TOI-954 b and K2-329 b: Short-Period Saturn-Mass Planets that Test whether Irradiation Leads to Inflation

Abstract

We report the discovery of two short-period Saturn-mass planets, one transiting the G subgiant TOI-954 (TIC 44792534, $V=10.343$, $T=9.78$) observed in TESS sectors 4 and 5, and one transiting the G dwarf K2-329 (EPIC 246193072, $V=12.70$, $K=10.67$) observed in K2 campaigns 12 and 19. We confirm and characterize these two planets with a variety of ground-based archival and follow-up observations, including photometry, reconnaissance spectroscopy, precise radial velocity, and high-resolution imaging. Combining all available data, we find that TOI-954 b has a radius of $0.852_{-0.062}^{+0.053}{R}_{\mathrm{J}}$ and a mass of $0.174_{-0.017}^{+0.018}{M}_{\mathrm{J}}$ and is in a 3.68 day orbit, while K2-329 b has a radius of $0.774_{-0.024}^{+0.026}{R}_{\mathrm{J}}$ and a mass of $0.260_{-0.022}^{+0.020}{M}_{\mathrm{J}}$ and is in a 12.46 day orbit. As TOI-954 b is 30 times more irradiated than K2-329 b but more or less the same size, these two planets provide an opportunity to test whether irradiation leads to inflation of Saturn-mass planets and contribute to future comparative studies that explore Saturn-mass planets at contrasting points in their lifetimes.

arXiv comment28 pages, 9 figures, 11 tables, accepted by AJ, ancillary data also available at https://github.com/vulpicastor/toi954-data

References in corpus (59)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• Astropy: A Community Python Package for Astronomy
• emcee: The MCMC Hammer
• Gaia Data Release 2. Summary of the contents and survey properties
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• The Transiting Exoplanet Survey Satellite
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• MESA Isochrones and Stellar Tracks (MIST). I: Solar-Scaled Models
• MESA Isochrones and Stellar Tracks (MIST) 0: Methods for the construction of stellar isochrones
• batman: BAsic Transit Model cAlculatioN in Python
• The Revised TESS Input Catalog and Candidate Target List
• Planetary Radii across Five Orders of Magnitude in Mass and Stellar Insolation: Application to Transits
• A box-fitting algorithm in the search for periodic transits
• Achieving better than 1 minute accuracy in the Heliocentric and Barycentric Julian Dates
• Efficient, uninformative sampling of limb darkening coefficients for two-parameter laws
• The NASA Exoplanet Archive: Data and Tools for Exoplanet Research
• EXOFAST: A fast exoplanetary fitting suite in IDL
• 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)
• Probabilistic Forecasting of the Masses and Radii of Other Worlds
• A Technique for Extracting Highly Precise Photometry for the Two-Wheeled Kepler Mission
• RadVel: The Radial Velocity Modeling Toolkit
• Accurate, Empirical Radii and Masses of Planets and their Host Stars with Gaia Parallaxes
• Nominal values for selected solar and planetary quantities: IAU 2015 Resolution B3
• HAT-P-11b: A Super-Neptune Planet Transiting a Bright K Star in the Kepler Field
• Possible Solutions to the Radius Anomalies of Transiting Giant Planets
• The GAPS Programme with HARPS-N@TNG XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets
• Evidence for a systematic offset of -80 micro-arcseconds in the Gaia DR2 parallaxes
• The Transit Light Curve Project. IX. Evidence for a Smaller Radius of the Exoplanet XO-3b
• Kepler Data Validation I -- Architecture, Diagnostic Tests, and Data Products for Vetting Transiting Planet Candidates
• Limb and gravity-darkening coefficients for the TESS satellite at several metallicities, surface gravities, and microturbulent velocities
• The K2 Ecliptic Plane Input Catalog (EPIC) and Stellar Classifications of 138,600 Targets in Campaigns 1-8
• CHIRON - A Fiber Fed Spectrometer for Precise Radial Velocities
• A Trend Filtering Algorithm for wide field variability surveys
• Lack of Inflated Radii for Kepler Giant Planet Candidates Receiving Modest Stellar Irradiation
• SOAR TESS Survey. I: Sculpting of TESS planetary systems by stellar companions
• CERES: A Set of Automated Routines for Echelle Spectra
• HATSouth: a global network of fully automated identical wide-field telescopes
• Planetary Candidates from the First Year of the K2 Mission
• Eclipsing Binary Stars as Benchmarks for Trigonometric Parallaxes in the Gaia Era
• Spin-Orbit Evolution Of Short-Period Planets
• New constraints on Saturn's interior from Cassini astrometric data
• Ten years of speckle interferometry at SOAR
• Empirical, Accurate Masses and Radii of Single Stars with TESS and Gaia
• The Complete transmission spectrum of WASP-39b with a precise water constraint
• Minerva-Australis I: Design, Commissioning, & First Photometric Results
• A Definition for Giant Planets Based on the Mass-Density Relationship
• LAMOST telescope reveals that Neptunian cousins of hot Jupiters are mostly single offspring of stars that are rich in heavy elements
• A Hot Saturn Orbiting An Oscillating Late Subgiant Discovered by TESS
• A Super-Solar Metallicity For Stars With Hot Rocky Exoplanets
• Factors Affecting the Radii of Close-in Transiting Exoplanets
• Four Sub-Saturns with Dissimilar Densities: Windows into Planetary Cores and Envelopes
• The transiting multi-planet system HD3167: a 5.7 MEarth Super-Earth and a 8.3 MEarth mini-Neptune
• HAT-P-65b and HAT-P-66b: Two Transiting Inflated Hot Jupiters and Observational Evidence for the Re-Inflation of Close-In Giant Planets
• TOI-257b (HD 19916b): A Warm sub-Saturn Orbiting an Evolved F-type Star
• KELT-6b: A P~7.9 d Hot Saturn Transiting a Metal-Poor Star with a Long-Period Companion
• HATS-43b, HATS-44b, HATS-45b, and HATS-46b: Four Short Period Transiting Giant Planets in the Neptune-Jupiter Mass Range

Cited by in corpus (8)

• TESS Delivers Five New Hot Giant Planets Orbiting Bright Stars from the Full Frame Images
• The TESS Grand Unified Hot Jupiter Survey. II. Twenty New Giant Planets
• The TESS Grand Unified Hot Jupiter Survey. I. Ten TESS Planets
• TOI-1842b: A Transiting Warm Saturn Undergoing Re-Inflation around an Evolving Subgiant
• The Spin-Orbit Alignment of 8 Warm Gas Giant Systems
• Hundreds of TESS exoplanets might be larger than we thought
• A close-in puffy Neptune with hidden friends: The enigma of TOI 620
• Kepler's Last Planet Discoveries: Two New Planets and One Single-Transit Candidate from K2 Campaign 19