|
|
The Question
(Submitted February 02, 1998)
What is a Nova?
Can you please simplify this for me since I'm new to
astronomy? What is the relationship between a Nova and
a Supernova?
The Answer
A nova is a sudden brightening of a star. Novae are thought to occur on
the surface of a white dwarf star in a binary system with another star.
If these two stars are close enough to each other, material from one
star can be pulled off its surface and onto the white dwarf. Occasionally,
the temperature of this new material on the surface of the white dwarf
may become hot enough to start nuclear fusion and suddenly the surface of
the white dwarf will start to fuse the hydrogen into helium over its
surface. This causes the white dwarf to suddenly become very bright.
Ancient astronomers, who did not have telescopes and other instruments
modern astronomers now have, did not realize that there was a star already
there, and so they would just see a new star where they had not seen one
before. "Stella Nova" means "new star" in Latin and this is where novae got
their
name. Supernovae were once thought to just be really bright novae (hence
the addition of "super" to their name). If you look at
http://imagine.gsfc.nasa.gov/docs/science/know_l2/supernovae.html
you can see there are two types of supernova, one of which occurs in the
same binary systems as nova. If a nova fails to clear enough material off
the surface of the white dwarf, enough may collect for the entire star to
be destroyed by a very large (a "super") nova explosion. The other type of
supernova is from the end of a massive isolated star and is not related to
nova at all.
Jesse Allen
for Ask a High-Energy Astronomer
|
