Projected Rotational Velocities of O-Type Stars

Penny, Laura R.

doi:10.1086/177286

Cited by 176 publications

(224 citation statements)

References 0 publications

Supporting

Mentioning

184

Contrasting

Unclassified

Order By: Relevance

“…The object has an emission line spectrum and manifests similar continuum emission variability as classical Be stars (Divan et al 1983, see also HD 39680) The object has a reported v sin i = 240 km s −1 (Penny 1996). There are no clusters, O-type or early B-type stars within a projected radius of 65 pc from HD 60848.…”

Section: Hd 60848 (≡Bn Gem)mentioning

confidence: 78%

See 1 more Smart Citation

The origin of massive O-type field stars

Wit¹,

Testi²,

Palla³

et al. 2004

A&A

109

136

View full text Add to dashboard Cite

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.

show abstract

Section: Hd 60848 (≡Bn Gem)mentioning

confidence: 78%

“…The star is reported to be a variable Oe star by Coté & van Kerkwijk 1993(see also MacConnell 1981. Having a rather small v sin i of 33 km s −1 (Penny 1996), the object's rotational axis is oriented probably at a near pole-on angle. The object is suggested to be a runaway star by Comeron et al (1998).…”

Section: Hd 57682mentioning

confidence: 99%

The origin of massive O-type field stars

Wit¹,

Testi²,

Palla³

et al. 2004

A&A

109

136

View full text Add to dashboard Cite

show abstract

“…For this parameter, the uncertainty varies from 0.1 to 0.2 dex, depending on the object. The rotational velocities (v sin i) were adopted from previous studies (e.g., Penny 1996;Howarth et al 1997) and/or refined/estimated from the fitting process when necessary. After we derived the basic photospheric properties (i.e., v sin i, log g, and T eff ) we switched to CMFGEN to continue our investigation.…”

Section: Methodsmentioning

confidence: 99%

Analysis of Galactic late-type O dwarfs: more constraints on the weak wind problem

Marcolino

Bouret

Martins

et al. 2009

A&A

118

169

View full text Add to dashboard Cite

Aims. We investigate the stellar and wind properties of a sample of late-type O dwarfs. Previous analyses of such stars have found very low mass-loss rates; rates much lower than predicted by theory (the weak wind problem). Methods. Far-UV to optical spectra of five Galactic O stars were analyzed: HD 216898 (O9IV/O8.5V), HD 326329 (O9V), HD 66788 (O8V/O9V), ζ Oph (O9.5Vnn), and HD 216532 (O8.5V((n))). We used a grid of TLUSTY models to obtain effective temperatures, gravities, rotational velocities, and to identify wind lines. Wind parameters for each object were obtained using expanding atmosphere models calculated with the CMFGEN code.Results. The spectra of our sample have primarily a photospheric origin. A weak wind signature is seen in C iv λλ1548, 1551, from which mass-loss rates consistent with previous CMFGEN results for O8-O9V stars were derived (∼10 −10 −10 −9 M yr −1 ). A discrepancy of roughly two orders of magnitude is found between these mass-loss rates and the values predicted by theory (Ṁ Vink ), confirming a breakdown or a steepening of the modified wind momentum-luminosity relation at log L /L < ∼ 5.2. We have estimated the carbon abundance for the stars of our sample and concluded that its value cannot be reduced to sufficiently small values to solve the weak wind problem. Upper limits onṀ were established for all objects using lines of different ions: P v λλ1118, 1128, C iii λ1176, N v λλ1239, 1243, Si iv λλ1394, 1403, and N iv λ1718. All the values obtained are in disagreement with theoretical predictions, bringing support to the reality of weak winds. Together with C iv λλ1548, 1551, the use of N v λλ1239, 1243 results in the lowest mass-loss rates: the upper limits indicate thatṀ must be less than about −1.0 dexṀ Vink . Upper mass-loss rate limits obtained for other transitions are also low: they indicate thatṀ must be less than about (−0.5 ± 0.2) dexṀ Vink . We studied the behavior of the Hα line with different mass-loss rates. For two stars, only models with very lowṀ's provide the best fit to the UV and optical spectra. We also explored ways to fit the observed spectra with the theoretical mass-loss rates. By using large amounts of X-rays, we could reduce the predicted wind emission to the observed levels. However, unrealistic X-ray luminosities had to be used (log L X /L Bol > ∼ −3.5). The validity of the models used in our analyses is discussed.

show abstract

“…So far, there has been no detailed study of the evolution of rotational velocities with spectral type among O stars. An average V sin i of 129±82 km s −1 results from the work of Penny (1996) Howarth et al (1997) found that the distribution of V sin i peaked at about 100 km s −1 . Concerning B stars, Abt et al (2002) found values of 100-130 km s −1 for B0-B5V stars.…”

Section: Hr Diagram and Evolutionary Statusmentioning

confidence: 99%

A quantitative study of O stars in NGC 2244 and the Monoceros OB2 association

Martins

Mahy

Hillier

et al. 2012

A&A

103

View full text Add to dashboard Cite

Aims. Our goal is to determine the stellar and wind properties of seven O stars in the cluster NGC 2244 and three O stars in the OB association Mon OB2. These properties give us insight into the mass loss rates of O stars. They allow us to both check the validity of rotational mixing in massive stars and to better understand the effects of the ionizing flux and wind mechanical energy release on the surrounding interstellar medium and its influence on triggered star formation. Methods. We collected optical and UV spectra of the target stars that we analyzed by means of atmosphere models computed with the code CMFGEN. The spectra of binary stars were disentangled and the components studied separately. Results. All stars have an evolutionary age less than 5 million years, with the most massive stars being among the youngest. Nitrogen surface abundances show no clear relation with projected rotational velocities. Binaries and single stars show the same range of enrichment. This is attributed to the youth and/or wide separation of the binary systems in which the components have not (yet) experienced strong interaction. A clear trend toward greater enrichment in higher luminosity objects is observed, consistent with what evolutionary models with rotation predict for a population of O stars at any given age. We confirm the weakness of winds in late O dwarfs. In general, mass loss rates derived from UV lines are lower than mass loss rates obtained from Hα. The UV mass loss rates are even lower than the single-line driving limit in the latest type dwarfs. These issues are discussed in the context of the structure of massive stars winds. The evolutionary and spectroscopic masses are in agreement above 25 M , but the uncertainties are large. Below this threshold, the few late-type O stars studied here indicate that the mass discrepancy still seems to hold.

show abstract

Projected Rotational Velocities of O-Type Stars

Cited by 176 publications

References 0 publications

The origin of massive O-type field stars

The origin of massive O-type field stars

Analysis of Galactic late-type O dwarfs: more constraints on the weak wind problem

A quantitative study of O stars in NGC 2244 and the Monoceros OB2 association

Contact Info

Product

Resources

About