Is Betelgeuse about to go Supernova?
You might have seen pieces on various media claiming that Betelgeuse, an elderly star in the constellation of Orion is about to provide us with the spectacular show of its final moments. Is this the case ?
Let’s start from the beginning: what is Betelgeuse, and how on Earth do you pronounce it?
Contrary to popular opinion, it is not pronounced “Beetlejuice” like the film with Michael Keaton. Sorry.
Betelgeuse, or αOri, is a Red Supergiant that lies on the top left hand side of the constellation of Orion as it is seen from the Northern Hemisphere. You can easily tell it apart from its orange-red hue from the other members of the constellation away from the influence of light pollution.
Orion, the Hunter, is depicted having his right arm raised and Betelgeuse lies right at his armpit. Its name in Arabic means exactly that, Ibt-al-jowza, “armpit of Orion”. This became corrupted to “Bit-al-jooz” and finally to Betelgeuse. So “Bit-Al-Jooz” is perhaps the better way to pronounce it rather than Beetlejuice (still wrong but hey).
Betelgeuse is a Red Supergiant of the spectral type M1; it has depleted the hydrogen in its core and is now fusing Helium into heavier elements. It is a huge star with a radius almost as large as the orbit of Jupiter. Its atmosphere is pulsating (expanding and contracting) and that is the cause behind its variable nature. The latter means that its brightness varies with time. This has been known since the observations of Sir William Herschel in 1836.
It is an extreme variation that has sparked the discussion and articles on the internet; Betelgeuse’s brightness has dropped to the lowest level ever recorded. Red Supergiants are elderly stars that are in the final stages of their life. They all explode in massive Supernovae explosions that blow their body to smithereens, enriching the interstellar medium with the elements that they fused during their lifetimes. Any element heavier than Iron that exists in the Universe today comes from such an explosion, including the material that the wedding ring I am currently wearing on my finger is made of (whether I should have mentioned that to my wife when I presented her with a ring is debatable). These explosions release so much energy that they outshine entire galaxies, and their unusually bright light can be visible for days.
Is this unprecedented drop in the stars’ brightness cause for alarm? Does this mean that the star is about to die in a spectacular supernova?
Probably not. More on the next post: Betelgeuse Drama.