J/ApJ/723/684 NIRSPEC ultracool dwarf radial velocity survey (Blake+, 2010)
The NIRSPEC ultracool dwarf radial velocity survey.
Blake C.H., Charbonneau D., White R.J.
<Astrophys. J., 723, 684-706 (2010)>
=2010ApJ...723..684B 2010ApJ...723..684B
ADC_Keywords: Stars, late-type ; Radial velocities ; Rotational velocities ;
Space velocities
Keywords: brown dwarfs - stars: low-mass - techniques: radial velocities
Abstract:
We report the results of an infrared Doppler survey designed to detect
brown dwarf and giant planetary companions to a magnitude-limited
sample of ultracool dwarfs (UCDs). Using the NIRSPEC spectrograph on
the Keck II telescope, we obtained approximately 600 radial velocity
(RV) measurements over a period of six years of a sample of 59 late-M
and L dwarfs spanning spectral types M8/L0 to L6. A subsample of 46 of
our targets has been observed on three or more epochs. We rely on
telluric CH4 absorption features in Earth's atmosphere as a
simultaneous wavelength reference and exploit the rich set of CO
absorption features found in the K-band spectra of cool stars and
brown dwarfs to measure RVs and projected rotational velocities. For a
bright, slowly rotating M dwarf standard we demonstrate an RV
precision of 50m/s and for slowly rotating L dwarfs we achieve a
typical RV precision of approximately 200m/s. This precision is
sufficient for the detection of close-in giant planetary companions to
mid-L dwarfs as well as more equal mass spectroscopic binary systems
with small separations (a<2AU). Using a kinematic age estimate, we
conclude that our UCDs have an age of 5.0+0.7-0.6Gyr, similar to
that of nearby sun-like stars.
Description:
Between 2003 March and 2009 May, we collected approximately 600
individual observations of a sample of 59 UCDs using the NIRSPEC
instrument on the Keck II telescope (resolution of R=25000).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 54 59 L dwarf sample
table2.dat 36 273 Table of RV measurements
table3.dat 61 59 Measured properties of L dwarfs
table10.dat 66 55 UVW velocity components
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
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/ApJ/710/1627 : Mid-IR photometry of cold brown dwarfs (Leggett+, 2010)
J/MNRAS/404/1817 : 2MASS/SDSS data for 806 ultracool dwarfs (Zhang+, 2010)
J/AJ/137/1 : PMs and astrometry of late-type dwarfs (Faherty+, 2009)
J/A+A/493/L27 : Parallaxes of 10 ultracool subdwarfs (Schilbach+, 2009)
J/A+A/505/L5 : Infrared radial velocities of vB10 (Zapatero+, 2009)
J/A+A/505/859 : M dwarfs radial velocities (Zechmeister+, 2009)
J/ApJ/705/1416 : M7-M9.5 dwarfs <20pc (Reiners+, 2009)
J/ApJ/688/362 : Brown dwarfs in σ Ori cluster (Luhman+, 2008)
J/AJ/136/1290 : Ultracool dwarfs from the 2MASS (Reid+, 2008)
J/MNRAS/382/515 : SDSS ultracool and halo WD candidates (Vidrih+, 2007)
J/AJ/133/2258 : Activity and kinematics of ultracool dwarfs (Schmidt+, 2007)
J/AJ/132/663 : Differential Velocities of very low mass SBs (Basri+, 2006)
J/AJ/132/891 : Binaries among nearby L dwarfs (Reid+, 2006)
J/A+A/416/655 : Atomic lines in IR spectra for UCDs (Lyubchik+, 2004)
J/AJ/126/1526 : IR photometry of ultracool dwarfs (Bouy+, 2003)
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/A+A/337/403 : Low-mass stars evolutionary models (Baraffe+ 1998)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Star name
14- 15 I2 h RAh Hour of right ascension (J2000) (1)
17- 18 I2 min RAm Minute of right ascension (J2000)
20- 24 F5.2 s RAs Second of right ascension (J2000)
26 A1 --- DE- Sign of declination (J2000) (1)
27- 28 I2 deg DEd Degree of declination (J2000) (1)
30- 31 I2 arcmin DEm Arcminute of declination (J2000)
33- 36 F4.1 arcsec DEs Arcsecond of declination (J2000)
38- 42 F5.2 mag Jmag J-band magnitude (1)
44- 48 F5.2 mag Kmag [10.47/12.94] K-band magnitude (1)
50- 54 A5 --- SpT MK spectral type (1)(2)
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Note (1): Coordinates, magnitudes, and spectral types of the targets in our
sample as gathered from http://www.dwarfarchives.com/ and cross
checked against the database of ultracompact dwarfs recently published
by Faherty et al. (2009, Cat. J/AJ/137/1).
