Astronomers have found a slew of stars lingering within the far fringes of our galaxy. And after we say far, we imply far.
Probably the most distant of those stars is situated greater than 1 million light-years away. That’s virtually midway to our largest galactic neighbor, the Andromeda Galaxy, which is situated some 2.5 million light-years away.
“This research is redefining what constitutes the outer limits of our galaxy,” mentioned Raja GuhaThakurta, professor and chair of astronomy and astrophysics at UC Santa Cruz, in a news release. “Our galaxy and Andromeda are each so massive, there’s hardly any space between the 2 galaxies.”
The outcomes have been introduced on January 9 and 11 on the 241st assembly of the American Astronomical Society (AAS) in Seattle, Washington.
Residing on the sting
The celebs recognized on this research are a particular class of star generally known as RR Lyrae stars. These stars are vital to astronomers as a result of they exhibit attribute pulsations and variations in brightness.
“The best way their brightness varies seems to be like an EKG — they’re just like the heartbeats of the galaxy — so the brightness goes up rapidly and comes down slowly, and the cycle repeats completely with this very attribute form,” GuhaThakurta mentioned within the launch. “As well as, for those who measure their common brightness, it’s the similar from star to star.”
This predictable conduct makes RR Lyrae stars a superb sort of distance indicator that astronomers name a “normal candle.” As a result of their intrinsic brightness is understood, it’s comparatively straightforward to find out their distance, with errors starting from simply 3 to five p.c, GuhaThakurta advised Astronomy on the assembly.
Not like the Solar, these newfound stars don’t reside within the Milky Way’s acquainted skinny disk, which is about 100,000 light-years throughout and residential to most of our galaxy’s younger stars. As an alternative, these RR Lyrae stars stay within the Milky Way’s expansive halo, a spherical shell of largely historic stars that encapsulates our galaxy’s spiral arms and central bulge.
