Milky Way is far fatter, say Sydeney astrophysicists

February 20th, 2008 - 7:02 pm ICT by admin  

By Neena Bhandari
Sydney, Feb 20 (IANS) Is our Milky Way galaxy fatter than we thought? A team of astrophysicists from the University of Sydney - including an Indian researcher - have calculated that it is 12,000 light years thick - double the previous estimate. They made the amazing discovery not by gazing at our galaxy through a powerful telescope, but while being engrossed in a stimulating discussion and analysing data downloaded from the Internet.

A team led by Bryan Gaensler and colleagues Shami Chatterjee, Greg Madsen and PhD student Ann Mao downloaded previously recorded data from the Internet and re-analysed it to find our galaxy is twice as thicker than previously thought.

“We were tossing around ideas about the size of the galaxy, and thought we had better check the standard numbers that everyone uses. It took us just a few hours to calculate this for ourselves. We thought we had to be wrong, so we checked and rechecked and couldn’t find any mistakes,” Gaensler told media.

Data was used from pulsars - neutron stars that emit regular pulses. The team members restricted themselves to using pulsars outside the disk of our galaxy. The longer wavelengths of the pulse slow down more than the shorter wavelengths, so by seeing how far the longer wavelengths lag behind the shorter wavelengths one can calculate how much ‘warm ionised medium’ (WIM) the pulse has travelled through.

“My work actually involves measuring distances to pulsars and based on how far away they are, one can infer the density of the interstellar medium in that direction,” Chatterjee, a post-doctoral fellow at the School of Physics at the university, told IANS.

“Radio waves from these pulsars travel to the earth, they interact with electrons scattered between the stars known as the WIM, which slows the radio waves down,” explained Chatterjee, who graduated in electronic engineering from the Indian Institute of Technology (IIT), Madras, and then the Cornell University in the US.

He worked at the National Radio Astronomy Observatory in Socorro, New Mexico, and at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, before joining Sydney University over a year ago.

Born in Kolkata, Chatterjee has been keen on astronomy since his school days. “I was influenced by Carl Sagan’s `Cosmos’. We also had access to a telescope in the Ramakrishna Mission school in Narendrapur, Kolkata.”

The new findings have drawn mixed reactions. Gaensler told media, “Some colleagues have come up to me and said: ‘That wrecks everything!’ And others have said: ‘Ah! Now everything fits together!’”

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