"In the Andromeda galaxy we have the unique combination of a global yet detailed view of a galaxy similar to our own. We have lots of detail in our own Milky Way, but not the global, external perspective," said study co-author Prof Puragra Guhathakurta of the University of California, Santa Cruz.
"The comparison to the Milky Way revealed substantial differences suggesting that Andromeda has had a more violent accretion history in the recent past. Even the most well ordered Andromeda stars are not as well ordered as the stars in the Milky Way's disk."
Hubble is reprising one of its greatest hits. Twenty years after the release of its iconic image of the Eagle nebula's "Pillars of Creation", the space telescope – which turns 25 this year – has captured two new, even sharper views that peer through the pillars' shrouds of dust.
The original image, taken in 1995 with Hubble's Wide Field and Planetary Camera 2, revealed three towering "elephant trunks" of gas and dust that are in the process of forming new stars. The columns are also being sculpted and eroded by winds from nearby young star.