Latest White dwarf Stories
Fluke observation 4 hours after star exploded allows stronger limits on size of progenitor Last year's discovery of the nearest Type Ia supernova in decades – captured only 11 hours after it exploded – allowed astronomers to finally cinch the identity of the stars behind these explosions, which have become key measures of cosmic distance. That supernova, called SN2011fe, and presumably most Type Ia supernovae were originally white dwarfs extremely dense and compact stars composed...
WASHINGTON, Jan. 11, 2012 /PRNewswire-USNewswire/ -- Using NASA's Hubble Space Telescope, astronomers have solved a longstanding mystery on the type of star, or so-called progenitor, which caused a supernova seen in a nearby galaxy. The finding yields new observational data for pinpointing one of several scenarios that trigger such outbursts. (Logo: http://photos.prnewswire.com/prnh/20081007/38461LOGO) Based on previous observations from ground-based telescopes, astronomers knew the...
Scientists have discovered that a supernova that exploded in August was a "white dwarf" star, and its companion star could not have been a "red giant." The thermonuclear Type Ia supernova exploded on August 24th in the Pinwheel galaxy, located in the "Big Dipper" star constellation. These supernovae are used to measure dark energy, which scientists believe is related to the expansion of the universe. The supernova, which is located about 21 million light-years away, could be seen in...
WASHINGTON, Oct. 24, 2011 /PRNewswire-USNewswire/ -- A mystery that began nearly 2,000 years ago, when Chinese astronomers witnessed what would turn out to be an exploding star in the sky, has been solved. New infrared observations from NASA's Spitzer Space Telescope and Wide-field Infrared Survey Explorer, or WISE, reveal how the first supernova ever recorded occurred and how its shattered remains ultimately spread out to great distances. (Logo:...
The photo of a nearby star and its orbiting companion -- whose temperature is like a hot summer day in Arizona -- will be presented by Penn State Associate Professor of Astronomy and Astrophysics Kevin Luhman during the Signposts of Planets conference at NASA's Goddard Space Flight Center on 20 October 2011. A paper describing the discovery will be published in the Astrophysical Journal. "This planet-like companion is the coldest object ever directly photographed outside our solar system,"...
Astronomers discover how mysterious stars stay so young Mysterious “blue stragglers” are old stars that appear younger than they should be: they burn hot and blue. Several theories have attempted to explain why they don’t show their age, but, until now, scientists have lacked the crucial observations with which to test each hypothesis. Armed with such observational data, two astronomers from Northwestern University and the University of Wisconsin-Madison report that a mechanism...
The largest survey to date of distant exploding stars is giving astronomers new clues to what’s behind the Type Ia supernovae they use to measure distances across the cosmos. These stellar explosions helped astronomers conclude more than a decade ago that dark energy is accelerating the expansion of the universe, and today (Tuesday, Oct. 4) earned the discoverers – including UC Berkeley physicist Saul Perlmutter – the 2011 Nobel Prize in Physics. But what caused them was a mystery....
Older stars may have to slow down their rotations before exploding as supernovae, according to a new study published earlier this month by scientists at the Harvard-Smithsonian Center for Astrophysics (CfA). In a September 6 press release, the researchers compare the phenomenon to "Speed," a motion picture whose plot revolves around a bus that will explode if it travels too slowly. According to their findings, which have been published in The Astrophysical Journal Letters, the...
WASHINGTON, Aug. 23, 2011 /PRNewswire-USNewswire/ -- Scientists using data from NASA's Wide-field Infrared Survey Explorer (WISE) have discovered the coldest class of star-like bodies, with temperatures as cool as the human body. (Logo: http://photos.prnewswire.com/prnh/20081007/38461LOGO ) Astronomers hunted these dark orbs, termed Y dwarfs, for more than a decade without success. When viewed with a visible-light telescope, they are nearly impossible to see. WISE's infrared vision allowed...
Type Ia supernovae are violent stellar explosions whose brightness is used to determine distances in the universe. Observing these objects to billions of light years away has led to the discovery that the universe is expanding at an accelerating rate, the foundation for the notion of dark energy. Although all Type Ia supernovae appear to be very similar, astronomers do not know for certain how the explosions take place and whether they all share the same origin. Now, a team of researchers has...
Latest White dwarf Reference Libraries
White Dwarf -- A white dwarf is a a star supported by electron degeneracy. A star like our Sun will become a white dwarf when it has exhausted its nuclear fuel. Near the end of its nuclear burning stage, such a star goes through a red giant phase and then expels most of its outer material (creating a planetary nebula) until only the hot (T > 100,000 K) core remains, which then settles down to become a young white dwarf. A typical white dwarf is half as massive as the Sun, yet only...
Stellar Evolution -- Stellar evolution is the process of formation, life, and death of stars. It is one of the major topics of cosmogony. Star Birth and Life A star starts out as an enormous cloud of gas and dust many light-years across. Star formation begins when the cloud begins to condense under its own gravity. The processes that initiate this contraction are not fully understood. The cloud fragments fuse into stellar mass clouds known as protostars. Protostars do not emit...
Nova -- A nova is an enormous nuclear explosion caused by the accretion of hydrogen onto the surface of a white dwarf star. When a white dwarf has a close companion star, the companion will often begin to have its outer atmosphere drawn away from it by the white dwarf's gravity as the companion star ages and expands into a red giant. The gases so captured consist primarily of hydrogen and helium, the two principle constituents of matter in the universe. The gases are compacted on the...
Cataclysmic Variable Star -- Cataclysmic variables are a class of binary stars containing a white dwarf and a companion star. The companion star is usually a red dwarf, although in some cases it is another white dwarf or a slightly evolved star (subgiant). Several hundreds of cataclysmic variables are known. From the observational viewpoint, cataclysmic variables are relatively easy to discover. They are usually quite blue objects, as the majority of stars are red. The variability of...
