J/AJ/132/663 Differential Velocities of very low mass SBs (Basri+, 2006)
A survey for spectroscopic binaries among very low mass stars.
Basri G., Reiners A.
<Astron. J., 132, 663-675 (2006)>
=2006AJ....132..663B 2006AJ....132..663B
ADC_Keywords: Binaries, spectroscopic ; Radial velocities
Keywords: binaries: close - stars: formation - stars: low-mass, brown dwarfs
Abstract:
We report on the results of a survey for radial velocity variability
in a heterogeneous sample of very low mass stars and brown dwarfs. One
distinguishing characteristic of the survey is its time span, which
allows an overlap between spectroscopic binaries and those that can be
found by high angular resolution imaging. Despite our relatively low
velocity precision, we are able to place a new constraint on the total
binary fraction in these objects, which suggests that they are more
likely the result of extending the same processes at work at higher
masses into this mass range, rather than a distinct mode of formation.
Description:
Our sample was largely determined by the observations discussed in
Mohanty & Basri (2003ApJ...583..451M 2003ApJ...583..451M). All observations were conducted
with the High Resolution Echelle Spectrometer (HIRES) on the Keck I
telescope. The sample consists of a collection of stars M5 and later,
which was assembled during the years of discovery of VLMs, and so is
rather heterogeneous. They are all field objects and tend to be at the
brighter end of the objects discovered.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 54 14 Stars with indications for radial velocity
variabilities
table3.dat 54 39 Stars with probably constant radial velocities
table5.dat 28 132 Differential radial velocities for all sets
of observations
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Byte-by-byte Description of file: table[23].dat
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Bytes Format Units Label Explanations
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1 I1 --- sigma [1,2]? 1 or 2 sigma detection (in table2 only)
3- 11 A9 --- Name Object name
12 A1 --- n_Name [f] f for flare star
14- 17 A4 --- SpType MK spectral type
20 I1 --- Nbsp Number of spectra
21 A1 --- n_Nbsp Note on Nbsp (1)
23- 25 F3.1 km/s DRV1 Differential radial velocity between the two
exposures, corrected for the barycentric
velocity on the two night of observation
27- 29 F3.1 km/s e_DRV1 ? rms uncertainty on DVstar
31- 34 F4.1 km/s DRV2 ?=- Mean absolute virtual shift from the stars
in which the reference value of the shift
has been derived from telluric bands
35 A1 --- n_DRV2 [c] c: From water bands
37- 39 F3.1 km/s DRV Final radial velocity variation
41- 43 F3.1 km/s e_DRV rms uncertainty on DRVtot
45- 48 I4 d DTmax Time difference between our earliest and
latest exposure
50- 54 F5.3 --- Prob Probability that a random measurement of a
radial velocity shift DRVtot in a single star
is smaller than the one we have measured
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Note (1): Notes as follows:
a = Only orders 41 and 44
b = Only orders 41 and 42
d = Only orders 41, 42, and 45
e = Only order 44
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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- 9 A9 --- Name Object name
11- 20 A10 "YYYY/MM/DD" Obs.Date Date of the observation
22- 24 F3.1 km/s DRV Differential radial velocity (1)
26- 28 F3.1 km/s e_DRV Uncertainty in DRV (2)
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Note (1): In each set, the bluemost observation is arbitrarily given a
differential radial velocity of zero, and the other epochs have the
difference in velocity relative to that one listed.
Note (2): The error given is the same as described in Section 2.1, except
that no telluric shift or error has been added.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 11-Jan-2008