Issue |
A&A
Volume 601, May 2017
|
|
---|---|---|
Article Number | A105 | |
Number of page(s) | 9 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361/201630021 | |
Published online | 11 May 2017 |
Variability of the symbiotic X-ray binary GX 1+4
Enhanced activity near periastron passage
1 Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Bartycka 18, 00716 Warsaw, Poland
e-mail: krystian.ilkiewicz@gmail.com
2 Kleinkaroo Observatory, Calitzdorp, Western Cape, South Africa
Received: 7 November 2016
Accepted: 22 February 2017
Context. GX 1+4 belongs to a rare class of X-ray binaries with red giant donors, symbiotic X-ray binaries. It has a history of complicated variability on multiple timescales in the optical light and X-rays. The nature of this variability remains poorly understood.
Aims. We aim to study variability of GX 1+4 on long timescale in X-ray and optical bands.
Methods. We took X-ray observations from the INTEGRAL Soft Gamma-Ray Imager and RXTE All Sky Monitor. Optical observations were made with the INTEGRAL Optical Monitoring Camera.
Results. The variability of GX 1+4 both in optical light and hard X-ray emission (>17 keV) is dominated by ~50–70 d quasi-periodic changes. The amplitude of this variability is highest during the periastron passage, while during the potential neutron star eclipse the system is always at minimum. This confirms the 1161 d orbital period that has had been proposed for the system based on radial velocity curve. Neither the quasi-periodic variability or the orbital period are detected in soft X-ray emission (1.3–12.2 keV), where the binary shows no apparent periodicity.
Key words: X-rays: binaries / binaries: symbiotic / stars: individual: GX 1+4
© ESO, 2017
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