Since the early 2000s, large-scale astronomical observations of the sky have begun, providing precise images of the speed and direction of stars’ movement. We have come to see the universe around us in terms of mechanics. The first stars from our galaxy were discovered about 20 years ago. It turns out that there are quite a few runaway stars, and most of them are massive. There are two main theories about how runaway stars form, and their speed and direction of motion do not match the merry-go-round of other matter in galaxies. One theory is that a supernova explosion in a binary star system gives the star its momentum, which then breaks free from the gravitational constraints of its partner and flies off into the distance. The second theory describes dynamic ejection when a pair of stars in a close binary system passes through a third massive object, such as a black hole. A hole tears one of the stars and gives her a second impulse to move.
Scientists can only debate which scenario prevails. But the same European astronomical telescope “Gaia” collected data on millions of stars in our galaxy, so a group of astronomers decided to find out the most likely of them. The researchers used his two catalogs of O-type and B-type stars and the Gaia data. These types of stars, including the Be subtype, are massive, young, and hot and frequently occur in groups, usually in the form of binary systems. Finally, the most common runaway stars discovered are massive stars. Comparison of the Gaia data with the GOSC and BeSS catalogs reveals the presence of 417 O-type stars and 1335 Be-type stars in all sources. This allowed us to calculate 106 runaway O-type stars and 69 similar Be-type stars. The proportion of runaway O-type stars (25.4%) was found to be much higher than that of B- and Be-type stars (5.2%). In other words, more massive O-type stars escape more often than B-type stars and generally move faster. Incidentally, thanks to the Gaia data, the study discovered a previously unknown runaway star : There should be 42 stars below the O-type stars and 47 below the B-type stars. Most of them will remain in our galaxy, but about a dozen have become so fast that they will eventually leave.
Based on the data obtained, the scientists concluded that dynamic ejection scenarios occur much more frequently and are widespread in the universe than the appearance of runaway stars in binary star systems with supernova formation. I did. In order for the heaviest stars to start flying at supergalactic speeds in all directions, instead of moving in a circular motion around the galaxy’s disk, they would need to be supplied with more energy than could be obtained by destroying a binary star. there is. A star system caused by a supernova explosion. And this happens much more often than previously thought. According to the most conservative estimates, there are about 10 million rogue stars in our galaxy alone.
source: https://www.aanda.org/component/article?access=doi&doi=10.1051/0004-6361/202346613