Grigoriev 1: New eclipsing variable star discovered in the Pegasus constellation
Tomasz Nowakowski
astronomy writer
Sadie Harley
scientific editor
Robert Egan
associate editor
Astronomers from the Center of Astronomical and Space Education in Moscow report the discovery of a new star, which turned out to be an eclipsing variable binary. The finding of the new star, which received designation Grigoriev 1, was reported in a research paper July 1 on the arXiv pre-print server.
Studies of variable stars could offer important hints into aspects of stellar structure and evolution. Such stars could also help us better understand the distance scale of the universe.
The Center of Astronomical and Space Education in Moscow has its own project dedicated to the search for variable stars and supernovae. The program, which started in 2021, has resulted in the detection of 120 variables, and the newest discovery was announced in a recent paper. The new variable star was found in the constellation Pegasus and named Grigoriev 1 after one of the discoverers—V. S. Grigoriev.
"The star was found through the systematic checking of ultraviolet sources of the GALEX space observatory in the Pegasus constellation," the researchers wrote in the paper.
According to the study, Grigoriev 1 is a binary system with an orbital period of approximately 6.6 days. The observations show that Grigoriev 1 exhibits eclipses lasting about 1.5 hours, with the partial phases at least 30 times shorter. The depth of eclipses is different in various bands of visible light, as in the g filter the brightness falls by 2 mag (6.3 times), while in the r filter, it falls by 1.4 mag (3.6 times).
Based on these findings, the astronomers conclude the size of the eclipsing component in Grigoriev 1 is about 30 times larger and about five times brighter than the star being eclipsed. Therefore, they assume that the eclipsing object is cooler than the eclipsed one.
Further investigation of Grigoriev 1 led the team to more precise estimations of the system's physical parameters. They found that the cold object has a radius of approximately 323,500 kilometers, while the radius of its companion is estimated to be some 10,000 kilometers. The orbital radius of the binary was measured to be 0.069 AU.
All in all, the collected data indicates that Grigoriev 1 is a detached eclipsing binary system of Algol type with a white dwarf seen edge-on. The so-called Algol-type binaries are a class of eclipsing binary stars related to the prototype member of this class, known as Beta Persei or Algol. In these systems, the less-massive component transfers mass to the more massive object due to filling its Roche lobe, causing mass and angular momentum loss.
Summing up the results, the authors of the paper note that Grigoriev 1 has the second longest orbital period among the known Algol-type binaries and that its hot component is most likely at the transition stage from one type of object to another.
"On the 'color-luminosity' diagram it occupies the intermediate position between hot subdwarfs and white dwarfs, which makes it even more interesting and worth studying at professional telescopes," the scientists conclude.
Written for you by our author , edited by , and fact-checked and reviewed by —this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a (especially monthly). You'll get an ad-free account as a thank-you.
More information: V. S. Grigoriev et al, Discovery and study of the eclipsing variable star Grigoriev 1, arXiv (2025).
Journal information: arXiv
© 2025 Science X Network
