Back in January of 2002, astronomers witnessed a huge explosion from the star V838 Monocerotis, a red variable star about 20,000 light years away from our Sun.
At first, they thought it was a typical supernova (the explosion of a dying star), but after watching the explosion dim then brighten twice over a period of only a few months (supernovas will usually only dim after the initial bright explosion), astronomers really weren’t sure what they were dealing with.
Check out a time-lapse of the explosion from 2002-2006 below (full screen highly suggested).
So what exactly is going on with this explosion? Well, there are five possibilities that have been proposed so far:
- The explosion was a supernova, just a very unique one with a multi-outburst pattern, which would explain the multiple brightening and dimming events. Most scientists agree that the large size and young age of the stars in that region makes this explanation unlikely, however.
- The explosion was a thermal pulse. When moderately-sized stars run out of fuel, they explode (in a supernova), leaving behind a dense core of hydrogen and helium. Sometimes this hydrogen and helium core can be re-ignited, illuminating the layers of ejected star material from the supernova explosion. Again, however, the star’s young age makes this possibility unlikely.
- Another theory also proposes a helium flash, but one that occurred as a result of thermonuclear processes in a massive supergiant star. Supergiants can be large enough for an outer layer of helium to ignite and start the fusion process without the whole star being destroyed. This theory fits with the star’s age, but it doesn’t seem that V838 Monocerotis had enough mass for this process occur.
- Planetary capture: when a star grows to large proportions, it can start consuming nearby planets. The friction generated when a very large planet gets pulled apart by the star’s gravity can produce enough energy to spark deuterium fusion, which releases massive amounts of energy (like what we see in the time-lapse).
- The explosion was a result of a mergeburst. Sometimes, in clusters of younger stars (where orbits can be very unstable), two main-sequence stars can collide, creating an explosion similar to the one in the video. The relatively young age of the stars near V838 Monocerotis make this a reasonable possibility, and this hypothesis has also been supported by computer modeling.
It’s awesome to study the stars and find out exactly why they act the way they do, but sometimes explanations can be elusive. So while we search for answers, we should also make sure we take the time to simply enjoy watching this mesmerizing cosmic phenomenon.