Feeds

Milky Way's spiral was a late addition

Galactic home improvement

The smart choice: opportunity from uncertainty

Scientists think they have found evidence that the middle of our galaxy formed separately and at a different time to the spiralling arms in which we reside.

Astronomers using the European Southern Observatory's Very Large Telescope (VLT) noticed that the stars in the galactic bulge, as it is known, have a different chemical composition from stars in the arms of the galaxy.

The galactic bulge is made up of only the very oldest stars in the galaxy, dating back 10bn years. The arms, meanwhile, are populated by stars of all ages.

The chemical makeup of stars gives astronomers clues to their pasts. Stars rich in heavier elements such as oxygen and iron, are probably second or even third generation - that is, they have been stars before.

Massive stars can end their lives in a number of different types of supernova. It takes a type II supernova to produce most oxygen, while while iron is forged in type I-a explosions. Thus, the amounts of each element reveal something about the ancestry of the star.

The astronomers studied fifty giant stars in four regions of the galaxy close to the central bulge. They found the amount of oxygen in disc and bulge stars was significantly different, suggesting that the two portions of the galaxy are "genetically different".

“For the first time, we have clearly established a ‘genetic difference’ between stars in the disc and the bulge of our Galaxy,” said Manuela Zoccali, lead author of the paper published in the journal Astronomy and Astrophysics.

“We infer from this that the bulge must have formed more rapidly than the disc, probably in less than a billion years and when the Universe was still very young.”

The team found that for a given amount of iron, stars in the disc contain less oxygen than their bulgier counterparts. This means that bulge stars formed independently, and did not originate in the disc and then migrate inward to build up the bulge, Zoccali concludes. ®

The Power of One Infographic

More from The Register

next story
World Solar Challenge contender claims new speed record
One charge sees Sunswift travel 500kms at over 100 km/h
SMELL YOU LATER, LOSERS – Dumbo tells rats, dogs... humans
Junk in the trunk? That's what people have
The Sun took a day off last week and made NO sunspots
Someone needs to get that lazy star cooking again before things get cold around here
Boffins discuss AI space program at hush-hush IARPA confab
IBM, MIT, plenty of others invited to fill Uncle Sam's spy toolchest, but where's Google?
Bad back? Show some spine and stop popping paracetamol
Study finds common pain-killer doesn't reduce pain or shorten recovery
Forty-five years ago: FOOTPRINTS FOUND ON MOON
NASA won't be back any time soon, sadly
Jurassic squawk: Dinos were Earth's early FEATHERED friends
Boffins research: Ancient dinos may all have had 'potential' fluff
prev story

Whitepapers

Top three mobile application threats
Prevent sensitive data leakage over insecure channels or stolen mobile devices.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Designing a Defense for Mobile Applications
Learn about the various considerations for defending mobile applications - from the application architecture itself to the myriad testing technologies.
Build a business case: developing custom apps
Learn how to maximize the value of custom applications by accelerating and simplifying their development.