J/AJ/126/2421 2MASS-Selected sample of ultracool dwarfs (Cruz+, 2003)
Meeting the cool neighbors. V. A 2MASS-Selected sample of ultracool dwarfs.
Cruz K.L., Reid I.N., Liebert J., Kirkpatrick J.D., Lowrance P.J.
<Astron. J., 126, 2421-2448 (2003)>
=2003AJ....126.2421C 2003AJ....126.2421C
ADC_Keywords: Stars, dwarfs ; Infrared sources ; Photometry, infrared ;
Stars, late-type ; Stars, distances
Keywords: Galaxy: stellar content - solar neighborhood -
stars: low-mass, brown dwarfs -
stars: luminosity function, mass function
Abstract:
We present the initial results of our effort to create a statistically
robust, volume-limited sample of ultracool dwarfs from the Two Micron
All Sky Survey Second Incremental Data Release (II/241). We are
engaged in a multifaceted search for nearby late-type objects, and
this is the first installment of our search using purely photometric
selection. The goal of this work is a determination of the low-mass
star and brown dwarf luminosity function in the infrared. Here we
outline the construction of the sample, dubbed 2MU2, and present our
first results, including the discovery of 186 M7-L6 dwarfs, 47 of
which are likely to be within 20pc of the Sun. These results represent
66% of the ultracool candidates in our sample yet constitute a 127%
increase in the number of ultracool dwarfs known within the volume
searched (covering 40% of the sky out to 20pc). In addition, we have
identified 10 M4-M6.5 objects that are likely to be within 20pc (or
within 1σ). Finally, based on these initial data, we present a
preliminary luminosity function and discuss several interesting
features of the partial sample presented here. Once our sample is
complete, we will use our measured luminosity function to constrain
the mass function of low-mass stars and brown dwarfs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 134 112 Previously known cool dwarfs recovered in the
2MU2 sample
refs.dat 80 51 References
table7.dat 132 47 M7-L8 Dwarfs Discovered within 20pc
table8.dat 129 139 M7-L8 Dwarfs Discovered outside 20pc
table9.dat 130 10 Early-Type M Dwarfs Discovered within 20pc
table10.dat 127 53 Early-Type M dwarfs Discovered outside 20pc
notes.dat 80 22 Notes of tables 7, 8, 9 and 10
table11.dat 88 5 Young objects
table12.dat 90 34 Spectroscopically confirmed giants
table13.dat 106 16 Spectroscopically confirmed carbon stars
table14.dat 44 56 JMAG/Spectral type calibration data
table15.dat 75 117 The J<9 Sources with IRAS Catalog Counterpart
table16.dat 72 138 The J<9 Sources with Stellar Counterparts
table17.dat 67 13 Carbon Stars
table18.dat 66 80 Miras and Long-Period Variables
table19.dat 67 16 Semiregular Variables
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See also:
II/241 : 2MASS Catalog Intermediate Data Release (IPAC/UMass, 2000)
J/AJ/123/2806 : Nearby stars in the NLTT catalogue (Reid+, 2002)
J/AJ/123/2822 : Photometry of southern NLTT stars (Reid+, 2002)
J/AJ/123/2828 : Spectroscopy of northern NLTT stars (Cruz+, 2002)
J/AJ/126/2449 : Nearby ultracool dwarfs in galactic plane (Reid+, 2003)
J/AJ/126/3007 : Spectroscopy of faint red NLTT dwarfs (Reid+, 2003)
J/AJ/128/463 : A preliminary 20pc census from the NLTT cat. (Reid+, 2004)
J/AJ/130/1680 : LSPM-North proper-motion catalog nearby stars (Lepine+, 2005)
Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- 2MASSI 2MASSI Designation
15- 16 A2 --- f_2MASSI [* ] star included in preliminary LF (1)
18- 46 A29 --- OName Other Names
48- 53 F6.3 mag Jmag J magnitude
54 A1 --- n_Jmag [a] Note on Jmag (2)
56- 60 F5.3 mag J-H J-H colour index
62- 66 F5.3 mag J-Ks J-Ks colour index
68- 72 A5 --- SpType Spectral type
73 A1 --- n_SpType [cd] Note on SpType (2)
75- 78 F4.1 mag JMAG ? Estimated absolute J magnitude
80- 82 F3.1 mag e_JMAG ? rms uncertainty on JMAG
83 A1 --- u_JMAG [)] ): estimate based on the system's combined
spectral type and photometry
85- 88 F4.1 pc Dist ? Estimated distance
90- 92 F3.1 pc e_Dist ? rms uncertainty on Dist
93 A1 --- u_Dist [)] ): estimate based on the system's combined
spectral type and photometry
94 A1 --- n_Dist [fhijkm] Note on JMAG and Dist (2)
96-100 F5.2 mag JpiMAG ? Absolute J magnitude based on trigonometric
parallax data
102-105 F4.2 mag e_JpiMAG ? rms uncertainty on JpiMAG
106 A1 --- f_JpiMAG [bge] Note on JpiMAG (2)
108-112 F5.2 pc Distpi ? Distance based on trigonometric parallax data
114-117 F4.2 pc e_Distpi ? rms uncertainty on Distpi
119-120 A2 --- r_Distpi Trigonometric Parallax references,
in refs.dat file
122-130 A9 --- r_Mult Multiplicity references, in refs.dat file
132-134 A3 --- r_Disc Discovery references, in refs.dat file
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Note (1): Objects included in our preliminary luminosity function
(Spectral type≥M7 and d≤20 pc) are marked with one asterisk;
binaries are marked with two asterisks.
