KU astronomer helps confirm first-ever planet found orbiting white dwarf

September 16, 2020

LAWRENCE -- A University of Kansas astronomer played a key role on the team that today announced the first-ever discovery of a planet orbiting a white dwarf. The finding, Nature, shows the likely presence of a Jupiter-sized planet, named WD 1856 b, orbiting the smaller star remnant every 34 hours.

"This planet is roughly the size of Jupiter, but it also has a very short orbital period -- a year on this planet is only 1.4 days, so it's quickly whipping around its white dwarf star," said Ian Crossfield,

A white dwarf is the vestige of a star, like our Sun, that has ballooned into a red giant then collapsed back into a dense, dim core that's often about the size of Earth; so this planet is much larger than what's left of its star! The process usually devours orbiting planets -- but not in the case of WD 1856 b, which appears somehow to have avoided destruction.

"This tells us white dwarfs can have planets, which is something we didn't know before," Crossfield said. "There are people who now are looking for transiting planets around white dwarfs that could be potentially habitable. It'd be a pretty weird system, and you'd have to think about how the planets actually survived all that time. But it's a big universe! Now we at least know some kinds of planets can survive and be found there, so that gives greater support and greater interest in continuing the search for even smaller planets around these white dwarfs."

At first, WD 1856 b captured astronomers' interest when they noticed a possible transiting object with NASA's TESS Space Telescope survey.

"TESS finds a planet by looking at a star, and it measures how bright the star is continuously for weeks," he said. "If a planet is orbiting the star, and if the planet passes between you and the star, some of that star's light is going to be blocked. Then the star will get brighter again as the planet passes -- we call this the 'transit' of the planet. And so, TESS looks for transiting exoplanet satellites. It tells you that something is there -- but it doesn't necessarily tell you what it is because it could be another dim star passing in front instead of a planet."

To help the international team of scientists confirm if WD 1856 b indeed was a planet orbiting the white dwarf, Crossfield studied the object's infrared emissions with NASA's now-defunct Spitzer Space Telescope in the months leading up to the satellite telescope's decommission.

"For this white dwarf object, it's tough to measure the mass of it -- so we knew how big it was, but not how heavy it was," he said. "This new object could have been a small star or a big planet. The way we could tell the difference was to look and see -- is this thing emitting infrared light as well? If it's a star, stars are generally hotter than planets and it should be glowing in the infrared. But if it's just a planet, planets are generally colder than stars and so there should be a little or no infrared light. What our Spitzer data showed is there's basically no infrared light at all. And the depths of these transits are identical between the TESS data, and our Spitzer datasets. That really put the final nail in the coffin that this thing is almost certainly a planet, rather than a star."

WD 1856 b is located about 80 light years away in the northern constellation Draco. The team behind the paper believes the gaseous planet was pulled in by the white dwarf's gravity long after the star had dwindled down from its red giant phase -- otherwise the planet would have been obliterated in its current orbit.

Asked if the discovery of the first planet orbiting a white dwarf meant the Earth stood a chance of surviving the sun's red-giant phase in the distant future, Crossfield said it remained unlikely.

"In around five billion years our Sun will become a white dwarf. There's a lot of open questions about whether planets can survive the process of a star inflating up to become a red giant, swallowing up some of the inner planets, and then shrinking back down and just being left over as the white dwarf again. Can planets actually survive that -- or is that impossible? And until now, there weren't any known planets around white dwarfs."

University of Kansas

Related Science Articles from Brightsurf:

75 science societies urge the education department to base Title IX sexual harassment regulations on evidence and science
The American Educational Research Association (AERA) and the American Association for the Advancement of Science (AAAS) today led 75 scientific societies in submitting comments on the US Department of Education's proposed changes to Title IX regulations.

Science/Science Careers' survey ranks top biotech, biopharma, and pharma employers
The Science and Science Careers' 2018 annual Top Employers Survey polled employees in the biotechnology, biopharmaceutical, pharmaceutical, and related industries to determine the 20 best employers in these industries as well as their driving characteristics.

Science in the palm of your hand: How citizen science transforms passive learners
Citizen science projects can engage even children who previously were not interested in science.

Applied science may yield more translational research publications than basic science
While translational research can happen at any stage of the research process, a recent investigation of behavioral and social science research awards granted by the NIH between 2008 and 2014 revealed that applied science yielded a higher volume of translational research publications than basic science, according to a study published May 9, 2018 in the open-access journal PLOS ONE by Xueying Han from the Science and Technology Policy Institute, USA, and colleagues.

Prominent academics, including Salk's Thomas Albright, call for more science in forensic science
Six scientists who recently served on the National Commission on Forensic Science are calling on the scientific community at large to advocate for increased research and financial support of forensic science as well as the introduction of empirical testing requirements to ensure the validity of outcomes.

World Science Forum 2017 Jordan issues Science for Peace Declaration
On behalf of the coordinating organizations responsible for delivering the World Science Forum Jordan, the concluding Science for Peace Declaration issued at the Dead Sea represents a global call for action to science and society to build a future that promises greater equality, security and opportunity for all, and in which science plays an increasingly prominent role as an enabler of fair and sustainable development.

PETA science group promotes animal-free science at society of toxicology conference
The PETA International Science Consortium Ltd. is presenting two posters on animal-free methods for testing inhalation toxicity at the 56th annual Society of Toxicology (SOT) meeting March 12 to 16, 2017, in Baltimore, Maryland.

Citizen Science in the Digital Age: Rhetoric, Science and Public Engagement
James Wynn's timely investigation highlights scientific studies grounded in publicly gathered data and probes the rhetoric these studies employ.

Science/Science Careers' survey ranks top biotech, pharma, and biopharma employers
The Science and Science Careers' 2016 annual Top Employers Survey polled employees in the biotechnology, biopharmaceutical, pharmaceutical, and related industries to determine the 20 best employers in these industries as well as their driving characteristics.

Three natural science professors win TJ Park Science Fellowship
Professor Jung-Min Kee (Department of Chemistry, UNIST), Professor Kyudong Choi (Department of Mathematical Sciences, UNIST), and Professor Kwanpyo Kim (Department of Physics, UNIST) are the recipients of the Cheong-Am (TJ Park) Science Fellowship of the year 2016.

Read More: Science News and Science Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.