J/MNRAS/433/457 76 T dwarfs from the UKIDSS LAS (Burningham+, 2013)
76 T dwarfs from the UKIDSS LAS: benchmarks, kinematics and an updated
space density.
Burningham B., Cardoso C.V., Smith L., Leggett S.K., Smart R.L., Mann A.W.,
Dhital S., Lucas P.W., Tinney C.G., Pinfield D.J., Zhang Z., Morley C.,
Saumon D., Aller K., Littlefair S.P., Homeier D., Lodieu N., Deacon N.,
Marley M.S., van Spaandonk L., Baker D., Allard F., Andrei A.H., Canty J.,
Clarke J., Day-Jones A.C., Dupuy T., Fortney J.J., Gomes J., Ishii M.,
Jones H.R.A., Liu M., Magazzu A., Marocco F., Murray D.N., Rojas-Ayala B.,
Tamura M.
<Mon. Not. R. Astron. Soc., 433, 457-497 (2013)>
=2013MNRAS.433..457B 2013MNRAS.433..457B
ADC_Keywords: Surveys ; Stars, dwarfs ; Stars, late-type ; Photometry ;
Spectroscopy
Keywords: surveys - brown dwarfs - stars: low-mass
Abstract:
We report the discovery of 76 new T dwarfs from the UKIRT Infrared
Deep Sky Survey (UKIDSS) Large Area Survey (LAS). Near-infrared broad-
and narrow-band photometry and spectroscopy are presented for the new
objects, along with Wide-field Infrared Survey Explorer (WISE) and
warm-Spitzer photometry. Proper motions for 128 UKIDSS T dwarfs are
presented from a new two epoch LAS proper motion catalogue. We use
these motions to identify two new benchmark systems: LHS 6176AB, a
T8p+M4 pair and HD 118865AB, a T5.5+F8 pair. Using age constraints
from the primaries and evolutionary models to constrain the radii, we
have estimated their physical properties from their bolometric
luminosity. We compare the colours and properties of known benchmark T
dwarfs to the latest model atmospheres and draw two principal
conclusions. First, it appears that the H-[4.5] and J-W2 colours are
more sensitive to metallicity than has previously been recognized,
such that differences in metallicity may dominate over differences in
Teff when considering relative properties of cool objects using
these colours. Secondly, the previously noted apparent dominance of
young objects in the late-T dwarf sample is no longer apparent when
using the new model grids and the expanded sample of late-T dwarfs and
benchmarks. This is supported by the apparently similar distribution
of late-T dwarfs and earlier type T dwarfs on reduced proper motion
diagrams that we present. Finally, we present updated space densities
for the late-T dwarfs, and compare our values to simulation
predictions and those from WISE.
Description:
Our broad-band NIR photometry was obtained using the UKIRT Fast Track
Imager (UFTI) and WFCAM, both mounted on UKIRT across a number of
observing runs spanning 2009 to the end of 2010.
Differential methane photometry was obtained using the Near Infrared
Camera Spectrometer (NICS) mounted on the TNG under programme AOT22
TAC 96 spanning from 2010 to 2012.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 163 81 Best available NIR photometry for our sample
table2.dat 152 76 *Spectral typing ratios for the confirmed T dwarfs
table3.dat 64 25 WISE photometry for 25 of the spectroscopically
confirmed T dwarfs presented here for the first time
table4.dat 94 11 *Spitzer photometry for a subset of T dwarfs,
table5.dat 111 127 Proper motions for T dwarfs within UKIDSS LAS sky
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Note on table2.dat: as set out by Burgasser et al. (2006ApJ...637.1067B 2006ApJ...637.1067B,
Cat. J/ApJ/637/1067) and Burningham et al. (2009MNRAS.395.1237B 2009MNRAS.395.1237B), along
with the types from by-eye comparison to template spectral standards and
the final adopted types.
Note on table4.dat: selected either as examples of late-T types, peculiar
spectra or as benchmark objects.
