Multiwaveband studies of the hard ROSAT SMC transient 1WGA J0053.8-7226: a new X-ray pulsar

Buckley, D.A.H., Coe, M.J., Stevens, J.B., van der Hayden, K., Angelini, L., White, N. and Giommi, P. (2001) Multiwaveband studies of the hard ROSAT SMC transient 1WGA J0053.8-7226: a new X-ray pulsar. Monthly Notices of the Royal Astronomical Society, 320 (2), 281-288. (doi:10.1046/j.1365-8711.2001.03982.x).

Abstract

We report on two optical candidates for the counterpart to an X-ray source in the Small Magellanic Cloud, 1WGA J0053.8-7226, identified as a serendipitous X-ray source from the ROSAT Position Sensitive Proportional Counter (PSPC) archive, and also observed by the Einstein Imaging Proportional Counter. Its X-ray properties, namely the hard X-ray spectrum, flux variability and column density, indicate a hard, transient source, with a luminosity of ~ 3.8×1035ergs-1. XTE and ASCA observations have confirmed the source to be an X-ray pulsar, with a 46-s spin period. Our optical observations reveal two possible candidates within the error circle. Both exhibit strong H? and weaker H? emission. The optical colours indicate that both objects are Be-type stars. The Be nature of the stars implies that the counterpart is most likely a Be/X-ray binary system. Subsequent infrared (IR) photometry (JHK) of one of the objects shows that the source varies by at least 0.5mag, while the (J-K) measured nearly simultaneously with the UBVRI and spectroscopic observations indicate an IR excess of ~0.3mag.

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Contributors

Author: M.J. Coe

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