Jun 14, 2011 08:56 GMT  ·  By
This diagram of the Milky Way shows the location of the Scutum-Centaurus Arm extension the CfA team confirms exists
   This diagram of the Milky Way shows the location of the Scutum-Centaurus Arm extension the CfA team confirms exists

By analyzing the chemical signature of molecules such as carbon monoxide, experts at the Harvard-Smithsonian Center for Astrophysics (CfA) were recently able to confirm the existence of a new spiral arm in our galaxy, the Milky Way.

The arm is in fact an extension, located at the far end of the Scutum-Centaurus Arm. This is one of the two immense spiral arms the Milky Way is known to have. The other one, called Perseus, is home to our solar system.

Observing the exact structure of our galaxy is tremendously complex, given that we are located inside it. Massive clouds of cosmic dust and hydrogen gas are blocking our view of the galactic core, and also of what lies exactly opposite of us in the galaxy.

But there are also some good news. While observing those features is impossible using visible-light telescopes, experts can see them in radio wavelengths, which can penetrate any gas or dust clouds.

Models of the Milky Way show the galaxy as having a massive central bar, from which two massive spiral arms extend outwards. But some experts have proposed a long time ago that the galaxy may in fact have more spiral arms. Testing their proposition has proven rather difficult.

The new study was conducted by CfA astronomers Tom Dame and Pat Thaddeus, who used a small, 1.2-meter aperture telescope on the roof of one of their Cambridge-based buildings. The team used the radio observatory to track carbon monoxide emissions in the Milky Way.

The existence of the Scutum-Centaurus Arm extension was demonstrated before, but the team now provides an independent verification of the previous results, using a completely different approach.

“After preliminary Galactic surveys in the mid-1970′s revealed the vast extent of CO emission on the sky. It became clear that even with the relatively large beams of the 1.2 meter telescopes a sensitive, well-sampled survey of the entire Galaxy would require many years,” Dame says.

The carbon monoxide the experts are seeing is produced by carbon stars, whose atmosphere contains a lot more carbon than hydrogen, Universe Today reports. These stars also have relatively low temperatures.