Betelgeuse is the eighth-brightest star in the night sky and second-brightest in the constellation of Orion. Distinctly reddish, it is a semiregular variable star. A new image from the Herschel Space Observatory, a European Space Agency mission with important NASA participation, reveals the shedding, aging star -- called Betelgeuse - is located near an odd, linear bar of material. While some earlier theories proposed that this bar was a result of matter ejected during a previous stage of the star's evolution, analysis of the new image suggests that it is a separate object: either a linear filament linked to the galaxy's magnetic field, or the edge of a nearby interstellar cloud that is being illuminated by Betelgeuse.
As an early M-type supergiant, Betelgeuse is one of the largest, most luminous and yet one of the most ethereal stars known. Its distance from Earth was estimated in 2008 at 640 light-years.
If the newly observed bar is completely separate from the star, then the outermost arc around Betelgeuse is estimated to collide with the bar in just 5,000 years, with the star itself hitting the bar about 12,500 years later.
Roughly 1,000 times the diameter of our sun and shining 100,000 times more brightly, Betelgeuse is likely on its way to a spectacular supernova explosion. It has already swelled into a red supergiant and shed a significant fraction of its outer layers.
The new, longer-wavelength infrared view from Herschel also shows how the star's winds are crashing against the surrounding interstellar medium, creating a bow shock as the star moves through space at speeds of around 30 kilometers per second (about 67,000 mph).
A series of broken, dusty arcs around the star, and ahead of the direction of its motion, testify to a turbulent history of mass loss in past years.
An intriguing linear structure is also seen further away from the star, beyond the dusty arcs. While some earlier theories proposed that this bar was a result of material ejected during a previous stage of stellar evolution, analysis of the new image suggests that it is either a linear filament linked to the Galaxy’s magnetic field, or the edge of a nearby interstellar cloud that is being illuminated by Betelgeuse.
For further information see Betelgeuse.
Bar image via NASA/ESA.