14 DAY TRIAL // Some think they are actually a star. Some think they are comets. Astronomers have just found a distant star that moves through space at enormous speeds and has a huge, comet-like tail.
The tail is colossal, 13 light years in length and was detected by NASA's Galaxy Evolution Explorer (Galex) space telescope. Mira A is the first star of this type ever discovered and will help researchers understand what happens when a star dies.
"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, a scientist at the Carnegie Observatories in Pasadena.
Mira A, located at approximately 350 light-years from Earth in the Cetus, is known for over four centuries and is part of a binary system, being accompanied by Mira B, a smaller secondary star.
Billions of years ago, Mira was a Sun-like star, but now it has started the demise process, being swollen into a type of star called red giant.
In its race through space at 130km/s (80 mi per second) it loses huge quantities of matter, forming the enormous tail, which remained unspotted till now. Only UV images taken by the Galex space telescope could unveil Mira's secret.
"Galex is so exquisitely sensitive to ultraviolet light and it has such a wide field of view that it is uniquely poised to scan the sky for previously undiscovered ultraviolet activity. The fact that Mira's tail only glows with ultraviolet light might explain why other telescopes have missed it." said co-author Barry Madore, senior research astronomer at the Carnegie Observatories.
The UV images also discovered a "bow shock" zone in front of the star, where hot gas stores as the star's atmosphere collides with clouds of interstellar gas and dust. The hot gas in the bow shock could raise the temperature of the gas shed by Mira into its turbulent tail. Researchers believe the tail contains material thrown over a period of 30,000 years.
"We hope to be able to read Mira's tail like a ticker tape to learn about the star's life." said Seibert.
"Studying the carbon, oxygen and other elements that make up the tail could also provide an insight into how new solar systems and possibly even life are formed. After 400 years of study, Mira continues to astound," wrote the researchers.