J/MNRAS/485/4423 The Gaia ultracool dwarf sample (Smart+, 2019)
The Gaia ultracool dwarf sample - II. Structure at the end of the main sequence.
Smart R.L., Marocco F., Sarro L.M., Barrado D., Beamin J.C.,
Caballero J.A., Jones H.R.A.
<Mon. Not. R. Astron. Soc., 485, 4423-4440 (2019)>
=2019MNRAS.485.4423S 2019MNRAS.485.4423S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Stars, brown dwarf ;
Stars, late-type ; Optical
Keywords: binaries: visual - brown dwarfs - stars: late-type -
Hertzsprung-Russell and colour-magnitude diagrams -
solar neighbourhood
Abstract:
We identify and investigate known late M, L, and T dwarfs in the Gaia
second data release. This sample is being used as a training set in
the Gaia data processing chain of the ultracool dwarfs work package.
We find 695 objects in the optical spectral range M8-T6 with accurate
Gaia coordinates, proper motions, and parallaxes which we combine with
published spectral types and photometry from large area optical and
infrared sky surveys. We find that 100 objects are in 47 multiple
systems, of which 27 systems are published and 20 are new. These will
be useful benchmark systems and we discuss the requirements to produce
a complete catalogue of multiple systems with an ultracool dwarf
component. We examine the magnitudes in the Gaia passbands and find
that the GBP magnitudes are unreliable and should not be used for
these objects. We examine progressively redder colour-magnitude
diagrams and see a notable increase in the main-sequence scatter and a
bivariate main sequence for old and young objects. We provide an
absolute magnitude-spectral subtype calibration for G and GRP
passbands along with linear fits over the range M8-L8 for other
passbands.
Description:
The initial list of known ultra cool dwarfs (UCDs) was the input
catalogue from Paper 1 (Smart et al. 2017MNRAS.469..401S 2017MNRAS.469..401S, Cat.
J/MNRAS/469/401) of 1885 objects with M, L, T, or Y spectral
classification. To this we added the photometrically identified LT
dwarfs from Skrzypek, Warren & Faherty (2016A&A...589A..49S 2016A&A...589A..49S, Cat.
J/A+A/589/A49) and a few other recent discoveries (e.g. Marocco et al.
2017MNRAS.470.4885M 2017MNRAS.470.4885M; Scholz & Bell 2018RNAAS...2...33S 2018RNAAS...2...33S; Smith et al.
2018MNRAS.474.1826S 2018MNRAS.474.1826S, Cat. II/364). The current list contains 3093 UCDs
ranging from M8 to Y2 dwarfs. The M dwarfs were retained to facilitate
differentiation of the spectral types in the magnitude and colour
space, as some objects are classed as M in optical spectra and L in
infrared spectra and vice versa. Since this input catalogue is
dominated by L and T dwarfs we refer to it as the LT catalogue
(hereafter LTC).
For all objects we have collected photometry from the Two Micron All
Sky Survey (2MASS; Skrutskie et al. 2006AJ....131.1163S 2006AJ....131.1163S, Cat.
VII/233), the Panoramic Survey Telescope and Rapid Response System
release 1 (PS1; Chambers et al. 2016arXiv161205560C 2016arXiv161205560C, Cat. II/349), and
the Wide-field Infrared Survey Explorer extension (AllWISE; Wright et
al. 2010AJ....140.1868W 2010AJ....140.1868W), providing up to 11 homogeneous magnitudes in
passbands ranging from Gunn g to WISE W3. The WISE W4 band was not
included as the number of objects with reliable magnitudes were very
low.
