Shrinking giants, exploding dwarvesAugust 28, 2007When white dwarf stars explode, they leave behind a rapidly expanding cloud of 'stardust' known as a Type Ia supernova. These exploding events, which shine billions of times brighter than our sun, are all presumed to be extremely similar, and thus have been used extensively as cosmological reference beacons to trace distance and the evolution of the Universe. Astronomers have now - for the first time ever - provided a unique set of observations obtained with the ESO Very Large Telescope in Chile and the 10-meter Keck telescope in Hawaii, enabling them to find traces of the material that had surrounded a white dwarf star before it exploded. Their data set is unique in that no Type Ia supernova event has ever been observed at this level of detail over a several-month period following the explosion. These observations support a widely accepted model proposing that a white dwarf star interacts with a companion star - a red giant. Due to the white dwarf's strong gravitational pull, this companion star continuously loses mass through 'force feeding' its gases to the white dwarf. When the mass of the white dwarf grows past a critical value, it explodes. Through their observations, which took place over the course of four months, and combined with archival data, the astronomers detected the presence of a number of expanding shells surrounding a Type Ia super-nova event. The make-up of these shells suggests they are the remnants of the red giant star that fed the white dwarf. These results were recently published in the journal Science. The data were collected by two teams of researchers; one at ESO headed by Dr. Ferdinando Patat, and one at the California Institute of Technology, USA, led by Dr. Avishay Gal-Yam. Dr. Gal-Yam has recently joined the Weizmann Institute of Science as a senior scientist in the Condensed Matter Physics Department. Weizmann Institute of Science |
|||||||||||||||||||||
| Related White Dwarf Current Events and White Dwarf News Articles German high-school students involved in an astronomical research project This week, Astronomy & Astrophysics publishes a somewhat unusual research article because it is co-authored by German high-school students. Berkeley Lab Scientists' Computer Code Gives Astrophysicists First Full Simulation of Star's Final Hours The precise conditions inside a white dwarf star in the hours leading up to its explosive end as a Type Ia supernova are one of the mysteries confronting astrophysicists studying these massive stellar explosions. XMM-Newton uncovers a celestial Rosetta stone ESA's XMM-Newton orbiting X-ray telescope has uncovered a celestial Rosetta stone: the first close-up of a white dwarf star, circling a companion star, that could explode into a particular kind of supernova in a few million years. Peculiar, junior-sized supernova discovered by New York teen In November 2008, Caroline Moore, a 14-year-old student from upstate New York, discovered a supernova in a nearby galaxy, making her the youngest person ever to do so. NC State Researchers Researchers at North Carolina State University have used a mathematical model that allows them to get a clearer picture of the galaxy's youngest supernova remnant by correcting for the distortions caused by cosmic dust. Largest collection of anomalous white dwarfs observed in new Hubble images Twenty-four unusual stars, 18 of them newly discovered, have been observed in new Hubble telescope images. The stars are white dwarfs, a common type of dead star, but they are odd because they are made of helium rather than the usual carbon and oxygen. This is the first extensive sequence of helium-core white dwarfs to be observed in a globular cluster, a dense swarm of some of the oldest stars in our galaxy. UBC researchers develop breakthrough technique to unlock the secret of plasmas University of British Columbia researchers have developed a technique that brings scientists a big step closer to unlocking the secrets of the most abundant form of matter in the universe. Action Replay of Powerful Stellar Explosion Astronomers have made the best ever determination of the power of a supernova explosion that was visible from Earth long ago. By observing the remnant of a supernova and a light echo from the initial outburst, they have established the validity of a powerful new method for studying supernovas. Supernova remnants dance in the LMC The Gemini South Multi-Object Spectograph (GMOS) recently captured a dramatic image of a vast cloud complex named DEM L316 located in the Large Magellanic Cloud. White Dwarf Pulses Like a Pulsar New observations from Suzaku, a joint Japanese Aerospace Exploration Agency (JAXA) and NASA X-ray observatory, have challenged scientists' conventional understanding of white dwarfs. Observers had believed white dwarfs were inert stellar corpses that slowly cool and fade away, but the new data tell a completely different story. More White Dwarf Current Events and White Dwarf News Articles |
|||||||||||||||||||||
|
|||||||||||||||||||||
|
|||||||||||||||||||||