The discovery and study of the optical counterparts of the transient X-ray pulsars RXJ0052.1-7319 and XTEJ0111.2-7317 in the SMC

Abstract

We report on the discovery and confirmation of the optical counterparts of the two transient X-ray pulsars, RXJ0052.1-7319 and XTEJ0111.2-7317. In the narrow (~3" radius) X-ray error circle of RXJ0052.1-7319 we found a V=14.6 (B-V=0.1) 09.5IIIe (a classification as a B0Ve star is also possible, since the luminosity class depends on the uncertainty on the adopted reddening). Medium resolution spectra for this object show Balmer lines in emission with an equivalent width of Halpha=-12/-16A. In the X-ray error box of XTEJ0111.2-7317 we found a relatively bright object (V=15.4, B-V=0.06) which has been classified as a B0.5-B1Ve star and that was later confirmed by Coe et al. (2000) as the most plausible counterpart for XTEJ0111.2-7317. Also in this case we easily detect Balmer emission lines with an Halpha equivalent width of about -21A. There is also evidence for the presence of a surrounding nebula, possibly a supernova remnant. A further bright B0Ve star was found just outside the X-ray error circle of XTEJ0111.2-7317. We discuss the implication of these results in the light of the current knowledge of Be/X-ray binary systems in the Magellanic Clouds and within our Galaxy.

Accepted by A&A. 8 pages, 8 figures

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Cited by in corpus (14)

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• Be/X-ray binaries and candidates: catalogue
• X-ray observations of Be/X-ray binaries in the SMC
• Spectral distribution of Be/X-ray binaries in the Small Magellanic Cloud
• Very Long-term Optical Variability of High Mass X-ray Binaries in the SMC
• Detection of a cyclotron line in SXP 15.3 during its 2017 outburst
• Quasi periodic oscillations in XTE J0111.2--7317, highest frequency among the HMXB pulsars
• Orbital Period Determinations for Four SMC Be/X-ray Binaries
• An Investigation of Be/X-ray Pulsars with OGLE-III Data
• XTE J0111.2-7317 : a nebula-embedded X-ray binary in the SMC
• Disentangling the neighbouring pulsars SXP 15.3 and SXP 305
• Discovery of a 0.8-mHz quasi-periodic oscillation in the transient X-ray pulsar SXP31.0 and associated timing transitions
• Super-critical accretion of BeXRB SXP 15.3