The Milky Way now has a twin (or two)

Aug 23, 2012
The Milky Way now has a twin (or two)
Credit: Dr Aaron Robotham, ICRAR/St Andrews using GAMA data

(Phys.org)—Research presented today at the International Astronomical Union General Assembly in Beijing has found the first group of galaxies that is just like ours, a rare sight in the local Universe.

The Milky Way is a fairly typical galaxy on its own, but when paired with its close - the Magellanic Clouds - it is very rare, and could have been one of a kind, until a survey of our local Universe found another two examples just like us.

Dr Aaron Robotham, jointly from the University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR) and the University of St Andrews in Scotland, searched for groups of galaxies similar to ours in the most of the local Universe yet, the Galaxy and Mass Assembly survey (GAMA).

"We've never found another galaxy system like the Milky Way before, which is not surprising considering how hard they are to spot! It's only recently become possible to do the type of analysis that lets us find similar groups," says Dr Robotham.

"Everything had to come together at once: we needed telescopes good enough to detect not just galaxies but their faint companions, we needed to look at large sections of the sky, and most of all we needed to make sure no galaxies were missed in the survey"

Sophisticated simulations of how galaxies form don't produce many examples similar to the Milky Way and its surrounds, predicting them to be quite a rare occurrence. Astronomers haven't been able to tell just how rare until now, with the discovery of not just one but two exact matches amongst the hundreds of thousands of galaxies surveyed.

"We found about 3% of galaxies similar to the Milky Way have companion galaxies like the Magellanic Clouds, which is very rare indeed. In total we found 14 galaxy systems that are similar to ours, with two of those being an almost exact match," says Dr Robotham.

The Milky Way is locked in a complex cosmic dance with its close companions the Large and Small Magellanic Clouds, which are clearly visible in the southern hemisphere night sky. Many galaxies have smaller in orbit around them, but few have two that are as large as the Magellanic Clouds.

Dr Robotham's work also found that although companions like the are rare, when they are found they're usually near a galaxy very like the Milky Way, meaning we're in just the right place at the right time to have such a great view in our night sky.

"The galaxy we live in is perfectly typical, but the nearby Magellenic are a rare, and possibly short-lived, occurrence. We should enjoy them whilst we can, they'll only be around for a few billion more years," adds Dr Robotham.

Dr Robotham and colleagues have been awarded further time on telescopes in New South Wales and Chile to study these twin systems now that they've been found.

Explore further: 'Perfect storm' quenching star formation around a supermassive black hole

More information: The paper "Galaxy and Mass Assembly (GAMA): In search of Milky-Way Magellanic Cloud Analogues" can be read here: adsabs.harvard.edu/abs/2012MNRAS.424.1448R

Related Stories

Hubble sees a vapor of stars

Jul 02, 2012

(Phys.org) -- Relatively few galaxies possess the sweeping, luminous spiral arms or brightly glowing center of our home galaxy the Milky Way. In fact, most of the Universe's galaxies look like small, amorphous ...

Milky way sidelined in galactic tug of war

Sep 29, 2010

(PhysOrg.com) -- The Magellanic Stream is an arc of hydrogen gas spanning more than 100 degrees of the sky as it trails behind the Milky Way's neighbor galaxies, the Large and Small Magellanic Clouds. Our ...

No stars in the clouds

Jan 10, 2006

A team of astronomers from the University of Pittsburgh and the Universitäts-Sternwarte München in Munich, Germany, announced today in a paper presented at the meeting of the American Astronomical Society in Washington, ...

Astronomers peer into the dark

Apr 21, 2011

(PhysOrg.com) -- Astronomers from the Scottish Universities Physics Alliance (SUPA) have produced a completely new catalogue of ~15,000 groups of galaxies that gives a new insight into dark matter, the material ...

Herschel and Spitzer see nearby galaxies' stardust

Jan 10, 2012

(PhysOrg.com) -- The cold dust that builds blazing stars is revealed in new images that combine observations from the Herschel Space Observatory, a European Space Agency-led mission with important NASA contributions; ...

Recommended for you

The hot blue stars of Messier 47

22 hours ago

Messier 47 is located approximately 1600 light-years from Earth, in the constellation of Puppis (the poop deck of the mythological ship Argo). It was first noticed some time before 1654 by Italian astronomer ...

Why is space black?

Dec 16, 2014

Imagine you're in space. Just the floating part, not the peeing into a vacuum hose or eating that funky "ice cream" from foil bags part. If you looked at the Sun, it would be bright and your retinas would ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.