Optical surveys , such as the MACHO project , often uncover variable stars whose classification requires followup observations by other instruments .
We performed X-ray spectroscopy and photometry of the unusual variable star MACHO 311.37557.169 with XMM-Newton in April 2018 , supplemented by archival X-ray and optical spectrographic data .
The star has a bolometric X-ray luminosity of about 1 \times 10 ^ { 32 } erg s ^ { -1 } cm ^ { -2 } and a heavily absorbed two-temperature plasma spectrum .
The shape of its light curve , its overall brightness , its X-ray spectrum , and the emission lines in its optical spectrum suggest that it is most likely a VY Scl cataclysmic variable .