with Polynomial Limb Darkening
• K2 rotation periods for low-mass Hyads and a quantitative comparison of the distribution of slow rotators in the Hyades and Praesepe
• A Temporary Epoch of Stalled Spin-Down for Low-Mass Stars: Insights from NGC 6811 with Gaia and Kepler
• On the Inference of a Star's Inclination Angle from its Rotation Velocity and Projected Rotation Velocity
• WIYN Open Cluster Study. LXXV. Testing the Metallicity Dependence of Stellar Lithium Depletion Using Hyades-Aged Clusters. 1. Hyades & Praesepe
• EXOFASTv2: A public, generalized, publication-quality exoplanet modeling code
• A comprehensive radial velocity error budget for next generation Doppler spectrometers
• A Versatile Technique to Enable sub-milli-Kelvin Instrument Stability for Precise Radial Velocity Measurements: Tests with the Habitable-zone Planet Finder
• Limits on the Spin-Orbit Angle and Atmospheric Escape for the 22 Myr-old Planet AU Mic b
• TESS Hunt for Young and Maturing Exoplanets (THYME) V: A Sub-Neptune Transiting a Young Star in a Newly Discovered 250 Myr Association
• Two young planetary systems around field stars with ages between 20-320 Myr from TESS
• BAFFLES: Bayesian Ages for Field Lower-Mass Stars
• A Closer Look at Exoplanet Occurrence Rates: Considering the Multiplicity of Stars Without Detected Planets
• Boron Abundances Across the "Li-Be Dip" in the Hyades
• ShaneAO: wide science spectrum adaptive optics system for the Lick Observatory
• H-alpha and Ca II Infrared Triplet Variations During a Transit of the 23 Myr Planet V1298 Tau c
• The obliquity of HIP 67522 b: a 17 Myr old transiting hot Jupiter-sized planet
• Discovery of a White Dwarf Companion to HD 159062

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• TOI-1859b: A 64-Day Warm Jupiter on an Eccentric and Misaligned Orbit
• TOI-1268b: the youngest, hot, Saturn-mass transiting exoplanet
• The Spin-Orbit Misalignment of TOI-1842b: The First Measurement of the Rossiter-McLaughlin Effect for a Warm Sub-Saturn around a Massive Star
• TOI-4562 b: A highly eccentric temperate Jupiter analog orbiting a young field star
• The effect of cloudy atmospheres on the thermal evolution of warm giant planets from an interior modelling perspective
• Evidence for Primordial Alignment II: Insights from Stellar Obliquity Measurements for Hot Jupiters in Compact Multiplanet Systems
• TOI-2005b: An Eccentric Warm Jupiter in Spin-Orbit Alignment
• The OATMEAL Survey. III. An Aligned Transiting Warm Brown Dwarf and Evidence for Quiescent Brown Dwarf Migration
• Homogeneous search for spot transits in Kepler and TESS photometry of K $-$ M-type main-sequence stars
• Evidence for the Late Arrival of Hot Jupiters in Systems with High Host-star Obliquities