Astronomers have found a slew of stars lingering within the far fringes of our galaxy. And once 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 examine is redefining what constitutes the outer limits of our galaxy,” stated Raja GuhaThakurta, professor and chair of astronomy and astrophysics at UC Santa Cruz, in a news release. “Our galaxy and Andromeda are each so large, there’s hardly any space between the 2 galaxies.”
The outcomes had been offered on January 9 and 11 on the 241st assembly of the American Astronomical Society (AAS) in Seattle, Washington.
Dwelling on the sting
The celebs recognized on this examine are a particular class of star often known as RR Lyrae stars. These stars are essential to astronomers as a result of they exhibit attribute pulsations and variations in brightness.
“The best way their brightness varies appears to be like like an EKG — they’re just like the heartbeats of the galaxy — so the brightness goes up shortly and comes down slowly, and the cycle repeats completely with this very attribute form,” GuhaThakurta stated within the launch. “As well as, for those who measure their common brightness, it’s the identical from star to star.”
This predictable habits makes RR Lyrae stars a superb kind of distance indicator that astronomers name a “commonplace candle.” As a result of their intrinsic brightness is understood, it’s comparatively simple to find out their distance, with errors starting from simply 3 to five p.c, GuhaThakurta advised Astronomy on the assembly.
In contrast to 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 dwell within the Milky Way’s expansive halo, a spherical shell of largely historical stars that encapsulates our galaxy’s spiral arms and central bulge.
