J/ApJ/752/56 BDKP. III. Parallaxes for 70 ultracool dwarfs (Faherty+, 2012)
The Brown Dwarf Kinematics Project (BDKP).
III. Parallaxes for 70 ultracool dwarfs.
Faherty J.K., Burgasser A.J., Walter F.M., Van der Bliek N., Shara M.M.,
Cruz K.L., West A.A., Vrba F.J., Anglada-Escude G.
<Astrophys. J., 752, 56 (2012)>
=2012ApJ...752...56F 2012ApJ...752...56F
ADC_Keywords: Positional data ; Parallaxes, trigonometric ; Photometry, SDSS ;
Photometry, infrared ; Spectral types ; Proper motions
Keywords: astrometry; brown dwarfs; stars: low-mass
Abstract:
We report parallax measurements for 70 ultracool dwarfs (UCDs)
including 11 late-M, 32 L, and 27 T dwarfs. In this sample, 14 M and L
dwarfs exhibit low surface gravity features, 6 are close binary
systems, and 2 are metal-poor subdwarfs. We combined our new
measurements with 114 previously published UCD parallaxes and
optical-mid-IR photometry to examine trends in spectral-type/absolute
magnitude, and color-color diagrams. We report new polynomial
relations between spectral type and MJHK. Including resolved L/T
transition binaries in the relations, we find no reason to
differentiate between a "bright" (unresolved binary) and a "faint"
(single source) sample across the L/T boundary. Isolating early T
dwarfs, we find that the brightening of T0-T4 sources is prominent in
MJ where there is a [1.2-1.4] mag difference. A similar yet dampened
brightening of [0.3-0.5] mag happens at MH and a plateau or dimming
of [-0.2 to -0.3] mag is seen in MK. Comparison with evolutionary
models that vary gravity, metallicity, and cloud thickness verifies
that for L into T dwarfs, decreasing cloud thickness reproduces brown
dwarf near-IR color-magnitude diagrams. However we find that a near
constant temperature of 1200 ±100 K along a narrow spectral subtype
of T0-T4 is required to account for the brightening and
color-magnitude diagram of the L-dwarf/T-dwarf transition. There is a
significant population of both L and T dwarfs which are red or
potentially "ultra-cloudy" compared to the models, many of which are
known to be young indicating a correlation between enhanced
photospheric dust and youth. For the low surface gravity or young
companion L dwarfs we find that 8 out of 10 are at least [0.2-1.0] mag
underluminous in MJHand/or MKcompared to equivalent spectral type
objects. We speculate that this is a consequence of increased dust
opacity and conclude that low surface gravity L dwarfs require a
completely new spectral-type/absolute magnitude polynomial for
analysis.
Description:
We compiled the parallax target list from the BDKP astrometric sample
reported in Faherty et al. (2009, Cat. J/AJ/137/1). Our full target
list consisted of 70 dwarfs, including 11 M, 32 L, and 27 T dwarfs
(see Table 1). In this sample there were 14 low surface gravity
dwarfs, 2 subdwarfs, 6 binary systems, and 9 calibrators with previous
parallax measurements.
We obtained parallax frames with the ANDICAM (A Novel Double-Imaging
CAMera- DePoy 2003) imager between 2006 November and 2010 March
(∼500hr of observations), in the Ic and J bands.
We collected parallax data for our faintest targets with the Infrared
Side Port Imager (ISPI) on the CTIO 4m Blanco telescope in the J band.
Observations were conducted over a period of just under 2yr (from
early 2008 March through late 2010 April) on 15 observing runs. We
obtained three more epochs over six nights of observing in 2011
November, 2012 January, and 2012 February.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 91 70 Target list
table2.dat 93 70 Astrometry of targets
table5.dat 216 176 *Photometry of full sample
refs.dat 70 103 References
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Note on table5.dat: This table contains all sources with parallaxes reported
in this work as well as all sources used in the astrometric analysis (with
absolute magnitude uncertainty <0.5mag).
