Scientists claim that Betelgeuse, a star 640 light years away from Earth, is going to explode soon. Nikolai Chugai, head of the department of Variable Stars and Astronomical Spectroscopy of the Russian Academy of Sciences’ Institute of Astronomy shares his views with RIA Novosti’s Samir Shakhbaz, on possible threats and impact this star may cause to our planet.
Samir Shakhbaz: Good afternoon, Mr. Chugai. An Australian scientist claims that the star Betelgeuse is going to explode. Betelgeuse is 640 light years away from the Earth, which is very close for objects in space. The explosion will be extremely powerful and we’ll be able to observe the supernova from the Earth. What have you heard about this news? Is it of legitimate interest to the scientific community?
Nikolai Chugai: Right now we cannot say for sure when it will explode. But yes, Betelgeuse is commanding the attention of astrophysicists for a number of reasons. First of all, it is one of the brightest red super giants.
S.S.: How much bigger is it than the Sun?
N.C.: If we are talking about visible stars, the Sun is a minus 26 but that won’t tell you much. It’s more useful to speak about its luminosity. Betelgeuse is about 100,000 times brighter than the Sun. We know that Betelgeuse is a huge star. It has ten to 15 times more mass than the Sun, so it is a red super giant. This also means the star is near the end of its life. For the bulk of its life, it was a blue super giant, like Rigel (Beta Orionis). It existed for ten million years as a blue supergiant, and became a red supergiant only in the last 100 thousand years. Betelgeuse is actually the brightest star in the constellation Orion in the winter sky.
S.S.: Can we see them from Earth with the naked eye?
N.C.: Yes, of course. These are among the brightest stars in the winter sky. Astrophysicists know that when a star becomes a red supergiant it is about to explode. We have already observed supernovas, for instance, in the Taurus Galaxy, which produced the Crab Nebula. In 1604, Kepler witnessed another supernova, the last one that was visible in our galaxy. However, we know that another supernova in the constellation Cassiopeia appeared 100 years after the one Kepler saw, but for some reason it wasn’t visible in Europe. It probably occurred in the fall or winter when the sky was overcast.
As for Betelgeuse, astrophysicists would love to witness it explode and become a supernova, but that could happen at any time in the course of its 100 thousand years as a red super giant. And we don’t know if we are in the beginning, middle, or end of this period.
S.S.: And could the star have already exploded but the light rays from it haven’t yet reached us?
N.C.: This is also possible. Betelgeuse is 640 light years away from the Earth, so it takes light from Betelgeuse 640 years to reach us.
S.S.: In other words, it may have already exploded but we just can’t see the effects. There are predictions of an apocalypse in 2012. Could the energy and particles emitted from the supernova put the Earth in danger? Should we be scared?
Nikolai Chugai: No, I don’t think there’s anything to be scared of. We will see a bright light, a flash, which will last for years. But even at its strongest, it will be about as bright as the Moon – not anywhere near as bright as the Sun. There are several types of supernovas, and we know that this one will be a type two. We also know what its maximum luminosity will be; we have seen similar ones in other galaxies. It will be bright enough to light up the night sky as much as the Moon does. As for gamma rays or high-energy particles, there’s no reason to worry about them. We have nothing to be concerned about before the shock wave reaches the Earth, and this won’t happen for a very long time. It will expand at a speed well below the speed of light. If it takes the speed of light 640 year to reach the Earth, something travelling a hundred times slower will take a very long time to reach us.
S.S.: As I understand, there are lots of potential research topics to choose from in your field. Why do you focus on supernovas?
N.C.: First, a supernova is just an amazing phenomenon. Apart from the birth of the universe, it is one of the most powerful explosions in the universe in terms of the energy released. One wonders about the mechanism behind these explosions. We know that stars explode when their life expires and we also know that there are two types of supernovas. There are many reasons to find supernovas interesting. For example, supernovas play a decisive role in the formation of elements in the universe. When the universe was born as a result of a Big Bang, it was initially composed of just two elements, hydrogen and helium. These elements alone could not produce planets, solid bodies or life. But when subjected to the thermonuclear processes inside stars, they combine to make new elements. When stars die, they explode, ejecting these new elements, created as a result of a thermonuclear fusion, into space. So, in a very real sense, we owe our very existence to supernovas.