A couple of years ago, the star Betelgeuse rose to the spotlight in connection with some pseudo-Mayan prophecies about the end of the world. Now at last we can talk about this star for purely scientific reasons as ESA’s Herschel space observatory allowed to obtain an image that shows how it’s approaching a wall of interstellar dust.
Betelgeuse is the second brightest star in the constellation of Orion after Rigel and makes its left shoulder. It’s a red supergiant whose brightness is variable because it’s in an unstable phase in which its outer layer shrinks and expands. Its size appear to us at the moment about a thousand times the Sun but because of its state those measurements vary over time.
The variability of the star Betelgeuse was discovered in 1831 by astronomer John Herschel therefore it seems appropriate to be studied using the space telescope named after his father William, who was also an astronomer. William Herschel was the discoverer of the infrared spectrum and that’s the reason why his name was given to a space observatory that covers the wavelengths of the infrared spectrum in addition to the submillimetre ones.
Betelgeuse is doomed to explode in a supernova and it’s impossible to predict when this will happen. As far as we know, it may have already happened but the electromagnetic radiation emitted are still traveling toward the Earth since this star is about 600 light years away. Given the intensity of this radiation, it’s a good thing that it’s so far away because if they were 60 light years the effects on the planet would be devastating.
The Herschel space observatory allowed us to see how the star Betelgeuse solar wind is colliding with interstellar dust. This creates a phenomenon called “bow shock” because the star is moving through space at a speed of about 30 km/s, enough to create shock waves. It’s a phenomenon visible in a particularly spectacular way near the star Zeta Ophiuchi.
The linear structure similar to a bar seemed to be the consequence of the material expelled from Betelgeuse during one of the stages of its evolution. Instead, the new Herschel space observatory images obtained make scientists think that it’s a linear string connected to the galactic magnetic field or the edge of a nearby interstellar cloud illuminated by the star.
If this bar is completely separate, the outer arc will collide with it in about 5,000 years while the star Betelgeuse will hit it about 12,500 years later. The greater question is that it might explode before it may happen sweeping away all the interstellar dust.