European Week of Astronomy and Space Science | 2018 Apr 02
The galaxy we inhabit, the Milky Way, may be getting even bigger, according to Cristina Martínez-Lombilla ...
Some star-forming regions are found at the outer edge of the disc, and models of galaxy formation predict that the new stars will slowly increase the size of the galaxy they reside in. One problem in establishing the shape of the Milky Way is that we live inside it, so astronomers look at similar galaxies elsewhere as analogues for our own.A composite image of NGC 4565 used in the new study. Credit: C. M. Lombilla / IAC
Martínez-Lombilla and her colleagues set out to establish whether other spiral galaxies similar to the Milky Way really are getting bigger, and if so what this means for our own galaxy. She and her team used the ground-based SDSS telescope for optical data, and the two space telescopes GALEX and Spitzer for near-UV and near-infrared data respectively, to look in detail at the colours and the motions of the stars at the end of the disc found in the other galaxies.
The researchers measured the light in these regions, predominantly originating from young blue stars, and measured their vertical movement (up and down from the disc) of the stars to work out how long it will take them to move away from their birthplaces, and how their host galaxies were growing in size.
Based on this, they calculate that galaxies like the Milky Way are growing at around 500 metres per second, fast enough to cover the distance from Liverpool to London in about twelve minutes. ...