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

Multiwaveband studies of the hard ROSAT SMC transient 1WGA J0053.8-7226: a new X-ray pulsar
Multiwaveband studies of the hard ROSAT SMC transient 1WGA J0053.8-7226: a new X-ray pulsar
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.
binaries: general, stars: emission-line, be, pulsars: general, infrared: stars, x-rays: stars
1365-2966
281-288
Buckley, D.A.H.
2b82e4e2-d175-4cb3-9868-46b13f4f890c
Coe, M.J.
04dfb23b-1456-46a3-9242-5cee983471d5
Stevens, J.B.
04c658cf-e1f9-4c28-a074-a93f8752cbea
van der Hayden, K.
90dec14d-8158-4aca-af72-b0107d7ccda6
Angelini, L.
0dfda843-4709-4423-bec2-831a2f39d596
White, N.
ffff19be-7e8b-42fe-8562-d3b95fc2f034
Giommi, P.
b4aad836-bdcd-453d-b8ca-9b344f13855a
Buckley, D.A.H.
2b82e4e2-d175-4cb3-9868-46b13f4f890c
Coe, M.J.
04dfb23b-1456-46a3-9242-5cee983471d5
Stevens, J.B.
04c658cf-e1f9-4c28-a074-a93f8752cbea
van der Hayden, K.
90dec14d-8158-4aca-af72-b0107d7ccda6
Angelini, L.
0dfda843-4709-4423-bec2-831a2f39d596
White, N.
ffff19be-7e8b-42fe-8562-d3b95fc2f034
Giommi, P.
b4aad836-bdcd-453d-b8ca-9b344f13855a

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).

Record type: Article

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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More information

Published date: January 2001
Keywords: binaries: general, stars: emission-line, be, pulsars: general, infrared: stars, x-rays: stars

Identifiers

Local EPrints ID: 52529
URI: http://eprints.soton.ac.uk/id/eprint/52529
ISSN: 1365-2966
PURE UUID: 54052c3f-f62e-47a9-bf42-be6d15b96f71
ORCID for M.J. Coe: ORCID iD orcid.org/0000-0002-0763-8547

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Date deposited: 10 Jul 2008
Last modified: 16 Mar 2024 02:35

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Contributors

Author: D.A.H. Buckley
Author: M.J. Coe ORCID iD
Author: J.B. Stevens
Author: K. van der Hayden
Author: L. Angelini
Author: N. White
Author: P. Giommi

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