Optical Spectroscopy of the High-mass X-ray Binary A0535+26 after the periastron
ATel #8633; K. A. Stoyanov & R. Zamanov (Institute of Astronomy and National Astronomical Observatory, Bulgaria)
on 4 Feb 2016; 07:31 UT
Credential Certification: R. K. Zamanov (rkz@astro.bas.bg)
Subjects: Optical, Binary, Neutron Star, Variables
We present optical spectroscopy of the High-mass X-ray Binary A0535+26 (HDE 245770, V725 Tau)
after the periastron passage (Giovannelli, Bisnovatyi-Kogan & Klepnev, 2013, A&A, 560, 1).
The observations are performed with the ESpeRo spectrograph on the 2m RCC telescope at Rozhen NAO (Bulgaria) on the nights of 2015 Dec 24 (JD2457381.4285) and 2016 Jan 30 (JD2457418.2045). The equivalent widths of H-alpha emission line are -(11.5±1.5) Angstrom and -(9.3±1.0)
Angstrom respectively. The equivalent widths of H-beta are -(1.1±0.1) Angstrom and
-(1.3±0.1) Angstrom respectively.
Since the H-alpha and H-beta lines have double-peaked structure, we estimated the outer radii of the H-alpha and H-beta emitting regions using the equation by Huang (1972, ApJ, 171, 549). For the
calculations we used radius of the donor star R=15 solar radii and projected rotational velocity
v sin i = 225 km/s (Grundstrom et al., 2007, ApJ, 667, 505; Haigh, Coe & Fabregat, 2004, MNRAS, 350, 1457).
We estimated the outer radius of the H-alpha circumstellar disc to be 96±5 solar radii on JD 2457381.42850 and 104±5 solar radii on JD2457418.2045. For the radius if the H-beta disc, we calculated 48±3 solar radii on JD 2457381.42850 and 46±3 solar
radii on JD2457418.2045.
H-alpha and H-beta emission lines
