Thanks to the AAVSO (American Association of Variable Star Observers ) network and the DASCH ( Digital Access to a Sky Century @ Harvard ) program, a team of astronomers from Vanderbilt and Harvard universities (USA) has discovered a binary system of stars (christened TYC 2505-672-1) about 10,000 light years from Earth where the largest stellar eclipse ever known occurs : every 69 years, the sun disappears almost completely because of another star for three and a half years, more than 1,200 days.
But this finding holds another record: “It is the longest duration of a stellar eclipse and the longest orbit for an eclipsing binary that has been found so far, ” says Joey Rodríguez, leader of the study.
This unknown binary star system has superseded with an eclipse every 69 years and for more than 1,000 days, the previous record set by Almaaz , a giant star located about 2,200 light-years from Earth, eclipsed by another – probably a little larger. – every 27 years and for periods between 640 and 730 days.
“Here we have a unique opportunity to study a phenomenon that reproduces itself over many decades and provides a window into the types of environments around stars that could represent monoliths of planetary construction at the end of the life of a star system,” explains Keivan Stassun, co-author of the work.
According to the researchers, the star system appears to be composed of a pair of red giant stars; one of them seems to have been stripped of its outer layers until it remains in a small nucleus surrounded by a large amount of material grouped in an extended disk that is what causes the eclipse to be so durable: it must be large enough to block a star for months.
The study has been published in The Astronomical Journal.
Image credit: Teaford / Vanderbilt University
