HD 161306: a radiatively interacting Be binary?

Koubský, P.; Kotková, L.; Kraus, M.; Yang, S.; Šlechta, M.; Harmanec, P.; Wolf, M.; Votruba, V.; Kubát, Jiřı́; Kubátová, B.; Niemczura, E.; Škoda, Petr

doi:10.1051/0004-6361/201424022

Cited by 18 publications

(17 citation statements)

References 14 publications

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“…HD 161306 was classified as B0:ne. Much like o Pup (see above), Koubský et al (2014) report a possible sdO companion orbiting the Be star at a period of about 100 d. Like o Pup and π Aqr, we therefore assign this object to class ii (binaries with uncertain or debated companions).…”

Section: B2 Binaries With Unknown Uncertain or Debated Companionsmentioning

confidence: 77%

“…Even though the majority of models suggest that the companion is a non-MS companion such as a hot He star or a compact object (e.g., Postnov et al 2017;Langer et al 2020b), a solar-type companion cannot be fully ruled out. Similar objects include the γ Cas analogue π Aqr and the suggested Be+sdO binary HD 161306 (Koubský et al 2014). This class also includes the potential Be+MS binary δ Sco (Miroshnichenko et al 2013).…”

Section: Analysis Of the Available Literaturementioning

confidence: 99%

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Investigating the lack of main-sequence companions to massive Be stars

Bodensteiner

Shenar

Sana

2020

A&A

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Context. About 20% of all B-type stars are classical Be stars – stars whose spectra imply the presence of a circumstellar decretion disk. The disk phenomenon is strongly correlated with rapid rotation, the origin of which remains unclear. It may be rooted in single- or binary-star evolution. In the framework of the binary channel, the initially more massive star transfers mass and angular momentum to the original secondary, which becomes a Be star. The system then evolves into a Be binary with a post-main-sequence companion, which, depending on the companion mass, may later be disrupted in a supernova event. Hence, if the binary channel dominates the formation of Be stars, one may expect a strong lack of close Be binaries with main sequence (MS) companions. Aims. We want to test the prediction of the binary channel. Through an extensive, star-by-star review of the literature of a magnitude-limited sample of Galactic early-type Be stars, we investigate whether Be binaries with MS companions are known to exist. Methods. Our sample is constructed from the BeSS database and cross-matched with all available literature on the individual stars. Archival and amateur spectra are used to verify the existing literature when conflicting reports are found. Results. Out of an initial list of 505 Be stars, we compile a final sample of 287 Galactic Be stars earlier than B1.5 with V ≤ 12 mag. Out of those, 13 objects were reported as Be binaries with known post-MS companions (i.e., compact objects or helium stars) and 11 as binaries with unknown, uncertain or debated companions. We find no confirmed reports of Be binaries with MS companions. For the remaining 263 targets, no significant reports of multiplicity exist in the literature, implying that they are either Be binaries with faint companions, or truly single. Conclusions. The clear lack of reported MS companions to Be stars, which stands in contrast to the high number of detected B+B MS binaries, strongly supports the hypothesis that early-type Be stars are binary interaction products that spun up after mass and angular momentum transfer from a companion star. Taken at face value, our results may suggest that a large majority of the early-type Be stars have formed through binary mass-transfer.

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Section: B2 Binaries With Unknown Uncertain or Debated Companionsmentioning

confidence: 77%

Section: Analysis Of the Available Literaturementioning

confidence: 99%

Investigating the lack of main-sequence companions to massive Be stars

Bodensteiner

Shenar

Sana

2020

A&A

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“…Another distinct subgroup of Be binaries are systems with hot and compact secondaries, the prototype of such systems being ϕ Per (Gies et al 1998;Božić et al 1995). Only five such systems are known (see Koubský et al 2012Koubský et al , 2014, and references therein). Finally, a subgroup of mass-exchanging semi-detached binaries exists in which the Be components are the mass-gaining components as predicted by the original binary hypothesis of the Be phenomenon (Kříž & Harmanec 1975;Harmanec & Kříž 1976).…”

Section: Br CMI Among Other Known Emission-line Semi-detached Binariesmentioning

confidence: 99%

Properties and nature of Be stars

Harmanec

Koubský

Nemravová

et al. 2015

A&A

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Reliable determination of the basic physical properties of hot emission-line binaries with Roche-lobe filling secondaries is important for developing the theory of mass exchange in binaries. It is a very hard task, however, which is complicated by the presence of circumstellar matter in these systems. So far, only a small number of systems with accurate values of component masses, radii, and other properties are known. Here, we report the first detailed study of a new representative of this class of binaries, BR CMi, based on the analysis of radial velocities and multichannel photometry from several observatories, and compare its physical properties with those for other well-studied systems. BR CMi is an ellipsoidal variable seen under an intermediate orbital inclination of ∼51• , and it has an orbital period of 12.d 919059(15) and a circular orbit. We used the disentangled component spectra to estimate the effective temperatures 9500(200) K and 4655(50) K by comparing them with model spectra. They correspond to spectral types B9.5e and G8III. We also used the disentangled spectra of both binary components as templates for the 2D cross-correlation to obtain accurate radial velocities and a reliable orbital solution. Some evidence of a secular period increase at a rate of (1.1 ± 0.5) s per year was found. This, together with a very low mass ratio of 0.06 and a normal mass and radius of the mass gaining component, indicates that BR CMi is in a slow phase of the mass exchange after the mass-ratio reversal. It thus belongs to a still poorly populated subgroup of Be stars for which the origin of Balmer emission lines is safely explained as a consequence of mass transfer between the binary components.

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“…Encouraged by the UV detection of the companion of φ Per, we subsequently launched an investigation of the UV spectra of Be binaries that were frequently observed by IUE, and our work led to the discovery of the hot subdwarf companions of FY CMa (Peters et al 2008) and 59 Cyg (Peters et al 2013). The presence of a hot companion in φ Per was first suggested by emission line variations caused by heating of the Be star's disk gas by the hot companion (Poeckert 1981;Hummel &Štefl 2001), and observations of similar emission line variations may indicate the presence of hot subdwarf companions to the Be stars o Pup (Koubský et al 2012) and HD 161306 (Koubský et al 2014).…”

Section: Introductionmentioning

confidence: 95%

THE HOT COMPANION AND CIRCUMBINARY DISK OF THE Be STAR HR 2142

Peters

Wang

Gies

et al. 2016

ApJ

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We present a spectroscopic investigation of the Be+sdO binary system HR 2142 that is based upon large sets of ultraviolet observations from the International Ultraviolet Explorer and ground-based Hα observations. We measured radial velocities for the Be star component from these spectra, and computed a revised orbit. In order to search for the spectral signature of the hot subdwarf, we cross-correlated the short wavelength end of each IUE spectrum with a model hot star spectrum, and then we used the predicted Doppler shifts of the subdwarf to shift-and-add all the cross-correlation functions to the frame of the subdwarf. This merged function shows the weak signal from the spectral lines of the hot

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HD 161306: a radiatively interacting Be binary?

Cited by 18 publications

References 14 publications

Investigating the lack of main-sequence companions to massive Be stars

Investigating the lack of main-sequence companions to massive Be stars

Properties and nature of Be stars

THE HOT COMPANION AND CIRCUMBINARY DISK OF THE Be STAR HR 2142

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