Hot, rocky and warm, puffy super-Earths orbiting TOI-402 (HD 15337)

Abstract

TESS is revolutionising the search for planets orbiting bright and nearby stars. In sectors 3 and 4, TESS observed TOI-402 (TIC-120896927), a bright V=9.1 K1 dwarf also known as HD 15337, and found two transiting signals with period of 4.76 and 17.18 days and radius of 1.90 and 2.21\,\Rearth. This star was observed as part of the radial-velocity search for planets using the HARPS spectrometer, and 85 precise radial-velocity measurements were obtained over a period of 14 years. In this paper, we analyse the HARPS radial-velocity measurements in hand to confirm the planetary nature of these two signals. By reanalysing TESS photometry and host star parameters using EXOFASTv2, we find that TOI-402.01 and TOI-402.02 have periods of 4.75642$\pm$0.00021 and 17.1784$\pm$0.0016 days and radii of 1.70$\pm$0.06 and 2.52$\pm$0.11\,\Rearth\,(precision 3.6 and 4.2\%), respectively. By analysing the HARPS radial-velocity measurements, we find that those planets are both super-Earths with masses of 7.20$\pm$0.81 and 8.79$\pm$1.67\,\Mearth\,(precision 11.3 and 19.0\%), and small eccentricities compatible with zero at 2$\sigma$. Although having rather similar masses, the radius of these two planets is really different, putting them on different sides of the radius gap. With stellar irradiation 160 times more important than Earth for TOI-402.01 and only 29 times more for TOI-402.02, it is likely that photo-evaporation is at the origin of this radius difference. Those two planets, being in the same system and therefore being in the same irradiation environment are therefore extremely important to perform comparative exoplanetology across the evaporation valley and thus bring constraints on the mechanisms responsible for the radius gap.

25 pages, 16 figures, 6 tables, accepted in A&A

References in corpus (37)

• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics
• Astrophysics Source Code Library
• Mass-Radius Relationships for Solid Exoplanets
• Most 1.6 Earth-Radius Planets are not Rocky
• EXOFAST: A fast exoplanetary fitting suite in IDL
• Atmospheric Escape from Hot Jupiters
• On the radiative equilibrium of irradiated planetary atmospheres
• Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system
• Rayleigh scattering in the transit spectrum of HD 189733b
• Planetary population synthesis coupled with atmospheric escape: a statistical view of evaporation
• Can we constrain interior structure of rocky exoplanets from mass and radius measurements?
• Three regimes of extrasolar planets inferred from host star metallicities
• A new code for automatic determination of equivalent widths: Automatic Routine for line Equivalent widths in stellar Spectra (ARES)
• Stellar Abundances in the Solar Neighborhood: The Hypatia Catalog
• The Extreme Ultraviolet and X-Ray Sun in Time: High-Energy Evolutionary Tracks of a Solar-Like Star
• Inevitability of Plate Tectonics on Super-Earths
• ARES v2 - new features and improved performance
• A generalized bayesian inference method for constraining the interiors of super Earths and sub-Neptunes
• Hubble PanCET: An extended upper atmosphere of neutral hydrogen around the warm Neptune GJ 3470 b
• Accurate fundamental parameters for Lower Main Sequence Stars
• A Kepler Study of Starspot Lifetimes with Respect to Light Curve Amplitude and Spectral Type
• High-resolution confirmation of an extended helium atmosphere around WASP-107b
• Characterization of exoplanets from their formation III: The statistics of planetary luminosities
• Radial-Velocity Fitting Challenge. II. First results of the analysis of the data set
• Kepler-21b: A rocky planet around a V = 8.25 magnitude star
• Characterization of the K2-18 multi-planetary system with HARPS: A habitable zone super-Earth and discovery of a second, warm super-Earth on a non-coplanar orbit
• A temperate exo-Earth around a quiet M dwarf at 3.4 parsecs
• The HARPS search for southern extra-solar planets. XXXI. Magnetic activity cycles in solar-type stars: statistics and impact on precise radial velocities
• The HARPS search for southern extra-solar planets XLII. A system of Earth-mass planets around the nearby M dwarf YZ Ceti
• Three Small Super-Earths Transiting the nearby star GJ 9827
• No hydrogen exosphere detected around the super-Earth HD97658 b
• The Transiting Multi-planet System HD15337: Two Nearly Equal-mass Planets Straddling the Radius Gap
• The SOPHIE search for northern extrasolar planets. XIV. A temperate ($T_{\mathrm{eq}}\sim 300$ K) super-earth around the nearby star Gliese 411
• A System of Three Super Earths Transiting the Late K-Dwarf GJ 9827 at Thirty Parsecs
• Proxima Centauri reloaded: Unravelling the stellar noise in radial velocities
• Evidence for at least three planet candidates orbiting HD20794

