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Astronomers may have solved the mystery behind an unusually bright star.
University of Washington doctoral student Anastasios Tzanidakis and Research Assistant Professor of Astronomy James Davenport were looking for “stars behaving strangely” when they received an alert about a possible stellar anomaly from the Gaia spacecraft.
The space observatory, launched by the European Space Agency in 2013, is on a mission to create the most accurate 3D map of the Milky Way to date. Astronomers focused on Gaia17bpp, a star that gradually increased in brightness over a period of 2.5 years.
The results of their investigation and analysis of the star were published Tuesday in the 241st Meeting of the American Astronomical Society In Seattle, he revealed that the star himself hasn’t changed. Instead, the star has an alien companion responsible for what researchers estimate to be “seven years of the light bomb.”
“We believe this star is part of an exceptionally rare type of binary system, between a large, older bloated star – Gaia17bpp – and a young companion star surrounded by an extended disk of dusty material,” Tzanidakis said in a statement.
“Based on our analysis, these two stars orbit each other over a very long period of time — up to 1,000 years. So catching this bright star obscured by its dusty companion is a once-in-a-lifetime opportunity.”
The Gaia spacecraft began observing the star in 2014. The researchers combined all Gaia observations of the star and tracked other observations of Gaia17bpp taken by the Pan-STARRS1 telescope in Hawaii, the NASA WISE/NEOWISE mission and the Zwicky Transit Facility in California back in 2010.
By comparing images of Gaia17bpp, the researchers determined that the star’s brightness is dimmed by 4.5 orders of magnitude, or 45,000 times. It stayed that way for 7 years, from 2012 to 2019.
Astronomers happened to notice the star at the end of an eclipse that had been going on for years.
No other stars located near Gaia17bpp have shown dimming of this magnitude. The team also searched a digital catalog of Harvard astrophotographic plates dating back to the 1950s.
“Over the 66-year history of observations, we have not found any other signs of significant dimming in this star,” Tzanidakis said.
So what happened to Gaia17bpp? “Based on the data currently available, this star appears to have a slow-moving companion surrounded by a large disk of material,” Tzanidakis said. “If this material existed in the solar system, it would extend from the sun to Earth’s orbit, or beyond.”
Although Gaia17bpp is unique in having such a long eclipse, it is not the only binary star system to display dimming behaviour. Also of interest to astronomers is Epsilon Origai, a star that is eclipsed about two out of every 27 years by a large companion — but the companion’s actual identity remains a mystery.
The giant star Betelgeuse also caught the attention of astronomers when it died down dramatically in late 2019, prompting speculation that it would explode in a supernova. Instead, it is The star was having a dusty tantrum.
For Gaia17bpp, the dust-making stellar companion could be a small, dead star called a white dwarf, but they’re not entirely sure what could be contributing to the debris disk around it.
Whatever the identity of its companion, Gaia17bpp and its mysterious cosmic partner are so far apart that another eclipse is centuries away.
“This was a serendipitous discovery,” Tzanidakis said. If we had been on vacation for a few years, we would have missed it. He also suggests that these types of pairings may be more common. If that is the case, we need to devise theories about how this kind of pairing arose. It is certainly an odd case, but it may be more common than anyone would appreciate.”