Astronomers have detected in the stellar halo that represents the outer boundary of the Milky Way, a cluster of stars more distant from Earth than any known within our own galaxy – about halfway to the neighboring galaxy.
Researchers said that these 208 stars live in the most remote areas of the world GalaxyThe corona is a spherical stellar cloud dominated by a mysterious invisible substance called dark matter, known only through its gravitational influence. The most distant of them is 1.08 million light years earth, A light year is the distance that light travels in one year, 5.9 trillion miles (9.5 trillion km).
These Stars, observed using the Canada–France–Hawaii Telescope on Mount Mauna Kea in Hawaii, is part of a class of stars called RR Lyrae that are relatively low-mass and typically have low abundances of elements heavier than hydrogen and helium. . The most distant mass appears to be about 70 percent of our mass Sunday, No other star in the Milky Way has been measured more confidently than these.
Stars that populate the outskirts of the galactic halo may be viewed as stellar orphans, probably originating at a smaller size. galaxies Which later collided with the larger Milky Way.
“Our explanation of the origin of these distant stars is that they most likely originated in the halo of dwarf galaxies and star clusters that were later merged — or more directly, cannibalized — by the Milky Way. ,” said Yuting Feng, an astronomy doctoral student at the University of California, Santa Cruz, who led the study, presented this week at an American Astronomical Society meeting in Seattle.
“Their host galaxies have been gravitationally crushed and digested, but these stars are left behind at such great distances as the debris of the merger event,” Feng said.
The Milky Way has evolved over time through such cataclysms.
“The larger galaxy grows by eating smaller galaxies — by eating its own kind,” said co-author Raja Guha Thakurta, UC Santa Cruz chair of astronomy and astrophysics.
Consisting of an inner and outer layer, the Milky Way’s halo is much larger than the main disk and central bulge of the Milky Way, which is filled with stars. The galaxy, with a supermassive black hole at its center about 26,000 light-years from Earth, containing perhaps 100 billion–400 billion stars, including our Sun, resides in one of the four primary spiral arms that make up the Milky Way’s disk. Is. The halo contains about 5 percent of the stars in the Milky Way.
Dark matter, which dominates the halo, makes up the majority of the universe’s mass and is thought to be responsible for its core structure, with its gravity influencing visible matter to come together and form stars and galaxies.
The far outer edge of the halo is a poorly understood region of the Milky Way. These newly identified stars are about half the distance from the Milky Way’s neighboring Andromeda galaxy.
“We can see that the suburbs of the Andromeda halo and the Milky Way halo are indeed extended – and are almost ‘back-to-back,'” Feng said.
The search for life beyond Earth has focused on rocky planets orbiting Earth in what are called “habitable zones” around stars. More than 5,000 planets, called exoplanets, have already been discovered beyond our solar system.
“We don’t know for sure, but about every one of these outer halo stars must be likely to have planets orbiting the Sun and other Sun-like stars in the Milky Way,” said Guha Thakurta.
© Thomson Reuters 2023