J/A+A/619/L8 Ultra-cool dwarfs candidates in Gaia DR2 (Reyle, 2018)
New ultra-cool and brown dwarf candidates in Gaia DR2.
Reyle C.
<Astron. Astrophys. 619, L8 (2018)>
=2018A&A...619L...8R 2018A&A...619L...8R (SIMBAD/NED BibCode)
ADC_Keywords: Positional data ; Parallaxes, trigonometric ; Stars, dwarfs;
Stars, late-type; HR diagrams
Keywords: stars: low-mass - solar neighborhood - Galaxy: stellar content -
surveys - catalogs
Abstract:
The second Gaia data release (Gaia DR2) contains high-precision
positions, parallaxes, and proper motions for 1.3 billion sources. The
resulting Hertzsprung-Russel diagram reveals fine structures
throughout the mass range.
This paper aims to investigate the content of Gaia DR2 at the low-mass
end and to characterize ultra-cool and brown dwarfs.
We first retrieved the sample of spectroscopically confirmed
ultra-cool and brown dwarfs in Gaia DR2.We used their locus in the
precise Hertzsprung-Russel diagram to select new candidates and to
investigate their properties.
The number of spectroscopically confirmed objects recovered in Gaia
DR2 corresponds to 61% and 74% of the expected number of objects with
an estimated Gaia magnitude Gest≤21.5 and 20.3, respectively. This
fills much of the gap to Gaia DR1. Furthermore, Gaia DR2 contains
∼13000≥M7 and 631 new L candidates. A tentative classification
suggests that a few hundred of them are young or subdwarf candidates.
Their distance distribution shows that the solar neighborhood census
is still incomplete. Conclusions. Gaia DR2 offers a great wealth of
information on low-mass objects. It provides a homogeneous and precise
catalog of candidates that is worthwhile to be further characterized
with spectroscopic observations.
Description:
Astrometric and photometric parameters, estimated spectral type and
pecularity of ultra-cool dwarfs candidates found in Gaia DR2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 117 14915 Parameters of 14915 ultra-cool dwarf candidates
found in Gaia DR2
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- Source Gaia DR2 identification (source_id)
21- 35 F15.11 deg RAdeg Right ascension (ICRS, epoch 2015.5) (ra)
37- 51 F15.11 deg DEdeg Declination (ICRS, epoch 2015.5) (dec)
53- 59 F7.4 mas Plx Trigonometric parallax (parallax)
61- 69 F9.3 mas/yr pmRA Proper motion in right ascension,
pmRA*cosDE (pmra)
71- 79 F9.3 mas/yr pmDE Proper motion in declination (pmdec)
81- 89 F9.6 mag Gmag Gaia G magnitude (G)
91- 98 F8.6 mag G-RP Gaia G-Grp color (G-Grp)
100-106 F7.3 km/s vtan Transverse velocity (vtan)
108-111 A4 --- sptphot Indicative spectral type computed from
absolute magnitude MG vs spectral type
relation (see table1) (sptphot)
113-117 A5 --- pec [sd young] Pecularity (subdwarf or young, or
none) (pecularity)
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Acknowledgements:
Celine Reyle, celine(at)obs-besancon.fr
History:
20-Nov-2018: on-line version
17-Oct-2019: Gaia Dr2 identifiers corrected
(End) Patricia Vannier [CDS] 26-Oct-2018