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 Some types of stars expire with titanic...

Radio Programs

Outbursts Flickering lights in the night sky Tuesday, February 11, 2014
‘Medium’ Nova A mid-size stellar explosion Tuesday, July 2, 2013
Multiple Blasts Multiple explosions from a single star Friday, November 2, 2012
Pulsars The steady beat of dead stars Saturday, January 7, 2012
Crab Nebula The “crabby” remains of an exploded star Friday, January 6, 2012
Betelgeuse A superstar among supergiants Thursday, December 1, 2011
Cassiopeia A Muffling the death throes of a star Wednesday, October 5, 2011
Scorpius Nova A bright stellar merger Monday, August 29, 2011
V404 Cygni A dark star system that puts on a show Sunday, August 14, 2011
IceCube Lighting up the Antarctic ice Thursday, July 21, 2011
Moon and Antares Giving birth to a big family of stars Monday, July 11, 2011
Brightest X-Ray Burst The brilliant death of a distant star Monday, June 20, 2011
Flickering Crab A dead but fascinating star Friday, April 8, 2011
Young Black Hole Watching an infant black hole Wednesday, March 9, 2011
Stellar Factory Forging elements in a stellar factory Tuesday, February 15, 2011
Nova Cygni 1975 A temporary tail feather for the swan Sunday, August 29, 2010
Supernova 1885 Lighting up the enormous universe Friday, August 20, 2010
Too Darn Hot Stars that can't stand the heat Thursday, April 1, 2010
Nova T Pyxidis Building up to a stellar suicide Sunday, March 7, 2010
Rigel Getting away from a brilliant star Thursday, February 11, 2010
Regal Explosions, Part 2 A bashful exploding star Friday, November 6, 2009
Regal Explosions A little star that packed a punch Thursday, November 5, 2009
More Moon and Antares Two stars that'll shed some weight Thursday, September 24, 2009
Aquila The eagle soars high overhead Monday, September 7, 2009
Nucleosynthesis Mixing up a chemical stew Monday, August 10, 2009
Moon and Scorpius A headful of stars for the scorpion Friday, June 5, 2009
RS Ophiuchi One star gives, another takes Monday, June 1, 2009
Brilliant Demise A brilliant blast from the past Thursday, March 19, 2009
S Monocerotis Lighting up the unicorn Sunday, February 22, 2009
Gamma-Ray Bursts III One more moment of glory Wednesday, January 28, 2009
Gamma-Ray Bursts II A startling birth announcement Tuesday, January 27, 2009

Featured Images

Artist's concept of the pulsar and planets in the system PSR B1257+12
Second-Chance Planets Sunday, January 8, 2012
M1, the Crab Nebula, in a Hubble Space Telescope image
Crab Nebula Friday, January 6, 2012
Plumes of gas spew into space from the roiling surface of Betelgeuse, the bright
Stellar Timebomb Thursday, December 1, 2011
X-ray view of the Carina Nebula, a stellar nursery 7,500 light-years from Earth
Star Factory Thursday, May 26, 2011
Visible and X-ray image of a supernova remnant in the Large Magellanic Cloud
Holiday Decoration Thursday, December 16, 2010
A multi-spectral view of a supernova remnant in the Small Magellanic Cloud
Life from Death Friday, September 17, 2010
Rings and bubbles from a dying star
Jumping Through Hoops Thursday, August 5, 2010
The remains of a supernova explosion form complex loops and filaments in this co
Colorful Aftermath Thursday, May 27, 2010
Dust Storm Friday, April 2, 2010
A Dose of Magnesium Wednesday, January 20, 2010
RS Ophiuchi Monday, June 1, 2009
Magnetar Thursday, March 5, 2009
Boom! Wednesday, January 28, 2009
Hot Bubble Saturday, December 6, 2008
On the Bubble Friday, July 18, 2008
Timebomb Wednesday, March 5, 2008
Thrown for a Loop Wednesday, January 9, 2008
Brilliant Discovery Thursday, September 20, 2007
Beautiful in Death Thursday, August 23, 2007
Stellar Cyclops Monday, July 16, 2007
Magnetic Blast Wednesday, May 30, 2007
Kepler's Odd Supernova Friday, March 9, 2007
Big Blast, Big Universe Thursday, February 22, 2007
Blast from the Past Tuesday, February 20, 2007
An X-ray image of Kepler's supernova of 1604.
New Twist on an Old Star Thursday, January 11, 2007
Cosmic Bauble Wednesday, December 6, 2006
Smokin' Galaxy Wednesday, May 24, 2006
Bright Reminder Monday, May 1, 2006

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