J/A+A/669/A139 Ultracool dwarfs in Gaia DR3 (Sarro+, 2023)
Ultracool dwarfs in Gaia DR3.
Sarro L.M., Berihuete A., Smart R.L., Reyle C., Barrado D.,
Garcia-Torres M., Cooper W.J., Jones H.R.A., Marocco F., Creevey O.L.,
Sordo R., Bailer-Jones C.A.L., Montegriffo P., Carballo R., Andrae R.,
Fouesneau M., Lanzafame A.C., Pailler F., Thevenin F., Lobel A.,
Delchambre L., Korn A.J., Recio-Blanco A., Schultheis M.S., De Angeli F.,
Brouillet N., Casamiquela L., Contursi G., de Laverny P., Garcia-Lario P.,
Kordopatis G., Lebreton Y., Livanou E., Lorca A., Palicio P.A.,
Slezak-Oreshina I., Soubiran C., Ulla A., Zhao H.
<Astron. Astrophys. 669, A139 (2023)>
=2023A&A...669A.139S 2023A&A...669A.139S (SIMBAD/NED BibCode)
ADC_Keywords: Associations, stellar ; Clusters, open ; Stars, dwarfs ; Optical
Keywords: brown dwarfs - stars: low-mass - stars: late-type -
methods: statistical - Hertzsprung-Russell and C-M diagrams -
stars: pre-main sequence
Abstract:
Previous Gaia Data Releases offered the opportunity to uncover
ultracool dwarfs (UCDs) through astrometric, rather than purely
photometric selection. The most recent, third data release offers in
addition the opportunity to use low-resolution spectra to refine and
widen the selection.
In this work we use the Gaia DR3 set of ultracool dwarf candidates and
complement the Gaia spectrophotometry with additional photometry in
order to characterise its global properties. This includes the
inference of the distances, their locus in the Gaia colour-absolute
magnitude diagram and the (biased through selection) luminosity
function in the faint end of the Main Sequence. We study the overall
changes in the Gaia RP spectra as a function of spectral type. We
study the UCDs in binary systems, attempt to identify low-mass members
of nearby young associations, star forming regions and clusters, and
analyse their variability properties.
We use a forward model and the Bayesian inference framework to produce
posterior probabilities for the distribution parameters and a
calibration of the colour index as a function of the absolute
magnitude in the form of a Gaussian Process. Additionally we apply the
HMAC unsupervised classification algorithm for the detection and
characterisation of overdensities in the space of celestial
coordinates, projected velocities and parallaxes.
We detect 57 young, kinematically homogeneous groups some of which are
identified as well known star forming regions, associations and
clusters of different ages. We find that the primary members of 880
binary systems with a UCD belong mainly to the thin and thick disk
components of the Milky Way. We identify 1109 variable UCDs using the
variability tables in the Gaia archive, 728 of which belong to the
star forming regions defined by HMAC. We define two groups of variable
UCDs with extreme bright or faint outliers.
The set of sources identified as UCDs in the Gaia archive contains a
wealth of information that will require focused follow-up studies and
observations. It will help to advance our understanding of the nature
of the faint end of the Main Sequence and the stellar/substellar
transition.
Description:
Cluster assignments using BANYAN SIGMA and the HMAC unsupervised
classification algorithm for the Gaia catalogue of ultracool dwarfs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 40 7630 Cluster assignments for Gaia ultracool dwarfs
from BANYAN and HMAC
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaDR3 Gaia DR3 source_id
23- 24 I2 --- HMACcl ?=- HMAC cluster identifier
29- 35 A7 --- BANYANcl BANYAN best hypothesis
(largest membership probability)
37- 40 F4.2 --- BANYANprob ?=- BANYAN membership probability for the
best hypothesis
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Acknowledgements:
Luis M. Sarro, lsb(at)dia.uned.es
(End) Luis M. Sarro [UNED, Spain], Patricia Vannier [CDS] 18-Jan-2023