Exploring the Neptunian desert: insights from a homogeneous planetary sample

ABSTRACT In this paper, we present a homogeneous analysis of close-in Neptune planets. To do this, we compile a sample of TESS-observed planets using a ranking criterion which takes into account the planet’s period, radius, and the visual magnitude of its host star. We use archival and new HARPS data to ensure every target in this sample has precise radial velocities. This yields a total of 64 targets, 46 of which are confirmed planets and 18 of which show no significant radial velocity signal. We explore the mass–radius distribution, planetary density, stellar host metallicity, and stellar and planetary companions of our targets. We find 26 per cent of our sample are in multiplanet systems, which are typically seen for planets located near the lower edge of the Neptunian desert. We define a ‘gold’ subset of our sample consisting of 33 confirmed planets with planetary radii between 2$R_{\oplus}$ and 10$R_{\oplus}$. With these targets, we calculate envelope mass fractions (EMF) using the GAS gianT modeL for Interiors (GASTLI). We find a clear split in EMF between planets with equilibrium temperatures below and above 1300 K, equivalent to an orbital period of $\sim$3.5 d. Below this period, EMFs are consistent with zero, while above they typically range from 20 per cent to 40 per cent, scaling linearly with the planetary mass. The orbital period separating these two populations coincides with the transition between the Neptunian desert and the recently identified Neptunian ridge, further suggesting that different formation and/or evolution mechanisms are at play for Neptune planets across different close-in orbital regions.

Authors

Institutions

Publication Details

Journal
Monthly Notices of the Royal Astronomical Society
Published
2025-04-24
DOI
https://doi.org/10.1093/mnras/staf670
Citations
8
Primary Topic
Astro and Planetary Science
Type
article
Field-Weighted Citation Impact
9.24

Funders

Controls
|||
ALL TIME
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
article

Exploring the Neptunian desert: insights from a homogeneous planetary sample

J. Lillo-Box, Lauren Doyle, J. Rodrigues, R. F. Díaz et al.
8 citations
Monthly Notices of the Royal Astronomical Society
Astro and Planetary Science
9.24
article

Exploring the Neptunian desert: insights from a homogeneous planetary sample

J. Lillo-Box, Lauren Doyle, J. Rodrigues, R. F. Díaz, Léna Parc, A. Santerne, Daniel Bayliss, D. J. Armstrong, Samuel Gill, J. S. Jenkins, A. Castro-González, Marcelo Aron Fetzner Keniger, P. J. Wheatley, Ares Osborn, L. Acuña, D. Barrado, Louise D. Nielsen, M. Lafarga, S. C. C. Barros, N. C. Santos, V. Bourrier, X. Dumusque, Kaiming Cui, Alejandro Hacker, S. G. Sousa, D. R. Alves, O. D. S. Demangeon, Fintan Eeles-Nolle, Isobel S Lockley
article en
8 citations

Abstract

ABSTRACT In this paper, we present a homogeneous analysis of close-in Neptune planets. To do this, we compile a sample of TESS-observed planets using a ranking criterion which takes into account the planet’s period, radius, and the visual magnitude of its host star. We use archival and new HARPS data to ensure every target in this sample has precise radial velocities. This yields a total of 64 targets, 46 of which are confirmed planets and 18 of which show no significant radial velocity signal. We explore the mass–radius distribution, planetary density, stellar host metallicity, and stellar and planetary companions of our targets. We find 26 per cent of our sample are in multiplanet systems, which are typically seen for planets located near the lower edge of the Neptunian desert. We define a ‘gold’ subset of our sample consisting of 33 confirmed planets with planetary radii between 2$R_{\oplus}$ and 10$R_{\oplus}$. With these targets, we calculate envelope mass fractions (EMF) using the GAS gianT modeL for Interiors (GASTLI). We find a clear split in EMF between planets with equilibrium temperatures below and above 1300 K, equivalent to an orbital period of $\sim$3.5 d. Below this period, EMFs are consistent with zero, while above they typically range from 20 per cent to 40 per cent, scaling linearly with the planetary mass. The orbital period separating these two populations coincides with the transition between the Neptunian desert and the recently identified Neptunian ridge, further suggesting that different formation and/or evolution mechanisms are at play for Neptune planets across different close-in orbital regions.

Monthly Notices of the Royal Astronomical SocietyVol. 539(4)
University of Geneva (CH), Consejo Nacional de Investigaciones Científicas y Técnicas (AR), Universidade do Porto (PT), Aix-Marseille Université (FR), National University of General San Martín (AR), University of Warwick (GB), Institute of Astrophysics and Space Sciences (PT), Max Planck Institute for Astronomy (DE), Centro de Astrobiología (ES), Instituto Tecnológico de Buenos Aires (ITBA) (AR), Bagnoud Observatory (CH), International Center for Advanced Studies (AR), University of Chile (CL), Ludwig-Maximilians-Universität München (DE), Universidad Diego Portales (CL), McMaster University (CA)
National Science Foundation, National Aeronautics and Space Administration, California Institute of Technology, UK Research and Innovation, European Space Agency, European Commission, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Centre National d’Etudes Spatiales, Centre National de la Recherche Scientifique, Agencia Nacional de Investigación y Desarrollo, Fundação para a Ciência e a Tecnologia, Agencia Estatal de Investigación
Openalex Percentile: Top 2%
Astro and Planetary Science
9.24
DOIOpen Access PDFOpenAlex
AI Navigator

Ask Laika to Summarize, Analyze, and Connect papers live on the map.

Summarize Papers & Methodologies

Extract key findings, datasets, and comparative methods across publications.

Benchmark Rankings & Visual Analytics

Rank top research institutions, authors, funders, topics, and journals by Field-Weighted Citation Impact (FWCI) and paper volume with instant charts.

Connect Distant Disciplines

Bridge topological clusters on the map to find hidden collaborative intersections.