The Orbital Solution and Spectral Classification of the High-Mass X-Ray Binary IGR J01054-7253 in the Small Magellanic Cloud

Abstract

We present X-ray and optical data on the Be/X-ray binary (BeXRB) pulsar IGR J01054-7253 = SXP11.5 in the Small Magellanic Cloud (SMC). Rossi X-ray Timing Explorer (RXTE) observations of this source in a large X-ray outburst reveal an 11.483 +/- 0.002s pulse period and show both the accretion driven spin-up of the neutron star and the motion of the neutron star around the companion through Doppler shifting of the spin period. Model fits to these data suggest an orbital period of 36.3 +/- 0.4d and Pdot of (4.7 +/- 0.3) x 10^{-10} ss^{-1}. We present an orbital solution for this system, making it one of the best described BeXRB systems in the SMC. The observed pulse period, spin-up and X-ray luminosity of SXP11.5 in this outburst are found to agree with the predictions of neutron star accretion theory. Timing analysis of the long-term optical light curve reveals a periodicity of 36.70 +/- 0.03d, in agreement with the orbital period found from the model fit to the X-ray data. Using blue-end spectroscopic observations we determine the spectral type of the counterpart to be O9.5-B0 IV-V. This luminosity class is supported by the observed V-band magnitude. Using optical and near-infrared photometry and spectroscopy, we study the circumstellar environment of the counterpart in the months after the X-ray outburst.

12 pages, 13 figures and 3 tables. This paper has been accepted for publication in MNRAS

References in corpus (9)

• RoboNet-II: Follow-up observations of microlensing events with a robotic network of telescopes
• On the Apparent Lack of Be X-ray Binaries with Black Holes
• A Long Look at the Be/X-Ray Binaries of the Small Magellanic Cloud
• Optical spectroscopy of 20 Be/X-ray Binaries in the Small Magellanic Cloud
• Optical and X-ray variability of two Small Magellanic Cloud X-ray binary pulsars - SXP46.6 and SXP6.85
• Exploring accretion theory with X-ray binaries in the SMC
• High mass X-ray binary SXP18.3 undergoes the longest Type II outburst ever seen in the Small Magellanic Cloud
• INTEGRAL deep observations of the Small Magellanic Cloud
• Be/X-ray binary SXP6.85 undergoes large Type II outburst in the Small Magellanic Cloud

Cited by in corpus (8)

• Spin period change and the magnetic fields of neutron stars in Be X-ray binaries in the Small Magellanic Cloud
• Advances in Understanding High-Mass X-ray Binaries with INTEGRAL and Future Directions
• INTEGRAL/IBIS 17-yr hard X-ray all-sky survey
• SXP 5.05 = IGR J00569-7226 : using X-rays to explore the structure of a Be stars circumstellar disk
• XMM-Newton observation of the highly magnetised accreting pulsar Swift J045106.8-694803: Evidence of a hot thermal excess
• Discovery of SXP265, a Be/X-ray binary pulsar in the Wing of the Small Magellanic Cloud
• Simulating the X-ray luminosity of Be X-ray binaries: the case for black holes versus neutron stars
• RXJ0123.4-7321, a Be/X-ray binary in the wing of the SMC