white dwarf Archives

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.

January 8, 2020January 8, 2020 by Evan Gough

Forget Betelgeuse, the Star V Sagittae Should Go Nova Within this Century

An artist's image of a white dwarf drawing material away from its companion. Image Credit: NASA

The star V Sagittae is the next candidate to explode in stellar pyrotechnics, and a team of astronomers set the year for that cataclysmic explosion at 2083, or thereabouts. V Sagittae is in the constellation Sagitta (latin for arrow,) a dim and barely discernible constellation in the northern sky. V Sagittae is about 1100 light years from Earth.

September 5, 2019September 5, 2019 by Evan Gough

This Star Has Reached the End of its Life

This Picture of the Week from the NASA/ESA Hubble Space Telescope shows NGC 5307, a planetary nebula which lies about 10000 light years from Earth. It can be seen in the constellation Centaurus (The Centaur), which can be seen primarily in the southern hemisphere. A planetary nebula is the final stage of a Sun-like star. As such, planetary nebulae allow us a glimpse into the future of our own Solar System. A star like our Sun will, at the end of its life, transform into a red giant. Stars are sustained by the nuclear fusion that occurs in their core, which creates energy. The nuclear fusion processes constantly try to rip the star apart. Only the gravity of the star prevents this from happening. At the end of the red giant phase of a star, these forces become unbalanced. Without enough energy created by fusion, the core of the star collapses in on itself, while the surface layers are ejected outward. After that, all that remains of the star is what we see here: glowing outer layers surrounding a white dwarf star, the remnants of the red giant star’s core. This isn’t the end of this star’s evolution though — those outer layers are still moving and cooling. In just a few thousand years they will have dissipated, and all that will be left to see is the dimly glowing white dwarf.

About 10,000 light years away, in the constellation Centaurus, is a planetary nebula called NGC 5307. A planetary nebula is the remnant of a star like our Sun, when it has reached what can be described as the end of its life. This Hubble image of NGC 5307 not only makes you wonder about the star’s past, it makes you ponder the future of our very own Sun.

February 19, 2019February 19, 2019 by Evan Gough

This Star Has Been Going Nova Every Year, for Millions of Years

A nova star is like a vampire that siphons gas from its binary partner. As it does so, the gas is compressed and heated, and eventually it explodes. The remnant gas shell from that explosion expands outward and is lit up by the stars at the center of it all. Most of these novae explode about once every 10 years.

But now astrophysicists have discovered one remnant so large that the star that created it must have been erupting yearly for millions of years.

December 31, 2018 by Paul M. Sutter

A Guide to Hunting Zombie Stars

R Aquarii is called a symbiotic star system because of their relationship. As the white dwarf draws in material from the Red Giant, it ejects some if it in weird looping patterns, seen in this Hubble image. Image Credit: By Judy Schmidt from USA - Symbiotic System R Aquarii, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=63473035

Apparently not all supernovas work. And when they fail, they leave behind a half-chewed remnant, still burning from leftover heat but otherwise lifeless: a zombie star. Astronomers aren’t sure how many of these should-be-dead creatures lurk in the interstellar depths, but with recent simulations scientists are making a list of their telltale signatures so that future surveys can potentially track them down.

Continue reading “A Guide to Hunting Zombie Stars”

December 13, 2018 by Evan Gough

You’re Looking at an Actual Image of a White Dwarf Feeding on Material from a Larger Red Giant, 650 Light Years from Earth.

This image is from the SPHERE/ZIMPOL observations of R Aquarii, and shows the binary star itself, with the white dwarf feeding on material from the Mira variable, as well as the jets of material spewing from the stellar couple. Image Credit: ESO/Schmid et al.

The SPHERE planet-hunting instrument on the European Southern Observatory’s Very Large Telescope captured this image of a white dwarf feeding on its companion star, a type of Red Giant called a Mira variable. Most stars exist in binary systems, and they spend an eternity serenely orbiting their common center of gravity. But something almost sinister is going on between these two.

Astronomers at the ESO have been observing the pair for years and have uncovered what they call a “peculiar story.” The Red Giant is a Mira variable, meaning it’s near the end of its life, and it’s pulsing up to 1,000 times as bright as our Sun. Each time it pulses, its gaseous envelope expands, and the smaller White Dwarf strips material from the Red Giant.

Continue reading “You’re Looking at an Actual Image of a White Dwarf Feeding on Material from a Larger Red Giant, 650 Light Years from Earth.”

October 10, 2018 by Evan Gough

348 Years Ago, a French Astronomer Monk Might have Witnessed the Collision Between a White and Brown Dwarf Star

This hourglass-shaped figure is named CK Vulpeculae. It was discovered by French Monk-Astronomer Per Dom Anthelme in 1670. A new study identifies it as the remnant of a collision between a white dwarf and a brown dwarf. Image Credit: ALMA (ESO/NAOJ/NRAO)/S. P. S. Eyres

There’s something poignant and haunting about ancient astronomers documenting things in the sky whose nature they could only guess at. It’s true in the case of Père Dom Anthelme, who in 1670 saw a star suddenly burst into view near the head of the constellation Cygnus, the Swan. The object was visible with the naked eye for two years, as it flared in the sky repeatedly. Then it went dark. We call that object CK Vulpeculae.

Continue reading “348 Years Ago, a French Astronomer Monk Might have Witnessed the Collision Between a White and Brown Dwarf Star”