Milky Way ties with neighbor in galactic arms race
Astronomers have discovered that our nearest large neighbour, the Andromeda galaxy, is roughly the same size as the Milky Way. It had been thought that Andromeda was two to three times the size of the Milky Way, and that our own galaxy would ultimately be engulfed by our supposedly bigger neighbour. But the latest research, published today, evens the score between the two galaxies.
The study found the weight of the Andromeda is 800 billion times heavier than the sun, on par with the Milky Way. Astrophysicist Dr Prajwal Kafle, from the University of Western Australia node of the International Centre for Radio Astronomy Research, said the study used a new technique to measure the speed required to escape a galaxy. "When a rocket is launched into space, it is thrown out with a speed of 11 km/s to overcome the Earth's gravitational pull," he said. "Our home galaxy, the Milky Way, is over a trillion times heavier than our tiny planet Earth so to escape its gravitational pull we have to launch with a speed of 550 km/s. We used this technique to tie down the mass of Andromeda."
Dr Kafle said the research suggests scientists previously overestimated the amount of dark matter in the Andromeda galaxy. "By examining the orbits of high speed stars, we discovered that this galaxy has far less dark matter than previously thought, and only a third of that uncovered in previous observations," he said. The Milky Way and Andromeda are two giant spiral galaxies in our local Universe, and light takes a cosmologically tiny two million years to get between them.
Read more at: https://phys.org/news/2018-02-milky-ties-neighbor-galactic-arms.html#jCp
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