J/AJ/133/439 Luminosity function of M7-L8 ultracool dwarfs (Cruz+, 2007)
Meeting the cool neighbors.
IX. The luminosity function of M7-L8 ultracool dwarfs in the field.
Cruz K.L., Reid I.N., Kirkpatrick J.D., Burgasser A.J., Liebert J.,
Solomon A.R., Schmidt S.J., Allen P.R., Hawley S.L., Covey K.R.
<Astron. J., 133, 439-467 (2007)>
=2007AJ....133..439C 2007AJ....133..439C
ADC_Keywords: Stars, dwarfs ; Stars, late-type ; Photometry, infrared
Keywords: Galaxy: stellar content - solar neighborhood - stars: late-type -
stars: low-mass, brown dwarfs -
stars: luminosity function, mass function
Abstract:
We present a 20pc, volume-limited sample of M7-L8 dwarfs created
through spectroscopic follow-up of sources selected from the Two
Micron All Sky Survey Second Incremental Release Point Source Catalog.
In this paper we present optical spectroscopy of 198 candidate nearby
ultracool dwarfs, including 12 late-M and L dwarfs likely to be within
20pc of the Sun and 94 more distant late-type dwarfs. We have also
identified five ultracool dwarfs with spectral signatures of low
gravity. Combining these data with previous results, we define a
sample of 99 ultracool dwarfs in 91 systems within 20pc. These are
used to estimate the J- and K-band luminosity functions for dwarfs
with optical spectral types between M7 and L8 (10.5<MJ<15,
9.5<MKs<13). We find a space density of 4.9x10-3/pc3 for late-M
dwarfs (M7-M9.5) and a lower limit of 3.8x10-3/pc3 for L dwarfs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 135 17 M6-L8 Dwarfs Discovered Within 20pc
table3.dat 133 103 M7-L8 Dwarfs Discovered Outside 20pc
table4.dat 142 34 Early-to-Mid Type M Dwarfs Discovered Outside 20pc
table5.dat 65 33 Spectroscopically confirmed giants
table6.dat 52 17 Spectroscopically confirmed carbon stars
table9.dat 149 99 The 20pc 2MU2 sample used to estimate the
luminosity function
table10.dat 138 33 Objects with distance estimates within 1σ of
20 parsecs
refs.dat 83 109 References
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See also:
II/241 : 2MASS Catalog Intermediate Data Release (IPAC/UMass, 2000)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
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/126/2421 : 2MASS-Selected sample of ultracool dwarfs (Cruz+, 2003)
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 catalogue (Reid+, 2004)
J/AJ/133/2825 : Activity and kinematics of ultracool dwarfs (Schmidt+, 2007)
Byte-by-byte Description of file: table[234].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- 2MASSI The 2MASSI designation (G1)
15 A1 --- m_2MASSI [ABC] Multiplicity index on 2MASSI
17- 21 I5 --- 2MUCD ? The 2MUCD number
23- 50 A28 --- OName Other name(s)
52 A1 --- n_OName [b] Common proper motion star (2)
54- 59 F6.3 mag Jmag ? 2MASS J band magnitude
61- 65 F5.3 mag J-H ? 2MASS (J-H) color
67- 71 F5.3 mag J-K ? 2MASS (J-KS) color
73- 82 A10 "YYYY/MM/DD" Obs.Date ? UT date of observation
84- 91 A8 --- Tel Telescope used in the observation
93-100 A8 --- SpType Optical spectral type
102 A1 --- f_SpType [abcde] Individual note on the spectrum (3)
104-108 F5.2 mag JMAG Absolute J band magnitude
110-113 F4.2 mag e_JMAG Uncertainty in JMAG
115-119 F5.1 pc Dist Distance
121-125 F5.1 pc e_Dist Uncertainty in Dist
127 A1 --- f_Dist [l] l: Dist and e_Dist represent the
range in the distance
129-142 A14 --- Refs Other references, in refs.dat file
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Note (2):
b = Ultracool common proper motion companion to a star as discussed
in Section 5.5.
Note (3): Notes as follows:
a = This object has been resolved into two components (Reid et al.,
2006ApJ...639.1114R 2006ApJ...639.1114R) and the spectral type listed here is for
the unresolved system. The distance and JMAG for the system is
based on a trigonometric parallax (Thorstensen & Kirkpatrick,
2003PASP..115.1207T 2003PASP..115.1207T).
b = A spectrum of this object is shown by Bessell (1991AJ....101..662B 1991AJ....101..662B)
but not mentioned in the text nor assigned a spectral type.
It appears to have been overlooked in the subsequent literature
on late-type M dwarfs. To our knowledge, it was first formally
assigned a spectral type by Reid et al. (2003AJ....125..354R 2003AJ....125..354R,
Paper VII) using the same data presented here.
c = Spectrum shows lithium absorption line as shown in Figure 2 and
discussed in Section 5.1.
d = Probable L/T binary (Cruz et al., 2004ApJ...604L..61C 2004ApJ...604L..61C; Burgasser
et al., 2006ApJS..166..585B 2006ApJS..166..585B). Combined-light optical spectral
type from Kirkpatrick et al., in prep.
e = Variable and/or flaring object that will be discussed in detail
in Schmidt et al., in prep.
