Shrinking giants, exploding dwarves

August 28, 2007

When 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.
The Weizmann Institute of Science in Rehovot, Israel, is one of the world's top-ranking multidisciplinary research institutions. Noted for its wide-ranging exploration of the natural and exact sciences, the Institute is home to 2,600 scientists, students, technicians and supporting staff. Institute research efforts include the search for new ways of fighting disease and hunger, examining leading questions in mathematics and computer science, probing the physics of matter and the universe, creating novel materials and developing new strategies for protecting the environment.

Weizmann Institute news releases are posted on the World Wide Web at .

Weizmann Institute of Science

Related White Dwarf Articles from Brightsurf:

Two planets around a red dwarf
The 'SAINT-EX' Observatory, led by scientists from the National Centre of Competence in Research NCCR PlanetS of the University of Bern and the University of Geneva, has detected two exoplanets orbiting the star TOI-1266.

A white dwarf's surprise planetary companion
For the first time, an intact, giant exoplanet has been discovered orbiting close to a white dwarf star.

KU astronomer helps confirm first-ever planet found orbiting white dwarf
A University of Kansas astronomer played a key role on the team that today announced the first-ever discovery of a planet orbiting a white dwarf.

HKU's Laboratory for Space Research member co-discovers first planet found around white dwarf star
An international team of astronomers led by the University of Wisconsin-Madison, including NASA co-authors, and Thomas G.

Experiments replicate high densities in 'white dwarf' stars
In a project conducted at the National Ignition Facility at Lawrence Livermore National Laboratory, a research team including University of Rochester engineering professor Gilbert (Rip) Collins, simulated the crushing pressure created as white dwarf stars cease to produce their own fuel, leaving only an extremely dense core.

Measuring the wind speed on a brown dwarf
Strong winds blow high in the atmosphere of the brown dwarf 2MASS J1047+21, according to a new study, which presents a simple method to deduce the windspeed in other brown dwarf atmospheres, too.

Astronomers measure wind speed on a brown dwarf
Using VLA and Spitzer observations, astronomers are able to determine wind speeds on a brown dwarf for the first time.

Observed: An occultation of a brown dwarf by another
An international team of astronomers in the project SPECULOOS, dedicated to the search for habitable planets, with scientists participating from the Instituto de Astrofísica de Canarias (IAC) has discovered an eclipse (termed an occultation) in a peculiar brown dwarf formed by two stars orbiting around each other.

Two stars merged to form massive white dwarf
A massive white dwarf star with a bizarre carbon-rich atmosphere could be two white dwarfs merged together according to an international team led by University of Warwick astronomers, and only narrowly avoided destruction.

Pulsar-white dwarf binary system confirms general relativistic frame-dragging
A century after it was first theorized, researchers have detected the effects of Lense-Thirring precession -- an effect of relativistic frame-dragging -- in the motion of a distant binary star system, a new study reports.

Read More: White Dwarf News and White Dwarf Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to