white dwarf Archives

June 12, 2021June 12, 2021 by Brian Koberlein

White Dwarf Measured Before it Exploded as a Supernova

Artist's impression of a supernova remnant. Credit: ESA/Hubble

Type Ia supernovae are an important tool for modern astronomy. They are thought to occur when a white dwarf star captures mass beyond the Chandrasekhar limit, triggering a cataclysmic explosion. Because that limit is the same for all white dwarfs, Type Ia supernovae all have about the same maximum brightness. Thus, they can be used as standard candles to determine galactic distances. Observations of Type Ia supernova led to the discovery of dark energy and that cosmic expansion is accelerating.

May 11, 2021May 10, 2021 by Paul M. Sutter

How can White Dwarfs Produce Such Powerful Magnetic Fields?

Illustration of the internal layers of a white dwarf star. Credit: University of Warwick/Mark Garlick

White dwarfs have some surprisingly strong magnetic fields, and one team of astronomers may have finally found the reason why. When they cool, they can activate a dynamo mechanism similar to what powers the Earth’s magnetic field.

February 1, 2021February 1, 2021 by Paul M. Sutter

White Dwarf Atmospheres Might Contain the Pulverized Crusts of Their Dead Planets

Astronomers have developed a new technique to search for exoplanets – by looking for their crushed up bones in the atmospheres of white dwarfs. And it’s working.

September 17, 2020September 17, 2020 by Evan Gough

James Webb Will Look for Signs of Life on Planets Orbiting Dead Stars

A planet orbiting a small star produces strong atmospheric signals when it passes in front, or “transits,” its host star, as pictured above. White dwarfs offer astronomers a rare opportunity to characterize rocky planets. Image Credit: Jack Madden/Carl Sagan Institute

Can the galaxy’s dead stars help us in our search for life? A group of researchers from Cornell University thinks so. They say that watching exoplanets transit in front of white dwarfs can tell us a lot about those planets.

It might even reveal signs of life.

July 30, 2020July 30, 2020 by Paul M. Sutter

There’s a flash of ultraviolet just as a white dwarf is exploding as a supernova

Artist's impression of a supernova. Supernovae bombarded Earth with radiation that has implications for the development of life on Earth. Image Credit: NASA

Astronomers recently spotted a rare type of supernova explosion that was accompanied by a massive flare of ultraviolet radiation. Untangling the mystery of the UV flash could help unravel the mysterious nature of these supernova explosions, and even help us understand the age of the universe.

July 20, 2020July 20, 2020 by Evan Gough

A Star had a Partial Supernova and Kicked Itself Into a High-Speed Journey Across the Milky Way

The material ejected by the supernova will initially expand very rapidly, but then gradually slow down, forming an intricate giant bubble of hot glowing gas. Eventually, the charred remains of the white dwarf that exploded will overtake these gaseous layers, and speed out onto its journey across the Galaxy. Credit: University of Warwick/Mark Garlick

Supernovae are some of the most powerful events in the Universe. They’re extremely energetic, luminous explosions that can light up the sky. Astrophysicists have a pretty good idea how they work, and they’ve organized supernovae into two broad categories: they’re the end state for massive stars that explode near the end of their lives, or they’re white dwarfs that draw gas from a companion which triggers runaway fusion.

Now there might be a third type.

July 16, 2020July 16, 2020 by Paul M. Sutter

White dwarfs are a big source of carbon in the Universe

Artist's rendition of a white dwarf from the surface of an orbiting exoplanet. Astronomers have found two giant planet candidates orbiting two white dwarfs. More proof that giant planets can surve their stars' red giant phases. Image Credit: Madden/Cornell University

In their nuclear hearts, stars fuse elements heavier than hydrogen, creating the ingredients necessary to make planets, oceans, and people. Tracing the origins of individual elements in the Milky Way has been a challenge, but a new analysis of white dwarf stars reveals that they may be responsible for one of the most essential elements of all: carbon.

April 21, 2020April 21, 2020 by Evan Gough

Astronomers Watch a Nova Go From Start to Finish for the First Time

Artistic representation of a nova eruption: During a nova eruption a white dwarf sucks matter from its companion star and stores this mass on its surface until the gas pressure becomes extremely high. CREDIT © Nova_by K. Ulaczyk, Warschau Universität Observatorium

A nova is a dramatic episode in the life of a binary pair of stars. It’s an explosion of bright light that can last weeks or even months. And though they’re not exactly rare—there are about 10 each year in the Milky Way—astronomers have never watched one from start to finish.

Until now.

April 7, 2020April 7, 2020 by Evan Gough

Astronomers Watched a Star System Die

This is an artist’s impression of a white dwarf (burned-out) star accreting rocky debris left behind by the star’s surviving planetary system. It was observed by Hubble in the Hyades star cluster. At lower right, an asteroid can be seen falling toward a Saturn-like disk of dust that is encircling the dead star. Infalling asteroids pollute the white dwarf’s atmosphere with silicon. Credit: NASA, ESA, and G. Bacon (STScI)

About 570 light years from Earth lies WD 1145+017, a white dwarf star. In many respects it’s a typical white dwarf star. Its mass is about 0.6 solar masses, and its temperature is about 15,900 Kelvin. But five years ago, a team of astronomers wrote a paper on the white dwarf, showing that something unusual was going on.

March 4, 2020March 4, 2020 by Evan Gough

Two White Dwarfs Merged Together Into a Single “Ultramassive” White Dwarf

An artist’s impression of two white dwarfs in the process of merging. Depending on the combined mass, the system may explode in a thermonuclear supernova, or coalesce into a single heavy white dwarf, as with WDJ0551+4135. This image is free for use if used in direct connection with this story but image copyright and credit must be University of Warwick/Mark Garlick

Astronomers have found a white dwarf that was once two white dwarfs. The pair of stars merged into one about 1.3 billion years ago. The resulting star, named WDJ0551+4135, is about 150 light years away.