Feeds

Suffering SPITZER! Boffins discover Milky Way's MISSING ARMS

New study affirms our galaxy has FOUR spiral arms

Choosing a cloud hosting partner with confidence

Pic For years, boffins have been arguing over whether our galaxy has four spiral arms or just two, as seen by NASA's Spitzer Space Telescope.

Artist's impression of the Milky Way

You spin me right round ... an artist's impression of the Milky Way

The only way to confirm the theory is to try to figure out where the stars are and their distances from us, since we're on the inside of the galaxy, making it tough to see what it might look like from the outside.

Now a new 12-year study has reaffirmed the theory that the Milky Way is a four-armed spiral galaxy, as originally hypothesised in the 1950s. Back then, astronomers used radio telescopes to map the galaxy, focusing on clouds of gas in which new stars are born, and deduced that there were four arms.

That theory was thrown into debate when Spitzer searched for the infrared light emitted by stars and announced in 2008 that it had spotted around 110 million of them, but only found evidence of two spiral arms.

The latest study is part of the Red MSX (RMS) Survey conceived by the University of Leeds to systematically search the entire galaxy for massive young stellar objects. Using several radio telescopes in Australia, the US and China, distances and luminosities of these massive stars were calculated, showing a distribution across four spiral arms.

"It isn't a case of our results being right and those from Spitzer's data being wrong – both surveys were looking for different things," said Professor Melvin Hoare, a co-author of the paper. "Spitzer only sees much cooler, lower mass stars – stars like our Sun – which are much more numerous than the massive stars that we were targeting."

Massive stars are much less common because they only live for a short time, galacticly speaking, around 10 million years. That shorter lifespan could be the answer to the discrepancy in the results.

"Lower mass stars live much longer than massive stars and rotate around our galaxy many times, spreading out in the disc. The gravitational pull in the two stellar arms that Spitzer revealed is enough to pile up the majority of stars in those arms, but not in the other two," explained Professor Hoare. "However, the gas is compressed enough in all four arms to lead to massive star formation.

"Star formation researchers, like me, grew up with the idea that our Galaxy has four spiral arms. It's great that we have been able to reaffirm that picture."

The full study, "The RMS survey: galactic distribution of massive star formation" was published in the Monthly Notices of the Royal Astronomical Society. ®

Intelligent flash storage arrays

More from The Register

next story
Antarctic ice THICKER than first feared – penguin-bot boffins
Robo-sub scans freezing waters, rocks warming models
I'll be back (and forward): Hollywood's time travel tribulations
Quick, call the Time Cops to sort out this paradox!
Your PHONE is slowly KILLING YOU
Doctors find new Digitillnesses - 'text neck' and 'telepressure'
Reuse the Force, Luke: SpaceX's Elon Musk reveals X-WING designs
And a floating carrier for recyclable rockets
Britain's HUMAN DNA-strewing Moon mission rakes in £200k
3 days, and Kickstarter moves lander 37% nearer takeoff
Rosetta science team thinks Philae might come to life in the spring
And disclose the biggest surprise of Comet 67P
Bond villains lament as Wicked Lasers withdraw death ray
Want to arm that shark? Better get in there quick
prev story

Whitepapers

10 ways wire data helps conquer IT complexity
IT teams can automatically detect problems across the IT environment, spot data theft, select unique pieces of transaction payloads to send to a data source, and more.
A strategic approach to identity relationship management
ForgeRock commissioned Forrester to evaluate companies’ IAM practices and requirements when it comes to customer-facing scenarios versus employee-facing ones.
How to determine if cloud backup is right for your servers
Two key factors, technical feasibility and TCO economics, that backup and IT operations managers should consider when assessing cloud backup.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Choosing a cloud hosting partner with confidence
Download Choosing a Cloud Hosting Provider with Confidence to learn more about cloud computing - the new opportunities and new security challenges.