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See also:
J/AJ/127/3553 : JHK photometry & spectroscopy for L & T dwarfs (Knapp+, 2004)
J/AJ/131/2722 : New L and T dwarfs from the SDSS (Chiu+, 2006)
J/ApJ/637/1067 : Near-IR spectral classification of T dwarfs (Burgasser+, 2006)
J/AJ/134/1162 : 11 new T dwarfs in 2MASS (Looper+, 2007)
J/ApJS/205/6 : T dwarf population revealed by WISE (Mace+, 2013)
J/ApJS/197/19 : First brown dwarfs discovered by WISE (Kirkpatrick+, 2011)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 25 A25 --- Name Name (full star name)
26 A1 --- n_Name [abc] Non-UKIDSS designation (2)
28- 29 I2 h RAh Right ascension (J2000)
31- 32 I2 min RAm Right ascension (J2000)
34- 38 F5.2 s RAs Right ascension (J2000)
40 A1 --- DE- Declination sign (J2000)
41- 42 I2 deg DEd Declination (J2000)
44- 45 I2 arcmin DEm Declination (J2000)
47- 51 F5.2 arcsec DEs Declination (J2000)
53 A1 --- l_z'mag Limit flag on z'mag
54- 58 F5.2 mag z'mag ?=- SDSS z' magnitude (4)
60- 63 F4.2 mag e_z'mag ?=- rms uncertainty on z'mag
64 A1 --- r_z'mag [ADE] Origin of z'mag (3)
66- 70 F5.2 mag Ymag MKO Y magnitude
72- 75 F4.2 mag e_Ymag rms uncertainty on Ymag
76 A1 --- r_Ymag [UW] Origin of Ymag (3)
78- 82 F5.2 mag Jmag MKO J magnitude
84- 87 F4.2 mag e_Jmag rms uncertainty on Jmag
88 A1 --- r_Jmag [UW] Origin of Jmag (3)
90- 94 F5.2 mag Hmag ?=- MKO H magnitude
96- 99 F4.2 mag e_Hmag ? rms uncertainty on Hmag
100 A1 --- r_Hmag [UW] Origin of Hmag (3)
102-106 F5.2 mag Kmag ?=- MKO K magnitude
108-111 F4.2 mag e_Kmag ? rms uncertainty on Kmag
112 A1 --- r_Kmag [W] Origin of Kmag (3)
114 A1 --- l_CH4i Limit flag on CH4i
115-119 F5.2 mag CH4i ?=- Methane filter colour index CH4s-CH4l (5)
121-124 F4.2 mag e_CH4i ? rms uncertainty on CH4i
125 A1 --- r_CH4i [L] Origin of CH4i
127-130 A4 --- Sp4 Spectral type from CH4
132-135 A4 --- b_Sp4 Lower value of CH4 type (min)
137-140 A4 --- B_Sp4 Upper value of CH4 type (max)
142-146 A5 --- SpT Adopted spectral type (G1)
148-163 A16 --- SName Short name (as in tables 2 and 3)
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Note (2): Origin of the name as follows:
a = Albert et al. (2011AJ....141..203A 2011AJ....141..203A);
UKIDSS designation: ULAS J013302.48+023128.9
b = Kirkpatrick et al. (2011ApJS..197...19K 2011ApJS..197...19K, Cat. J/ApJS/197/19);
UKIDSS designation: ULAS J092906.75+04:0957.7
c = Mace et al. (2013ApJS..205....6M 2013ApJS..205....6M, Cat. J/ApJS/205/6);
UKIDSS designation: ULAS J151721.12+052929.0
Note (3): Nothing indicates UKIDSS survey photometry for YJHK, SDSS DR8 for z'
band. Unless indicated otherwise, all CH4 photometry is from TNG/NICS.
Codes refer to the following instruments, as follows:
A = ACAM (WHT)
D = DOLORES (TNG)
E = EFOSC2 (NTT)
L = LIRIS (WHT)
U = UFTI (UKIRT)
W = WFCAM (UKIRT)
Note (4): z' band photometry has been converted to the SDSS system as
described in the text.
