Three super-Earths and a possible water world from TESS and ESPRESSO

Abstract

Since 2018, the ESPRESSO spectrograph at the VLT has been hunting for planets in the Southern skies via the RV method. One of its goals is to follow up candidate planets from transit surveys such as the TESS mission, particularly small planets. We analyzed photometry from TESS and ground-based facilities, high-resolution imaging, and RVs from ESPRESSO, HARPS, and HIRES, to confirm and characterize three new planets: TOI-260 b, transiting a late K-dwarf, and TOI-286 b and c, orbiting an early K-dwarf. We also update parameters for the known super-Earth TOI-134 b , hosted by an M-dwarf. TOI-260 b has a $13.475853_{-0.000011}^{+0.000013}$ d period, $4.23\pm 1.60{\mathrm{M}}_{\oplus }$ mass and $1.71\pm 0.08{\mathrm{R}}_{\oplus }$ radius. For TOI-286 b we find a $4.5117244_{-0.0000027}^{+0.0000031}$ d period, $4.53\pm 0.78{\mathrm{M}}_{\oplus }$ mass and $1.42\pm 0.10{\mathrm{R}}_{\oplus }$ radius; for TOI-286 c, a $39.361826_{-0.000081}^{+0.000070}$ d period, $3.72\pm 2.22{\mathrm{M}}_{\oplus }$ mass and $1.88\pm 0.12{\mathrm{R}}_{\oplus }$ radius. For TOI-134 b we obtain a $1.40152604_{-0.00000082}^{+0.00000074}$ d period, $4.07\pm 0.45{\mathrm{M}}_{\oplus }$ mass, and $1.63\pm 0.14{\mathrm{R}}_{\oplus }$ radius. Circular models are preferred for all, although for TOI-260 b the eccentricity is not well-constrained. We compute bulk densities and place the planets in the context of composition models. TOI-260 b lies within the radius valley, and is most likely a rocky planet. However, the uncertainty on the eccentricity and thus on the mass renders its composition hard to determine. TOI-286 b and c span the radius valley, with TOI-286 b lying below it and having a likely rocky composition, while TOI-286 c is within the valley, close to the upper border, and probably has a significant water fraction. With our updated parameters for TOI-134 b, we obtain a lower density than previous findings, giving a rocky or Earth-like composition.

61 pages (of which pp. 24-61 are appendices), 20 figures (main text). Accepted for publication in A&A

References in corpus (28)

• The Gaia mission
• Gaia Data Release 3: Summary of the content and survey properties
• The Transiting Exoplanet Survey Satellite
• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• Growth Model Interpretation of Planet Size Distribution
• Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system
• The TESS Objects of Interest Catalog from the TESS Prime Mission
• Density, not radius, separates rocky and water-rich small planets orbiting M dwarf stars
• The Hipparcos-Gaia Catalog of Accelerations: Gaia EDR3 Edition
• The HARPS search for southern extra-solar planets. X. A m sin i = 11 Mearth planet around the nearby spotted M dwarf GJ 674
• Stellar and substellar companions from Gaia EDR3 -- Proper motion anomaly and resolved common proper motion pairs
• Revisited Mass-Radius relations for exoplanets below 120 Earth masses
• The CARMENES search for exoplanets around M dwarfs: Different roads to radii and masses of the target stars
• Magnetic activity in the HARPS M-dwarf sample. The rotation-activity relationship for very low-mass stars through R'HK
• Fluxes in Hαand Ca II H and K for a sample of Southern stars
• Main-Sequence Effective Temperatures from a Revised Mass-Luminosity Relation Based on Accurate Properties
• High-resolution imaging of $Kepler$ planet host candidates. A comprehensive comparison of different techniques
• A Spectroscopic Analysis of the California-Kepler Survey Sample: I. Stellar Parameters, Planetary Radii and a Slope in the Radius Gap
• Empirical limb-darkening coefficients & transit parameters of known exoplanets from TESS
• The Densities of Planets in Multiple Stellar Systems
• The Na I D resonance lines in main sequence late-type stars
• A fading radius valley towards M-dwarfs, a persistent density valley across stellar types
• Why do warm Neptunes present nonzero eccentricity?
• SteParSyn: A Bayesian code to infer stellar atmospheric parameters using spectral synthesis
• ExoMDN: Rapid characterization of exoplanet interior structures with Mixture Density Networks
• An unusually low-density super-Earth transiting the bright early-type M-dwarf GJ 1018 (TOI-244)
• The K2-OjOS Project: New and revisited planets and candidates in K2 campaigns 5, 16, & 18
• Planetary system around LTT 1445A unveiled by ESPRESSO: Multiple planets in a triple M-dwarf system

Cited by in corpus (3)

• Two neighbours of the ultra-short-period Earth-sized planet K2-157 b in the warm Neptunian savanna
• Tidally Heated Sub-Neptunes, Refined Planetary Compositions, and Confirmation of a Third Planet in the TOI-1266 System
• No Robust Statistical Evidence for a Population of Water Worlds in a 2025 Sample of Planets Orbiting M Stars