Astronomers have discovered a brand-new magnetic catastrophic variable by examining data from the Transiting Exoplanet Survey Satellite (TESS) and Spektr-RG (SRG) satellite. The SRGE J075818-612027 new item most likely belongs to the polar subtype. The discovery was detailed in a manuscript that was posted on the pre-print service arXiv on February 26.
In binary star systems called cataclysmic variables (CVs), a white dwarf is accreting matter from a partner normal star. They erratically get significantly brighter before returning to a quiet condition. Polars are a subclass of cataclysmic variables that are distinguishable from other CVs by having white dwarfs with extremely potent magnetic fields.
Recently, a group of astronomers lead by Samet Ok of the Leibniz Institute for Astrophysics Potsdam (AIP) in Germany used TESS and the eROSITA X-ray telescope of Spektr-RG to study observational data of the field of the open cluster NGC 2516. They consequently unintentionally came into a fresh Resume.
In their work, the researchers reported the accidental finding of SRGE J075818-612027, a deep stream-eclipsing magnetic cataclysmic variable that was discovered in SRG/eROSITA CalPV studies of the open cluster NGC 2516 as an unrelated X-ray source.
During the eROSITA Calibration and Performance Verification (CalPV) phase of observations, SRGE J075818-612027 was recognised as one of the field’s brightest X-ray objects. It was discovered to be an accretion-driven background object between 4,000 and 13,500 light-years away.
Further research of SRGE J075818-variability 612027’s revealed that it has a period of roughly 106 minutes. The hydrogen Balmer emission of this variable can be seen superimposed on a flat or slightly blue continuum in the low-resolution identification spectrum. These results corroborated the magnetic catastrophic nature of SRGE J075818-612027.
The X-ray spectra of SRGE J075818-612027, according to the study, is consistent with polar-typical single temperature thermal plasma emission at about 10 keV. The object also displays significant magnitude changes over extended periods at optical and X-ray wavelengths. Such actions could be seen as high and low states, which would reinforce the idea that they are polar.
The finding of SRGE J075818-612027, the authors of the report concluded, highlights the high sensitivity of the eROSITA telescope. Due to this and eROSITA’s improved scanning method, they were able to find SRGE J075818-612027 despite its great distance and fluctuating status between high and low. The researchers anticipate finding many more magnetic CVs with the use of this device.
“By conducting systematic follow-up observations of all point-like X-ray sources identified by the eRASS [eROSITA All-Sky Survey], it is possible that the eROSITA will discover a great number additional magnetic CVs. Because the duty of the polars may be as low as 50%, there is a particularly good possibility to locate those that escaped identification in the ROSAT all-sky survey while being in a low state at the time “Finally, the astronomers said.