Note (5): The methane filters used in this work are denoted as CH4s and CH4l,
(filter characteristics are 1.57±0.05µm and 1.69±0.05µm resp.,
see http://www.ifa.hawaii.edu/~tokunaga/NB_special_ordersorting.html)
The comparison of these two filters provides information about the strength
of the methane absorption bands in late-T dwarfs. CH4l samples the methane
absorption bands present between 1.6 and 1.8um, while the CH4s samples a
pseudo-continuum outside the methane band.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- SName Short name
18- 22 A5 --- SpT Adopted spectral type (G1)
24- 28 A5 --- Templ Template spectral type
30- 34 F5.3 --- H2O-J H2O-J index
36- 40 F5.3 --- e_H2O-J rms uncertainty on H2O-J
42- 45 A4 --- n_H2O-J Spectral type from H2O-J (G1)
47- 51 F5.3 --- CH4-J CH4-J index
53- 57 F5.3 --- e_CH4-J rms uncertainty on CH4-J
59- 62 A4 --- n_CH4-J Spectral type from CH4-J (G1)
64- 68 F5.3 --- WJ WJ index [F(1.180-1.230)/F(1.260-12.285)]
70- 74 F5.3 --- e_WJ rms uncertainty on WJ
76- 79 A4 --- n_WJ Spectral type from WJ (G1)
81- 85 F5.3 --- H2O-H ?=- H2O-H index
87- 91 F5.3 --- e_H2O-H ? rms uncertainty on H2O-H
93- 96 A4 --- n_H2O-H Spectral type from H2O-H (G1)
98-102 F5.3 --- CH4-H ?=- CH4-H index
104-108 F5.3 --- e_CH4-H ? rms uncertainty on CH4-H
110-113 A4 --- n_CH4-H Spectral type from CH4-H (G1)
115-119 F5.3 --- CH4-K ?=- CH4-K index
121-125 F5.3 --- e_CH4-K ?=- rms uncertainty on CH4-K
127-130 A4 --- n_CH4-K Spectral type from CH4-K (G1)
132-152 A21 --- Note References and other spectral type (6)
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Note (6): The notes column indicates spectral types determined by authors where:
A11 = Albert et al. (2011AJ....141..203A 2011AJ....141..203A)
K11 = Kirkpatrick et al. (2011ApJS..197...19K 2011ApJS..197...19K, Cat. J/ApJS/197/19)
S10 = Scholz (2010A&A...515A..92S 2010A&A...515A..92S)
S12 = Scholz et al. (2012A&A...541A.163S 2012A&A...541A.163S)
In the case of T8+ objects, the notes column indicates the spectral type
using the Cushing et al. (2011ApJ...743...50C 2011ApJ...743...50C) system.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- SName Short name
18 A1 --- l_W1mag Limit flag on W1mag
19- 23 F5.2 mag W1mag WISE W1 magnitude
25- 28 F4.2 mag e_W1mag ? rms uncertainty on W1mag
30- 34 F5.2 mag W2mag WISE W2 magnitude
36- 39 F4.2 mag e_W2mag rms uncertainty on W2mag
41 A1 --- l_W3mag Limit flag on W3mag
42- 46 F5.2 mag W3mag WISE W3 magnitude
48- 51 F4.2 mag e_W3mag ? rms uncertainty on W3mag
53 A1 --- l_W4mag Limit flag on W4mag
54- 57 F4.2 mag W4mag WISE W4 magnitude
59- 62 F4.2 mag e_W4mag ? rms uncertainty on W4mag
64 A1 --- blend [Y/N] WISE blend?
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 25 A25 --- Name Star full name (1)
27- 31 A5 --- SpT Spectral type (G1)
32 A1 --- r_SpT [a-d] Reference for SpT (2)
34- 38 I5 --- PID Programme number
40- 49 A10 "date" ObsDate Observation date (UT)
51- 58 A8 --- Pipe Pipeline version
60- 61 I2 s Frame Frame time
63- 66 F4.1 min Tint Integration time
68- 70 F3.1 arcsec Ap Aperture
72- 76 F5.2 mag [3.6] IRAC 3.6um magnitude
78- 81 F4.2 mag e_[3.6] rms uncertainty on [3.6]
83- 87 F5.2 mag [4.5] IRAC 4.5um magnitude
89- 92 F4.2 mag e_[4.5] rms uncertainty on [4.5]
94 A1 --- Notes [AB] Notes (3)
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Note (1): Here the full name is given, while the printed table gives full
designations only for those objects whose discoveries are reported in
other publications.
