Open AccessX‐ray/optical bursts from GS 1826–24
Author(s) -
Kong A. K. H.,
Homer L.,
Kuulkers E.,
Charles P. A.,
Smale A. P.
Publication year - 2000
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2000.03121.x
Subject(s) - physics , astrophysics , radius , flux (metallurgy) , accretion (finance) , x ray , accretion disc , x ray binary , orbital period , wavelength , astronomy , optics , neutron star , stars , materials science , computer security , computer science , metallurgy
We report results from the first simultaneous X‐ray ( RXTE ) and optical (SAAO) observations of the low‐mass X‐ray binary GS 1826–24 in 1998 June. A type I burst was detected in both X‐ray and optical wavelengths. Its energy‐dependent profile, energetics and spectral evolution provide evidence for an increase in the X‐ray burning area but not for photospheric radius expansion. However, we may still derive an upper limit for its distance of 7.5±0.5 kpc, assuming a peak flux of ∼2.8×10 −8 erg cm −2 s −1 . A ∼3‐s optical delay with respect to the X‐ray burst is also observed, and we infer that this is related to the X‐ray reprocessing in the accretion disc. The delay provides additional support for the recently proposed orbital period of ∼2 h. We also present an ASCA observation from 1998 March, during which two X‐ray bursts were detected.