Discovery of TOI-1260d and the characterisation of the multi-planet system

Abstract

We report the discovery of a third planet transiting the star TOI-1260, previously known to host two transiting sub-Neptune planets with orbital periods of 3.127 and 7.493 days, respectively. The nature of the third transiting planet with a 16.6-day orbit is supported by ground-based follow-up observations, including time-series photometry, high-angular resolution images, spectroscopy, and archival imagery. Precise photometric monitoring with CHEOPS allows to improve the constraints on the parameters of the system, improving our knowledge on their composition. The improved radii of TOI-1260b, TOI-1260c are $2.36\pm 0.06{\mathrm{R}}_{\oplus }$, $2.82\pm 0.08{\mathrm{R}}_{\oplus }$, respectively while the newly discovered third planet has a radius of $3.09\pm 0.09{\mathrm{R}}_{\oplus }$. The radius uncertainties are in the range of 3\%, allowing a precise interpretation of the interior structure of the three planets. Our planet interior composition model suggests that all three planets in the TOI-1260 system contains some fraction of gas. The innermost planet TOI-1260b has most likely lost all of its primordial hydrogen-dominated envelope. Planets c and d were also likely to have experienced significant loss of atmospheric through escape, but to a lesser extent compared to planet b.

18 pages, 10 figures, accepted for publication in MNRAS

References in corpus (25)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Gaia Early Data Release 3: Parallax bias versus magnitude, colour, and position
• Growth Model Interpretation of Planet Size Distribution
• The TESS Objects of Interest Catalog from the TESS Prime Mission
• The CHEOPS mission
• CLES, Code Liegeois d'Evolution Stellaire
• Stellar Winds on the Main-Sequence II: the Evolution of Rotation and Winds
• Six transiting planets and a chain of Laplace resonances in TOI-178
• AQUA: A Collection of H${}_2$O Equations of State for Planetary Models
• On Correlated-noise Analyses Applied To Exoplanet Light Curves
• Revising the ages of planet-hosting stars
• The hot dayside and asymmetric transit of WASP-189b seen by CHEOPS
• Transit detection of the long-period volatile-rich super-Earth ${\nu }^2$ Lupi d with $CHEOPS$
• CHEOPS observations of the HD 108236 planetary system: A fifth planet, improved ephemerides, and planetary radii
• GJ 367b: A dense ultra-short period sub-Earth planet transiting a nearby red dwarf star
• WASP-186 and WASP-187: two hot Jupiters discovered by SuperWASP and SOPHIE with additional observations by TESS
• A pair of Sub-Neptunes transiting the bright K-dwarf TOI-1064 characterised with CHEOPS
• Reinvestigating $\alpha$ Cen AB in light of asteroseismic forward and inverse methods
• Spi-OPS: Spitzer and CHEOPS confirm the near-polar orbit of MASCARA-1 b and reveal a hint of dayside reflection
• Close-in sub-Neptunes reveal the past rotation history of their host stars: atmospheric evolution of planets in the HD3167 and K2-32 planetary systems
• The Kepler-11 system: evolution of the stellar high-energy emission and {initial planetary} atmospheric mass fractions
• Investigating the architecture and internal structure of the TOI-561 system planets with CHEOPS, HARPS-N and TESS
• Evidence of energy-, recombination-, and photon-limited escape regimes in giant planet H/He atmospheres
• The Bimodal Distribution in Exoplanet Radii: Considering Varying Core Compositions and ${\mathrm{H}}_2$ Envelope's Sizes
• Hot planets around cool stars -- two short-period mini-Neptunes transiting the late K-dwarf TOI-1260

Cited by in corpus (1)

• Shallower radius valley around low-mass hosts: Evidence for icy planets, collisions or high-energy radiation scatter