Odd Star Sheds Cometlike Tail

<< Back to Page 1   Page 2 of 2

In fact, Mira is speeding through the galaxy at 291,000 miles (468,000 kilometers) an hour—an unusually fast clip that may be the result of gravitational boosts from other passing stars.

Mira's supersonic speed causes a type of shock wave known as a bow shock to form in front of the star, study co-author Mark Seibert, from the Observatories of the Carnegie Institution of Washington in Pasadena, explained at the briefing.

"It's compressing the interstellar medium like a boat moving through the water ... and the gas in this bow shock is actually very hot," he said.

Cool wind blowing off the star mixes with this hot bow-shock gas, and the mixture flows around and behind Mira, creating the long wake, he added.

Eventually, Mira will eject all of its remaining gas into space, forming a shell called a planetary nebula.

The nebula will fade with time, leaving only the burnt-out core of the original star, an extremely dense object called a white dwarf. (Related: "Solar System's Fate Predicted by Nearby White Dwarf?" [December 21, 2006].)

Common Process?

The material in Mira's tail was shed over the past 30,000 years. Studying the tail will allow scientists to understand how stars like the sun die and seed new solar systems in the process, Caltech's Martin said.

Mira is a common type of star, Carnegie's Seibert added, and even though the cometlike tail phenomenon has never been seen before, the behavior is likely widespread.

Michael Shara is a curator at the American Museum of Natural History in New York and a professor of astronomy at Columbia University.

He was not involved in the study but participated in the briefing to offer perspective on the discovery.

"It's giving us this fantastic insight, I think, into the death processes of stars and their renewals—their phoenix-like revivals as their ashes get cycled back into the next generation of stars," Shara said.

Free Email News Updates
Sign up for our Inside National Geographic newsletter. Every two weeks we'll send you our top stories and pictures (see sample).

<< Back to Page 1   Page 2 of 2


SOURCES AND RELATED WEB SITES

ADVERTISEMENT

NATIONAL GEOGRAPHIC'S PHOTO OF THE DAY

NEWS FEEDS     After installing a news reader, click on this icon to download National Geographic News's XML/RSS feed.   After installing a news reader, click on this icon to download National Geographic News's XML/RSS feed.

Get our news delivered directly to your desktop—free.
How to Use XML or RSS

National Geographic Daily News To-Go

Listen to your favorite National Geographic news daily, anytime, anywhere from your mobile phone. No wires or syncing. Download Stitcher free today.
Click here to get 12 months of National Geographic Magazine for $15.