J/A+A/564/A39 VFTS. OVz stars in 30 Dor (Sabin-Sanjulian+, 2014)
The VLT-FLAMES Tarantula Survey.
XIII: On the nature of O Vz stars in 30 Doradus.
Sabin-Sanjulian C., Simon-Diaz S., Herrero A., Walborn N.R., Puls J.,
Maiz Apellaniz J., Evans C.J., Brott I., De Koter A., Garcia M.,
Markova N., Najarro F., Ramirez-Agudelo O.H., Sana H., Taylor W.D.,
Vink J.S.
<Astron. Astrophys., 564, A39-39 (2014)>
=2014A&A...564A..39S 2014A&A...564A..39S
ADC_Keywords: Magellanic Clouds ; Stars, early-type
Keywords: Magellanic Clouds - stars: atmospheres - stars: early-type -
stars: fundamental parameters - stars: massive
Abstract:
OVz stars, a subclass of O-type dwarfs characterized by having
HeIIλ4686 stronger in absorption than any other helium line in
their blue-violet spectra, have been suggested to be on or near the
zero-age main sequence (ZAMS). If their youth were confirmed, they
would be key objects with which to advance our knowledge of the
physical properties of massive stars in the early stages of their
lives.
We test the hypothesis of OVz stars being at a different (younger)
evolutionary stage than are normal O-type dwarfs.
We have performed the first comprehensive quantitative spectroscopic
analysis of a statistically meaningful sample of OVz and OV stars in
the same star-forming region, exploiting the large number of OVz stars
identified by the VLT-FLAMES Tarantula Survey in the 30 Doradus region
of the Large Magellanic Cloud (LMC). We obtained the stellar and wind
parameters of 38 OVz stars (and a control sample of 46 OV stars) using
the FASTWIND stellar atmosphere code and the IACOB-GBAT, a grid-based
tool developed for automated quantitative analysis of optical spectra
of O stars. In the framework of a differential study, we compared the
physical and evolutionary properties of both samples, locating the
stars in the logg vs. logTeff, logQ vs. logTeff, and logL/L☉
vs. logTeff diagrams. We also investigated the predictions of the
FASTWIND code regarding the OVz phenomenon.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 92 31 Stellar and wind parameters obtained from
quantitative analysis of our sample of OVz stars
tablea2.dat 91 40 Stellar and wind parameters obtained from
quantitative analysis of our sample of OV stars
tablea3.dat 63 13 First estimates of stellar and wind parameters
from HHeN analysis of the subsample of stars for
which HeI-II analysis alone was considered
unreliable (see notes in Sect. 4)
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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+, 2013)
J/A+A/550/A109 : VLT-FLAMES Tarantula Survey: vsini measures (Dufton+ 2013)
J/A+A/560/A29 : O-stars in VLT-FLAMES Tarantula Survey (Ramirez-Agudelo+ 2013)
J/A+A/564/L7 : VLT-FLAMES Tarantula Survey: VFTS 822 (Kalari+, 2014)
J/A+A/564/A40 : VFTS. O-type stellar content of 30 Dor (Walborn+, 2014)
Byte-by-byte Description of file: tablea1.dat tablea2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- VFTS [14/849] VLT-FLAMES Tarantula Survey number
(Evans et al. 2011, J/A+A/530/A108)
5- 8 A4 --- SpT Spectral O-type
10- 26 A17 --- LC Luminosity class
28- 31 F4.1 mag VMAG ?=- Absolute V magnitude (G1)
33- 35 I3 km/s vsini Rotational velocity
37- 41 I5 K Teff Effective temperature
43- 46 I4 K e_Teff rms uncertainty on Teff
48- 51 F4.2 [cm/s2] logg Surface gravity
53- 56 F4.2 [cm/s2] e_logg rms uncertainty on logg (minimum of 0.1)
58- 61 F4.2 [cm/s2] loggc ?=- loggc=log[g+(vsini)2/R*] (G3)
63 A1 --- l_Y(He) Limit flag on Y(He)
64- 67 F4.2 --- Y(He) Helium abundance N(He)/N(H) (error=0.02)
69 A1 --- l_logQ Limit flag on logQ
70- 74 F5.1 [-] logQ Wind-strength parameter (G2)
76- 78 F3.1 [-] e_logQ ?=- rms uncertainty on logQ
80- 83 F4.2 [Lsun] logL ?=- Luminosity (G5)
85- 92 A8 --- Com Comments (G6)
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Byte-by-byte Description of file: tablea3.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- VFTS VFTS identification number
5- 8 A4 --- SpT Spectral O-type
10- 22 A13 --- LC Luminosity class
24- 27 F4.1 mag VMAG Absolute V magnitude (G1)
29- 31 I3 km/s vsini Rotational velocity
33- 37 I5 K Teff Effective temperature
39- 42 F4.2 [cm/s2] logg Surface gravity
44- 47 F4.2 [cm/s2] loggc loggc=log[g+(vsini)2/R*] (G3)
49- 53 F5.1 [-] logQ Wind-strength parameter
55- 58 F4.2 [Lsun] logL Luminosity (G5)
60- 63 A4 --- Com Comments (G6)
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Global notes:
Note (G1): Values taken from Maiz Apellaniz et al. (in prep); the estimated
average uncertainties are e_VMAG=0.3mag, accounting for uncertainties in
the distance modulus (see Gibson 2000MmSAI..71..693G 2000MmSAI..71..693G) and the apparent
magnitudes.
Note (G2): log Q = log (dM/dt)/(v∞R*)3/2, combination of the
mass-loss rate and the terminal wind velocity v∞.
Note (G3): gravity corrected to account for the centrifugal acceleration, see
Herrero et al. (1992A&A...261..209H 1992A&A...261..209H), Repolust et al. (2004A&A...415..349R 2004A&A...415..349R)
Note (G5): The combined uncertainties in VMAG and Teff (from the IACOB-GBAT
analysis) lead to an estimated average error in luminosity of e_logL=0.13.
Note (G6): Relevant comments from Table 1 of Walborn et al. (in prep.):
SB = spectroscopic binary
SB1 = single lined
SB2 = double lined
SB1s, SBs = small amplitude (10-20km/s)
SBvs = very small amplitude (<10km/s)
SB? = stellar absorption displaced from nebular emission lines but no
radial-velocity variation measured
SB2? = confirmed SB with possible second companion or unconfirmed SB but two
companions visible in the line-of-sight
VMn = visual multiple of n components within the 1.2" Medusa fibre,
as determined from HST/WFC3 images
NC = no WFC3 coverage
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History:
From electronic version of the journal
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...545L...1H 2012A&A...545L...1H
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 2013A&A...550A.108V 2013A&A...550A.108V, Cat. J/A+A/550/A108
Dufton et al., Paper X 2013A&A...550A.109D 2013A&A...550A.109D, Cat. J/A+A/550/A109
Doran et al., Paper XI 2013A&A...558A.134D 2013A&A...558A.134D
Ramirez-Agudelo et al., Paper XII 2013A&A...560A..29R 2013A&A...560A..29R, Cat. J/A+A/560/A29
Walborn et al., Paper XIV 2014A&A...564A..40W 2014A&A...564A..40W, Cat. J/A+A/564/A40
Kalari et al., Paper XV 2014A&A...564L...7K 2014A&A...564L...7K, Cat. J/A+A/564/L7
Maiz Apellaniz et al., Paper XVI 2014A&A...564A..63M 2014A&A...564A..63M
(End) Patricia Vannier [CDS] 07-Oct-2014