TOI-3862 b: A dense super-Neptune deep in the hot Neptune desert
Journal article, 2026
Context. The structure and evolution of close-in exoplanets are shaped by atmospheric loss and migration processes, which give rise to key population features such as the hot Neptune desert, ridge, and savanna-regions of the period-radius space whose boundaries offer critical insights into planetary formation and survival.
Aims. As part of the KESPRINT collaboration, we selected the TESS transiting planet candidate TOI-3862.01 for radial velocity follow-up to confirm its planetary nature and characterize its mass and bulk properties. This planet candidate is of particular interest due to its position in the middle of the hot Neptune desert, making it a valuable probe for testing theories of planet migration and atmospheric loss.
Methods. We confirmed the planetary nature and determined the mass of TOI-3862.01 (hereinafter TOI-3862 b) by performing a joint fit with both transit and radial velocity data, precisely characterizing the bulk properties of this planet.
Results. TOI-3862b is a super-Neptune on a 1.56-day orbit around a Sun-like star with an effective temperature of 5300±50 K. It has a mass of 53.7−2.9+2.8 M⊕ and a radius of 5.53 ± 0.18 R⊕, corresponding to a density of 1.7±0.2 g/cm3. This places it among the rare population of hot and dense super-Neptune desert planets. Conclusions. TOI-3862b, residing deep in the hot Neptune desert, represents a rare occurrence in an otherwise sparsely populated region, offering a valuable opportunity to probe the processes that may allow planets to survive in such environments.
Aims. As part of the KESPRINT collaboration, we selected the TESS transiting planet candidate TOI-3862.01 for radial velocity follow-up to confirm its planetary nature and characterize its mass and bulk properties. This planet candidate is of particular interest due to its position in the middle of the hot Neptune desert, making it a valuable probe for testing theories of planet migration and atmospheric loss.
Methods. We confirmed the planetary nature and determined the mass of TOI-3862.01 (hereinafter TOI-3862 b) by performing a joint fit with both transit and radial velocity data, precisely characterizing the bulk properties of this planet.
Results. TOI-3862b is a super-Neptune on a 1.56-day orbit around a Sun-like star with an effective temperature of 5300±50 K. It has a mass of 53.7−2.9+2.8 M⊕ and a radius of 5.53 ± 0.18 R⊕, corresponding to a density of 1.7±0.2 g/cm3. This places it among the rare population of hot and dense super-Neptune desert planets. Conclusions. TOI-3862b, residing deep in the hot Neptune desert, represents a rare occurrence in an otherwise sparsely populated region, offering a valuable opportunity to probe the processes that may allow planets to survive in such environments.
techniques: radial velocities
planets and satellites: detection
stars: fundamental parameters
planets and satellites: fundamental parameters
Author
Ilaria Carleo
Istituto nazionale di astrofisica (INAF)
Instituto de Astrofísica de Canarias
A. Castro-González
University of Geneva
Enric Palle
University of La Laguna
Instituto de Astrofísica de Canarias
F. Murgas
University of La Laguna
Instituto de Astrofísica de Canarias
G. Nowak
Nicolaus Copernicus University (SGMK)
G. Lacedelli
University of La Laguna
Instituto de Astrofísica de Canarias
T. Masseron
Instituto de Astrofísica de Canarias
University of La Laguna
Emily W. Wong
University of Geneva
Patrick Eggenberger
University of Geneva
V. Bourrier
University of Geneva
D. Jankowski
Nicolaus Copernicus University (SGMK)
K. Goździewski
Nicolaus Copernicus University (SGMK)
Douglas R. Alves
University of Chile (UCH)
Centro de Astrofísica y Tecnologías Afines (CATA),
James S. Jenkins
Diego Portales University
Centro de Astrofísica y Tecnologías Afines (CATA),
Sergio Messina
Istituto nazionale di astrofisica (INAF)
Keivan G. Stassun
Vanderbilt University
José I. Vines
University of Chile (UCH)
M. Brogi
Istituto nazionale di astrofisica (INAF)
University of Turin
D. R. Ciardi
California Institute of Technology (Caltech)
Catherine A. Clark
California Institute of Technology (Caltech)
William D. Cochran
University of Texas
Karen A. Collins
Harvard-Smithsonian Center for Astrophysics
H. Deeg
University of La Laguna
Instituto de Astrofísica de Canarias
Elise Furlan
California Institute of Technology (Caltech)
D. Gandolfi
University of Turin
S. Geraldía-González
University of La Laguna
Instituto de Astrofísica de Canarias
A. Hatzes
Thüringer Landessternwarte Tautenburg
Coel Hellier
Keele University
S.B. Howell
National Aeronautics and Space Administration (NASA)
Judith Korth
University of Geneva
J. Lillo-Box
European Space Agency (ESA)
J.H. Livingston
The Graduate University for Advanced Studies (SOKENDAI)
National Astronomical Observatory of Japan
National Institutes of Natural Sciences
J. Orell-Miquel
University of Texas
Carina Persson
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
S. Redfield
Wesleyan University
B. S. Safonov
Moscow State University
D. Baker
Austin College
Rafael Delfin Barrena Delgado
University of La Laguna
Instituto de Astrofísica de Canarias
Allyson Bieryla
Harvard-Smithsonian Center for Astrophysics
A. W. Boyle
California Institute of Technology (Caltech)
College of Arts & Sciences
P. Bosch-Cabot
Albanyà Astronomical Observatory
Núria Casasayas-Barris
Instituto de Astrofísica de Canarias
University of La Laguna
Stavros Chairetas
Instituto de Astrofísica de Canarias
Jerome P. De Leon
University of Tokyo
Izuru Fukuda
University of Tokyo
A. Fukui
University of Tokyo
Instituto de Astrofísica de Canarias
P. Guerra
Albanyà Astronomical Observatory
Kai Ikuta
Hitotsubashi University
Kiyoe Kawauchi
College of Life Sciences
Emil Knudstrup
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Aarhus University
Florence Libotte
Sabadell Astronomical Society
Instituto de Astrofísica de Canarias
Belgian Institute for Space Aeronomy (BIRA-IASB)
M. B. Lund
California Institute of Technology (Caltech)
R. Luque
Spanish National Research Council (CSIC)
Eduardo Lorenzo Martín Guerrero De Escalante
Instituto de Astrofísica de Canarias
Bob Massey
Edward J. Michaels
Waffelow Creek Observatory
Giuseppe Morello
Spanish National Research Council (CSIC)
Istituto nazionale di astrofisica (INAF)
Norio Narita
University of Tokyo
National Institutes of Natural Sciences
Instituto de Astrofísica de Canarias
Hannu Parvianien
University of La Laguna
Instituto de Astrofísica de Canarias
R. Schwarz
Harvard-Smithsonian Center for Astrophysics
Avi Shporer
Massachusetts Institute of Technology (MIT)
M. Stangret
Instituto de Astrofísica de Canarias
University of La Laguna
Noriharu Watanabe
University of Tokyo
Cristilyn N. Watkins
Independent researcher
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 707 A4Exoplanets from space -CHEOPS and PLATO ESA's next two projects (Phase 2)
Swedish National Space Board (65/19), 2020-01-01 -- 2022-12-31.
Swedish National Space Board (177/19), 2020-01-01 -- 2022-12-31.
Subject Categories (SSIF 2025)
Astronomy, Astrophysics, and Cosmology
DOI
10.1051/0004-6361/202557186