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/A+A/556/A133 : Low-mass companion to ultracool dwarf orbit (Sahlmann+, 2013)
J/ApJ/746/23 : Radio observations of ultracool dwarf stars (McLean+, 2012)
J/ApJS/201/19 : Hawaii Infrared Parallax Program. I. (Dupuy+, 2012)
J/ApJS/197/19 : First brown dwarfs discovered by WISE (Kirkpatrick+, 2011)
J/A+A/512/A37 : Velocities of 43 nearby L dwarfs (Seifahrt+, 2010)
J/AJ/139/1808 : Colors and kinematics of SDSS L dwarfs (Schmidt+, 2010)
J/A+A/497/619 : New ultra-cool dwarfs from SDSS and 2MASS (Zhang+, 2009)
J/A+A/493/L27 : Parallaxes of 10 ultracool subdwarfs (Schilbach+, 2009)
J/AJ/137/1 : Paper I - Late-type dwarfs astrometry (Faherty+, 2009)
J/AJ/136/1290 : Ultracool dwarfs from the 2MASS (Reid+, 2008)
J/ApJ/689/1295 : Li test implications for brown dwarfs (Kirkpatrick+, 2008)
J/AJ/134/1162 : 11 new T dwarfs in 2MASS (Looper+, 2007)
J/AJ/131/2722 : New L and T dwarfs from the SDSS (Chiu+, 2006)
J/PASP/118/659 : RI photometry of 2MASS late M and L dwarfs (Liebert+, 2006)
J/ApJ/637/1067 : Near-IR spectral classification of T dwarfs (Burgasser+, 2006)
J/AJ/127/2856 : Brown dwarfs in the 2MASS Survey (Burgasser+, 2004)
J/AJ/127/3553 : JHK phot. and spectroscopy for L and T dwarfs (Knapp+, 2004)
J/AJ/126/2421 : 2MASS-Selected sample of ultracool dwarfs (Cruz+, 2003)
J/AJ/126/2487 : T dwarfs in the southern hemisphere (Burgasser+, 2003)
J/AJ/125/1598 : New high PM stars in the northern sky (Lepine+, 2003)
J/AJ/123/3409 : SDSS M, L, and T dwarfs (Hawley+, 2002)
J/ApJ/564/421 : Spectra of T dwarfs. I. (Burgasser+, 2002)
J/ApJ/476/311 : 2MASS M-dwarf discoveries (Kirkpatrick+ 1997)
J/AJ/103/638 : USNO Photographic Parallaxes. I. (Monet+, 1992)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 23 A23 --- Name Source name
25- 36 A12 --- SpT.o Optical MK spectral type (G2)
38- 43 A6 --- SpT.i NIR optical MK spectral type
45- 46 I2 --- Nobs [5/25] Number of observing nights
48- 49 I2 --- Nf [11/91] Number of frames used in the parallax
solution
51- 52 I2 --- Nr [21/99] Number of reference stars used in the
parallax solution
54- 57 F4.2 yr Dt [1/4] Time of observing in years (Δt)
59- 63 F5.2 mag Jmag [10.1/17.1] MKO J-band magnitude
65- 68 F4.2 mag e_Jmag [0.02/0.2] Jmag uncertainty
70 A1 --- Inst Instrument code (1)
72- 77 A6 --- Note Note (G1)
79- 81 A3 --- Flag Large uncertainties (2)
83- 91 A9 --- Ref Reference(s) (see refs.dat file)
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Note (1): Code as follows:
I = ISPI
A = ANDICAM
Note (2): Flag as follows:
F = object with <9 parallax frames;
N = object with MJHK uncertainties >0.5mag therefore; unless otherwise
noted, it indicates that the target was not used in the analysis
throughout the paper.
