Be–X-ray binaries and candidates

Raguzova, N. V.; Попов, С. Б.

doi:10.1080/10556790500497311

Cited by 99 publications

(99 citation statements)

References 182 publications

(307 reference statements)

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“…Throughout explicitly excluding the brightening of the source caused by circumstellar emission leads to a underestimation of the distance. In two cases, our distance determinations are much higher than those quoted in Raguzova & Popov (2005). In both 7.9 ± 1.2/5.9 ± 0.9 3.8 RP05 GROJ1008-57 9.7 ± 0.8/5.8 ± 0.5 2.0 RP05 XTE 1946+27…”

Section: Milky Way Starscontrasting

confidence: 65%

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Circumstellar emission in Be/X-ray binaries of the Magellanic Clouds and the Milky Way

Riquelme

Torrejón

Negueruela

2012

A&A

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Aims. We study the optical and near-infrared colour excesses produced by circumstellar emission in a sample of Be/X-ray binaries. Our main goals are exploring whether previously published relations, valid for isolated Be stars, are applicable to Be/X-ray binaries and computing the distance to these systems after correcting for the effects of the circumstellar contamination. Methods. Simultaneous UBVRI photometry and spectra in the 3500−7000 Å spectral range were obtained for 11 optical counterparts to Be/X-ray binaries in the LMC, 5 in the SMC and 12 in the Milky Way. As a measure of the amount of circumstellar emission we used the H α equivalent width corrected for photospheric absorption. Results. We find a linear relationship between the strength of the H α emission line and the component of E(B − V) originating from the circumstellar disk. This relationship is valid for stars with emission lines weaker than EW ≈ −15 Å. Beyond this point, the circumstellar contribution to E(B − V) saturates at a value ≈0.17 mag. A similar relationship is found for the (V − I) near infrared colour excess, albeit with a steeper slope and saturation level. The circumstellar excess in (B − V) is found to be about five times higher for Be/X-ray binaries than for isolated Be stars with the same equivalent width EW(H α ), implying significant differences in the physical properties of their circumstellar envelopes. The distance to Be/X-ray binaries (with non-shell Be star companions) can only be correctly estimated by taking into account the excess emission in the V band produced by free-free and free-bound transitions in the circumstellar envelope. We provide a simple method to determine the distances that includes this effect.

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Section: Milky Way Starscontrasting

confidence: 65%

“…NO01 cases, though, the discrepancy comes from the assumed parameters and has nothing to do with the method presented here. For example GRO J1008−57: the distance quoted in Raguzova & Popov (2005) was taken from a work by Haberl & Sasaki (2005). These last authors used, in turn, results from Macomb et al (1994).…”

Section: Milky Way Starsmentioning

confidence: 99%

Circumstellar emission in Be/X-ray binaries of the Magellanic Clouds and the Milky Way

Riquelme

Torrejón

Negueruela

2012

A&A

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“…Although there is a perceived deficiency of short-period Be star binaries (e.g., Abt & Levy 1978), recent work has led to the discovery of 55 Be star binaries with periods <100 days (Gies 2000;Raguzova & Popov 2005), and Be stars have been observed in nearly all stages of the proposed binary evolution scenario. The initially more massive star expands to fill its critical Roche lobe during the H shellburning phase, triggering Case B mass transfer and causing the spin-up of the mass gainer (Gies 2000).…”

Section: Discussionmentioning

confidence: 99%

The Evolutionary Status of Be Stars: Results from a Photometric Study of Southern Open Clusters

McSwain

Gies

2005

ASTROPHYS J SUPPL S

179

238

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Be stars are a class of rapidly rotating B stars with circumstellar disks that cause Balmer and other line emission. There are three possible reasons for the rapid rotation of Be stars: they may have been born as rapid rotators, spun up by binary mass transfer, or spun up during the main-sequence (MS) evolution of B stars. To test the various formation scenarios, we have conducted a photometric survey of 55 open clusters in the southern sky. Of these, five clusters are probably not physically associated groups and our results for two other clusters are not reliable, but we identify 52 definite Be stars and an additional 129 Be candidates in the remaining clusters. We use our results to examine the age and evolutionary dependence of the Be phenomenon. We find an overall increase in the fraction of Be stars with age until 100 Myr, and Be stars are most common among the brightest, most massive B-type stars above the zero-age main sequence (ZAMS). We show that a spin-up phase at the terminal-age main sequence (TAMS) cannot produce the observed distribution of Be stars, but up to 73% of the Be stars detected may have been spun-up by binary mass transfer. Most of the remaining Be stars were likely rapid rotators at birth. Previous studies have suggested that low metallicity and high cluster density may also favor Be star formation. Our results indicate a possible increase in the fraction of Be stars with increasing cluster distance from the Galactic center (in environments of decreasing metallicity). However, the trend is not significant and could be ruled out due to the intrinsic scatter in our data. We also find no relationship between the fraction of Be stars and cluster density. Subject headingg s: open clusters and associations: individual

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“…Zhang et al (2004a) extended the application of the viscous decretion disc model of Okazaki and Negueruela (2001) to compact companions of arbitrary mass and showed that the most effective Be disc truncation would occur in relatively narrow systems. Using the population synthesis results of Podsiadlowski et al (2003), which state that binary black holes are most likely to be born in systems with narrow orbits (P orb 30 days), the reason for the lack of these systems can be attributed to the difficulty Liu et al (2007) and Liu et al (2006) catalogs plus update from the 4th IBIS/ISGRI soft gamma-ray survey catalog b Sources in the updated on-line version of the Raguzova and Popov (2005) catalog (http://xray.sai.msu.ru/ ∼ raguzova/BeXcat/) c Systems with known optical counterpart and verified X-ray behavior (from Table 1) to detecting them. Be/BH binaries are expected to be X-ray transients with very long quiescent states.…”

Section: High-mass X-ray Binariesmentioning

confidence: 99%

Be/X-ray binaries

Reig

2011

Astrophys Space Sci

544

522

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The purpose of this work is to review the observational properties of Be/X-ray binaries. The open questions in Be/X-ray binaries include those related to the Be star companion, that is, the so-called "Be phenomenon", such as, timescales associated to the formation and dissipation of the equatorial disc, mass-ejection mechanisms, V/R variability, and rotation rates; those related to the neutron star, such as, mass determination, accretion physics, and spin period evolution; but also, those that result from the interaction of the two constituents, such as, disc truncation and mass transfer. Until recently, it was thought that the Be stars' disc was not significantly affected by the neutron star. In this review, I present the observational evidence accumulated in recent years on the interaction between the circumstellar disc and the compact companion. The most obvious effect is the tidal truncation of the disc. As a result, the equatorial discs in Be/X-ray binaries are smaller and denser than those around isolated Be stars.Comment: "The final publication is available at http://www.springerlink.com". This review article has been accepted for publication in Astrophysics and Space Scienc

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Be–X-ray binaries and candidates

Cited by 99 publications

References 182 publications

Circumstellar emission in Be/X-ray binaries of the Magellanic Clouds and the Milky Way

Circumstellar emission in Be/X-ray binaries of the Magellanic Clouds and the Milky Way

The Evolutionary Status of Be Stars: Results from a Photometric Study of Southern Open Clusters

Be/X-ray binaries

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