Of the 11 farthest stars yet detected, all of which are located far outside the boundaries of the spiral confines — relatively speaking — of the Milky Way galaxy, at least five seem to have not actually originated within the Milky Way itself. According to new research from Harvard astronomers, it would appear that the home galaxy is a star thief.
Space Daily reported last week that an extremely distant string of 11 stars, the farthest away that have as yet been detected and are still held in the gravitational sway of the Milky Way at roughly 300,000 light years from Earth, have been found to have been stolen from the Sagittarius dwarf galaxy, according to a study using computer simulation models tracking 8 million years of galaxy migration. Marion Dierickx of the Harvard-Smithsonian Center for Astrophysics (CfA), lead author of the study, and her Ph.D. advisor, Harvard theorist Avi Loeb, ran the models and established that, by varying the velocity and angle of the dwarf galaxy’s fly-by, at least five of the trail of farthest stars had long ago been taken from Sagittarius on its way past as it orbited the Milky Way.
The Sagittarius dwarf galaxy is only one of a dozen small galaxies that surround the Milky Way, and it has made several swings around, having its cohesion pulled apart in the process. The computer simulation indicated that the dwarf galaxy was 10 billion times the mass of our own sun (just one percent of the galaxy’s mass) at the beginning. Over time, the galaxy lost at least a third of its stars and roughly nine-tenths of its dark matter by being ripped apart by gravitational tides.
And five of the 11 farthest stars seem to be part of that loss.
The entire string of 11 stretches for about one million light years, which is about 10 times the width of the Milky Way itself. The simulations predicted that over time, three streams (only one of which was plotted by the study) of pulled-away stars presented themselves, reaching out as far from galactic center as a million light-years. (Note: According to NASA, the Milky Way, at its widest, is just 100,000 light years across.)
The streams (which have not been fully extended to their fullest) are considered one of the largest structures observable in the sky, according to Space Daily.
As yet, the other six stars in that farthest string do not appear to have come from the Sagittarius dwarf galaxy. However, it is speculated that the half-dozen stellar masses may have been captured as other dwarf galaxies made passes by the Milky Way.
Dierickx said she believes that other “interlopers from Sagittarius are out there just waiting to be found.”
She went on to say, “The star streams that have been mapped so far are like creeks compared to the giant river of stars we predict will be observed eventually.”
It is believed that the employment of more sensitive instruments like the Large Synoptic Survey Telescope in Chile (which is scheduled to begin full scientific operations in 2022), a telescope that will detect faraway and faint stars across the sky that are currently beyond science’s technological reach, should be able to identify a number of the stars in the predicted streams.
In other star news regarding the Milky Way galaxy, a new study has revealed that some stars, about one every thousand years or so, that get pulled into the gravitational roil of a black hole, such as the one at the galactic core, do not always get torn apart and trapped in the gravitational field. As the Inquisitr reported, some stars get shredded instead in a process that takes roughly a day and are shot back out into space in a stream of “star-stuff” that could encompass hundreds of fragments. Some of the fragments will coalesce into planet-sized missiles traveling at speeds as high as 20 million miles per hour through space.
Alarmingly, astronomers believe that those hurled fireballs could be within about a few hundred light years of Earth, undetected due to the low magnitude of their glow.
As the study suggested, like the as-yet-undetected stars in the predicted pilfered galaxy streams, more powerful instruments should soon be able to tell if any of the massive objects are in our galactic neighborhood.
[Featured Image by ITSARIYAPHON CHAIKULAP/Shutterstock]