Note (2): The spectral types listed here are those derived from optical
diagnostics. Optical spectral types are not available for 2M1705-05
and 2M1854+84 but based on their broadband colors these objects are
expected to be L dwarfs.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Star name
14- 23 F10.2 d HJD [2452713/2454964] Heliocentric Julian Date
25- 31 F7.2 km/s RV [-106.48/80.59] Radial velocity
33- 36 F4.2 km/s e_RV [0.08/1.54] The 1σ uncertainty in RV
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Star name
13 A1 --- f_Name [a] gravity assumed: logg=5.5 (3)
15- 16 I2 --- Nobs [2/16] Number of observations
18- 21 I4 d DelT [1/2249] Time span ΔT for RV observations
23- 26 I4 K Teff [1600/2300] Effective temperature (3)
28 A1 --- l_vsini Limit flag on vsini
29- 33 F5.2 km/s vsini [9/69.88] Rotational velocity
35- 38 F4.2 km/s e_vsini [0.13/5]? vsini uncertainty (4)
40- 45 F6.2 km/s RV Systemic velocity ()
47- 50 F4.2 km/s e_RV [0.05/0.47] RV uncertainty (4)
52- 55 F4.2 km/s rms RV rms
57 A1 --- l_P(bin) Limit flag on P(bin)
58- 61 F4.2 --- P(bin) [0/1] Probability for binarity (5)
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Note (3): Teff is based on the best-fit synthetic template with logg=5.0(cgs),
except for LSR1610-0040 (see flag a).
Note (4): The errors on vsini are estimated from the scatter in fits to
multiple observations. The errors on the systemic velocity are
also determined from the scatter in the fits to multiple observations.
Note (5): The value of P(χ2RV≤) is the probability of getting a
smaller value of χ2RV and assumes the null hypothesis of no
intrinsic RV variations
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Byte-by-byte Description of file: table10.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Star name
14- 20 F7.2 km/s Uvel ? U velocity component (6)
22- 26 F5.2 km/s e_Uvel ? Uvel uncertainty
28- 34 F7.2 km/s Vvel ? V velocity component (6)
36- 40 F5.2 km/s e_Vvel ? Vvel uncertainty
42- 47 F6.2 km/s Wvel ? W velocity component (6)
49- 53 F5.2 km/s e_Wvel ? Wvel uncertainty
55- 60 F6.2 km/s Vtot ? Total space velocity (6)
62- 66 F5.2 km/s e_Vtot ? Vtot uncertainty
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Note (6): UVW velocity components and Vtot for the portion of our sample with
distance estimates and proper motions in Faherty et al. (2009,
Cat. J/AJ/137/1). We use a right handed system with U>0 toward the
galactic center. Errors are derived from a Monte Carlo simulation that
includes the errors on RV, distance, and proper motion.
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History:
* 18-Jul-2012: From electronic version of the journal
* 14-Aug-2014: Label "Per" of table 3 corrected into "ΔT" thanks to
Ken Slatten correction.
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 18-Jul-2012