Note (2): Notes:
a: Photometry listed is from Dahn et al., 2002AJ....124.1170D 2002AJ....124.1170D
as the 2MASS photometry is contaminated by a meteor.
b: JMAG=13.85 for both components.
c: SpType changed from M8 in Gizis et al., 2000AJ....120.1085
d: SpType changed from M6 in PMSU (Reid et al., 2002AJ....124.2721R 2002AJ....124.2721R)
e: JMAG=11.80 and 12.40 (Close et al., 2003ApJ...587..407C 2003ApJ...587..407C).
f: JMAG=11.16 and 12.01 (Close et al., 2003ApJ...587..407C 2003ApJ...587..407C); d=21.8pc
g: JMAG=11.09 and 14.92 (Freed, Close, & Siegler 2003ApJ...584..453F 2003ApJ...584..453F)
h: JMAG=13.55 and 13.95 (Bouy et al., 2003, Cat. J/AJ/126/1526); d=21.8pc
i: JMAG=11.32 and 12.10 (Close et al., 2003ApJ...587..407C 2003ApJ...587..407C). d=24.9pc
j: Based on photometric distance found by Tinney, Mould, & Reid,
1993AJ....105.1045T 1993AJ....105.1045T
k: JMAG=14.45 and 15.10 (Bouy et al., 2003, Cat. J/AJ/126/1526); d=25.4pc
l: SpType changed from M5.5 in PMSU (Reid et al. 2002AJ....124.2721R 2002AJ....124.2721R)
m: JMAG=11.16 and 11.33 (Close et al., 2003ApJ...587..407C 2003ApJ...587..407C); d=24.4pc
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- Ref Reference code
5- 23 A19 --- BibCode BibCode
25- 46 A22 --- Aut Author's name
48- 80 A33 --- Com Comments
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Byte-by-byte Description of file: table[789].dat table10.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- --- [2MASSI]
8- 21 A14 --- 2MASSI The 2MASS designation
23- 51 A29 --- OName Other name
53- 58 F6.3 mag Jmag The 2MASS J-band magnitude
60- 64 F5.3 mag J-H The 2MASS (J-H) color
66- 70 F5.3 mag J-Ks The 2MASS (J-Ks) color
72- 81 A10 "YYYY/MM/DD" Date Date of spectroscopic observation
83- 89 A7 --- TCode Telescope used for spectroscopic
observation (G1)
91- 94 A4 --- SpType Spectral type
96 A1 --- n_SpType Note on SpType, in notes.dat file
97 A1 --- u_SpType [?] Uncertainty flag on SpType (2)
99-102 F4.1 mag JMAG Absolute J-band magnitude (3)
104-106 F3.1 mag e_JMAG ? Error in JMAG
108 A1 --- n_JMAG Note on JMAG, in notes.dat file
109-113 F5.1 pc Dist Distance (3)
115-118 F4.1 pc e_Dist ? Error in Dist
120 A1 --- n_Dist Note on Dist detailed in notes.dat file
122-132 A11 --- r_2MASSI Other references, in refs.dat file
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Note (2): A "?" indicates that the uncertainty is either 1 or 2 types.
For objects without a "?," the uncertainty is 0.5 types.
Note (3): Estimates obtained using our calibration.
In table7.dat, data for multiple systems are based on the system's
combined spectral type and photometry.
