A team of ESO astronomers has detected a giant ‘flickering’ star towards the center of our galaxy, more than 25,000 light-years away. The star, named VVV-WIT-08 and about 100 times larger than our Sun, was observed using the VISTA telescope (visible and infrared exploration telescope) located at the Paranal Observatory in Chile. According to the researchers, the star’s brightness decreased by a factor of 30, or 97%, meaning it almost completely disappeared from the sky, before returning to normal. A star that blinks?
While it is true that many stars change in brightness because they pulse or are dwarfed by another star, astronomers say that it is “exceptionally rare” for a star to become dimmer over a period of several months and then brighter again. Also, it disappears after something “dark, big and long”, and they are not sure what it is exactly.
This ‘flicker’ takes place every few decades , something that usually indicates some type of transit; that something has happened in front of him. If it happens regularly, something is probably orbiting it. What would it be in this case? This invisible companion could be a planet or another star surrounded by a vast opaque disk of dust causing the eclipsing event and completely covering the star as it passes in front of us.
“It is surprising that we have just observed a dark, large and elongated object passing between us and the distant star and we can only speculate what its origin is,” Sergey Koposov of the University of Edinburgh and a co-author of the study said in a statement.
Since the star is located in a dense region of the Milky Way, the researchers considered whether some unknown dark object could have simply drifted in front of the giant star by chance. However , computer simulations showed that there would have to be an incredibly large number of dark bodies floating around the galaxy for this scenario to be plausible.
Astronomers believe the star could belong to a new class of stars: giant beasts more than 100 times the Sun that are dwarfed by a mysterious orbiting body once every few decades. This is a rather peculiar case because although other stars have exhibited similar light falls, none have been as deep.
“Occasionally, we find variable stars that don’t fit into any set category, which we call ‘what is this?’ U ‘WIT’. We really don’t know what these blinking giants look like. It is exciting to see such discoveries after so many years of planning and data collection “ , clarifies Philip Lucas of the University of Hertfordshire and co-author of the work.” There is certainly more to find, but the challenge now is to discover what are the hidden companions and how they became surrounded by disks, despite orbiting so far from the giant star, “continues Leigh Smith, an astronomer at the University of Cambridge Institute of Astronomy and leader of the work.” By doing so, we could learn something new about how this type of systems “.
The team also found, among the VISTA data, two more of these peculiar giant stars, hence they believe they may represent a new class of ‘blinking giants’ stars that should be investigated.
Referencia: Leigh C. Smith et al. 2021. VVV-WIT-08: the giant star that blinked. Monthly Notices of the Royal Astronomical Society (2021). DOI: 10.1093/mnras/stab1211
