‘Ultrahot Jupiter’ exoplanet has blistering surface temperatures of 6,000°F and blitzes around its star in just 16 HOURS – the shortest orbit of any known gas giant yet

  • The planet, dubbed TOI-2019b was discovered with NASA’s TESS satellite
  • It has an unusually short orbit and blisteringly hot surface temperatures
  • Experts hope its discovery will shed light on the formation of ‘hot Jupiter’ planets

An ‘ultrahot Jupiter’ exoplanet has been discovered with blistering surface temperatures of 6,000°F.

The planet, dubbed TOI-2109b, also has an unusually short orbit of just 16 hours – the shortest of any known gas giant yet.

For comparison, Jupiter takes 12 years to complete a full orbit around the sun!

Researchers from MIT hope that its discovery could help to unravel the mystery of how hot Jupiter exoplanets come to be in the first place.

‘From the beginning of exoplanetary science, hot Jupiters have been seen as oddballs,’ said Avi Shporer, co-author of the study.

‘How does a planet as massive and large as Jupiter reach an orbit that is only a few days long? We don’t have anything like this in our solar system, and we see this as an opportunity to study them and help explain their existence.’

The planet, dubbed TOI-2109b, also has an unusually short orbit of just 16 hours – the shortest of any known gas giant yet

TOI-2109b – an ‘ultrahot Jupiter’ exoplanet 

Temperature: 6,000°F

Mass: Five times more massive than Jupiter

Size: 35% larger than Jupiter 

Distance from star: 1.5 million miles 

Length of year: 16 hours 

The researchers discovered TOI-2109b 855 light years from Earth, using NASA’s Transiting Exoplanet Survey Satellite (TESS).

Due to its extremely tight orbit and proximity to its star, the planet’s day side is estimated to be at around 3,500 Kelvin, or close to 6,000 degrees Fahrenheit.

This makes it the second hottest detected so far, according to the researchers.

‘Meanwhile, the planet’s night side brightness is below the sensitivity of the TESS data, which raises questions about what is really happening there,’ Dr Shporer said.

‘Is the temperature there very cold, or does the planet somehow take heat on the day side and transfer it to the night side? 

‘We’re at the beginning of trying to answer this question for these ultrahot Jupiters.’

By analysing measurements over various optical and infrared wavelengths, the researchers determined that TOI-2109b is about five times as massive as Jupiter, 35 per cent larger, and is just 1.5 million miles away from its star.

For comparison, Mercury is around 36 million miles away from the sun.

Its properties indicate that the planet may be undergoing ‘orbital decay’ – a process in which a planet spirals towards its star, with TOI-2109b predicted to be spiralling at a rate of 10 to 750 milliseconds per year.

The team now hopes to study the planet with more powerful tools, including the James Webb Space Telescope, which is set to launch on December 22.

‘Ultrahot Jupiters such as TOI-2109b constitute the most extreme subclass of exoplanet,’ said Ian Wong, lead author of the discovery. 

‘We have only just started to understand some of the unique physical and chemical processes that occur in their atmospheres – processes that have no analogs in our own solar system.

‘In one or two years, if we are lucky, we may be able to detect how the planet moves closer to its star.

‘In our lifetime we will not see the planet fall into its star. But give it another 10 million years, and this planet might not be there.’ 


NASA’s new ‘planet hunter,’ set to be Kepler’s successor, is equipped with four cameras that will allow it to view 85 per cent of the entire sky, as it searches exoplanets orbiting stars less than 300 light-years away.

By studying objects much brighter than the Kepler targets, it’s hoped TESS could uncover new clues on the possibility of life elsewhere in the universe.

Its four wide-field cameras will view the sky in 26 segments, each of which it will observe one by one.

In its first year of operation, it will map the 13 sectors that make up the southern sky.

Then, the following year, it will scour the northern sectors.

‘We learned from Kepler that there are more planets than stars in our sky, and now TESS will open our eyes to the variety of planets around some of the closest stars,’ said Paul Hertz, Astrophysics Division director at NASA’s Headquarters. 

‘TESS will cast a wider net than ever before for enigmatic worlds whose properties can be probed by NASA’s upcoming James Webb Space Telescope and other missions.’

Tess is 5 feet (1.5 meters) wide and is shorter than most adults.

The observatory is 4 feet across (1.2 meters), not counting the solar wings, which are folded for launch, and weighs just 800 pounds (362 kilograms). 

NASA says it’s somewhere between the size of a refrigerator and a stacked washer and dryer. 

Tess will aim for a unique elongated orbit that passes within 45,000 miles of Earth on one end and as far away as the orbit of the moon on the other end.

It will take Tess two weeks to circle Earth.   

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