Astronomers discover peculiar cataclysmic variable
(ORDO NEWS) — Using the NASA Transiting Exoplanet Survey Satellite (TESS), astronomers have detected a highly asynchronous short-period magnetic cataclysmic peculiar variable SDSS J134441.83+204408.3 (or J1344 for short).
Cataclysmic Variables (CVs) are binary star systems in which a primordial white dwarf accretes material from an ordinary companion star.
Stars brighten unevenly and then go back to rest. Polar stars are a subclass of cataclysmic variables, distinguished from other CVs by the presence of a very strong magnetic field in white dwarfs.
When white dwarfs in CV have field strengths greater than 10 MHz, their rotation frequency is expected to be synchronized with the frequency of the dual orbit due to the radial dependence of the magnetic field.
However, a team of astronomers report the discovery of a cataclysmic variable that falls short of these expectations and therefore challenges existing theoretical models.
“What makes J1344 remarkable is the combination of three things: its moderately high magnetic field strength, short orbital period, and high degree of asynchrony.
Together, these properties paint an interesting picture of the magnetic field,” the researchers explained.
J1344 is about 1950 light years away. New TESS data show that J1344 has a high surface field strength of around 56 MHz.
Its orbital period is estimated to be approximately 114 minutes, indicating a relatively short distance between orbits.
New observations have shown that this system exhibits asynchronous rotation, since its spin-to-orbit ratio is at 0.893, which is unusual for magnetic CVs.
The astronomers stressed that the highly asynchronous rotation in J1344 is a problem for theoretical studies of the evolution of the rotation period.
They noted that this proved that surface field strengths above 10 MHz and short binary separation did not guarantee fast system synchronization.
Overall, the researchers suggest that some combination of a weakly magnetic secondary star or an unusually massive white dwarf is the most plausible hypothesis that could explain J1344’s inability to achieve synchronous rotation.
According to them, the J1344 case suggests that some of the other CVs classified as synchronous polars need to be reconsidered as they may be asynchronous systems.
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