J/MNRAS/385/2210 Spectroscopy around lam Ori and sig Ori (Maxted+, 2008)
A survey for low-mass spectroscopic binary stars in the young clusters around
σ Orionis and λ Orionis.
Maxted P.F.L., Jeffries R.D., Oliveira J.M., Naylor T., Jackson R.J.
<Mon. Not. R. Astron. Soc., 385, 2210-2224 (2008)>
=2008MNRAS.385.2210M 2008MNRAS.385.2210M
ADC_Keywords: Stars, pre-main sequence ; Binaries, spectroscopic ;
Radial velocities ; Spectroscopy
Keywords: binaries: spectroscopic - stars: low-mass, brown dwarfs
Abstract:
We have obtained multi-epoch, high-resolution spectroscopy of 218
candidate low-mass stars and brown dwarfs (BDs) in the young clusters
around λ Ori and σ Ori. We find that 196 targets are
cluster members based on their radial velocity, the equivalent width
of their NaI 8200 lines and the spectral type from their TiO band
strength. We have identified 11 new binary stars among the cluster
members based on their variable radial velocity and an additional
binary from the variation in its linewidth and shape. Of these, six
are double-lined spectroscopic binaries (SB2) where the components of
the binary are of comparable brightness. The others are single-lined
binaries (SB1) in which the companion is faint or the spectra of the
stars are blended. There are three narrow-lined SB1 binaries in our
sample for which the companion is more than 2.5mag fainter than the
primary.
Description:
Radial velocities and spectral indices for 218 stars and brown dwarfs
around σ and λ Orionis. Observations were obtained with
the FLAMES/GIRAFFE multi-object spectrograph on ESO's VLT UT2 (Kueyen)
telescope (programme ID 076.C_145). The equivalent width of the NaI
8200Å and the strength of the TiO 8442Å spectral features were
measured from the median average spectrum. Radial velocities were
measured by cross-correlation against a template spectrum of the brown
dwarf star USco CTIO 055 at multiple epochs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 45 844 Radial velocity for each star at each epoch
table3.dat 70 218 Mean radial velocities and spectral indices
table4.dat 97 13 Properties of the binaries discovered by our survey
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See also:
J/MNRAS/356/89 : sigma Ori low-mass stars (Kenyon+, 2005)
J/ApJ/610/1064 : Substellar population of young cluster lam Ori (Barrado+ 2004)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- [MJO2008] Identifier for star, JHHMMSS.s+DDMMSS (G1)
18- 26 F9.3 d MJD Modified heliocentric Julian date of observation
28- 34 F7.2 km/s RV Measured radial velocity
36- 41 F6.2 km/s e_RV Standard error of RVel
43- 45 I3 km/s FWHM Full-width at half-maximum of the
cross-correlation function
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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- 16 A16 --- [MJO2008] Identifier for star, JHHMMSS.s+DDMMSS (G1)
18- 22 F5.2 --- Icmag Kron-Cousins Ic band magnitude
24 I1 --- o_ Number of radial velocity measurements
26- 33 F8.2 km/s Mean radial velocity
35- 39 F5.2 km/s e_ Standard error for
41- 46 F6.2 --- logp ?=-99.99 Logarithm of the probability that
measured radial velocities are consistent
with a constant value (1)
48- 51 F4.2 0.1nm EW(NaI) Equivalent width of the NaI 8200Å doublet
53- 56 F4.2 0.1nm e_EW(NaI) Standard error for EW(NaI)
58- 62 F5.3 --- TiO(8442) Strength of the TiO 8442Å feature
64- 68 F5.3 --- e_TiO(8442) Standard error for TiO(8442)
70 A1 --- SB [*] * for SB binary
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Note (1): Values ←30 are denoted by the nominal value -99.99.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- Name Identifier for star, JHHMMSS.s+DDMMSS (G1)
18- 22 F5.2 --- Icmag Kron-Cousins Ic band magnitude
24- 27 F4.2 mag Rc-Ic Cousins R-I colour index
29 I1 --- o_ Number of radial velocity measurements
31- 36 F6.2 km/s Mean radial velocity
38- 41 F4.2 km/s e_ Standard error for
43- 47 F5.1 --- logp ?=-99.9 Logarithm of the probability that
measured radial velocities are consistent
with a constant value (1)
49- 52 F4.2 0.1nm EW(NaI) Equivalent width of the NaI 8200Å doublet
54- 57 F4.2 0.1nm e_EW(NaI) Standard error for EW(NaI)
59- 63 F5.3 --- TiO(8442) Strength of the TiO 8442Å feature
65- 69 F5.3 --- e_TiO(8442) Standard error for TiO(8442)
71- 73 A3 --- Type SB type
75- 76 A2 --- Mm [nm] nm for non-member
78 A1 --- n_[MJO2008] [ab] Note on cross-correlation function (2)
80- 95 A16 --- [MJO2008] Name as in tables 2 and 3
97 A1 --- f_[MJO2008] [*] * when [MJO2008] differs from Name
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Note (1): Values ←42 are denoted by the nominal value -99.9.
Note (2): Notes as follows:
a = Hint of companion in cross-correlation function (CCF)
b = Identified from variation in width of CCF
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Global notes:
Note (G1): J2000 coordinates truncated to 1 decimal place for RA and
truncated to the nearest arcsecond for declination.
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History:
From electronic version of the journal
(End) Pierre Maxted [Keele, UK], Patricia Vannier [CDS] 22-May-2008