ESA | Space Science | Gaia | 2017 Jun 26
[c][attachment=0]Stars_speeding_through_the_Galaxy.jpg[/attachment][/c][hr][/hr]With the help of software that mimics a human brain, ESA’s Gaia satellite spotted six stars zipping at high speed from the centre of our Galaxy to its outskirts. This could provide key information about some of the most obscure regions of the Milky Way.
Our galactic home, the Milky Way, houses more than a hundred billion stars, all kept together by gravity. Most are located in a flattened structure – the Galactic disc – with a bulge at its centre, while the remaining stars are distributed in a wider spherical halo extending out to about 650 000 light-years from the centre.
Stars are not motionless in the Galaxy but move around its centre with a variety of velocities depending on their location – for example, the Sun orbits at about 220 km/s, while the average in the halo is of about 150 km/s.
Occasionally, a few stars exceed these already quite impressive velocities.
Some are accelerated by a close stellar encounter or the supernova explosion of a stellar companion, resulting in runaway stars with speeds up to a few hundred km/s above the average.
A new class of high-speed stars was discovered just over a decade ago. Swooping through the Galaxy at several hundred of km/s, they are the result of past interactions with the supermassive black hole that sits at the centre of the Milky Way and, with a mass of four million Suns, governs the orbits of stars in its vicinity. ...
An Artificial Neural Network to Discover Hypervelocity Stars: Candidates in Gaia DR1/TGAS - T. Marchetti et al
- Monthly Notices of the RAS (online 25 May 2017) DOI: 10.1093/mnras/stx1304
arXiv.org > astro-ph > arXiv:1704.07990 > 26 Apr 2017 (v1), 29 May 2017 (v2)