Mass estimates of the young TOI-451 transiting planets: multidimensional Gaussian Process on stellar spectroscopic and photometric signals

ABSTRACT The young TOI-451 planetary system, aged 125 Myr, provides a unique opportunity to test theories of planetary internal structures and atmospheric mass-loss through examination of its three transiting planets. We present an exhaustive photometric and spectroscopic follow-up to determine the orbital and physical properties of the system. We perform multidimensional Gaussian Process regression with the code pyaneti on spectroscopic time-series and NGTS/LCO light curves to disentangle the stellar and planetary signal in ESPRESSO radial velocities. We show how contemporaneous photometry serves as an activity indicator to inform RV modelling within a multidimensional Gaussian Processes framework. We argue that this can be exploited when spectroscopic observations are adversely affected by low signal-to-noise and/or poor sampling. We estimate the Doppler semi-amplitudes of $k_{\rm b}=$ $2.6_{-1.2}^{+1.1}$ $\mathrm{m\, s^{-1}}$, $k_{\rm c}=$ $1.2_{-0.8}^{+1.0}$ $\mathrm{m\, s^{-1}}$ , and $k_{\rm d}=$ $2.7 \pm 1.2$ $\mathrm{m\, s^{-1}}$ . This translates in 2$\sigma$ mass estimates for TOI-451 b and d of $M_{\rm b}=$ $4.7_{-2.2}^{+2.1}$ $\mathrm{M_{\rm{\oplus }}}$ and $M_{\rm d}=$ $10.2_{-4.5}^{+4.6}$ $\mathrm{M_{\rm{\oplus }}}$; as well as a mass upper limit for TOI-451 c of $M_{\rm c} \lt 11.5\, M_{\rm{\oplus }}$. The derived planetary properties suggest that planets c and d contain significant hydrogen-rich envelopes. The inferred parameters of TOI-451 b are consistent with either a rocky world that still retains a small hydrogen envelope or a water world. These insights make the TOI-451 system an ideal laboratory for future follow-up studies aimed at measuring atmospheric compositions, detecting atmospheric mass-loss signatures, and further exploring planetary formation and evolution processes.

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Publication Details

Journal
Monthly Notices of the Royal Astronomical Society
Published
2026-01-14
DOI
https://doi.org/10.1093/mnras/stag087
Primary Topic
Stellar, planetary, and galactic studies
Type
article
Field-Weighted Citation Impact
0.00

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article

Mass estimates of the young TOI-451 transiting planets: multidimensional Gaussian Process on stellar spectroscopic and photometric signals

Baptiste Klein, Edward Gillen, Annabella Meech, S. Saha et al.
Monthly Notices of the Royal Astronomical Society
Stellar, planetary, and galactic studies
article

Mass estimates of the young TOI-451 transiting planets: multidimensional Gaussian Process on stellar spectroscopic and photometric signals

Baptiste Klein, Edward Gillen, Annabella Meech, S. Saha, M. Mallorquín, James J. McCormac, S. Aigrain, M. Cretignier, Faith Hawthorn, P. Cortés-Zuleta, Haochuan Yu, Edward M. Bryant, Louise D. Nielsen, M. Lafarga, José I Vines, D. R. Anderson, Matthew P. Battley, N. Lodieu, M. Moyano, T. G. Wilson, Alix Violet Freckelton, Ioannis Apergis, R. J. West, Annelies Mortier, J. M. Jenkins, Felipe Mergas, Erik A. Meier-Valdés, Samuel Gill, Peter J Wheatley, Oscar Barragán, Yoshi N E Eschen, Víctor J S Béjar, Jorge Fernández-Fernández
article en

Abstract

ABSTRACT The young TOI-451 planetary system, aged 125 Myr, provides a unique opportunity to test theories of planetary internal structures and atmospheric mass-loss through examination of its three transiting planets. We present an exhaustive photometric and spectroscopic follow-up to determine the orbital and physical properties of the system. We perform multidimensional Gaussian Process regression with the code pyaneti on spectroscopic time-series and NGTS/LCO light curves to disentangle the stellar and planetary signal in ESPRESSO radial velocities. We show how contemporaneous photometry serves as an activity indicator to inform RV modelling within a multidimensional Gaussian Processes framework. We argue that this can be exploited when spectroscopic observations are adversely affected by low signal-to-noise and/or poor sampling. We estimate the Doppler semi-amplitudes of $k_{\rm b}=$ $2.6_{-1.2}^{+1.1}$ $\mathrm{m\, s^{-1}}$, $k_{\rm c}=$ $1.2_{-0.8}^{+1.0}$ $\mathrm{m\, s^{-1}}$ , and $k_{\rm d}=$ $2.7 \pm 1.2$ $\mathrm{m\, s^{-1}}$ . This translates in 2$\sigma$ mass estimates for TOI-451 b and d of $M_{\rm b}=$ $4.7_{-2.2}^{+2.1}$ $\mathrm{M_{\rm{\oplus }}}$ and $M_{\rm d}=$ $10.2_{-4.5}^{+4.6}$ $\mathrm{M_{\rm{\oplus }}}$; as well as a mass upper limit for TOI-451 c of $M_{\rm c} \lt 11.5\, M_{\rm{\oplus }}$. The derived planetary properties suggest that planets c and d contain significant hydrogen-rich envelopes. The inferred parameters of TOI-451 b are consistent with either a rocky world that still retains a small hydrogen envelope or a water world. These insights make the TOI-451 system an ideal laboratory for future follow-up studies aimed at measuring atmospheric compositions, detecting atmospheric mass-loss signatures, and further exploring planetary formation and evolution processes.

Monthly Notices of the Royal Astronomical SocietyVol. 546(2)
University of Geneva (CH), Universidad de La Laguna (ES), Queen Mary University of London (GB), University of St Andrews (GB), Universidad Católica del Norte (CL), University of Warwick (GB), University of Oxford (GB), Chinese Academy of Science South America Center for Astronomy (CL), Center for Astrophysics Harvard & Smithsonian (US), Instituto de Astrofísica de Canarias (ES), University of Birmingham (GB), Ludwig-Maximilians-Universität München (DE), Universidad Diego Portales (CL)
National Science Foundation, National Aeronautics and Space Administration, California Institute of Technology, UK Research and Innovation, Ministerio de Ciencia, Innovación y Universidades, European Commission, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Ministerio de Ciencia e Innovación, Agencia Nacional de Investigación y Desarrollo, Jet Propulsion Laboratory, University of California, Los Angeles, Science and Technology Facilities Council, Agencia Estatal de Investigación
Openalex Percentile: Top 86%
Stellar, planetary, and galactic studies
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