On the variability of the visual binary WR 86

Paardekooper, Sijme-Jan; Veen, P. M.; Genderen, A. M. van; Hucht, K. A. van der

doi:10.1051/0004-6361:20020085

“…Likewise Veen & Wieringa (2000) cast serious doubt upon the photometric variability suggested for WR 50 by van Genderen et al (1991). Finally, Paardekooper et al (2002) show that the periodicity associated with WR86 is instead attributable to a β-Cephei companion.…”

Section: Possible Binary Pathwaysmentioning

confidence: 94%

A VLT/FLAMES survey for massive binaries in Westerlund 1

Clark

¹

,

Ritchie

²

,

Negueruela

³

et al. 2011

A&A

View full text Add to dashboard Cite

Context. There is growing evidence that a treatment of binarity amongst OB stars is essential for a full theory of stellar evolution. However the binary properties of massive stars -frequency, mass ratio & orbital separation -are still poorly constrained. Aims. In order to address this shortcoming we have undertaken a multiepoch spectroscopic study of the stellar population of the young massive cluster Westerlund 1. In this paper we present an investigation into the nature of the dusty Wolf-Rayet star and candidate binary W239. Methods. To accomplish this we have utilised our spectroscopic data in conjunction with multi-year optical and near-IR photometric observations in order to search for binary signatures. Comparison of these data to synthetic non-LTE model atmosphere spectra were used to derive the fundamental properties of the WC9 primary. Results. We found W239 to have an orbital period of only ∼5.05 days, making it one of the most compact WC binaries yet identified. Analysis of the long term near-IR lightcurve reveals a significant flare between 2004-6. We interpret this as evidence for a third massive stellar component in the system in a long period (>6 yr), eccentric orbit, with dust production occuring at periastron leading to the flare. The presence of a near-IR excess characteristic of hot (∼1300 K) dust at every epoch is consistent with the expectation that the subset of persistent dust forming WC stars are short (<1 yr) period binaries, although confirmation will require further observations. Non-LTE model atmosphere analysis of the spectrum reveals the physical properties of the WC9 component to be fully consistent with other Galactic examples. Conclusions. The simultaneous presence of both short period Wolf-Rayet binaries and cool hypergiants within Wd 1 provides compelling evidence for a bifurcation in the post-Main Sequence evolution of massive stars due to binarity. Short period O+OB binaries will evolve directly to the Wolf-Rayet phase, either due to an episode of binary mediated mass loss -likely via case A mass transfer or a contact configuration -or via chemically homogenous evolution. Conversely, long period binaries and single stars will instead undergo a red loop across the HR diagram via a cool hypergiant phase. Future analysis of the full spectroscopic dataset for Wd 1 will constrain the proportion of massive stars experiencing each pathway; hence quantifying the importance of binarity in massive stellar evolution up to and beyond supernova and the resultant production of relativistic remnants.

show abstract

“…4, Table 2). If the frequency resolution of the observations made by Paardekooper et al (2002) is taken into account, it can be stated that the first two modes are the same as those found by Paardekooper et al (2002).…”

Section: Appendix A: Notes On Individual Starsmentioning

confidence: 74%

“…Owing to the evident variability, the star was named V1035 Sco (Kazarovets & Samus 1997). A detailed photometric and spectroscopic study was later performed by Paardekooper et al (2002). They concluded that the short-period photometric variability of V1035 Sco should be attributed to the secondary component and can be described by two modes with frequencies 6.914 and 7.236 d −1 .…”