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Byte-by-byte Description of file: table5.dat table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- 2MASSI 2MASSi designation (G1)
16- 21 F6.3 mag Jmag J magnitude
23- 27 F5.3 mag J-H J-H colour index
29- 33 F5.3 mag J-Ks J-Ks colour index
35- 44 A10 "YYYY/MM/DD" Obs.Date UT date of observation
46- 52 A7 --- Tel Telescope used
54- 63 A10 --- SpType Optical spectral type
65 A1 --- n_SpType [b] b: Spectrum displays Hα in
emission
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Byte-by-byte Description of file: table9.dat table10.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- 2MASSI The 2MASSI designation (G1)
15 A1 --- m_2MASSI [ABC] Multiplicity index on 2MASSI
17 A1 --- f_2MASSI [eghl] Individual note on 2MASSI (2)
19- 23 I5 --- 2MUCD ? The 2MUCD number
25- 51 A27 --- OName Other name(s)
52 A1 --- n_OName [de] Individual note on OName (3)
54- 59 F6.3 mag Jmag ? 2MASS J band magnitude
61- 65 F5.3 mag J-H ? 2MASS (J-H) color index
67- 71 F5.3 mag J-K ? 2MASS (J-KS) color index
73- 77 A5 --- SpType Optical spectral type (4)
78 A1 --- f_SpType [efhijkl] Individual note on spectrum (2)
80- 84 F5.2 mag JMAG Absolute J band magnitude
86- 89 F4.2 mag e_JMAG Uncertainty in JMAG
91 A1 --- f_JMAG [g] Individual note on JMAG (2)
93- 97 F5.2 mag KsMAG ? Absolute Ks band magnitude
99-102 F4.2 mag e_KsMAG ? Uncertainty in KsMAG
104-108 F5.2 pc Dist Distance
110-113 F4.2 pc e_Dist Uncertainty in Dist
115-122 A8 --- n_Dist Method of distance determination (7)
124-140 A17 --- DRefs Discovery reference(s) (table9) or
reference(s) (table10), in refs.dat file
142-149 A8 --- PRefs Parallax reference(s) (table9),
in refs.dat file
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Note (2): Notes as follows:
e = Bouy et al. (2005AJ....129..511B 2005AJ....129..511B) report a T dwarf as a possible
third component to the system. The T dwarf is not included in
the luminosity function estimate.
f = Variable and/or flaring object that will be discussed in detail
in Schmidt et al., in prep.
g = The absolute magnitude for this object, based on a trigonometric
parallax, is brighter than our brightest JMAG bin and is not
included in our space density per magnitude analysis. However,
it is included in our estimates of the total space densities of
ultracool dwarfs. It is also a suspected unresolved binary as
discussed in Section 5.6.
h = This object has been resolved into an L/T binary by Burgasser et
al. (2005ApJ...634L.177B 2005ApJ...634L.177B). The T dwarf is not included in the
luminosity function estimate.
i = This object displays features of low gravity and a spectral type
of M9: was used to estimate JMAG.
j = Change in spectral type from Paper V (Cruz et al.,
Cat. J/AJ/126/2421).
k = Suspected low-metallicity dwarf as discussed in Section 5.4.
l = Suspected unresolved binary as discussed in Section 5.6.
Note (3): Notes as follows:
d = Henry et al. (1999ApJ...512..864H 1999ApJ...512..864H) reported the possible
existence of a fourth component, LHS 1070D, at a separation of
50mas; further observations have shown the original apparent
detection to be spurious (T. Henry 2006, priv. comm.).
e = Bouy et al. (2005AJ....129..511B 2005AJ....129..511B) report a T dwarf as a possible
third component to the system. The T dwarf is not included in
the luminosity function estimate.
Note (4): A single or double colon indicates an uncertainty on the spectral
type of ±1 or ±2 types respectively due to a low signal-to-noise
spectrum. A single colon is also used to indicate uncertainty on the
spectral type of individual objects in multiple systems where resolved
spectroscopy has not been obtained.
Note (7): Distance flag as follows:
ST = Distance are spectrophotometric
Parallax = Distance are from trigonometric parallax
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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- 3 I3 --- Ref Reference code
5- 23 A19 --- BibCode BibCode
25- 49 A25 --- Aut Author's name
51- 83 A33 --- Com Comments
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Global notes:
Note (G1): The 2MASS designation is 2MASSI Jhhmmss[.]s-ddmmss.
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History:
From electronic version of the journal
References:
Reid et al., 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 et al., Paper III 2002AJ....123.2828C 2002AJ....123.2828C, Cat. J/AJ/123/2828
Reid et al., Paper IV 2003AJ....125..354R 2003AJ....125..354R
Cruz et al., Paper V 2003AJ....126.2421C 2003AJ....126.2421C, Cat. J/AJ/126/2421
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
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) Patricia Vannier [CDS] 17-Aug-2007