Six stars, spotted by the Gaia telescope in the Milky Way, broke all speed records: the two fastest reached 1,694 km/s, and 2,285 km/s. They would have been propelled by explosions of particular stars. A spectacular proof of the great disorder that reigns in the cosmos, behind his fearless appearance.
Hervé Poirier, editor-in-chief of the science magazine Epsiloontells us today about a strange record: we have seen the fastest star in the entire galaxy.
franceinfo: Super fast stars escape from galaxies?
Herve Poirier: The Gaia telescope developed by the European Space Agency has just flashed it: J1235 – that’s its name – flies at 8,226,000 kilometers per hour. We had never seen such a fast object in our galaxy. By comparison, our star, the Sun, orbits the center of the Milky Way at 850,000 km/h. There, it’s 10 times faster! And the astronomers have calculated that the speed of this star, originally, must have been even greater: up to 9 million km/h!
How is it possible for a star to go so fast?
Normally, only stars that orbit very close to a black hole can reach these speeds, but they are trapped by the black hole and won’t get out. While there, our bolide is a star which spins freely in hyperspeed through the galaxy. Given its temperature and composition, scientists have a somewhat complicated, but plausible scenario to explain what happened.
J1235 was originally to be in a couple with another star. This companion would have sucked a good part of its helium, and would have partly exploded, but would then have continued to suck material from its neighbor, until its temperature and its pressure in its heart reached a critical level, causing the fusion of its carbon and its hydrogen, and a second explosion, much more violent. The shock wave of this second explosion would then have propelled its companion through the galaxy, 4000 times faster than a rifle bullet.
What will become of this galactic racing car?
In view of its speed, its destiny is all mapped out: J1235 will escape from the Milky Way, and become a star wandering through space, until, why not, integrating other galaxies. Astronomers estimate that a star is thus ejected from the Milky Way every thousand years. Since the birth of our galaxy (about 10 billion years ago), that would still make 10 million wandering stars. 10 million intergalactic wanderers.
We remember the discovery, a few years ago, of Oumuama, this large pebble which had escaped from its system to come and graze our Sun, like an interstellar wanderer. J1235 completes the table. And illustrates the great disorder that reigns at all scales in the cosmos, behind its calm, impassive appearance. The cosmos is filled with wandering speedsters.