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 23 A23 --- Name Source name
25- 34 A10 --- SpT Final MK spectral type (G2)
36- 40 F5.1 mas PlxR [18/195] Relative parallax
42- 45 F4.1 mas e_PlxR [2/15] PlxR uncertainty
47- 51 F5.1 mas Plx [19/196] Final parallax with absolute
corrections (section 3.3)
53- 56 F4.1 mas e_Plx [2/15] PlxA uncertainty
58- 64 F7.1 mas/yr pmRA [-2928/2330] Proper motion along RA
66- 69 F4.1 mas/yr e_pmRA [2/13] pmRA uncertainty
71- 77 F7.1 mas/yr pmDE [-1954/1644] Proper motion along DE
79- 82 F4.1 mas/yr e_pmDE [2/13] pmDE uncertainty
84- 88 F5.1 km/s Vtan [2/312] Tangential velocity
90- 93 F4.1 km/s e_Vtan [0.3/46] Vtan uncertainty
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 23 A23 --- Name Source name
25- 36 A12 --- SpT.o Optical MK spectral type (G2)
38- 43 A6 --- SpT.i Near-IR MK spectral type
45- 50 F6.2 mas Plx [9.8/276] Parallax
52- 56 F5.2 mas e_Plx [0.3/33] Uncertainty in Plx
58- 62 F5.2 mag rmag [18.6/26]? SDSS r band magnitude
64- 67 F4.2 mag e_rmag [0.01/0.9]? Uncertainty in rmag
69- 73 F5.2 mag imag ? SDSS i band magnitude
75- 78 F4.2 mag e_imag ? Uncertainty in imag
80- 84 F5.2 mag zmag ? SDSS z band magnitude
86- 89 F4.2 mag e_zmag ? Uncertainty in zmag
91- 95 F5.2 mag Ymag [12.8/20]? MKO Y band magnitude
97-100 F4.2 mag e_Ymag [0.02/0.2]? Uncertainty in Ymag
102-106 F5.2 mag Lmag ? MKO L band magnitude
108-111 F4.2 mag e_Lmag ? Uncertainty in Lmag
113-117 F5.2 mag Mmag ? MKO M band magnitude
119-122 F4.2 mag e_Mmag ? Uncertainty in Mmag
124-128 F5.2 mag Jmag [11.3/19] MKO J band magnitude
130-133 F4.2 mag e_Jmag [0/1.2] Uncertainty in Jmag
135-139 F5.2 mag Hmag MKO H band magnitude
141-144 F4.2 mag e_Hmag Uncertainty in Hmag
146-150 F5.2 mag Kmag [10/20] MKO K band magnitude
152-155 F4.2 mag e_Kmag [0/0.5] Uncertainty in Kmag
157-161 F5.2 mag [3.6] [9.8/16]? Spitzer/IRAC 3.6 micron band magnitude
163-166 F4.2 mag e_[3.6] [0.01/0.06]? Uncertainty in [3.6]
168-172 F5.2 mag [4.5] ? Spitzer/IRAC 4.5 micron band magnitude
174-177 F4.2 mag e_[4.5] ? Uncertainty in [4.5]
179-183 F5.2 mag [5.8] ? Spitzer/IRAC 5.8 micron band magnitude
185-188 F4.2 mag e_[5.8] ? Uncertainty in [5.8]
190-194 F5.2 mag [8.0] [8.9/14.3]? Spitzer/IRAC 8.0um band magnitude
196-199 F4.2 mag e_[8.0] [0/0.3]? Uncertainty in [8.0]
201-204 A4 --- Note Source note (G1)
206-216 A11 --- Ref Reference(s) (see refs.dat file)
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Byte-by-byte Description of file: refs.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Ref Reference code
5- 23 A19 --- BibCode Bibcode
25- 49 A25 --- Aut Author's name(s)
52- 70 A19 --- Comm Comment
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Global notes:
Note (G1): Note as follows:
LG = a low surface gravity dwarf;
Cal = a calibrator ultracool dwarf;
SD = an ultracool subdwarf;
B = a tight binary unresolved in 2MASS.
Note (G2): the spectral types includes a γ for low-gravity stars,
and β for intermediate between dwarf and low-gravity stars.
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History:
From electronic version of the journal
References:
Faherty et al. Paper I. 2009AJ....137....1F 2009AJ....137....1F Cat. J/AJ/137/1
Faherty et al. Paper II. 2010AJ....139..176F 2010AJ....139..176F
Faherty et al. Paper III. 2012ApJ...752...56F 2012ApJ...752...56F This catalog
Burgasser et al. Paper IV. 2015ApJS..220...18B 2015ApJS..220...18B Cat. J/ApJS/220/18
Hsu et al. Paper V. 2021ApJS..257...45H 2021ApJS..257...45H Cat. J/ApJS/257/45
Hsu et al. Paper VI. 2024ApJS..274...40H 2024ApJS..274...40H Cat. J/ApJS/274/40
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 29-Jan-2014