J/A+A/680/A16 RV measurements for 12 stars (Unger+, 2023)
Exploring the brown dwarf desert with precision radial velocities and Gaia DR3
astrometric orbits.
Unger N., Segransan D., Barbato D., Delisle J.-B., Sahlmann J., Holl B.,
Udry S.
<Astron. Astrophys. 680, A16 (2023)>
=2023A&A...680A..16U 2023A&A...680A..16U (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Stars, brown dwarf ;
Radial velocities
Keywords: methods: data analysis - techniques: radial velocities -
astrometry - planets and satellites: general
Abstract:
The observed scarcity of brown dwarfs in close orbits (within 10AU)
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 under- standing 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.
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 Gaia DR3 astrometry, to
gain a clearer understanding of their true mass and occurrence rates.
We selected a sample of 31 sources with substellar companion
candidates validated by Gaia 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.
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, 18 were confirmed as sub- stellar, 12 are
determined to be stars, and 2 have inconclusive results with the
current data. Importantly, using these updated masses, we reevaluated
the occurrence rate of brown dwarf companions (13-80MJup) on close
orbits (<10AU) in the CORALIE sample, determining an upper limit of
0.08+0.03_-0.02^%.
Description:
Radial velocity measurements taken with the CORALIE spectrograph for
BD-170063, CD-4610046, HD112758, HD151528, HD162020, HD164427A,
HD17155, HD17289, HD3277, HD52756, HD89707, HR810.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 34 12 List of studied stars
rvdata.dat 64 377 CORALIE radial velocities
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Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Star Star name
12- 13 I2 h RAh Simbad right ascension (J2000.0)
15- 16 I2 min RAm Simbad right ascension (J2000.0)
18- 22 F5.2 s RAs Simbad right ascension (J2000.0)
24 A1 --- DE- Simbad declination sign (J2000.0)
25- 26 I2 deg DEd Simbad declination (J2000.0)
28- 29 I2 arcmin DEm Simbad declination (J2000.0)
31- 34 F4.1 arcsec DEs Simbad declination (J2000.0)
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Byte-by-byte Description of file: rvdata.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Star Star name
12- 29 F18.12 d RJD Reduced Julian Date of observation
(BJD-2450000)
31- 43 F13.6 m/s RV Radial velocity
45- 54 F10.6 m/s e_RV Uncertainty on the radial velocity
56- 64 A9 --- Inst Name of instrument
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Acknowledgements:
Nicolas Unger, nicolas.unger(at)unige.ch
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(End) Patricia Vannier [CDS] 09-Oct-2023