J/AJ/144/130 Rotational velocities of nearby HIP B stars (Braganca+, 2012)
Projected rotational velocities and stellar characterization of 350 B stars in
the nearby Galactic disk.
Braganca G.A., Daflon S., Cunha K., Bensby T., Oey M.S., Walth G.
<Astron. J., 144, 130 (2012)>
=2012AJ....144..130B 2012AJ....144..130B
ADC_Keywords: Stars, nearby ; Stars, early-type ; Rotational velocities ;
Spectral types ; Stars, B-type ; Stars, double and multiple
Keywords: stars: early-type - stars: fundamental parameters - stars: rotation
Abstract:
Projected rotational velocities (vsini) are presented for a sample of
350 early B-type main-sequence stars in the nearby Galactic disk. The
stars are located within ∼1.5kpc from the Sun, and the great majority
within 700pc. The analysis is based on high-resolution spectra
obtained with the MIKE spectrograph on the Magellan Clay 6.5m
telescope at the Las Campanas Observatory in Chile. Spectral types
were estimated based on relative intensities of some key line
absorption ratios and comparisons to synthetic spectra. Effective
temperatures were estimated from the reddening-free Q index, and
projected rotational velocities were then determined via interpolation
on a published grid that correlates the synthetic FWHM of the HeI
lines at 4026, 4388 and 4471Å with vsini. As the sample has been
selected solely on the basis of spectral types, it contains a
selection of B stars in the field, in clusters, and in OB
associations. The vsini distribution obtained for the entire sample is
found to be essentially flat for vsini values between 0 and 150km/s,
with only a modest peak at low projected rotational velocities.
Considering subsamples of stars, there appears to be a gradation in
the vsini distribution with the field stars presenting a larger
fraction of the slow rotators and the cluster stars distribution
showing an excess of stars with vsini between 70 and 130km/s.
Furthermore, for a subsample of potential runaway stars we find that
the vsini distribution resembles the distribution seen in denser
environments, which could suggest that these runaway stars have been
subject to dynamical ejection mechanisms.
Description:
We selected 379 O9 to B4 main-sequence stars from the Hipparcos
catalog (Perryman et al. 1997, Cat. I/239). High-resolution spectra
were then obtained on 2007 January 8, 9 and April 8 with the MIKE
spectrograph at the Magellan Clay 6.5m telescope on Las Campanas
observatory in Chile. MIKE is a double echelle spectrograph that
registers the whole spectrum on two CCDs (red side 4900-9500Å and
blue side 3350-5000Å) in a single exposure. Here, the blue spectra
are analyzed. The spectral resolution of the observed spectra is
R∼55000 and was obtained using a slit width of 0.7arcsec.
We screened the observed spectra in order to exclude all evolved
stars. Our final sample consists of 350 stars and is expected to
contain only main-sequence stars and not giants or supergiants.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 32 78 Binary/multiple Stars
table2.dat 70 272 vsini results for the entire sample
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See also:
III/244 : Catalog of Stellar Rotational Velocities (Glebocki+ 2005)
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
III/195 : Atlas of Optical Spectral Classification OB Stars (Walborn+ 1990)
J/MNRAS/410/190 : Young runaway stars within 3kpc (Tetzlaff+, 2011)
J/ApJ/722/605 : A stellar rotation census of B stars (Huang+, 2010)
J/MNRAS/392/448 : Rotational velocities of early-type binaries (Howe+, 2009)
J/MNRAS/389/869 : Multiplicity among bright stellar systems (Eggleton+, 2008)
J/AJ/133/1092 : vsini of B0-B3 stars in 7 young clusters (Wolff+, 2007)
J/AJ/134/1570 : Rotational velocities of OB stars (Daflon+, 2007)
J/ApJ/648/580 : Rotational velocities in 19 open clusters (Huang+, 2006)
J/A+A/444/941 : Effective temperature of B stars (Paunzen+, 2005)
J/ApJ/616/562 : Rotational velocities in binaries (Abt+, 2004)
J/ApJ/573/359 : Rotational velocities of B stars from BSC (Abt+, 2002)
J/AJ/117/354 : OB associations from Hipparcos (de Zeeuw+, 1999)
J/A+A/345/471 : Memberships of open clusters (Robichon+, 1999)
J/MNRAS/284/265 : Rotational velocities of 373 OB stars (Howarth+ 1997)
J/A+A/289/101 : Orion OB1 association. I. (Brown+, 1994)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HIP [17563/100881] HIPPARCOS number
8- 14 A7 --- SpT Spectral type from SIMBAD
16 A1 --- u_Mult Flag on m_HIP (? or :)
17- 20 A4 --- Mult Multiplicity flag on HIP: asym = the star has an
asymetric line profile; SB = spectroscopic binary
22- 32 A11 --- r_Mult Reference (1)
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Note (1): Reference as follows:
Lef09 = star listed as binaries in Lefevre et al. (2009A&A...507.1141L 2009A&A...507.1141L);
ET08 = star listed as binaries in Eggleton & Tokovinin (2008,
Cat. J/MNRAS/389/869).
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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- 6 I6 --- HIP [14898/101909] HIPPARCOS number
8- 15 A8 --- SpT Spectral type
17- 21 F5.2 mag Vmag [2.81/10.68]? Apparent V band magnitude
23- 27 F5.2 --- Q Value of the classical reddening free
parameter Q (1)
29- 33 I5 K Teff [14610/35300] Effective temperature (2)
35- 37 F3.1 0.1nm FWHM1 [0.9/8]? HeI 4026Å FWHM; in Å
39- 41 F3.1 0.1nm FWHM2 [0.7/8.9]? HeI 4388Å FWHM; in Å
43- 45 F3.1 0.1nm FWHM3 [0.7/8.8]? HeI 4471Å FWHM; in Å
47- 49 I3 km/s vsini1 ? HeI 4026Å projected rotational velocity
51- 53 I3 km/s vsini2 ? HeI 4388Å projected rotational velocity
55- 57 I3 km/s vsini3 ? HeI 4471Å projected rotational velocity
59- 61 I3 km/s ? Mean projected rotational velocity
63- 64 I2 km/s e_ ? Standard deviation in between the
available measures
66 I1 --- N Number of HeI lines used
68- 70 A3 --- M [ACR.? ] Membership classification
(A=association, C=cluster, R=runaway star)
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Note (1): Q=(U-B)-X(B-V), where X=E(U-B)/E(B-V) (Johnson, 1958LowOB...4...37J 1958LowOB...4...37J).
Note (2): Estimated from the T(Q) calibration presented in Massey et al.
(1989AJ.....97..107M 1989AJ.....97..107M) and defined as:
log(Teff)=(3.994-0.267)Q+(0.364)Q2.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 21-Nov-2013