J/ApJ/676/1281 L and T dwarfs in 2MASS/SDSS (Metchev+, 2008)
A cross-match of 2MASS and SDSS: newly found L and T dwarfs and an estimate of
the space density of T dwarfs.
Metchev S.A., Kirkpatrick J.D., Berriman G.B., Looper D.
<Astrophys. J., 676, 1281-1306 (2008)>
=2008ApJ...676.1281M 2008ApJ...676.1281M
ADC_Keywords: Stars, dwarfs ; Photometry, infrared ; Photometry, SDSS
Keywords: stars: individual (2MASS J00521232+0012172, 2MASS J01040750-0053283,
2MASS J01262109+1428057, 2MASS J09175418+6028065,
2MASS J12144089+6316434, 2MASS J13243553+6358281,
2MASS J15461461+4932114) - stars: low-mass, brown dwarfs - surveys
Abstract:
We report new L and T dwarfs found in a cross-match of the SDSS Data
Release 1 and 2MASS. Our simultaneous search of the two databases
effectively allows us to relax the criteria for object detection in
either survey and to explore the combined databases to a greater
completeness level. We find two new T dwarfs in addition to the 13
already known in the SDSS DR1 footprint. We also identify 22 new
candidate and bona fide L dwarfs, including a new young L2 dwarf and a
peculiar potentially metal-poor L2 dwarf with unusually blue near-IR
colors. These discoveries underscore the utility of simultaneous
database cross-correlation in searching for rare objects.
Description:
Our targets were selected from the 2099deg2 imaging footprint of
SDSS DR1. We used the combined optical (from SDSS) and near-IR (from
2MASS) characteristics of cataloged objects to identify suitable
targets. This section details our cross-correlation approach and the
target selection process.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 86 43 Optical and near-IR photometry of candidate and
known ultracool dwarfs
table2.dat 16 7 Additional candidates near bright stars
table3.dat 55 33 Discarded candidates
table5.dat 84 3 Spitzer IRAC observations and photometry of
ultracool dwarfs
table6.dat 97 24 Spectral types and colors of confirmed
and candidate ultracool dwarfs
table7.dat 154 15 All Known T Dwarfs in SDSS DR1 and SDSS Flags
(tables 7 and 14 of the paper)
refs.dat 60 11 References
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/AJ/123/3409 : SDSS M, L, and T dwarfs (Hawley+, 2002)
J/AJ/126/2487 : T dwarfs in the southern hemisphere (Burgasser+, 2003)
J/AJ/127/2856 : Brown dwarfs in the 2MASS Survey (Burgasser+, 2004)
J/AJ/127/3553 : Land T dwarfs JHK phot. and spectroscopy (Knapp+, 2004)
J/AJ/131/2722 : New L and T dwarfs from the SDSS (Chiu+, 2006)
J/AJ/134/1162 : 11 new T dwarfs in 2MASS (Looper+, 2007)
J/AJ/136/1290 : Ultracool dwarfs from the 2MASS (Reid+, 2008)
J/MNRAS/384/1399 : Proper motions of field L and T dwarfs (Jameson+, 2008)
J/other/ARA+A/43.195 : L and T dwarf stars (Kirkpatrick, 2005)
http://www.sdss.org : SDSS Home Page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- 2MASS 2MASS name (HHMMSSss+DDMMSSs, J2000.0)
18 A1 --- l_imag Limit flag in imag
19- 23 F5.2 mag imag SDSS i magnitude (1)
25- 28 F4.2 mag e_imag ? rms uncertainty on imag
29 A1 --- n_imag [d] Note on imag (2)
31- 35 F5.2 mag zmag SDSS z magnitude
37- 40 F4.2 mag e_zmag rms uncertainty on zmag
42 A1 --- l_Jmag Limit flag on Jmag
43- 47 F5.2 mag Jmag 2MASS J magnitude
49- 52 F4.2 mag e_Jmag ? rms uncertainty on Jmag
53 A1 --- n_Jmag [c] Note on Hmag (2)
55 A1 --- l_Hmag Limit flag on Hmag
56- 60 F5.2 mag Hmag 2MASS H magnitude
62- 65 F4.2 mag e_Hmag ? rms uncertainty on Hmag
67 A1 --- l_Ksmag Limit flag on Ksmag
68- 72 F5.2 mag Ksmag 2MASS Ks magnitude
74- 77 F4.2 mag e_Ksmag ? rms uncertainty on Ksmag
78 A1 --- n_Ksmag [c] Note on Ksmag (2)
80- 83 A4 --- SpType MK spectral type (3)
85- 86 I2 --- Ref ? Reference, in refs.dat file
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Note (1): SDSS i-band magnitudes are listed if they are brighter than the
i∼23.0mag 3σ detection limit. Otherwise, 23.00mag is listed as
the lower magnitude limit.
