Astronomers have spotted stars moving at high speed between galaxies

Using the latest data set from the Gaia satellite, astronomers have spotted more than a dozen stars hurtling toward the Milky Way at high speeds. Researchers say there could be many more such stars.

Syndromeó³ astronomerów from Leiden University have used the most detailedólar map of the galaxy to look for stars ejected from it. Instead, the researchers observed more than a dozen stars speeding in the opposite direction, that is, toward the Milky Way.

At the end of April, scientists working on the Gaia mission published the richest catalog of stars to date, containing precise measurements of nearly 1.3 billion of them. The data includes the positions, distance ratios and movements, brightness and colors of more than a billion stars, as well as precise measurements of asteroids in our solar system and stars and other objectóin beyond our own galaxy. For more on the data from the Gaia mission, see New catalog of stars with precise measurements of more than a billion of them. Importantly, the data set includes radial velocities of stars (for 7 millionów of them), that is, information about how fast they are moving toward or away from us.

– Spośród seven millionóin stars with full velocity measurements included in the Gaia data, we found two dozen thatóre can travelótravel fast enough to eventually escape from the Milky Way – said Elena Maria Rossi, one of the authors of the new study. – But instead of flying away from the galactic center, most of the stars moving at high speeds które we have noticed, it seems to be heading in the opposite direction – added Tommaso Marchetti, whoóryóis also one of the współautoróin a publication.

It is possible that the observed stars podrófeeding through interstellar space come from the Large Magellanic Cloud, a relatively small galaxy orbiting around theół of the Milky Way. Although they can równo well come from other, farther-away galaxies. Regardless of their place of origin, their study can provide new information about the past of galaxies, with któwhere they come from, as well as on the very nature of stars.

– Stars can be accelerated to high speeds when they interact with a supermassive black hole. The presence of these stars could be a sign of such black holes in nearby galaxies. But these stars could równ to have once been part of the sub systemójnego and were ejected toward the Milky Way when their companion star exploded as a supernova. Either way, studying them may tell us more about such processes in nearby galaxies – explained Rossi.

Another explanation for the origin of subróChewing through space of superfast stars is the halo of our galaxy. These stars may have been accelerated and pushed inward through interactions with one of the dwarf galaxies orbiting the Milky Way. Information about the age and composition of stars can pomóc astronomers to explain their origin.

The stars are orbiting around theól of our galaxy at speeds of hundreds of kilometersów per second. The fastest class of these stars are the so-called. hypervelocity stars (hypervelocity stars), które begin their lives near the galactic center and are then ejected toward the edge of the Milky Way through interactions with a black hole at the center of the galaxy.

The Milky Way alone contains about 100 billionów stars. Most of them are located near a supermassive black hole at the galactic center – in a dense region called the central galactic thickening. The remaining stars are scattered in a huge, spherical halo, whichóre surrounds the galaxy.

New data from future Gaia releases will help to better understand the nature and origin of these stars. Syndromeół also intends to use ground-based telescopesów to learn more about them.

SourceóSource: Royal Astronomical Society, photo. ESA / Marchetti et al. 2018 / NASA / ESA / Hubble / CC BY-SA 3.0 IGO