J/MNRAS/538/3144 GUCDS VI. 51 Gaia UCDs (Cheng+, 2025)
The Gaia ultracool dwarf sample.
VI. Spectral types and properties of 51 ultracool dwarfs.
Cheng G., Jones H.R.A., Smart R.L., Marocco F., Cooper W.J., Burgasser A.,
Beamin J.C., Pinfield D.J., Gagne J., Moranta L.
<Mon. Not. R. Astron. Soc. 538, 3144 (2025)>
=2025MNRAS.538.3144C 2025MNRAS.538.3144C (SIMBAD/NED BibCode)
ADC_Keywords: Stars, late-type ; Stars, M-type ; Stars, L-type ; Stars, T-type;
Proper motions ; Spectral types ; Spectra, infrared
Keywords: brown dwarfs - stars: late-type - stars: low mass
Abstract:
Near-infrared spectra from the IRTF/SpeX and Blanco/ARCoIRIS
telescope/instrument combinations are used for spectroscopic
classification, to measure radial velocities, and for the inference of
astrophysical properties of 51 Gaia-selected nearby ultracool dwarfs.
In this sample, 44 are newly classified in the near infrared. All but
one of the UCDs are within 100pc, and 37 lie within 50pc. We
find a total of 26 M-types, 24 L-types, and one T-type in our sample.
The positions of the majority of the UCDs on colour-magnitude
diagrams and with evolutionary cooling track plots indicate that they
are largely old and stellar in nature. There are a few UCDs of
particular interest which lie away from expected trends, highlighting
potential young, binary, and thick disc/subdwarf UCDs. From spectral
and kinematic analyses, we identify UCDs of particular interest for
further investigation, including seven potentially young UCDs, three
thick disc UCDs, one subdwarf, six wide binaries, and six unresolved
binaries.
Description:
We have collated data for our sample of 51 UCDs detected by Gaia. We
include object short names; Gaia DR3 source IDs; Gaia and 2MASS
photometry, and Gaia astrometric properties. We also derive
spectroscopic and photometric spectral type classifications; effective
temperatures, and radial and space velocities from IRTF SpeX and
Blanco ARCoIRIS NIR spectral observations, as well as classifying each
UCD as potentially young, thick disc or binary (where applicable).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tabled1.dat 565 51 Collated data for the UCDs in the sample
fits/* . 51 Individual fits spectra
--------------------------------------------------------------------------------
See also:
J/MNRAS/485/4423 : The Gaia ultracool dwarf sample. II. (Smart+, 2019)
Byte-by-byte Description of file: tabled1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- SName Object short name (JHHMM+DDMMA)
13- 31 I19 --- GaiaDR3 ? Gaia DR3 source ID
33- 43 F11.7 deg RAdeg Right ascension (ICRS) at Ep=2016.0
45- 53 F9.7 mas e_RAdeg ? Uncertainty in RA
55- 65 F11.7 deg DEdeg Declination (ICRS) at Ep=2016.0)
67- 75 F9.7 mas e_DEdeg ? Uncertainty in DE
77-104 A28 --- Simbad SIMBAD object name
106-118 F13.9 mas plx ? Gaia DR3 parallax
120-130 F11.9 mas e_plx ? Uncertainty in parallax
132-136 F5.1 pc Dist ?=0 Parallactic distance from
Gaia DR3 parallax
138-141 F4.1 pc e_Dist ?=0 Uncertainty in parallactic distance
143-146 F4.1 pc SpecDist Spectrophotometric distance
148-151 F4.1 pc e_SpecDist Uncertainty in spec_distance
153-166 F14.9 mas/yr pmRA ? Gaia proper motion in RA
168-178 F11.9 mas/yr e_pmRA ? Uncertainty in pmRA
180-193 F14.9 mas/yr pmDE ? Gaia proper motion in DE
195-205 F11.9 mas/yr e_pmDE ? Uncertainty in pmDE
207-210 A4 --- SpType Spectroscopic spectral classification
212-214 F3.1 --- e_SpType Uncertainty in SpType
216-219 A4 --- SpTypeL Spectroscopic spectral classification
from literature
221-239 A19 --- r_SpTypeL Bibcode for literature SpType
241-244 A4 --- PhType Photometric spectral type classification
246-248 F3.1 --- e_PhType Uncertainty in pht
250-253 A4 --- PhTypeL Photometric spectral classification
from literature
255-273 A19 --- r_PhType Bibcode for literature PhType
275-282 F8.4 km/s vtan ? Tangential velocity
284-290 F7.4 km/s e_vtan ? Uncertainty in vtan
292-296 F5.1 km/s RV ? Radial velocity
298-301 F4.1 km/s e_RV ? Uncertainty in RV
303-307 F5.1 km/s RVL ? Radial velocity from literature
309-327 A19 --- r_RVL ? Bibcode for literature RV
329-333 F5.1 km/s Uvel ? Space velocity U-component
335-339 F5.1 km/s Vvel ? Space velocity V-component
341-345 F5.1 km/s Wvel ? Space velocity W-component
347-350 I4 K Teff Effective temperature
352-354 I3 K e_Teff Uncertainty on teff
356-361 F6.4 --- RUWE ? Gaia DR3 re-normalized unit weight error
value
363-402 A40 --- Companion Gaia DR3 source ID of wide companion object
404-420 A17 --- Banyan BANYAN sigma young moving group
422-426 F5.3 --- PBanyan Probability of group membership
428-432 A5 --- gravity Surface gravity classification
434-451 A18 --- Notes Young, thick disc, binary
453-458 F6.3 mag Jmag 2MASS J-band magnitude
460-464 F5.3 mag e_Jmag ? Uncertainty in Jmag
466-471 F6.3 mag Hmag ? 2MASS H-band magnitude
473-477 F5.3 mag e_Hmag ? Uncertainty in Hmag
479-484 F6.3 mag Kmag ? 2MASS K-band magnitude
486-490 F5.3 mag e_Kmag ? Uncertainty in Kmag
492-497 F6.3 mag W1mag ? CatWISE2020 W1-band magnitude
499-504 F6.3 mag e_W1mag ? Uncertainty in W1mag
506-511 F6.3 mag W2mag ? CatWISE2020 W2-band magnitude
513-517 F5.3 mag e_W2mag ? Uncertainty in W2mag
518 A1 --- l_Gmag Limit flag on Gmag for J1243+6001
519-524 F6.3 mag Gmag Gaia DR3 G-band magnitude
526-530 F5.3 mag e_Gmag ? Uncertainty in Gmag
532-537 F6.3 mag GMAG ? Gaia DR3 G-band absolute magnitude
539-543 F5.3 mag e_GMAG ? Uncertainty in GMAG
545-565 A21 --- FileName Name of the fits spectrum file in
subdirectory fits
--------------------------------------------------------------------------------
Acknowledgements:
Gemma Cheng, g.j.cheng(at)herts.ac.uk
References:
Smart et al., Paper I 2017MNRAS.469..401S 2017MNRAS.469..401S
Smart et al., Paper II 2019MNRAS.485.4423S 2019MNRAS.485.4423S, Cat. J/MNRAS/485/4423
Marocco et al., Paper III 2020MNRAS.494.4891M 2020MNRAS.494.4891M
Cooper et al., Paper IV 2024MNRAS.534..695C 2024MNRAS.534..695C
Baing et al., Paper V 2024MNRAS.533.3784B 2024MNRAS.533.3784B
(End) Patricia Vannier [CDS] 11-Sep-2025