Newly Discovered Cataclysmic Variable Shocks Scientists

Astronomers from the Special Astrophysical Observatory (SAO) in Russia, along with other researchers, have announced the discovery of a new cataclysmic variable system, named SRGe J194401.8+284452, or simply J1944. Located about 1,350 light years away from Earth, this system was detailed in a research paper released on August 26 on the pre-print server arXiv.

Cataclysmic variables are binary star systems featuring a white dwarf that accretes matter from a companion normal star. These systems are known for their unpredictable brightness changes, where they can suddenly brighten significantly before dimming again.

CVs can be observed in various environments, such as the core of the Milky Way, our solar neighborhood, and within both open and globular star clusters. A specific type of CV, called polars, is distinguished by a strong magnetic field present in their white dwarfs.

J1944 was first identified in 2008 as an X-ray source, initially suspected to be a pulsar wind nebula (PWN). However, subsequent observations have shown it is too dim to be a PWN, leaving its true nature uncertain.

To better understand J1944, a team led by Alexander Kolbin from SAO performed extensive multi-wavelength observations. They discovered that J1944 experiences rapid fluctuations between high and low brightness levels in both optical and X-ray ranges, with periods of stability lasting several months or even years.

Optical observations indicated that J1944 does not display flare activity but instead shows consistent variations in brightness with a cycle of approximately eight minutes. During periods of high brightness, the optical spectrum is predominantly influenced by disk emission.

The researchers concluded that J1944 is a cataclysmic variable with a white dwarf and a late-type star that contributes material. The eight-minute cycle rules out the possibility of it being a binary system with a neutron star, which would be expected to show millisecond pulsar characteristics.

Their findings suggest that J1944 is a tightly bound binary system with an orbital period of around 89 minutes. The white dwarf's mass is estimated between 0.3 and 0.9 times that of the Sun, while the donor star's mass is likely less than 0.08 solar masses. The researchers identified J1944 as an intermediate polar, notable for having one of the shortest orbital periods within this subclass of CVs.