An international team of astronomers has discovered an ancient and dramatic head-on collision between the Milky Way and a smaller object, dubbed ‘the Sausage galaxy’. The cosmic crash was a defining event in the early history of the Milky Way and reshaped the structure of our galaxy, fashioning both the galaxy’s inner bulge and its outer halo, the astronomers report in a series of new papers.
The European Space Agency’s Gaia mission has produced the richest star catalogue to date, including high-precision measurements of nearly 1.7 billion stars and revealing previously unseen details of our home Galaxy.
Astronomers have looked back to a time soon after the Big Bang, and have discovered swirling gas in some of the earliest galaxies to have formed in the Universe. These ‘newborns’ – observed as they appeared nearly 13 billion years ago – spun like a whirlpool, similar to our own Milky Way. This is the first time that it has been possible to detect movement in galaxies at such an early point in the Universe’s history.
A group of astronomers have shown that the fastest-moving stars in our galaxy – which are travelling so fast that they can escape the Milky Way – are in fact runaways from a much smaller galaxy in orbit around our own.
The discovery of two massive holes punched through a stream of stars could help answer questions about the nature of dark matter, the mysterious substance holding galaxies together.
With its very first – and last – observation, the Hitomi x-ray observatory has discovered that the gas in the Perseus cluster of galaxies is much less turbulent than expected, despite being home to NGC 1275, a highly energetic active galaxy.
Black holes are the most powerful gravitational force in the Universe. So what could cause them to be kicked out of their host galaxies? Cambridge researchers have developed a method for detecting elusive ‘black hole kicks.’
An international team of astronomers have detected glowing oxygen in a distant galaxy seen just 700 million years after the Big Bang. This is the most distant galaxy in which oxygen has ever been unambiguously detected, and it is most likely being ionised by powerful radiation from young giant stars. This galaxy could be an example of one type of source responsible for cosmic reionisation in the early history of the Universe.
Astronomers have discovered some of the oldest stars in the galaxy, whose chemical composition and movements could tell us what the Universe was like soon after the Big Bang.