Cosmic cannibalising: Images show one galaxy engulfing another

As cosmic events go, this one is hard to beat. Scientists have built up a dramatic time-lapse picture of one galaxy swallowing up another in a cannabilistic act that takes place over a period of three billion years – about as long as it took for slime-like earthlings to evolve into humans.





Astronomers have been able to witness a feature of galaxy evolution that they have long suspected but have been unable to visualise whereby one swirling mass of stars devours another that happens to have come within its gravitational sphere of influence.

A telescopic study of the Andromeda galaxy some 2.3 million light years away, the nearest spiral galaxy to our own Milky Way that can be seen with the naked eye, has exposed the galaxy’s immense gravitational tides that are eating away at the smaller Triangulum galaxy as it slowly orbits its galactic master.

The images captured by the Andromeda Archaeological Survey team, using the Canada-France-Hawaii Telescope on the summit of Mauna Kea in Hawaii, show for the first time the immense tidal forces and interactions that cause one galaxy to slowly swallow the stars and cosmic gases of another.

The findings, published in the journal Nature, support a central hypothesis in cosmology called the “hierarchical model” which predicts that large galaxies should be surrounded by the relics of smaller galaxies that the larger galaxies have either completely digested or have begun to engulf.

“Galaxies like our own Milky Way were not born in their current state and they grow by cannabilising smaller galaxies in their path – this is exactly the same with Andromeda,” said Mike Irwin of Cambridge University’s Institute of Astronomy, a member of the international research team.

“What these images tell us is that even galaxies that look beautiful and symmetrical when looked at through a telescope have structure and interactions that you don’t see,” Dr Irwin said.

“This is a startlingly visual demonstration of the truly vast scale of galaxies. The survey has produced an unrivalled panorama of galaxy structure which reveals that galaxies are the result of an ongoing process of accretion and interaction with their neighbour,” he said.

The results of the study were made possible because of the huge area of sky surveyed by the telescope’s powerful digital camera. The observations covered an area with a diameter equivalent to a million light years, a panorama of space that the scientists said is the broadest and deepest view of a galaxy ever made.

One of the problems of finding the evidence to support the hierarchical model of galaxy evolution is that the “leftovers” of the galactic dinner are too faint to be seen over an area that is hundreds of times larger than the galaxy’s central disc of bright stars and gas.

“We mapped Andromeda’s unexplored outskirts for the first time and found stars and giant structures that are remnants of smaller galaxies, which have been incorporated into Andromeda as part of its ongoing growth,” said Professor Geraint Lewis of the University of Sydney.

“The big surprise in the data was finding that Andromeda is interacting with its neighbour, the Triangulum galaxy, a galaxy which is also visible in the northern hemisphere using a small telescope. Millions of Triangulum’s stars have been pulled in by Andromeda as part of the encounter,” Professor Lewis said.

It takes about 3 billion years for the two galaxies to complete one round of their cosmic dance but eventually they are expected to merge into one entity. Some of the stars in Andromeda are so far from the galactic core that they could only have formed in another galaxy that had long-since been swallowed up.

Another surprise for the survey team is finding the immense scale of a galaxy’s influence. “We’ve found coherent structures and star formations over the entire survey area, showing that galaxies are much bigger than we originally thought. Andromeda is considered by astronomers to be a typical galaxy, so it’s surprising to see how vast it really is,” Professor Lewis said.

“We found loosely bound stars at distances up to a hundred times the radius of the large galaxy’s central disc,” he said.

Start your day with The Independent, sign up for daily news emails
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Guru Careers: Software Developer / C# Developer

£40-50K: Guru Careers: We are seeking an experienced Software / C# Developer w...

Guru Careers: Software Developer

£35 - 40k + Benefits: Guru Careers: We are seeking a Software Developer (JavaS...

SThree: Trainee Recruitment Consultant / Resourcer

£18000 - £23000 per annum + Commission: SThree: As a Trainee Recruitment Consu...

Ashdown Group: UI Developer - (UI, HTML, CSS, JavaScript, AngularJS)

£25000 - £40000 per annum: Ashdown Group: UI Developer - (UI, JavaScript, HTML...

Day In a Page

Sun, sex and an anthropological study: One British academic's summer of hell in Magaluf

Sun, sex and an anthropological study

One academic’s summer of hell in Magaluf
From Shakespeare to Rising Damp... to Vicious

Frances de la Tour's 50-year triumph

'Rising Damp' brought De la Tour such recognition that she could be forgiven if she'd never been able to move on. But at 70, she continues to flourish - and to beguile
'That Whitsun, I was late getting away...'

Ian McMillan on the Whitsun Weddings

This weekend is Whitsun, and while the festival may no longer resonate, Larkin's best-loved poem, lives on - along with the train journey at the heart of it
Kathryn Williams explores the works and influences of Sylvia Plath in a new light

Songs from the bell jar

Kathryn Williams explores the works and influences of Sylvia Plath
How one man's day in high heels showed him that Cannes must change its 'no flats' policy

One man's day in high heels

...showed him that Cannes must change its 'flats' policy
Is a quiet crusade to reform executive pay bearing fruit?

Is a quiet crusade to reform executive pay bearing fruit?

Dominic Rossi of Fidelity says his pressure on business to control rewards is working. But why aren’t other fund managers helping?
The King David Hotel gives precious work to Palestinians - unless peace talks are on

King David Hotel: Palestinians not included

The King David is special to Jerusalem. Nick Kochan checked in and discovered it has some special arrangements, too
More people moving from Australia to New Zealand than in the other direction for first time in 24 years

End of the Aussie brain drain

More people moving from Australia to New Zealand than in the other direction for first time in 24 years
Meditation is touted as a cure for mental instability but can it actually be bad for you?

Can meditation be bad for you?

Researching a mass murder, Dr Miguel Farias discovered that, far from bringing inner peace, meditation can leave devotees in pieces
Eurovision 2015: Australians will be cheering on their first-ever entrant this Saturday

Australia's first-ever Eurovision entrant

Australia, a nation of kitsch-worshippers, has always loved the Eurovision Song Contest. Maggie Alderson says it'll fit in fine
Letterman's final Late Show: Laughter, but no tears, as David takes his bow after 33 years

Laughter, but no tears, as Letterman takes his bow after 33 years

Veteran talkshow host steps down to plaudits from four presidents
Ivor Novello Awards 2015: Hozier wins with anti-Catholic song 'Take Me To Church' as John Whittingdale leads praise for Black Sabbath

Hozier's 'blasphemous' song takes Novello award

Singer joins Ed Sheeran and Clean Bandit in celebration of the best in British and Irish music
Tequila gold rush: The spirit has gone from a cheap shot to a multi-billion pound product

Join the tequila gold rush

The spirit has gone from a cheap shot to a multi-billion pound product
12 best statement wallpapers

12 best statement wallpapers

Make an impact and transform a room with a conversation-starting pattern
Paul Scholes column: Does David De Gea really want to leave Manchester United to fight it out for the No 1 spot at Real Madrid?

Paul Scholes column

Does David De Gea really want to leave Manchester United to fight it out for the No 1 spot at Real Madrid?