News

Fossil globular star clusters reveal their age

28 July 2015 Astronomy Now

Using a new age-dating method and the W. M. Keck Observatory, an international team of astronomers have determined that globular star clusters formed in two distinct epochs — 12.5 and 11.5 billion years ago. They formed alongside galaxies, rather than prior to galaxies, as previously thought.

News

The dark matter conspiracy

3 May 2015 Astronomy Now

A new study finds that elliptical galaxies maintain a remarkably constant circular speed out to large distances from their centres, in the same way that spiral galaxies do. In these very different types of galaxies, stars and dark matter somehow conspire to redistribute themselves to produce this effect, or does modified Newtonian dynamics offer an explanation?