Astronomers have discovered a hot Jupiter exoplanet with the shortest orbit. A year on that planet lasts only 18.4 hours.
The new-found exoplanet, called NGTS-10b, orbits around its star, NGTS-10, every 18.4 hours. This hot Jupiter is 1.2 times larger than Jupiter and 2.2 times more massive.
“NGTS-10b orbits its host star at only 4.4 stellar radii,” said the University of Warwick astronomer James McCormac and his colleagues from the United Kingdom, Australia, Germany, Chile, and the United States.
That’s nearly as close as the planet can get to the host star without being ripped apart by gravitational forces. But the planet is getting even closer.
Astronomers have estimated that the exoplanet’s orbit is shrinking, and it will spiral into the star about 38 million years from now.
The planet’s parent star, NGTS-10, is a K5-type main-sequence star about 70% equal to the sun in mass and diameter. It lies 1,060 light-years away from us.
The star is not very hot. It has a surface temperature of about 1,380 degrees Celsius (2,485 degrees Fahrenheit) cooler than the sun’s surface.
“As the stellar effective temperature is lower than other ultra-short period hot Jupiter host stars, the level of insolation is also reduced,” explained McCormac. “Therefore, while the period is the shortest yet discovered, the received radiation is significantly less than that of planets such as WASP-18b or WASP-19b.”
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Astronomers examined this alien world using the Next-Generation Transit Survey (NGTS). NGTS is a robotic array of 12 telescopes at the Paranal Observatory in the Atacama Desert in Chile.
During recent years, astronomers have discovered other hot Jupiters orbiting their stars in less than one Earth day. These “ultra-short-period hot Jupiters” are ideal targets for astronomers to investigate the nature of gravitational interactions between planets and stars.
The exoplanet NGTS-10b is just over 1.2 times the size of Jupiter and just over 2.1 times its mass.
But this hot Jupiter isn’t the closest planet to its star. There are other worlds that orbit even closer but they are much smaller planets.
The current record holder is KOI 1843.03, which takes just 4.3 hours to complete one orbit around its M-dwarf star.
Researchers detailed the study in a paper published in the journal Monthly Notices of the Royal Astronomical Society.