A Radio Look at Star Formation

Seeing Protostellar Baby Steps

Until well into the 20th century, astronomers didn’t have a clear look into the process of star formation. That’s because the places where stars are born are veiled in heavy clouds of gas and dust. It had to be frustrating, seeing these blobs of star stuff in space and not being able to see into the crèche. But, astronomers are smart people, and as they built advanced capability and techniques into their telescopes and detectors, their chances of being able to lift the veil on starbirth cradles improved to the point where they can look nearly directly onto stellar babies at their earliest stages of formation.  In particular, astronomers use infrared detectors and radio telescopes quite frequently to delve into the mysteries of star formation. The results can be pretty remarkable.

The image at left is not an impressionist painting, but a radio telescope view of a star-forming complex called B5, which lies about 800 light-years away from Earth. The entire cloud and its stars “vibrate” at radio frequencies that can be detected here on Earth, which gives us a chance to see the action that would normally be hidden from our inquiring telescopes.

The cloud has several hot “cores” where gas has been compressed by gravity so much that it has heated up and has started to glow. One area (the brightest one) in the blobs is a protostar—that is, a stellar core that will soon become hot enough to initiate fusion and become a star. The other hot cores will initiate fusion sometime in the next 40,000 years. That’s the speed of stellar starbirth folks: a few tens of thousands of years from blob of gas and dust to newborn star.

This radio “image” was made using data collected by three radio telescope installations: the Very Large Array in New Mexico, the James Clerk Maxwell Telescope in Hawai’i, and the Green Bank Telescope in Virginia. At least three of the “stars in forming” will be a multiple-star system in the future (shown in the artist’s concept at the right), and what astronomers learn about them at this stage in their birth will help them understand the very complex actions and processes that go on in interstellar clouds when the process of star formation begins.  This is particularly important because at least half of all star in the galaxy are in multiple-star systems, so understanding how they are born gives astronomers a good handle on a major portion of the star-forming activity in the Milky Way.