We present a detailed optical and X-ray study of the 2013 outburst of the Small Magellanic Cloud Be/X-ray binary SXP 7.92 , as well as an overview of the last 18 years of observations from OGLE , RXTE , Chandra and XMM-Newton .
We revise the position of this source to RA ( J2000 ) =00:57:58.4 , Dec ( J2000 ) =-72:22:29.5 with a 1 \sigma uncertainty of 1.5 \arcsec , correcting the previously reported position by \citet Coe2009 by more than 20 arcminutes .
We identify and spectrally classify the correct counterpart as a B1Ve star .
The optical spectrum is distinguished by an uncharacteristically deep narrow Balmer series , with the H { \alpha } line in particular having a distinctive shell profile , i.e .
a deep absorption core embedded in an emission line .
We interpret this as evidence that we are viewing the system edge on and are seeing self obscuration of the circumstellar disc .
We derive an optical period for the system of 40.0 \pm 0.3 days , which we interpret as the orbital period , and present several mechanisms to describe the X-ray/Optical behaviour in the recent outburst , in particular the ‘ ‘ flares ’ ’ and ‘ ‘ dips ’ ’ seen in the optical light curve , including a transient accretion disc and an elongated precessing disc .