Space and astronomy news
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.
Continue reading “Ancient People Saw a Kilonova Light up the Sky”
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.
Continue reading “White Dwarfs are Often Polluted With Heavier Elements. Now We Know Why”
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?
Continue reading “What Happens to Solar Systems When Stars Become White Dwarfs?”
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.
Continue reading “This Supernova Lit Up the Sky in 1181. Here’s What it Looks Like Now”
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.
Continue reading “White Dwarfs Might Be Less Dead Than We Thought”
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.
Continue reading “Astronomers Can See the Impact Site Where an Asteroid Crashed Into a White Dwarf”
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.
Continue reading “Webb Directly Images Two Planets Orbiting White Dwarfs”
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?
Continue reading “White Dwarfs Could Support Life. So Where are All Their Planets?”
Debris disks are quite common in the Universe. Young stars have protoplanetary disks from which planets form. Black holes have accretion disks that are the source of the galactic jets. Supernova remnants can form a disk around neutron stars. So what about white dwarfs?
Continue reading “JWST Looks at the Debris Disc Around a White Dwarf”
All supernovae are exploding stars. But the nature of a supernova explosion varies quite a bit. One type, named Type 1a supernovae, involves a binary star where one of the pair is a white dwarf. And while supernovae of all types usually involve a single explosion, astronomers have found something that breaks that mould: A Type 1a supernova that may have detonated twice.
Continue reading “Did this Supernova Explode Twice?”