J/A+A/560/A29 O-stars in VLT-FLAMES Tarantula Survey (Ramirez-Agudelo+ 2013)
The VLT-FLAMES Tarantula Survey.
XII. Rotational velocities of the single O-type stars.
Ramirez-Agudelo O.H., Simon-Diaz S., Sana H., de Koter A.,
Sabin-Sanjulian C., de Mink S.E., Dufton P.L., Grafener G., Evans C.J.,
Herrero A., Langer N., Lennon D.J., Maiz Apellaniz J., Markova N.,
Najarro F., Puls J., W.D, Vink J.S.
<Astron. Astrophys. 560, A29 (2013)>
=2013A&A...560A..29R 2013A&A...560A..29R
ADC_Keywords: Magellanic Clouds ; Stars, O ; Rotational velocities
Keywords: stars: early-type - stars: rotation - line: profiles -
Magellanic Clouds - galaxies: star clusters: individual: 30 Doradus
Abstract:
The 30 Doradus (30 Dor) region of the Large Magellanic Cloud, also
known as the Tarantula Nebula, is the nearest starburst region. It
contains the richest population of massive stars in the Local Group
and it is thus the best possible laboratory to investigate open
questions in the formation and evolution of massive stars.
Using ground based multi-object optical spectroscopy obtained in the
framework of the VLT-FLAMES Tarantula Survey (VFTS), we aim to
establish the (projected) rotational velocity distribution for a
sample of 216 presumably single O-type stars in 30 Dor.
The size of the sample is large enough to obtain statistically
significant information and to search for variations among
sub-populations - in terms of spectral type, luminosity class, and
spatial location - in the field of view.
We measured projected rotational velocities, Vrot, by means of a
Fourier transform method and a profile fitting method applied on a set
of isolated spectral lines. We also used an iterative deconvolution
procedure to infer the probability density, P(Veq), of the equatorial
rotational velocity, Veq.
The distribution of Vrot shows a two-component structure: a peak
around 80km/s and a high-velocity tail extending up to ∼600km/s. This
structure is also present in the inferred distribution P(Veq) with
around 80% of the sample having 0<Veq≤300km/s and the other 20%
distributed in the high-velocity region. The presence of the
low-velocity peak is consistent with that found in other studies for
late O- and early B-type stars.
Most of the stars in our sample rotate with a rate less than 20% of
their break-up velocity. For the bulk of the sample, mass-loss in a
stellar wind and/or envelope expansion is not efficient enough to
significantly spin down these stars within the first few Myr of
evolution. If massive-star formation results in stars rotating at
birth with a large fraction of their break-up velocities, an
alternative braking mechanism, possibly magnetic fields, is thus
required to explain the present day rotational properties of the
O-type stars in 30 Dor. The presence of a sizeable population of fast
rotators is compatible with recent population synthesis computations
that investigate the influence of binary evolution on the rotation
rate of massive stars. Despite the fact that we have excluded stars
that show significant radial velocity variations, our sample may have
remained contaminated by post-interaction binary products. The fact
that the high-velocity tail may be preferentially (and perhaps even
exclusively), populated by post-binary interaction products, has
important implications for the evolutionary origin of systems that
produce gamma-ray bursts.
Description:
Projected rotational velocity measurements of 216 O-type stars
observed at multi-epochs as part as the VLT-FLAMES Tarantula Survey.
We measured projected rotational velocities by means of a Fourier
transform method and a profile fitting method applied on a set of
isolated spectral lines.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 33 216 Projected rotational velocity measurements for
every star and spectral line
table4.dat 18 216 Averaged projected rotational velocity
measurements and their error bars
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See also:
J/A+A/530/A108 : VLT-FLAMES Tarantula Survey (Evans+, 2011)
J/A+A/550/A107 : RV catalogue of O stars in 30 Doradus (Sana+, 2013)
J/A+A/550/A108 : DIB in VLT-FLAMES Tarantula Survey (van Loon+, 2012)
J/A+A/550/A109 : VLT-FLAMES Tarantula Survey: vsini measures (Dufton+ 2013)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- VFTS [14/892] VFTS identification number
5 A1 --- l_v4387 Limit flag on v4387
6- 8 I3 km/s v4387 ?=- Rotational velocity from HeI 4387 line (1)
11- 13 I3 km/s v4471 ?=- Rotational velocity from HeI 4471 line (1)
16- 18 I3 km/s v4552 ?=- Rotational velocity from SiIII 4552 line (1)
21- 23 I3 km/s v4713 ?=- Rotational velocity from HeI 4713 line (1)
26- 28 I3 km/s v4922 ?=- Rotational velocity from HeI 4471 line (1)
31- 33 I3 km/s v4541 ?=- Rotational velocity from HeII 4541 line (1)
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Note (1): An '-' indicates that it has not been used. Therefore, projected
rotational values of: VFTS 072, 125, 267, 405, 451, 465, 484, 529, 559, 565,
571, 587, 709, and 724 are calculated by comparison with synthetic spectra
(see paper). VFTS102 was obtained with HeI4026 (see Dufton et al., 2013,
Cat. J/A+A/550/A109).
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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- 3 I3 --- VFTS [14/892] VFTS identification number
6 A1 --- Q [A/B] Category in terms of quality (1)
9- 11 I3 km/s vsini Averaged projected rotational
15- 16 I2 km/s e_vsini ? 1 sigma dispersion
18 I1 --- N ? Number of lines used
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Note (1): Categories are:
A = diagnostics provide the most reliable measurements
B = diagnostics provide lesser quality than A
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Acknowledgements:
Oscar Hernan Ramirez Agudelo, o.h.ramirezagudelo(at)uva.nl
References:
Evans et al., Paper I 2011A&A...530A.108E 2011A&A...530A.108E, Cat. J/A+A/530/A108
Taylor et al., Paper II 2011A&A...530L..10T 2011A&A...530L..10T
Bestenlehner et al., Paper III 2011A&A...530L..14B 2011A&A...530L..14B
Bressert et al., Paper IV 2012A&A...542A..49B 2012A&A...542A..49B
Dunstall et al., Paper V 2012A&A...542A..50D 2012A&A...542A..50D
Henault-Brunet et al., Paper VI 2012A&A...542A..49B 2012A&A...542A..49B
Henault-Brunet et al., Paper VII 2012A&A...546A..73H 2012A&A...546A..73H
Sana et al., Paper VIII 2013A&A...550A.107S 2013A&A...550A.107S, Cat. J/A+A/550/A107
van Loon et al., Paper IX 2012A&A...550A.108V 2012A&A...550A.108V, Cat. J/A+A/550/A108
Dufton et al., Paper X 2012A&A...550A.109D 2012A&A...550A.109D, Cat. J/A+A/550/A109
(End) Patricia Vannier [CDS] 16-Sep-2013