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Byte-by-byte Description of file: notes.dat
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Bytes Format Units Label Explanations
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1 A1 --- Note Note code
3- 80 A78 --- Text Text of the note
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Byte-by-byte Description of file: table11.dat table12.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- 2MASSI The 2MASSI designation
16- 21 F6.3 mag Jmag The 2MASS J-band magnitude
23- 27 F5.3 mag J-H The 2MASS (J-H) color
29- 33 F5.3 mag J-Ks The 2MASS (J-Ks) color
35- 44 A10 "YYYY/MM/DD" Date Date of spectroscopic observation
46- 52 A7 --- TCode Telescope used for spectroscopic
observation (G1)
54- 63 A10 --- SpType Spectral type
65- 96 A32 --- Com Comments
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Byte-by-byte Description of file: table13.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- 2MASSI The 2MASSI designation
16- 21 F6.3 mag Jmag The 2MASS J-band magnitude
23- 27 F5.3 mag J-H The 2MASS (J-H) color
29- 33 F5.3 mag J-Ks The 2MASS (J-Ks) color
35- 44 A10 "YYYY/MM/DD" Date Date of spectroscopic observation
46- 52 A7 --- TCode Telescope used for spectroscopic
observation (G1)
54- 56 A3 --- VisPM [Yes No] Visual proper motion (2)
58 A1 --- --- [(]
59- 75 A17 --- Epoch Epoch
76 A1 --- --- [)]
78-104 A27 --- Com Comments (3)
106 A1 --- Note [b] Note (4)
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Note (2): Possible visual proper motion determined by P.J. Lowrance
from examining DSS, XDSS, and 2MASS images.
Note (3): Epochs listed are either DSS-2MASS or XDSS R-2MASS.
Note (4): A discussion of these new carbon dwarfs will appear in
Lowrance et al. (2003, in prep.)
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Byte-by-byte Description of file: table14.dat
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Bytes Format Units Label Explanations
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1- 23 A23 --- Name Name
25- 28 F4.1 --- SpType Spectral type (M5 = 5, L0 = 10, L8 = 18)
33- 37 F5.2 mag JMAG Absolute J magnitude
39- 42 F4.2 mag e_JMAG rms uncertainty on JMAG
44 I1 --- Ref Reference (1)
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Note (1): References:
(1) The 8pc sample;
(2) Dahn et al., 2002AJ....124.1170D 2002AJ....124.1170D
(3) PMSU, Reid et al., 2002AJ....124.2721R 2002AJ....124.2721R
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Byte-by-byte Description of file: table1[5-9].dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 h RAh Hour of right ascension (J2000)
4- 5 I2 min RAm Minute of right ascension (J2000)
7- 10 F4.1 s RAs Second of right ascension (J2000)
12 A1 --- DE- Sign of the declination (J2000)
13- 14 I2 deg DEd Degree of declination (J2000)
16- 17 I2 arcmin DEm Arcminute of declination (J2000)
19- 20 I2 arcsec DEs Arcsecond of declination (J2000)
22- 26 F5.2 mag Vmag ? The V-band magnitude
28- 32 F5.3 mag J-H ? The 2MASS (J-H) color
34- 38 F5.3 mag H-Ks ? The 2MASS (H-Ks) color
40- 44 F5.3 mag Ksmag ? The 2MASS Ks band magnitude
46- 50 F5.3 mag J-Ks ? The 2MASS (J-Ks) color
52- 73 A22 --- ID Other identifications
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Global notes:
Note (G1): Telescopes:
KT = Kitt Peak;
CT = Cerro Tololo.
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History:
From electronic version of the journal
References:
Reid & Cruz, Paper I 2002AJ....123.2806R 2002AJ....123.2806R, Cat. J/AJ/123/2806
Reid et al., Paper II 2002AJ....123.2822R 2002AJ....123.2822R, Cat. J/AJ/123/2822
Cruz & Reid, Paper III 2002AJ....123.2828C 2002AJ....123.2828C, Cat. J/AJ/123/2828
Reid et al., Paper IV 2003AJ....125..354R 2003AJ....125..354R
Reid, Paper VI 2003AJ....126.2449R 2003AJ....126.2449R, Cat. J/AJ/126/2449
Reid et al., Paper VII 2003AJ....126.3007R 2003AJ....126.3007R, Cat. J/AJ/126/3007
Reid et al., Paper VIII 2004AJ....128..463R 2004AJ....128..463R, Cat. J/AJ/128/463
Cruz et al., Paper IX 2007AJ....133..439C 2007AJ....133..439C, Cat. J/AJ/133/439
Reid et al., Paper X 2008AJ....136.1290R 2008AJ....136.1290R, Cat. J/AJ/136/1290
Reid et al., Paper XI 2007AJ....133.2825R 2007AJ....133.2825R, Cat. J/AJ/133/2825
Cruz et al., Paper XII 2018AJ....155...34C 2018AJ....155...34C
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 12-Jan-2004