Fans of Douglas Adams’s Hitchhiker’s Guide to the Galaxy series will hold the number 42 in high regard, as the the answer to the ultimate question of life, the universe and everything.
But an international team of astronomers has now found an extra significance for the number. Well, almost. Asantha Cooray from the University of California Irvine, US, led the team that has worked out how much dark matter is needed to make the perfect galaxy. It turns out that the number is about 6×1041kg, which at a push you could round to 1042kg. That’s about 300 million times the mass of our own sun.
But what do they mean by the perfect galaxy? ‘If you start with too little dark matter, then a developing galaxy would peter out,’ said Cooray in a statement. ‘If you have too much, then gas doesn’t cool efficiently to form one large galaxy, and you end up with lots of smaller galaxies. But if you have just the right amount of dark matter, then a galaxy bursting with stars will pop out.’
Phillip Broadwith
Reference: A Amblard et al, Nature, 470, 510 (DOI: 10.1038/nature09771)
