Spectroscopic studies of O-type stars. VII. Rotational velocities V*sin(i) and evidence for macroturbulent motions.

Conti, Peter S.; Ebbets, Dennis

doi:10.1086/155173

Cited by 186 publications

(153 citation statements)

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“…Literature values for the spectral type are between O5 V((f)) (Underhill & Gilroy 1990;Maíz-Apellániz et al 2004) and O5.5 V((f)) (Conti & Ebbets 1977;Garmany et al 1980). The detailed study of Mahy et al (2009) confirms the O5.5 V((f)) spectral type.…”

Section: Introductionsupporting

confidence: 50%

Variability in the CoRoT photometry of three hot O-type stars

Blomme

Mahy

Catala

et al. 2011

A&A

108

121

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Context. The detection of pulsational frequencies in stellar photometry is required as input for asteroseismological modelling. The second short run (SRa02) of the CoRoT mission has provided photometric data of unprecedented quality and time-coverage for a number of O-type stars. Aims. We analyse the CoRoT data corresponding to three hot O-type stars, describing the properties of their light curves and search for pulsational frequencies, which we then compare to theoretical model predictions. Methods. We determine the amplitude spectrum of the data, using the Lomb-Scargle and a multifrequency HMM-like technique. Frequencies are extracted by prewhitening, and their significance is evaluated under the assumption that the light curve is dominated by red noise. We search for harmonics, linear combinations, and regular spacings among these frequencies. We use simulations with the same time sampling as the data as a powerful tool to judge the significance of our results. From the theoretical point of view, we use the MAD non-adiabatic pulsation code to determine the expected frequencies of excited modes. Results. A substantial number of frequencies is listed, but none can be convincingly identified as being connected to pulsations. The amplitude spectrum is dominated by red noise. Theoretical modelling shows that all three O-type stars can have excited modes, but the relation between the theoretical frequencies and the observed spectrum is not obvious. Conclusions. The dominant red noise component in the hot O-type stars studied here clearly points to a different origin than the pulsations seen in cooler O stars. The physical cause of this red noise is unclear, but we speculate on the possibility of sub-surface convection, granulation, or stellar wind inhomogeneities being responsible.

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Section: Introductionsupporting

confidence: 50%

Variability in the CoRoT photometry of three hot O-type stars

Blomme

Mahy

Catala

et al. 2011

A&A

108

121

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“…On the other hand, HD 14434 may have a normal nitrogen spectrum (Schild & Berthet 1986). Both stars have been reported as blue straggler candidates by Kendall et al (1995) who considered they could have followed a quasi-homogeneous Conti & Leep (1974), (2) Walborn (1972), (3) Walborn (1973), (4) this study, (5) Bieging et al (1989), (6) Conti & Burnichon (1975), (7) Leitherer (1988), (8) Kendall et al (1995), (9) Gies & Bolton (1986), (10) Humphreys (1978), (11) Conti & Ebbets (1977 The two values quoted are respectively the spectroscopic and the evolutionary masses. b The first value of the radius is calculated for an assumed value of the distance modulus, and the second one is derived from the spectral type.…”

Section: Introductionmentioning

confidence: 63%

Line profile variability in the spectra of Oef stars

Becker¹,

Rauw²

2004

A&A

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Abstract. We present the very first analysis of the spectroscopic variability of the three rapidly rotating Oef stars HD 192281 (O5(ef)), HD 14442 (O5.5ef) and HD 14434 (O6.5(ef)). Radial velocities of the He  λ 4541 line reveal no evidence of binarity on time scales of a few days, or from one year to the next, for any of the targets. The He  λ 4686 double-peaked emission and, to some extent, the Hβ absorption line display significant profile variability in the spectra of all three stars. Data gathered during different observing runs spread over six years reveal a rather stable time scale for HD 192281 and HD 14442, whereas the variability pattern changes significantly from one year to the other. The case of HD 14434 is less clear as no obvious time scale emerges from our analysis. In a tentative way to interpret this variability, stellar rotation remains a possible clock for HD 192281 and HD 14442. However, currently available models addressing stellar rotation fail to explain some crucial aspects of the observed variability behaviour, which appear to be even more complex in the case of HD 14434.

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“…The object is visually a single star and spectroscopically a double-line binary candidate (Conti & Ebbets 1977;Howarth et al 1997). There is an IRAS source (IRAS 02245+5217) located at 2 arcmin (∼2 pc) south of HD 15137, that could be part of a larger loop-like structure visible on the IRAS 60 µm image.…”

Section: Hd 15137mentioning

confidence: 99%

“…The object is a variable emission line star and a rapid rotator with v sin i = 350 kms −1 (Conti & Ebbets 1977). HD 120678 is of unknown spectroscopic multiplicity status.…”

Section: Hd 120678mentioning

confidence: 99%

The origin of massive O-type field stars

Wit¹,

Testi²,

Palla³

et al. 2004

A&A

110

136

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Abstract. We present a study aimed at clarifying the birthplace for 43 massive O-type field stars. In this first paper we present the observational part: a search for stellar clusters near the target stars. We derive stellar density maps at two different resolving scales, viz. ∼0.25 pc and ∼1.0 pc from NTT and TNG imaging and the 2MASS catalogue. These scales are typical for cluster sizes. The main result is that the large majority of the O-type field population are isolated stars: only 12% (5 out of 43) of the O-type field stars is found to harbour a small-scale stellar cluster. We review the literature and aim at characterizing the stellar field of each O-type field star with the emphasis on star formation and the presence of known young stellar clusters. An analysis of the result of this paper and a discussion of the O-type field population as products of a dynamical ejection event is presented in an accompanying paper.

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Spectroscopic studies of O-type stars. VII. Rotational velocities V*sin(i) and evidence for macroturbulent motions.

Cited by 186 publications

References 0 publications

Variability in the CoRoT photometry of three hot O-type stars

Variability in the CoRoT photometry of three hot O-type stars

Line profile variability in the spectra of Oef stars

The origin of massive O-type field stars

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