The binary frequency of the OBN and OBC stars

Bolton, C. T.; Rogers, G. L.

doi:10.1086/156139

Cited by 37 publications

(43 citation statements)

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“…Bolton & Rogers (1978) investigated binarity among OC stars. Their results indicated a low binary fraction, although results were not conclusive for some stars.…”

Section: Discussionmentioning

confidence: 99%

Surface abundances of OC supergiants

Martins

Foschino

Bouret

et al. 2016

A&A

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Context. Some O and B stars show unusually strong or weak lines of carbon and/or nitrogen. These objects are classified as OBN or OBC stars. It has recently been shown that nitrogen enrichment and carbon depletion are the most likely explanations for the existence of the ON class. Aims. We investigate OC stars (all being supergiants) to check that surface abundances are responsible for the observed anomalous line strengths. Methods. We perform a spectroscopic analysis of three OC supergiants using atmosphere models. A fourth star was previously studied by us. Our sample thus comprises all OC stars known to date in the Galaxy. We determine the stellar parameters and He, C, N, and O surface abundances. Results. We show that all stars have effective temperatures and surface gravities fully consistent with morphologically normal O supergiants. However, OC stars show little, if any, nitrogen enrichment and carbon surface abundances consistent with the initial composition. OC supergiants are thus barely chemically evolved, unlike morphologically normal O supergiants.

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“…Bolton & Rogers (1978) investigated binarity among OC stars. Their results indicated a low binary fraction, although results were not conclusive for some stars.…”

Section: Discussionmentioning

confidence: 99%

Surface abundances of OC supergiants

Martins

Foschino

Bouret

et al. 2016

A&A

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“…The nature of the tentative variability observed in the giant sample is also unclear: binarity or wind or photospheric variability? Of the five dwarfs or subgiants, HD 48279 is constant in radial velocity (Mahy et al 2009), HD 12323 is a single-lined spectroscopic binary (SB1; Bolton & Rogers 1978), HD 14633 an SB1 with a low-mass component and high eccentricity (Boyajian et al 2005), HD 102415 is reported as "likely variable" by Walborn et al (2011), and HD 201345 has an unclear status. Figure 11 provides more information on the line-profile and radial-velocity variations of ten of the ON stars studied in the present paper.…”

Section: Rotation and The On Phenomenonmentioning

confidence: 99%

Surface abundances of ON stars

Martins

Simón‐Díaz

Palacios

et al. 2015

A&A

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Context. Massive stars burn hydrogen through the CNO cycle during most of their evolution. When mixing is efficient or when mass transfer in binary systems occurs, chemically processed material is observed at the surface of O and B stars. Aims. ON stars show stronger lines of nitrogen than morphologically normal counterparts. Whether this corresponds to the presence of material processed through the CNO cycle is not known. Our goal is to answer this question. Methods. We performed a spectroscopic analysis of a sample of ON stars with atmosphere models. We determined the fundamental parameters as well as the He, C, N, and O surface abundances. We also measured the projected rotational velocities. We compared the properties of the ON stars to those of normal O stars. Results. We show that ON stars are usually rich in helium. Their CNO surface abundances are fully consistent with predictions of nucleosynthesis. ON stars are more chemically evolved and rotate − on average − faster than normal O stars. Evolutionary models including rotation cannot account for the extreme enrichment observed among ON main sequence stars. Some ON stars are members of binary systems, but others are single stars as indicated by stable radial velocities. Mass transfer is therefore not a simple explanation for the observed chemical properties. Conclusions. We conclude that ON stars show extreme chemical enrichment at their surface, consistent with nucleosynthesis through the CNO cycle. Its origin is not clear at present.

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“…Savage and Massa classified the qtar as BN1 11-lb on the basis of the UV spectrum and previous optical types, while N. Houk classified it B1/2 lab/b in the Michigan HD Catalogue. Its galactic latitude is +11 0 , in keeping with the relatively high latitudes of the OBN class (Walborn 1970;Bolton and Rogers 1978;Bisiacchi, López, and Firmani 1982). Further investigation of the optical spectrum is planned for the coming season.…”

Section: Hd 93840mentioning

confidence: 71%

“…It is possible that all OBN objects are a result of either active or previous mass transfer in close binary systems (Bolton and Rogers 1978). Two exceptionally interesting active systems, both of$ Lyrae type, are HD 72754 and HD 163181.…”

Section: Mass-transfer Binariesmentioning

confidence: 99%

Evolutionary helium and cno anomalies in the atmospheres and winds of massive hot stars

Walborn

Atmospheric Diagnostics of Stellar Evolution: Chemical Peculiarity, Mass Loss, and Explosion

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The binary frequency of the OBN and OBC stars

Cited by 37 publications

References 0 publications

Surface abundances of OC supergiants

Surface abundances of OC supergiants

Surface abundances of ON stars

Evolutionary helium and cno anomalies in the atmospheres and winds of massive hot stars

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