Note (2): References as follows:
a = Cushing et al. (2011ApJ...743...50C 2011ApJ...743...50C)
b = Albert et al. (2011AJ....141..203A 2011AJ....141..203A)
c = Looper, Kirkpatrick & Burgasser (2007AJ....134.1162L 2007AJ....134.1162L, Cat. J/AJ/134/1162)
d = Burningham et al. (2010MNRAS.406.1885B 2010MNRAS.406.1885B)
Note (3): Notes as follows:
A = The data were taken when Spitzer was cold, and longer wavelength
photometry was also obtained: [5.8]=14.24±0.03, [8.0]=13.31±0.03
B = Separate, non-annular, skies used due to background structure
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 25 A25 --- Name Name
28- 29 I2 h RAh Right ascension (J2000)
31- 32 I2 min RAm Right ascension (J2000)
34- 38 F5.2 s RAs Right ascension (J2000)
40 A1 --- DE- Declination sign (J2000)
41- 42 I2 deg DEd Declination (J2000)
44- 45 I2 arcmin DEm Declination (J2000)
47- 51 F5.1 arcsec DEs Declination (J2000)
53- 57 A5 --- SpT Spectral type on the system of Burningham
et al. (2008MNRAS.391..320B 2008MNRAS.391..320B) (G1)
59- 60 I2 --- r_pm ? Proper motion reference (3)
62- 68 F7.2 mas/yr pmRA Proper motion along RA, pmRA*cosDE
70- 74 F5.2 mas/yr e_pmRA rms uncertainty on pmRA
76- 82 F7.2 mas/yr pmDE Proper motion along DE
84- 88 F5.2 mas/yr e_pmDE rms uncertainty on pmDE
90- 93 F4.2 yr dt Epoch baseline
94 A1 --- n_dt [W] The baseline includes our follow-up (1)
96- 99 F4.1 pc Dmin Minimum plausible distance (2)
101-105 F5.1 pc Dmax Maximum plausible distance (2)
107-111 F5.1 pc Dmax2 Maximum plausible distance for binary (2)
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Note (1): Epoch baselines denoted with W indicate that the proper motion has
been calculated from our own WFCAM follow-up following the same method as
used for the Smith et al. (in prep.) catalogue.
Note (2): Maximum and minimum plausible distances have been calculated using the
mean magnitudes for each spectral subtype from Dupuy & Liu
(2012ApJS..201...19D 2012ApJS..201...19D, Cat. J/ApJS/201/19) and assuming ±0.5 subtype
precision on types.
An additional maximum distance to account for possible unresolved binaries is
given in the final column.
Note (3): References as follows:
0 = catalogue of Smith et al. (in preparation)
1 = Chiu et al. (2006AJ....131.2722C 2006AJ....131.2722C, Cat. J/AJ/131/2722)
2 = Knapp et al. (2004AJ....127.3553K 2004AJ....127.3553K, Cat. J/AJ/127/3553)
3 = Kirkpatrick et al. (2011ApJS..197...19K 2011ApJS..197...19K, Cat. J/ApJS/197/19)
4 = Burgasser et al. (2006ApJ...637.1067B 2006ApJ...637.1067B, Cat. J/ApJ/637/1067)
5 = Burningham et al. (2010MNRAS.406.1885B 2010MNRAS.406.1885B)
6 = Pinfield et al. (2008MNRAS.390..304P 2008MNRAS.390..304P)
7 = Lodieu et al. (2007MNRAS.379.1423L 2007MNRAS.379.1423L)
8 = Albert et al. (2011AJ....141..203A 2011AJ....141..203A)
9 = Burningham et al. (2008MNRAS.391..320B 2008MNRAS.391..320B)
10 = Burningham et al. (2011MNRAS.414.3590B 2011MNRAS.414.3590B)
11 = Tsvetanov et al. (2000ApJ...531L..61T 2000ApJ...531L..61T)
12 = Burningham et al. (2010MNRAS.404.1952B 2010MNRAS.404.1952B)
13 = Kendall et al. (2007A&A...466.1059K 2007A&A...466.1059K)
14 = Murray et al. (2011MNRAS.414..575M 2011MNRAS.414..575M)
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Global notes:
Note (G1): Suffixes used in the spectral type:
p = objects that show substantial discrepancy either between the spectral
types indicated by their spectral indices, or in comparison to their
best-fitting spectral template have been classified as peculiar, and
are denoted with the suffix "p". The suffix
d = spectral type on the spectral typing system of Burningham et al.
(2008MNRAS.391..320B 2008MNRAS.391..320B).
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History:
* 12-Sep-2014: From electronic version of the journal
* 19-May-2015: some names in table5 corrected
(End) Patricia Vannier [CDS] 08-Jul-2014