Issue |
A&A
Volume 680, December 2023
|
|
---|---|---|
Article Number | A16 | |
Number of page(s) | 24 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/202347578 | |
Published online | 05 December 2023 |
Exploring the brown dwarf desert with precision radial velocities and Gaia DR3 astrometric orbits★
1
Département d’Astronomie, Université de Genève,
Chemin Pegasi 51,
1290
Versoix, Switzerland
e-mail: nicolas.unger@unige.ch
2
National Center of Competence in Research, PlanetS,
Gesellschaftsstrasse 6,
3012
Bern, Switzerland
3
RHEA Group for the European Space Agency (ESA), European Space Astronomy Centre (ESAC),
Camino Bajo del Castillo s/n,
28692
Villanueva de la Cañada, Madrid, Spain
Received:
27
July
2023
Accepted:
24
September
2023
Context. The observed scarcity of brown dwarfs in close orbits (within 10 au) around solar-type stars has posed significant questions about the origins of these substellar companions. These questions not only pertain to brown dwarfs but also impact our broader understanding of planetary formation processes. However, to resolve these formation mechanisms, accurate observational constraints are essential. Notably, most of the brown dwarfs have been discovered by radial velocity surveys, but this method introduces uncertainties due to its inability to determine the orbital inclination, leaving the true mass – and thus their true nature – unresolved. This highlights the crucial role of astrometric data, helping us distinguish between genuine brown dwarfs and stars.
Aims. This study aims to refine the mass estimates of massive companions to solar-type stars, mostly discovered through radial velocity measurements and subsequently validated using Gαìα DR3 astrometry, to gain a clearer understanding of their true mass and occurrence rates.
Methods. We selected a sample of 31 sources with substellar companion candidates validated by Gaia Data Release (DR3) and with available radial velocities. Using the Gaia DR3 solutions as prior information, we performed an MCMC fit with the available radial velocity measurements to integrate these two sources of data and thus obtain an estimate of their true mass.
Results. Combining radial velocity measurements with Gaia DR3 data led to more precise mass estimations, leading us to reclassify several systems initially labeled as brown dwarfs as low-mass stars. Out of the 32 analyzed companions, 13 have been determined to be stars, 17 are substellar, and two have inconclusive results with the current data. Importantly, using these updated masses, we reevaluated the occurrence rate of brown dwarf companions (13–80 MJup) on close orbits (<10 au) in the CORALIE sample, determining a tentative occurrence rate of 0.8−0.2+0.3%.
Key words: methods: data analysis / techniques: radial velocities / astrometry / planets and satellites: general
The CORALIE data are available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/680/A16
© The Authors 2023
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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