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Swift J004427.3-734801-a probable Be/white dwarf system in the Small Magellanic Cloud

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posted on 2022-07-12, 07:51 authored by MJ Coe, JA Kennea, PA Evans, A Udalski
Swift J004427.3−734801 is an X-ray source in the Small Magellanic Cloud (SMC) that was first discovered as part of the Swift S-CUBED programme in 2020 January. It was not detected in any of the previous 3 yr worth of observations. The accurate positional determination from the X-ray data has permitted an optical counterpart to be identified that has the characteristics of an O9V−B2III star. Evidence for the presence of an infrared excess and significant Iband variability strongly suggests that this is an OBe-type star. Over 17 yr worth of optical monitoring by the OGLE (Optical Gravitational Lensing Experiment) project reveals periods of time in which quasi-periodic optical flares occur at intervals of ∼21.5 d. The X-ray data obtained from the S-CUBED project reveal a very soft spectrum, too soft to be that from accretion on to a neutron star or black hole. It is suggested here that this is a rarely identified Be star-white dwarf binary in the SMC.

History

Author affiliation

Department of Physics and Astronomy, University of Leicester

Version

  • AM (Accepted Manuscript)

Published in

Monthly Notices of the Royal Astronomical Society: Letters

Volume

497

Issue

1

Pagination

L50 - L55

Publisher

Oxford University Press (OUP) for Royal Astronomical Society

issn

0035-8711

eissn

1365-2966

Acceptance date

2020-06-08

Copyright date

2020

Available date

2022-07-12

Language

English

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