Cal Tech Astronomers using the GALEX telescope, made a very interesting and unprecedented discovery of a massive tail being left in the trail of a well-known star, Mira. The faint tail, seen in ultraviolet light, spans more than 13 light years in the wake of Mira. The discovery of this phenomenon includes a ‘bow-shock’ ahead of the star, analogous to a vessel underway on the sea.
Mira, a late-sequence red-giant star, is shedding it’s outer layers as it hurtles through the universe at amazingly high speeds (relative to our Sun). As scientists study this interesting discovery, they are likely to learn more about the ultimate destiny of our own star, which, as we know, will be similar to Mira in about five billion years.
From Science@NASA:
August 15, 2007: Astronomers using a NASA space telescope, the Galaxy Evolution Explorer, have spotted an amazingly long comet-like tail behind a star streaking through space. The star, named Mira after the Latin word for “wonderful,” has been a favorite of astronomers for about 400 years, yet this is the first time the tail has been seen.
Galaxy Evolution Explorer–“GALEX” for short–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.
NASA and JPL/Caltech prepared a half-minute animation which is an artist’s conception of Mira generating her tail. Be sure and watch this neat little video.
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. The star, named Mira (pronounced my-rah) after the Latin word for “wonderful,” sheds material that will be recycled into new stars, planets and possibly even life. NASA’s Galaxy Evolution Explorer discovered the long trail of material behind Mira during its survey of the entire sky in ultraviolet light.
The animation begins by showing a close-up of Mira – a red-giant star near the end of its life. Red giants are red in color and extremely bloated; for example, if a red giant were to replace our sun, it would engulf everything out to the orbit of Mars. They constantly blow off gas and dust in the form of stellar winds, supplying the galaxy with molecules, such as oxygen and carbon, that will make their way into new solar systems. Our sun will mature into a red giant in about 5 billion years.
As the animation pulls out, we can see the enormous trail of material deposited behind Mira as it hurls along between the stars. Like a boat traveling through water, a bow shock, or build up of gas, forms ahead of the star in the direction of its motion. Gas in the bow shock is heated and then mixes with the cool hydrogen gas in the wind that is blowing off Mira. This heated hydrogen gas then flows around behind the star, forming a turbulent wake.
Why does the trailing hydrogen gas glow in ultraviolet light? When it is heated, it transitions into a higher-energy state, which then loses energy by emitting ultraviolet light – a process known as fluorescence.
Finally, the artist’s rendering gives way to the actual ultraviolet image taken by the Galaxy Evolution Explorer
Mira is located 350 light-years from Earth in the constellation Cetus, otherwise known as the whale. Coincidentally, Mira and its “whale of a tail” can be found in the tail of the whale constellation.
Images and video courtesy and credit NASA and JPL/Caltech via Science@NASA