Browsing by Subject "stars: emission-line, Be"

Now showing 1 - 3 of 3
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    Long-term evolution of the neutron-star spin period of SXP 1062
    (2013) Sturm, R; Haberl, F; Oskinova, L M; Schurch, M P E; Hénault-Brunet, V; Gallagher, J S; Udalski, A
    Context. The Be/X-ray binary SXP 1062 is of especial interest owing to the large spin period of the neutron star, its large spin-down rate, and the association with a supernova remnant constraining its age. This makes the source an important probe for accretion physics.
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    Open Access
    Long-term optical and X-ray variability of the Be/X-ray binary H 1145-619: Discovery of an ongoing retrograde density wave
    (2017) Alfonso-Garzón, J; Fabregat, J; Reig, P; Kajava, J J E; Sánchez-Fernández, C; Townsend, L J; Mas-Hesse, J M; Crawford, S M; Kretschmar, P; Coe, M J
    Context. Multiwavelength monitoring of Be/X-ray binaries is crucial to understand the mechanisms producing their outbursts. H 1145-619 is one of these systems, which has recently displayed X-ray activity.
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    Open Access
    SXP 7.92: a recently rediscovered be/x-ray binary in the small magellanic cloud, viewed edge on
    (2017) Bartlett, E S; Coe, M J; Israel, G L; Clark, J S; Esposito, P; D’Elia, V; Udalski, A
    We present a detailed optical and X-ray study of the 2013 outburst of the Small Magellanic Cloud Be/X-ray binary SXP 7.92, as well as an overview of the last 18 years of observations from OGLE (Optical Gravitational Lensing Experiment), RXTE, Chandra and XMM-Newton. We revise the position of this source to RA(J2000) = 00:57:58.4, Dec(J2000) = −72:22:29.5 with a 1σ uncertainty of 1.5 arcsec, correcting the previously reported position by Coe et al. by more than 20 arcmin. We identify and spectrally classify the correct counterpart as a B1Ve star. The optical spectrum is distinguished by an uncharacteristically deep narrow Balmer series, with the Hα line in particular having a distinctive shell profile, i.e. a deep absorption core embedded in an emission line. We interpret this as evidence that we are viewing the system edge on and are seeing self-obscuration of the circumstellar disc. We derive an optical period for the system of 40.0 ± 0.3 d, which we interpret as the orbital period, and present several mechanisms to describe the X-ray/optical behaviour in the recent outburst, in particular the ‘flares'and ‘dips’ seen in the optical light curve, including a transient accretion disc and an elongated precessing disc.