White dwarf Archives

July 12, 2021July 12, 2021 by Matt Williams

A Nearby White Dwarf Might be About to Collapse Into a Neutron Star

About 97% of all stars in our Universe are destined to end their lives as white dwarf stars, which represents the final stage in their evolution. Like neutron stars, white dwarfs form after stars have exhausted their nuclear fuel and undergo gravitational collapse, shedding their outer layers to become super-compact stellar remnants. This will be the fate of our Sun billions of years from now, which will swell up to become a red giant before losing its outer layers.

Unlike neutron stars, which result from more massive stars, white dwarfs were once about eight times the mass of our Sun or lighter. For scientists, the density and gravitational force of these objects is an opportunity to study the laws of physics under some of the most extreme conditions imaginable. According to new research led by researchers from Caltech, one such object has been found that is both the smallest and most massive white dwarf ever seen.

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.

January 21, 2021January 21, 2021 by Brian Koberlein

Strange Green Star is the Result of a Merger Between two White Dwarfs

Artist view of a binary white dwarf. Credit: University of Sheffield

A white dwarf isn’t your typical kind of star. While main sequence stars such as our Sun fuse nuclear material in their cores to keep themselves from collapsing under their own weight, white dwarfs use an effect known as quantum degeneracy. The quantum nature of electrons means that no two electrons can have the same quantum state. When you try to squeeze electrons into the same state, they exert a degeneracy pressure that keeps the white dwarf from collapsing.

December 12, 2020December 12, 2020 by Brian Koberlein

Is There a way to Detect Strange Quark Stars, Even Though They Look Almost Exactly Like White Dwarfs?

A neutron star (~25km across) next to a quark star (~16km across). Original Image Credit: NASA's Goddard Space Flight Center

The world we see around us is built around quarks. They form the nuclei of the atoms and molecules that comprise us and our world. While there are six types of quarks, regular matter contains only two: up quarks and down quarks. Protons contain two ups and a down, while neutrons contain two downs and an up. On Earth, the other four types are only seen when created in particle accelerators. But some of them could also appear naturally in dense objects such as neutron stars.

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.

August 24, 2020August 24, 2020 by Brian Koberlein

Scientists Recreate the Density of a White Dwarf in the Lab

The density of a white dwarf star defies our imagination. A spoonful of white dwarf matter would weigh as much as a car on Earth. Atoms within the star are squeezed so tightly that they are on the edge of collapse. Squeeze a white dwarf just a bit more, and it will collapse into a neutron star. And now, we can recreate the density of a white dwarf within a lab.

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.

May 1, 2020May 1, 2020 by Evan Gough

Rocky Planets Orbiting White Dwarf Stars Could be the Perfect Places to Search for Life

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

Some very powerful telescopes will see first light in the near future. One of them is the long-awaited James Webb Space Telescope (JWST.) One of JWST’s roles—and the role of the other upcoming ‘scopes as well—is to look for biosignatures in the atmospheres of exoplanets. Now a new study is showing that finding those biosignatures on exoplanets that orbit white dwarf stars might give us our best chance to find them.

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.