Andromeda reaches out to touch Milky Way | Science News

Real Science. Real News.

Science News is a nonprofit.

Support us by subscribing now.


Andromeda reaches out to touch Milky Way

Gaseous halo extends 1 million light-years from neighboring galaxy’s spiral disk

10:25am, May 12, 2015
Andromeda galaxy

LIVING IN A BUBBLE  The Andromeda galaxy, the closest spiral to the Milky Way, is embedded in a tenuous bubble of gas that extends halfway to our galaxy.

View the graphic

The spiral disk of the Andromeda galaxy, the Milky Way’s neighbor, is just a tiny part of a much larger entity. The visible part of the galaxy is embedded in a tenuous halo of gas about six times as large as previously measured, researchers report in the May 10 Astrophysical Journal.

The halo is roughly 2 million light-years across — about 10 times as wide as the disk of stars — and extends nearly halfway to the Milky Way. If our galaxy has a similarly sized halo (which is tricky to measure for astronomers stuck inside the Milky Way), then the galaxies might be on the verge of touching (SN: 7/14/12, p. 10), says astrophysicist Nicolas Lehner of the University of Notre Dame in Indiana. Roughly 30 percent of Andromeda’s ordinary matter (excluding the

This article is only available to Science News subscribers. Already a subscriber? Log in now.
Or subscribe today for full access.

Get Science News headlines by e-mail.

More from Science News

From the Nature Index Paid Content