Guo Shoujing telescope discovers "mysterious planet"

Artistic imagination of a cataclysmic variable star. Image credit: Mark A. Garlick

Recently, the reporter learned from the National Astronomical Observatory of the Chinese Academy of Sciences that an international research team composed of astronomers from the United States, Germany and China used the data of the Guo Shoujing Telescope (LAMOST) to discover a "mysterious planet" - a rare new type of catapult variable star that has never been observed, named LAMOST J0140355+ 392651. This study provides substantial evidence for further understanding the formation and evolutionary history of cataclysmic variable stars. The paper was published in the Monthly Journal of the Royal Astronomical Society.

A cataclysmic variable star is a type of celestial body with a dual identity, which is both a binary and a variable star. Most of the main stars of the radical variable are white dwarfs , and the companions are late-type main sequence stars. "Gluttonous" host stars continuously aspirate and swallow material from more massive companion stars and form accretion disks around the host star.

In recent years, LAMOST's large-scale spectral survey project has provided an excellent resource for searching for cataclysmic variable stars using spectral signatures. Based on lamost's tens of millions of spectral databases, researchers have discovered a total of 245 cataclysmic variable stars.

According to researchers, for the newly discovered "mysterious planet", there have been theories that predicted the existence of such stars, but they have never been observed. An international team of researchers led by Dr. Kareem El-Badry of Harvard University discovered it using LAMOST data. This could be an unusually cataclysmic variable star.

It is understood that in past studies, for cataclysmic variable stars with an orbital period of less than 6 hours, astronomers usually calculate the temperature, mass and other properties of their companions based on the orbital period of the cataclysmic variable, and have formed a series of empirical laws that have become the "baton" for the study of such cataclysmic variable stars. Observational data show that the orbital period of this "mysterious planet" is 3.81 hours, but its temperature, mass and the relationship between the corresponding binary orbital period are completely inconsistent with the traditional "baton".

In order to confirm this new discovery, the researchers further analyzed the data of LAMOST's multiple observations of the object at different nights, and used the Shane telescope of the Using The Lick Observatory and the ESA Gaia satellite for follow-up observations, and finally found that the new object is a rare cataclysmic variable star in the transition stage of evolution. Its companion star is not a main sequence star, but an expanding star's helium nucleus. At the same time, based on the binary star evolution model, researchers speculate that when the companion star of the radical variable star began to transfer mass to the white dwarf host star, it had already ended the main sequence stage and underwent a significant evolutionary process.

Experts believe that the observation of rare cataclysmic variable stars fully demonstrates LAMOST's advantages in searching for rare objects.

(Reporter Gan Xiao)

Source: China Science Daily