White dwarf Archives

December 3, 2024December 3, 2024 by Brian Koberlein

White Dwarfs Could Have Habitable Planets, Detectable by JWST

An Earth-sized remnant of a Sun-like star is ringed by dust and debris. Credit: NASA’s Goddard Space Flight Center/Scott Wiessinger

In a few billion years, our Sun will die. It will first enter a red giant stage, swelling in size to perhaps the orbit of Earth. Its outer layers will be cast off into space, while its core settles to become a white dwarf. Life on Earth will boil away, and our planet itself might be consumed by the Sun. White dwarfs are the fate of all midsize stars, and given the path of their demise, it seems reasonable to assume that any planets die with their sun. But the fate of white dwarf planets may not be lifeless after all.

October 28, 2024October 28, 2024 by Evan Gough

This Ancient Supernova Remnant Looks Like a Stellar Dandelion

An artist’s concept of a supernova remnant called Pa 30—the leftover remains of a supernova explosion that was witnessed from Earth in the year 1181. Unusual filaments of sulfur protrude beyond a dusty shell of ejected material. The remains of the original star that exploded, now a hot inflated star which may cool to become a white dwarf, are seen at the center of the remnant. The Keck Cosmic Web Imager (KCWI) at the W.M. Keck Observatory in Hawai‘i has mapped the strange filaments in 3-D and shown that they are flying outward at approximately 1,000 kilometers per second. Image Credit: W.M. Keck Observatory/Adam Makarenko

In 1181, Japanese and Chinese astronomers saw a bright light appear in the constellation Cassiopeia. It shone for six months, and those ancient observers couldn’t have known it was an exploding star. To them, it looked like some type of temporary star that shone for 185 days.

In the modern astronomical age, we’ve learned a lot more about the object. It was a supernova called SN 1181 AD, and we know that it left behind a remnant “zombie” star. New research examines the supernova’s aftermath and the strange filaments of gas it left behind.

July 9, 2024July 9, 2024 by Carolyn Collins Petersen

Ancient People Saw a Kilonova Light up the Sky

A comparison between the observed XMM-Newton image of the kilonova 1181 with an IRAS-derived schematic of infrared contours (presumably of the dust ring) around the resulting white dwarf. This kilonova occurred when two white dwarfs collided and were observed in 1181. Courtesy Ko, et al, 2024.

What happens when aging white dwarf stars come together? Observers in feudal Japan in the year 1181 had a front-row view of the superpowerful kilonova created by such a merger. Their records show that a rare “guest star” flared up and then faded. It took until 2021 for astronomers to find the place in the sky where it occurred.

May 14, 2024May 14, 2024 by Matt Williams

White Dwarfs are Often Polluted With Heavier Elements. Now We Know Why

In this artist's illustration, lumps of debris from a disrupted planetesimal are irregularly spaced on a long and eccentric orbit around a white dwarf. Credit: Dr Mark Garlick/The University of Warwick

When stars exhaust their hydrogen fuel at the end of their main sequence phase, they undergo core collapse and shed their outer layers in a supernova. Whereas particularly massive stars will collapse and become black holes, stars comparable to our Sun become stellar remnants known as “white dwarfs.” These “dead stars” are extremely compact and dense, having mass comparable to a star but concentrated in a volume about the size of a planet. Despite being prevalent in our galaxy, the chemical makeup of these stellar remnants has puzzled astronomers for years.

For instance, white dwarfs consume nearby objects like comets and planetesimals, causing them to become “polluted” by trace metals and other elements. While this process is not yet well understood, it could be the key to unraveling the metal content and composition (aka. metallicity) of white dwarf stars, potentially leading to discoveries about their dynamics. In a recent paper, a team from the University of Colorado Boulder theorized that the reason white dwarf stars consume neighboring planetesimals could have to do with their formation.

April 9, 2024April 9, 2024 by Evan Gough

What Happens to Solar Systems When Stars Become White Dwarfs?

In a couple billion years, our Sun will be unrecognizable. It will swell up and become a red giant, then shrink again and become a white dwarf. The inner planets aren’t expected to survive all the mayhem these transitions unleash, but what will happen to them? What will happen to the outer planets?

March 28, 2024March 28, 2024 by Evan Gough

This Supernova Lit Up the Sky in 1181. Here’s What it Looks Like Now

A composite image of the remnant of supernova 1181. A spherical bright nebula sits in the middle surrounded by a field of white dotted stars. Within the nebula several rays point out like fireworks from a central star. G. Ferrand and J. English (U. of Manitoba), NASA/Chandra/WISE, ESA/XMM, MDM/R.Fessen (Dartmouth College), Pan-STARRS

Historical astronomical records from China and Japan recorded a supernova explosion in the year 1181. It was in the constellation Cassiopeia and it shone as bright as the star Vega for 185 days. Modern astronomers took their cue from their long-gone counterparts and have been searching for its remnant.

But it took them time to find it because they were looking for the wrong thing.

March 9, 2024March 15, 2024 by Brian Koberlein

White Dwarfs Might Be Less Dead Than We Thought

Artist illustration of crystals forming within a white dwarf. Credit: University of Warwick/Mark Garlick

At the end of their lives, most stars including the Sun will become white dwarfs. After a red dwarf or sun-like star consumes all the hydrogen and helium it can, the remains of the star will collapse under its own weight, shrinking ever more until the quantum pressure of electrons becomes strong enough to counter gravity. White dwarfs begin their days as brilliantly hot embers of degenerate matter and grow ever cooler and dimmer as they age.

March 4, 2024March 4, 2024 by Brian Koberlein

Astronomers Can See the Impact Site Where an Asteroid Crashed Into a White Dwarf

This artist’s impression shows the magnetic white dwarf WD 0816-310. Credit: ESO/L. Calçada

Nothing is immortal. Everything has a finite existence, including the stars themselves. How a star dies depends on several factors, most importantly their mass. For the Sun, this means that in several billion years it will swell to a red giant as it churns through the last of its nuclear fuel. The core that remains will then collapse to become a white dwarf. Of course, the Sun is home to several planets, including Earth. What of their fate? What of ours? According to a recent study, the Sun’s death might consume Earth in the end.

January 30, 2024January 30, 2024 by Evan Gough

Webb Directly Images Two Planets Orbiting White Dwarfs

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 several billion years, our Sun will become a white dwarf. What will happen to Jupiter and Saturn when the Sun transitions to become a stellar remnant? Life could go on, though the giant planets will likely drift further away from the Sun.

November 1, 2023November 1, 2023 by Evan Gough

White Dwarfs Could Support Life. So Where are All Their Planets?

Artist's view of old white dwarfs surrounded by planetary debris. Credit: University of Warwick/Dr Mark Garlick

Astronomers have found plenty of white dwarf stars surrounded by debris disks. Those disks are the remains of planets destroyed by the star as it evolved. But they’ve found one intact Jupiter-mass planet orbiting a white dwarf.

Are there more white dwarf planets? Can terrestrial, Earth-like planets exist around white dwarfs?