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Novae and Supernovae

A nova is an explosion from the surface of a white-dwarf star in a binary star system. A nova occurs when the white dwarf, which is the dense core of a once-normal star, “steals” gas from its nearby companion star. When enough gas builts up on the surface of the white dwarf it triggers an explosion. For a brief time, the system can shine up to a million times brighter than normal. As long as it continues to take gas from its companion star, the white dwarf can produce nova outbursts at regular intervals. A supernova is a violent stellar explosion that can shine as brightly as an entire galaxy of billions of normal stars. Astronomers divide supernovae into two groups: Type I and Type II. Type I supernovae most likely form as a white dwarf “steals” hot gas from a companion star. If enough gas piles up on the surface of the white dwarf, a runaway thermonuclear explosion blasts the star to bits, leaving nothing behind. These are the brightest supernovae, and can be used to measure the distances to other galaxies. Type II supernovae are the final stage in the evolution of stars that are at least eight times as massive as the Sun. Such a star reaches a point where it can no longer produce nuclear energy in its core. Without the outward pressure created by this energy, gravity wins out and causes the star’s core to collapse to form a neutron star or black hole. The star’s outer layers “rebound” violently, blasting into space at several percent of the speed of light.

Resources

Exploding Stars May 21, 2010

Radio Programs

Outbursts Flickering lights in the night sky February 10, 2014

‘Medium’ Nova A mid-size stellar explosion July 1, 2013

Multiple Blasts Multiple explosions from a single star November 1, 2012

Pulsars The steady beat of dead stars January 6, 2012

Crab Nebula The “crabby” remains of an exploded star January 5, 2012

Betelgeuse A superstar among supergiants November 30, 2011

Cassiopeia A Muffling the death throes of a star October 4, 2011

Scorpius Nova A bright stellar merger August 28, 2011

V404 Cygni A dark star system that puts on a show August 13, 2011

IceCube Lighting up the Antarctic ice July 20, 2011

Moon and Antares Giving birth to a big family of stars July 10, 2011

Brightest X-Ray Burst The brilliant death of a distant star June 19, 2011

Flickering Crab A dead but fascinating star April 7, 2011

Young Black Hole Watching an infant black hole March 8, 2011

Stellar Factory Forging elements in a stellar factory February 14, 2011

Featured Images

Artist's concept of the pulsar and planets in the system PSR B1257+12

Second-Chance Planets January 8, 2012

M1, the Crab Nebula, in a Hubble Space Telescope image

Crab Nebula January 6, 2012

Plumes of gas spew into space from the roiling surface of Betelgeuse, the bright

Stellar Timebomb December 1, 2011

X-ray view of the Carina Nebula, a stellar nursery 7,500 light-years from Earth

Star Factory May 26, 2011

Visible and X-ray image of a supernova remnant in the Large Magellanic Cloud

Holiday Decoration December 16, 2010

A multi-spectral view of a supernova remnant in the Small Magellanic Cloud

Life from Death September 17, 2010

Rings and bubbles from a dying star

Jumping Through Hoops August 5, 2010

The remains of a supernova explosion form complex loops and filaments in this co

Colorful Aftermath May 27, 2010

Dust Storm April 2, 2010

A Dose of Magnesium January 20, 2010