Strong optical activity in HDE245770/A0535+26 system around the periastron
ATel #7487; F. Giovannelli (INAF-Istituto di Astrofisica e Planetologia Spaziali, Roma, Italy), C. Rossi (Dpt of Physics, La Sapienza University, Roma, Italy), G. S. Bisnovatyi-Kogan (IKI- Space Research Institute, Moscow, Russia), I. Bruni (INAF-Osservatorio Astronomico di Bologna, Stazione Astronomica di Loiano, Italy), A. Fasano (Dpt of Physics, La Sapienza University, Roma, Italy), J. Salas Procas (Agrupacion Astronomica de Huesca, Spain)
on 9 May 2015; 07:21 UT
Credential Certification: Corinne Rossi (corinne.rossi@uniroma1.it)
Subjects: Optical, X-ray, Binary, Neutron Star
Optical photometry of HDE 245770 around the periastron passage of the neutron star A0535+26 (JD 2457154) following the ephemeris of Giovannelli et al.: 2013, A&A, 560, A1G [JD_opt-out = JD_0(2444944) +- n(111.0 +- 0.4) days]. This passage is just 110 orbital periods after the 811205-E. The results of photometry show an enhancement in the optical luminosity in V band of about 0.04 mag around the periastron passage. This is an indication that the X-ray pulsar is close to experience a strong X-ray outburst after about 8 days from the periastron passage, with an expected intensity of 2.5 +-0.5 Crab. We expect an equivalent width of H_alpha line in emission of -(17 +- 3) Angstrom. X-ray measurements are strongly required.
