Speeding-Bullet Star Leaves Enormous Streak Across Sky
NASA's Galaxy Evolution Explorer has spotted an amazingly long comet-like tail behind a star streaking through space at supersonic speeds. The star, named Mira after the Latin word for "wonderful," has been a favorite of astronomers for about 400 years. It is a fast-moving, older star called a red giant that sheds massive amounts of surface material.
The space-based Galaxy Evolution Explorer scanned the popular star during its ongoing survey of the entire sky in ultraviolet light. Astronomers then noticed what looked like a comet with a gargantuan tail. In fact, material blowing off Mira is forming a wake 13 light-years long, or about 20,000 times the average distance of Pluto from the sun. Nothing like this has ever been seen before around a star.
Astronomers say Mira's tail offers a unique opportunity to study how stars like our sun die and ultimately seed new solar systems. As Mira hurtles along, its tail sheds carbon, oxygen and other important elements needed for new stars, planets and possibly even life to form. This tail material, visible now for the first time, has been released over the past 30,000 years.
"This is an utterly new phenomenon to us, and we are still in the process of understanding the physics involved," said co-author Mark Seibert of the Observatories of the Carnegie Institution of Washington in Pasadena. "We hope to be able to read Mira's tail like a ticker tape to learn about the star's life."
Billions of years ago, Mira was similar to our sun. Over time, it began to swell into what's called a variable red giant - a pulsating, puffed-up star that periodically grows bright enough to see with the naked eye. Mira will eventually eject all of its remaining gas into space, forming a colorful shell called a planetary nebula. The nebula will fade with time, leaving only the burnt-out core of the original star, which will then be called a white dwarf.
1. Johnny Appleseed of the Cosmos
A new ultraviolet mosaic from NASA's Galaxy Evolution Explorer shows a speeding star named Mira (pronounced my-rah) that is leaving an enormous trail of "seeds" for new solar systems.
2. A Real Shooting Star
This artist's animation illustrates a star flying through our galaxy at supersonic speeds, leaving a 13-light-year-long trail of glowing material in its wake.
3. Evolution of Mira's Enormous Tail
This chart illustrates the length (top) and age (bottom) of a long comet-like tail of material trailing behind a speeding star called Mira (pronounced My-rah).
4. Anatomy of a Shooting Star
A close-up view of a star racing through space faster than a speeding bullet can be seen in this image from NASA's Galaxy Evolution Explorer.
5. Supersonic Bullet
A bullet traveling through air at about 1.5 times the speed of sound can be seen in this image.
6. Mira's Tail There All Along
As this composite demonstrates, Mira's tail is only visible in ultraviolet light (top), and does not show up in visible light (bottom).