The fastest stars of the Milky Way are newcomers from other galaxies
Ken Shen of the University of California was so excited he couldn’t sleep. That day, the European Space Agency published data on the motion of more than 1.3 billion stars in the Milky Way. The information was collected thanks to the work of the Gaia probe. They are quite a treat for astrophysicists and astronomers from around the world, who from that day on began the race for new cosmic discoveries. And they have not disappointed. After just a few weeks, some very important new findings have been made about our galaxy.
Shen and its compositeo³ to begin with, they looked at data on the fastest stars in the galaxy. By determining their trajectories, the researchers were able to go back in time and see what made them move at such high speeds now. Overall, astronomers from the roThe scientists of other universities have discovered dozens of stars thatore are not bound by the Milky Way’s gravity and may come from other galaxies.
Astronomers can easily measure the speed of a star moving toward or away from Earth using the Doppler phenomenon. The most difficult part was measuring the lateral movement across the sky, which is necessary to determine the actual speed of the star and the trajectory of its flight. Until now, such studies have been slow and tedious. However, everything has changed since the launch of the Gaia mission. The telescope has begun measuring minute changes in the apparent positions of stars. As a result, we know the lateral motion for 1.3 billion stars and also closer to the speed of 7 millionoin the brightest objectoin the sky.
What makes stars rush so?
Last week, a compositeoShen’s team discovered three white dwarfs – Dying remnants of Sun-like stars – speeding through our galaxy at speeds of thousands of kilometersow per second. Perhaps their behavior is the result of a white dwarf explosion. Shen hoped the fast stars would help test the theory.
Scientists explain that thermonuclear explosions occur when a white dwarf sucks material from a companion star until it is heavy enough for atomic fusion to occur in its nucleusoin coal. There are two scenarios for similar cosmic events. In one, a white dwarf steals material from an ordinary star. In the second a pair of white dwarfsow rotate together, increasing in speed until, just before fusion, one of them acquires enough material to explode, and the other is released into space.
Thanks to data obtained from the Gaia telescope, the anastomosingoShen checked the selected stars with ground-based telescopesoin California, the Canary Islands and South Africa. Within 24 hours, the scientists thus discovered theob three white dwarfs. One of them is moving at a speed of 2,400 kilometersoIn per second, making it one of the fastest objectoin the galaxy.
Syndromeoł checked roalso the paths taken by these stars over the past 100,000 years. One of the objectow returns to a nearby supernova remnant, a cloud of debris from a previous explosion, which may support Shen’s theory of why stars move so fast.
Stars from other galaxies
Other groups of scientistsow rohave also addressed the subject. One has found more than two dozen fast-moving stars. Someore likely to have been ejected into space by the gravitational force of a black hole located in the center of our galaxy. Another discovery involved a star thatora most likely flew into the Milky Way from a neighboring galaxy: The Large Magellanic Cloud.
Another teamo³ led by Tommaso Marchetti of the University of Leiden in the Netherlands has searched Gaia’s data and discovered two stars thatore not bound by the gravitational interaction of the black hole located at the center of the Milky Way, but are probably now returning to the Large Magellanic Cloud.
Another star, called HVS3, was discovered in 2005, suspiciously close to the Large Magellanic Cloud, in the halo of the Milky Way. Data from the Gaia probe show that HVS3 comes from the heart of our neighboring galaxy, the team claimsoł led by astronomer Denis Erkal of the University of Surrey in the UK. The star is moving so fast that it was probably knocked out by the gravity of a central black hole in a neighboring galaxy. The discovery of more similar objectsow would give a better idea of the size of black holes found in other galaxies.
What is Gaia?
Thanks to data collected by the Gaia space observatory, astronomers have created the richest catalog of stars to date, containing precise measurements of nearly 1.3 billion of them and revealing previously unseen details of the starsocalves of our Galaxy. This is the most precise map of the Milky Way ever produced.
The long-awaited star catalog was the result of the Gaia probe, whichora has been in orbit since late 2013. The new data revealed on April 25 of this year include the positions, distance ratios and motions, brightness and colors of more than a billion stars, as well as precise measurements of asteroids in our solar system and stars and other objectoin outside our own Galaxy. Shortly after they were made public, astronomers from around the world literally „they threw up” They are constantly processing data and coming up with new conclusions. One such scientistow was Ken Shen. He got up from the excitement long before the map of the Milky Way was published.
Preliminary analysis of the data reveals the finest detailos about the stellar population of the Milky Way and how stars move. This is essential information for studying the formation and evolution of our Galaxy.