Forget what you learned at school, astronomers have re-calculated the existing data on a ring of stars surrounding our galaxy and have concluded that it belongs to the Milky Way. They now estimate that the Milky Way is not 100,000, but 150,000 light years across.
Previously, astronomers thought that the so-called Monoceros Ring belonged to the Canis Major dwarf galaxy close to the Milky Way. But the researchers at Rensselaer Polytechnic Institute in New York now say this is wrong. They believe that due to the interactions between the Milky Way and Canis Major, this outer ring of stars may have been distorted by the dwarf galaxy.
According to the MailOnline, the Monoceros Ring is located 65,000 light-years from our galaxy’s center and is 200,000 light-years in length.
Discovery News says that the ring of stars oscillates above and below the Milky Way’s flat galactic disk in a wave-like, rippling pattern. They postulate that this could have been caused when a dwarf galaxy passed through the Milky Way. Other invasive galaxies may have pulled the ring of stars into wave patterns which then formed a spiral arm.
Dr Heidi Newberg from the Institute said:
“We thought it was a tidal debris stream — a dwarf galaxy that came in and spread itself out in this big ring. For 15 years, there’s been a controversy in the field where half the astronomers think it’s a tidal stream and half the astronomers think its something in the disk. I was in the stream camp.”
“What I was trying to do was find more evidence that it was streams. It took a very long time to get this result, partly because I had to change my whole way of thinking. It now looks to me like it’s part of the disk.”
The MailOnline says that the present discovery pushes the Milky Way into the category of “middle weight” galaxies. New re-evaluations might also increase the estimated size of our galaxy even further. A new study is taking place into another ring called the TriAnd Ring to see if it should also be included as part of the galaxy.
The scientists collected data from the Sloan Digital Sky Survey, in order to re-examine the brightness and distance of stars on the fringes of the Milky Way. They will now be using Europe’s Gaia telescope to try to confirm their theory.
The findings will be published this week in the Astrophysical Journal.