We started by searching for any objects in the Gaia DR2 release that
had a parallax larger than 10mas and was within 20arcsec of the LTC
entry at the Gaia DR2 epoch. We choose 20arcsec as not all entries
have published proper motions, the epoch difference can be up to 20yr,
and typical proper motions are 500-1000mas/yr. This resulted in 753
entries from Gaia DR2. For each entry we then propagated the Gaia DR2
position to the epoch of the LTC positions in the input catalogue
using the Gaia DR2 proper motions.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 83 34 Input catalogue entries with multiple Gaia DR2
matches within 20 arcsec
table2.dat 74 5 Intrinsically bright (MG<14.0mag) objects
matched to LT objects sorted by absolute
magnitude (top) and matches with offset
>5.0 arcsec sorted by separation (bottom)
table3.dat 528 695 Data for Ultra-Cool Dwarfs in Gaia DR2
table4.dat 38 16 Objects with published parallax estimates
differing by more than 2.5σ with the Gaia
DR2 parallax
table5.dat 91 33 New candidate binary systems containing LT
dwarfs, identified in Gaia DR2
table6.dat 46 2 J1711+5430 and NLTT 44368 Gaia DR2 parameters
--------------------------------------------------------------------------------
See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+, 2016)
II/328 : AllWISE Data Release (Cutri+ 2013)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- ID Short name
13- 15 A3 --- f_ID Flag on ID (1)
17- 43 A27 --- Name Discovery name
45- 48 F4.1 arcsec Offset Offset on the sky of the LTC position
(generally 2MASS coordinates)
50- 55 F6.3 mag Gmag Gaia DR2 G-band magnitude (G1)
57- 61 F5.1 mag G-Gest G-Gest difference where Gest is the average
magnitude for all objects in the LTC
63- 66 F4.1 mas plx Gaia DR2 parallax (G1)
68- 70 F3.1 mas e_plx Error on plx (G1)
72- 77 F6.1 mas/yr pm Total proper motion
79- 83 F5.1 deg pmPA Position angle of the proper motion
--------------------------------------------------------------------------------
Note (1): Objects with 'Bin' in this column are found to be physical binaries
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- ID Short name
13- 28 A16 --- Name Discovery name
30- 48 I19 --- GaiaDR2 Gaia DR2 Source identifier (G1)
50- 53 F4.2 arcsec Offset Offset on the sky of the LTC position
(generally 2MASS coordinates)
55- 60 F6.3 mag Gmag Gaia DR2 G-band magnitude (G1)
62- 67 F6.3 mag Gestmag Gest is the average magnitude for all objects
in the LTC
69- 74 F6.3 mag GMAG Absolute magnitude in the G band
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- ID Short name
13- 25 F13.9 deg RAdeg Right ascension (ICRS) at Ep=2015.5 (G1)
27- 39 F13.9 deg DEdeg Declination (ICRS) at Ep=2015.5 (G1)
41- 65 A25 --- Name Discovery name
67- 85 A19 --- r_Name Reference for Name
87-105 I19 --- GaiaDR2 Gaia DR2 Source identifier (G1)
107-110 F4.2 arcsec Distcat Distance DR2 to catalogue position
112-116 A5 --- VBURMG Multiple code VB/UR/MG/SB
118-136 A19 --- r_VBURMG Reference for VBURMG
138-145 A8 --- SpTop Optical Spectral type
147-165 A19 --- r_SpTop Reference for SPTop
167-176 A10 --- SpTnir Near infrared Spectral type
178-196 A19 --- r_SpTnir Reference for SpTnir
198-203 A6 --- SpTph Photometric Spectral type
205-223 A19 --- r_SpTph Reference for SpTph
225-231 F7.3 mas plxlit ? Published parallax
233-238 F6.3 mas e_plxlit ? Error on plxlit
240-258 A19 --- r_plxlit Reference for plxlit
260-265 F6.3 mag Jmag ? 2MASS J-band magnitude
267-271 F5.3 mag e_Jmag ? Error on Jmag
273-278 F6.3 mag Hmag ? 2MASS H-band magnitude
280-284 F5.3 mag e_Hmag ? Error on Hmag
286-291 F6.3 mag Kmag ? 2MASS K-band magnitude
293-297 F5.3 mag e_Kmag ? Error on Kmag
299-304 F6.3 mag W1mag ? AllWISE W1-band magnitude
306-310 F5.3 mag e_W1mag ? Error on W1mag
312-317 F6.3 mag W2mag ? AllWISE W2-band magnitude
319-323 F5.3 mag e_W2mag ? Error on W2mag
325-330 F6.3 mag W3mag ? AllWISE W3-band magnitude
332-336 F5.3 mag e_W3mag ? Error on W3mag
338-343 F6.3 mag gmagPS ? Pan-STARRS g-band magnitude
345-349 F5.3 mag e_gmagPS ? Error on gmagPS
