Planet That Orbits Its Star Every 18 Hours on Path of Destruction Discovered by Astronomers

Scientists have identified a record-breaking planet outside our solar system that orbits its star in just over 18 hours.

The distant world, dubbed NGTS-10b, is a "hot Jupiter"—a class of large, gaseous exoplanets that orbit very closely to their host stars.

According to a study published in the journal Monthly Notices of the Royal Astronomical Society, the planet has the shortest orbital period of any hot Jupiter ever discovered, completing a year in less time than it takes for one day on Earth to pass.

The planet, which is located around 1,000 light-years from Earth, has such a short orbital period because it is extremely close to its star. In fact, it orbits at a distance which is only double that of the star's diameter.

Being so close to the star, the planet experiences extreme high temperatures—an average of more than 1,000 degrees Celsius (1,832 degrees Fahrenheit,) according to the researchers. NGTS-10b is also tidally locked, meaning one side always faces the star, while the other is constantly turned away from it.

Given its proximity to the star, NGTS-10b is being subjected to powerful gravitational forces that will eventually lead to the planet's destruction, the authors said.

The planet was discovered by the Next-Generation Transit Survey (NGTS)—a project aimed at searching for exoplanets around bright stars, based at the Paranal Observatory in the Chilean Atacama Desert.

NGTS identifies new planets using the "transit method," which involves looking for periodic dips in the brightness of stars. This can be a sign that a planet has passed in front of the star.

"We're excited to announce the discovery of NGTS-10b, an extremely short period Jupiter-sized planet orbiting a star not too dissimilar from our sun," James McCormac, lead author of the study, from the University of Warwick in the U.K., said in a statement. "We are also pleased that NGTS continues to push the boundaries in ground-based transiting exoplanet science through the discovery of rare classes of exoplanets."

"Although in theory hot Jupiters with short orbital periods—less than 24 hours—are the easiest to detect due to their large size and frequent transits, they have proven to be extremely rare. Of the hundreds of hot Jupiters currently known there are only seven that have an orbital period of less than one day," he said.

hot jupiter, star
Artist's illustration of a hot Jupiter orbiting close to its host star. Mark Garlick/University of Warwick

According to the authors, NGTS-10b could help shed light on the lifecycle of planets such as this—in particular, the question of how long they can orbit their stars at extremely close proximities before spiraling to their destruction.

"It's thought that these ultra-short planets migrate in from the outer reaches of their solar systems and are eventually consumed or disrupted by the star," David Brown, a co-author of the study, also from Warwick, said in the statement. "We are either very lucky to catch them in this short period orbit, or the processes by which the planet migrates into the star are less efficient than we imagine, in which case it can live in this configuration for a longer period of time."

In order to find out, the astronomers plan to continue observing NGTS-10b over the next ten years or so. In this time, they hope that the planet might reveal whether it is indeed spiraling into its star.

While scientists only know of just over 400 hot Jupiters, according to Smithsonian Magazine, they are some of the most intriguing worlds in the universe.

For example, one hot Jupiter located around 670 light-years away known as ELT-9b experiences surface temperatures up to 7,800 degrees Fahrenheit, which is greater than those found on some stars.

Temperatures are so high on ELT-9b—the hottest known exoplanet—that its atmosphere vaporizes heavy metals and rips molecules apart.

Another hot Jupiter called WASP-121b, located around 900 light-years from Earth, is so close to being torn apart by its star's powerful gravitational forces that it has warped into the shape of a football.