Section: Appendix A: Notes On Individual Starsmentioning

confidence: 99%

β Cephei stars in the ASAS-3 data

Pigulski¹,

Pojmański²

2007

A&A

View full text Add to dashboard Cite

Aims. We analyse V-filter ASAS-3 photometry of 41 known β Cephei-type stars. The ASAS-3 photometry is combined with the archival data, if available, to determine long-term stability of periods and amplitudes of excited modes. Methods. Frequencies of modes are derived by means of Fourier periodograms with consecutive prewhitening. The results are examined in the context of detection threshold. Results. We detected amplitude changes in three β Cephei stars, BW Cru, V836 Cen, and V348 Nor. Period changes were found in KK Vel and V836 Cen. Our analysis shows that intrinsic period changes are more common among multiperiodic stars, apparently because they are caused by some kind of mode interaction. In addition, we found new modes for seven stars, and for ten others we provide new solutions or remove ambiguities in the detected frequencies. One candidate hybrid β Cephei/SPB star, HD 133823, is discovered.

show abstract

“…Likewise Veen & Wieringa (2000) cast serious doubt upon the photometric variability suggested for WR 50 by van Genderen et al (1991). Finally, Paardekooper et al (2002) show that the periodicity associated with WR86 is instead attributable to a β-Cephei companion.…”

Section: Possible Binary Pathwaysmentioning

confidence: 94%

A VLT/FLAMES survey for massive binaries in Westerlund 1. III. The WC9d binary W239 and implications for massive stellar evolution

Clark,

Ritchie,

Negueruela

et al. 2011

Preprint

0

View full text Add to dashboard Cite

Context. There is growing evidence that a treatment of binarity amongst OB stars is essential for a full theory of stellar evolution. However the binary properties of massive stars -frequency, mass ratio & orbital separation -are still poorly constrained. Aims. In order to address this shortcoming we have undertaken a multiepoch spectroscopic study of the stellar population of the young massive cluster Westerlund 1. In this paper we present an investigation into the nature of the dusty Wolf-Rayet star and candidate binary W239. Methods. To accomplish this we have utilised our spectroscopic data in conjunction with multi-year optical and near-IR photometric observations in order to search for binary signatures. Comparison of these data to synthetic non-LTE model atmosphere spectra were used to derive the fundamental properties of the WC9 primary. Results. We found W239 to have an orbital period of only ∼5.05 days, making it one of the most compact WC binaries yet identified. Analysis of the long term near-IR lightcurve reveals a significant flare between 2004-6. We interpret this as evidence for a third massive stellar component in the system in a long period (>6 yr), eccentric orbit, with dust production occuring at periastron leading to the flare. The presence of a near-IR excess characteristic of hot (∼1300 K) dust at every epoch is consistent with the expectation that the subset of persistent dust forming WC stars are short (<1 yr) period binaries, although confirmation will require further observations. Non-LTE model atmosphere analysis of the spectrum reveals the physical properties of the WC9 component to be fully consistent with other Galactic examples. Conclusions. The simultaneous presence of both short period Wolf-Rayet binaries and cool hypergiants within Wd 1 provides compelling evidence for a bifurcation in the post-Main Sequence evolution of massive stars due to binarity. Short period O+OB binaries will evolve directly to the Wolf-Rayet phase, either due to an episode of binary mediated mass loss -likely via case A mass transfer or a contact configuration -or via chemically homogenous evolution. Conversely, long period binaries and single stars will instead undergo a red loop across the HR diagram via a cool hypergiant phase. Future analysis of the full spectroscopic dataset for Wd 1 will constrain the proportion of massive stars experiencing each pathway; hence quantifying the importance of binarity in massive stellar evolution up to and beyond supernova and the resultant production of relativistic remnants and X-ray binaries.

show abstract

On the variability of the visual binary WR 86

Abstract: Abstract.We discuss the variability of WR 86 (WC7 (+B0 III)), a known visual binary, confirmed by Hubble Space Telescope observations (Niemela et al. 1998

Cited by 13 publications

References 12 publications

A VLT/FLAMES survey for massive binaries in Westerlund 1

A VLT/FLAMES survey for massive binaries in Westerlund 1

β Cephei stars in the ASAS-3 data

A VLT/FLAMES survey for massive binaries in Westerlund 1. III. The WC9d binary W239 and implications for massive stellar evolution

Contact Info

Product

Resources

About