351-356 F6.3 mag rmagPS ? Pan-STARRS r-band magnitude
358-362 F5.3 mag e_rmagPS ? Error on rmagPS
364-369 F6.3 mag imagPS ? Pan-STARRS i-band magnitude
371-375 F5.3 mag e_imagPS ? Error on imagPS
377-382 F6.3 mag zmagPS ? Pan-STARRS z-band magnitude
384-388 F5.3 mag e_zmagPS ? Error on zmagPS
390-395 F6.3 mag ymagPS ? Pan-STARRS y-band magnitude
397-401 F5.3 mag e_ymagPS ? Error on ymagPS
403-408 F6.3 mag Gmag Gaia DR2 G-band magnitude (G1)
410-414 F5.3 mag e_Gmag Error on Gmag (1)
416-422 F7.1 e-/s FG Gaia DR2 G-band flux (G1)
424-428 F5.1 e-/s e_FG Error on FG (G1)
430-435 F6.3 mag BPmag ? Gaia DR2 BP-band magnitude (G1)
437-441 F5.3 mag e_BPmag ? Error on BPmag (1)
443-448 F6.1 e-/s FBP ? Gaia DR2 BP-band flux (G1)
450-454 F5.1 e-/s e_FBP ? Error on FBP (G1)
456-461 F6.3 mag RPmag ? Gaia DR2 RP-band magnitude (G1)
463-467 F5.3 mag e_RPmag ? Error on RPmag (1)
469-475 F7.1 e-/s FRP ? Gaia DR2 RP-band flux (G1)
477-481 F5.1 e-/s e_FRP ? Error on FRP (G1)
483-488 F6.3 mag GaiaGest Estimated DR2 G from spectral type
490-495 F6.2 mas plx Gaia DR2 parallax (G1)
497-500 F4.2 mas e_plx Error on plx (G1)
502-509 F8.2 mas/yr pmRA Gaia DR2 proper motion in right
ascension (G1)
511-514 F4.2 mas/yr e_pmRA Error on pmRA (G1)
516-523 F8.2 mas/yr pmDE Gaia DR2 proper motion in declination (G1)
525-528 F4.2 mas/yr e_pmDE Error on pmDE (G1)
--------------------------------------------------------------------------------
Note (1): Errors are the mean of the flux uncertainties transformed into
magnitudes
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- ID Short name
13- 18 F6.2 mas plx Gaia DR2 parallax
20- 23 F4.2 mas e_plx Error on plx
25- 30 F6.2 mas plxlit Published parallax
32- 36 F5.2 mas e_plxlit Error on plxlit
38 A1 --- r_plxlit Reference for plxlit (1)
--------------------------------------------------------------------------------
Note (1): References as follows:
a = Faherty et al. (2012ApJ...752...56F 2012ApJ...752...56F, Cat. J/ApJ/752/56)
b = Sahlmann et al. (2014A&A...565A..20S 2014A&A...565A..20S)
c = Dupuy & Liu (2012ApJS..201...19D 2012ApJS..201...19D, Cat. J/ApJS/201/19)
d = Ducourant et al. (2008A&A...477L...1D 2008A&A...477L...1D)
e = Dahn et al. (2002AJ....124.1170D 2002AJ....124.1170D)
f = Dieterich et al. (2014AJ....147...94D 2014AJ....147...94D, Cat. J/AJ/147/94)
g = Marsh et al. (2013ApJ...762..119M 2013ApJ...762..119M)
h = Dahn et al. (2008ApJ...686..548D 2008ApJ...686..548D)
i = Wang et al. (2014PASP..126...15W 2014PASP..126...15W)
j = Dittmann et al. (2014ApJ...784..156D 2014ApJ...784..156D, Cat. J/ApJ/784/156)
k = Liu, Dupuy & Allers (2016ApJ...833...96L 2016ApJ...833...96L, Cat. J/ApJ/833/96)
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 27 A27 --- Name Discovery name
29- 34 F6.1 arcsec rho ? Separation on the sky of the two components
36- 46 F11.7 deg RAdeg Right ascension (ICRS) at Ep=2015.5 (G1)
48- 58 F11.7 deg DEdeg Declination (ICRS) at Ep=2015.5 (G1)
60- 64 A5 --- SpType ?=- Spectral type
66- 70 F5.2 mag Gmag Gaia DR2 G-band magnitude (G1)
72- 75 F4.1 mas plx Gaia DR2 parallax (G1)
77- 79 F3.1 mas e_plx Error on plx (G1)
81- 85 F5.1 mas/yr pm Total proper motion
87- 91 F5.1 deg pmPA Position angle of the proper motion
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- ID Short name
12- 16 F5.2 mas plx Gaia DR2 parallax (G1)
18- 21 F4.2 mas e_plx Error on plx (G1)
23- 28 F6.2 mas/yr pmRA Proper motion in right ascension from Gaia
DR2 (G1)
30- 33 F4.2 mas/yr e_pmRA Error on pmRA (G1)
35- 40 F6.2 mas/yr pmDE Proper motion in declination from Gaia DR2 (G1)
42- 46 F5.3 mas/yr e_pmDE Error on pmDE (G1)
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Global notes:
Note (G1): Values taken from Gaia DR2 (Gaia Collaboration, 2018A&A...616A...1G 2018A&A...616A...1G,
Cat. I/345)
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History:
From electronic version of the journal
References:
Smart et al., Paper I 2017MNRAS.469..401S 2017MNRAS.469..401S, Cat. J/MNRAS/469/401
(End) Ana Fiallos [CDS] 05-Oct-2022