Optical follow-up of new Small Magellanic Cloud wing Be/X-ray binaries |
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| Authors: | M P E Schurch M J Coe K E McGowan V A McBride D A H Buckley J L Galache R H D Corbet M Still P Vaisanen A Kniazev K Nordsieck |
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| Institution: | School of Physics and Astronomy, Southampton University, Highfield, Southampton SO17 1BJ;South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa;Harvard–Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA;Universities Space Research Association, X-ray Astrophysics Laboratory, Mail Code 662, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA |
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| Abstract: | We investigate the optical counterparts of recently discovered Be/X-ray binaries in the Small Magellanic Cloud (SMC). In total four sources, SXP101, SXP700, SXP348 and SXP65.8 were detected during the Chandra survey of the wing of the SMC. SXP700 and SXP65.8 were previously unknown. Many optical ground-based telescopes have been utilized in the optical follow-up, providing coverage in both the red and blue bands. This has led to the classification of all of the counterparts as Be stars and confirms that three lie within the Galactic spectral distribution of known Be/X-ray binaries. SXP101 lies outside this distribution and is the latest spectral type known. Monitoring of the Hα emission line suggests that all the sources barring SXP700 have highly variable circumstellar discs, possibly a result of their comparatively short orbital periods. Phase-resolved X-ray spectroscopy has also been performed on SXP65.8, revealing that the emission is indeed harder during the passage of the X-ray beam through the line of sight. |
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| Keywords: | stars: emission-line Be Magellanic Clouds X-rays: binaries |
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