Skip to main content

White dwarf star unexpectedly emitting bright ‘supersoft’ X-rays

The discovery of a white dwarf star emitting supersoft X-rays calls into question the conventional wisdom about how X-rays are produced by dying stars.

When stars run out of fuel after millions of years they shrink down to a smaller size and become much fainter, in a phase known as a white dwarf. The mass of the star remains the same but the size becomes much smaller, so these dwarfs have very strong gravity. White dwarfs are often found in pairs called binary systems, and their strong gravity means that they can pull matter away from their companion stars.

Recommended Videos

One such system has been identified by NASA’s Chandra X-Ray Observatory project, which found unusual X-ray emissions coming from the binary system containing a white dwarf called ASASSN-16oh. Normally, a star would be expected to produce low-energy X-rays, called soft X-rays. But the ASASSN-16oh white dwarf is emitting X-rays that are much brighter than expected, earning it the unusual classification of being a source of “supersoft” X-rays.

The supersoft X-rays suggest that the white dwarf must have a temperature of several hundred thousand degrees, which is hotter than normal stars. However, this high temperature is only found at certain points on the surface of the star. Astronomers believe this may be because ASASSN-16oh is pulling material away from its companion red giant at a fast rate, and this matter gets hotter and hotter as it spirals towards the white dwarf. The hot gas settles on the accretion disk (the disk of matter swirling around the star), where it eventually merges with the surface of the star and produces X-rays. However, because this process happens at a varying rate, there are some times when the matter flows more quickly and the star temporarily produces brighter X-rays.

An illustration of a white dwarf star drawing matter from a red giant. NASA

It was previously believed that supersoft X-rays were only observed when nuclear fusion was occurring in white dwarfs. But in the case of ASASSN-16oh, the uneven distribution of the X-rays in addition to the optical light given out being too faint indicate that fusion is not happening in this star. “Our result contradicts a decades-long consensus about how supersoft X-ray emission from white dwarfs is produced,” Thomas Nelson from the University of Pittsburgh told NASA. “We now know that the X-ray emission can be made in two different ways: by nuclear fusion or by the accretion of matter from a companion.”

Georgina Torbet
Georgina has been the space writer at Digital Trends space writer for six years, covering human space exploration, planetary…
ChatGPT’s awesome Deep Research gets a light version and goes free for all
Deep Research option for ChatGPT.

There’s a lot of AI hype floating around, and it seems every brand wants to cram it into their products. But there are a few remarkably useful tools, as well, though they are pretty expensive. ChatGPT’s Deep Research is one such feature, and it seems OpenAI is finally feeling a bit generous about it. 

The company has created a lightweight version of Deep Research that is powered by its new o4-mini language model. OpenAI says this variant is “more cost-efficient while preserving high quality.” More importantly, it is available to use for free without any subscription caveat. 

Read more
Star Wars legend Ian McDiarmid gets questions about the Emperor’s sex life
Ian McDiarmid as the Emperor in Star Wars: The Rise of Skywalker.

This weekend, the Star Wars: Revenge of the Sith 20th anniversary re-release had a much stronger performance than expected with $25 million and a second-place finish behind Sinners. Revenge of the Sith was the culmination of plans by Chancellor Palpatine (Ian McDiarmid) that led to the fall of the Jedi and his own ascension to emperor. Because McDiarmid's Emperor died in his first appearance -- 1983's Return of the Jedi -- Revenge of the Sith was supposed to be his live-action swan song. However, Palpatine's return in Star Wars: Episode IX -- The Rise of Skywalker left McDiarmid being asked questions about his character's comeback, particularly about his sex life and how he could have a granddaughter.

While speaking with Variety, McDiarmid noted that fans have asked him "slightly embarrassing questions" about Palpatine including "'Does this evil monster ever have sex?'"

Read more
Waymo and Toyota explore personally owned self-driving cars
Front three quarter view of the 2023 Toyota bZ4X.

Waymo and Toyota have announced they’re exploring a strategic collaboration—and one of the most exciting possibilities on the table is bringing fully-automated driving technology to personally owned vehicles.
Alphabet-owned Waymo has made its name with its robotaxi service, the only one currently operating in the U.S. Its vehicles, including Jaguars and Hyundai Ioniq 5s, have logged tens of millions of autonomous miles on the streets of San Francisco, Los Angeles, Phoenix, and Austin.
But shifting to personally owned self-driving cars is a much more complex challenge.
While safety regulations are expected to loosen under the Trump administration, the National Highway Traffic Safety Administration (NHTSA) has so far taken a cautious approach to the deployment of fully autonomous vehicles. General Motors-backed Cruise robotaxi was forced to suspend operations in 2023 following a fatal collision.
While the partnership with Toyota is still in the early stages, Waymo says it will initially study how to merge its autonomous systems with the Japanese automaker’s consumer vehicle platforms.
In a recent call with analysts, Alphabet CEO Sundar Pichai signaled that Waymo is seriously considering expanding beyond ride-hailing fleets and into personal ownership. While nothing is confirmed, the partnership with Toyota adds credibility—and manufacturing muscle—to that vision.
Toyota brings decades of safety innovation to the table, including its widely adopted Toyota Safety Sense technology. Through its software division, Woven by Toyota, the company is also pushing into next-generation vehicle platforms. With Waymo, Toyota is now also looking at how automation can evolve beyond assisted driving and into full autonomy for individual drivers.
This move also turns up the heat on Tesla, which has long promised fully self-driving vehicles for consumers. While Tesla continues to refine its Full Self-Driving (FSD) software, it remains supervised and hasn’t yet delivered on full autonomy. CEO Elon Musk is promising to launch some of its first robotaxis in Austin in June.
When it comes to self-driving cars, Waymo and Tesla are taking very different roads. Tesla aims to deliver affordability and scale with its camera, AI-based software. Waymo, by contrast, uses a more expensive technology relying on pre-mapped roads, sensors, cameras, radar and lidar (a laser-light radar), that regulators have been quicker to trust.

Read more