Note (2): Notes as follows:
c = Below the S/N=5 limit in 2MASS. The photometry was obtained by
fitting a PSF to the signal at the known location of the object
from the other two 2MASS bands.
d = The deblending of the source from a nearby star in SDSS was
redone to obtain more reliable photometry.
Note (3): The spectral types of all previously known T dwarfs have been
updated to conform to the uniform near-IR T dwarf classification
scheme of Burgasser et al. (2006, Cat. J/ApJ/637/1067) and are as
listed at http://dwarfarchives.org (Kirkpatrick 2003IAUS..211..189K 2003IAUS..211..189K;
Gelino et al. 2004AAS...205.1113G 2004AAS...205.1113G).
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Byte-by-byte Description of file: table2.dat table3.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- 2MASS 2MASS name (HHMMSSss+DDMMSSs, J2000.0)
18- 55 A38 --- Com Comments
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- 2MASS 2MASS name (HHMMSSss+DDMMSSs, J2000.0)
18- 27 A10 "YYYY/MM/DD" Date Observation date
29- 36 I8 --- AOR AOR key
38- 40 I3 s Exp Exposure time
42- 46 F5.2 mag [3.6] Spitzer/IRAC 3.6um magnitude
48- 51 F4.2 mag e_[3.6] rms uncertainty on [3.6]
53- 57 F5.2 mag [4.5] Spitzer/IRAC 4.5um magnitude
59- 62 F4.2 mag e_[4.5] rms uncertainty on [4.5]
64- 68 F5.2 mag [5.8] Spitzer/IRAC 5.8um magnitude
70- 73 F4.2 mag e_[5.8] rms uncertainty on [5.8]
75- 79 F5.2 mag [8.0] Spitzer/IRAC 8.0um magnitude
81- 84 F4.2 mag e_[8.0] rms uncertainty on [8.0]
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- 2MASS 2MASS name (HHMMSSss+DDMMSSs, J2000.0)
18- 29 A12 --- SpType MK spectral type
31 A1 --- l_i-z Limit flag on i-z
32- 35 F4.2 mag i-z SDSS i-z colour index
37- 40 F4.2 mag e_i-z ? rms uncertainty on i-z
42 A1 --- l_z-J Limit flag on z-J
43- 46 F4.2 mag z-J SDSS-2MASS z-J colour index
48- 51 F4.2 mag e_z-J ? rms uncertainty on z-J
53 A1 --- l_J-H Limit flag on J-H
54- 57 F4.2 mag J-H 2MASS J-H colour index
59- 62 F4.2 mag e_J-H ? rms uncertainty on J-H
64 A1 --- l_H-Ks Limit flag on H-Ks
65- 68 F4.2 mag H-Ks ?=- 2MASS H-Ks colour index
70- 73 F4.2 mag e_H-Ks ? rms uncertainty on H-Ks
75 A1 --- l_J-Ks Limit flag on J-Ks
76- 79 F4.2 mag J-Ks ?=- 2MASS J-Ks colour index
81- 84 F4.2 mag e_J-Ks ? rms uncertainty on J-Ks
86 A1 --- l_Jmag Limit flag on Jmag
87- 91 F5.2 mag Jmag 2MASS J magnitude
93- 96 F4.2 mag e_Jmag ? rms uncertainty on Jmag
97 A1 --- n_Jmag [a] a: H-only detection in 2MASS
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Byte-by-byte Description of file:table7.dat
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Bytes Format Units Label Explanations
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1 A1 --- Flag [PN] Previously known or New T dwarf
3- 20 A18 --- SDSS SDSS name (HHMMSS.ss+DDMMSS.s, J2000.0)
22- 37 A16 --- 2MASS 2MASS name (HHMMSSss+DDMMSSs, J2000.0)
39- 48 A10 --- SpType MK spectral type
50- 51 I2 --- Ref Reference, in refs.dat file
53 A1 --- Note [ab] Note on SDSS star (1)
55-154 A100 --- SDSSf SDSS Flags
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Note (1): Notes as follows:
a = Not recovered in the present cross-match (see Sect. 5.1).
b = The field containing this object
[run,rerun,camcol,field)=(2125, 40, 1, 49)] is included in the
SDSS Data Archive Server (DAS), but data for the object are
unavailable through the Catalog Archive Server (CAS).
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Ref Reference number
4- 22 A19 --- BibCode BibCode
24- 41 A18 --- Aut Author's name
43- 60 A18 --- Com Comments
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 25-Sep-2010