Cited by in corpus (29)

• Revisited Mass-Radius relations for exoplanets below 120 Earth masses
• A public HARPS radial velocity database corrected for systematic errors
• Planetary evolution with atmospheric photoevaporation I. Analytical derivation and numerical study of the evaporation valley and transition from super-Earths to sub-Neptunes
• A super-Earth and a sub-Neptune orbiting the bright, quiet M3 dwarf TOI-1266
• A pair of TESS planets spanning the radius valley around the nearby mid-M dwarf LTT 3780
• The CARMENES search for exoplanets around M dwarfs. Two planets on the opposite sides of the radius gap transiting the nearby M dwarf LTT 3780
• GJ 367b is a dark, hot, airless sub-Earth
• An unusually low density ultra-short period super-Earth and three mini-Neptunes around the old star TOI-561
• A hot terrestrial planet orbiting the bright M dwarf L 168-9 unveiled by TESS
• Utilizing Small Telescopes Operated by Citizen Scientists for Transiting Exoplanet Follow-up
• Mass determinations of the three mini-Neptunes transiting TOI-125
• TOI-431/HIP 26013: a super-Earth and a sub-Neptune transiting a bright, early K dwarf, with a third RV planet
• The Magellan-TESS Survey I: Survey Description and Mid-Survey Results
• Shallower radius valley around low-mass hosts: Evidence for icy planets, collisions or high-energy radiation scatter
• TESS Reveals a Short-period Sub-Neptune Sibling (HD 86226c) to a Known Long-period Giant Planet
• A pair of warm giant planets near the 2:1 mean motion resonance around the K-dwarf star TOI-2202
• TOI-2525 b and c: A pair of massive warm giant planets with a strong transit timing variations revealed by TESS
• HD 191939: Three Sub-Neptunes Transiting a Sun-like Star Only 54 pc Away
• A hot mini-Neptune in the radius valley orbiting solar analogue HD 110113
• Unveiling $\delta$ Scuti and $\gamma$ Doradus Hybrid Pulsation of HD 53166 and HD 53349 Plus Rich Frequencies in HD 52788 -- Catalogs of 70552 $\delta$ Sct and 8080 $\gamma$ Dor
• Exoplanet atmosphere evolution: emulation with neural networks
• Low 4.5 μm Dayside Emission Disfavors a Dark Bare-Rock scenario for the Hot Super-Earth TOI-431 b
• TOI-1696 and TOI-2136: Constraining the Masses of Two Mini-Neptunes with HPF
• Dynamical Architectures of S-type Transiting Planets in Binaries I: Target Selection using Hipparcos and Gaia proper motion anomalies
• Determining Which Binary Component Hosts the TESS Transiting Planet
• Precise characterisation of HD 15337 with CHEOPS: a laboratory for planet formation and evolution
• Uniform Reanalysis of JWST MIRI 15μm Exoplanet Eclipse Observations using Frame-Normalized Principal Component Analysis
• Dynamical Architectures of S-type Transiting Planets in Binaries II: A Dichotomy in Orbital Alignment of Small Planets in Close Binary Systems
• HyDRo: Atmospheric Retrieval of Rocky Exoplanets in Thermal Emission