SUPERNOVA
A supernova is the
explosion of a star. It is the largest explosion that takes place in space.
WHERE DO SUPERNOVAS TAKE PLACE?
Supernovas are
often seen in other galaxies. But supernovas are difficult to see in our own
Milky Way galaxy because dust blocks our view. In 1604, Johannes Kepler
discovered the last observed supernova in the Milky Way. NASA’s Chandra
telescope discovered the
remains
of a more recent supernova. It exploded in the Milky Way more than a hundred
years ago.
WHAT CAUSES A SUPERNOVA?
A supernova happens where
there is a change in the core, or center, of a star. A change can occur in two
different ways, with both resulting in a supernova.
The first type of
supernova happens in binary star systems. Binary stars are two stars that orbit
the same point. One of the stars, a carbon-oxygen white dwarf, steals matter from its companion star.
Eventually, the white dwarf accumulates too much matter. Having too much matter
causes the star to explode, resulting in a supernova.
The second type of
supernova occurs at the end of a single star’s lifetime. As the star runs out
of nuclear fuel, some of its mass flows into its core. Eventually, the core is
so heavy that it cannot withstand its own gravitational force. The core
collapses, which results in the giant explosion of a supernova. The sun is a
single star, but it does not have enough mass to become a supernova.
WHY DO SCIENTISTS STUDY SUPERNOVAS?
A supernova burns for only
a short period of time, but it can tell scientists a lot about the universe.
One kind of supernova has
shown scientists that we live in an expanding universe, one that is growing at
an ever increasing rate.
Scientists
also have determined that supernovas play a key role in distributing elements
throughout the universe. When the star explodes, it shoots elements and debris
into space. Many of the elements we find here on Earth are made in the core of
stars. These elements travel on to form new stars, planets and everything else
in the universe.
HOW DO NASA SCIENTISTS LOOK FOR SUPERNOVAS?
NASA scientists use different types of
telescopes to look for and study supernovas. Some telescopes are used to
observe the visible light from the explosion. Others record data from the X-rays and gamma
rays that are also produced. Both NASA’s Hubble Space Telescope and Chandra X-ray Observatory have captured
images of supernovas.
In June 2012, NASA
launched the first orbiting telescope that focuses light in the high-energy
region of the electromagnetic spectrum. The NuSTAR mission has a number of jobs
to do. It will look for collapsed stars and black holes. It also will search for
the remains of supernovas. Scientists hope to learn more about how stars
explode and the elements that are created by supernovas.
