Skip to main content

Hellishly hot planet orbits so close to its star that a year lasts a few days

A group of astronomers from the Physical Research Laboratory (PRL) in Ahmedabad, India has discovered a scorching new exoplanet where a year lasts just a few days, according to the Indian Space Research Organization.

The team, led by Prof. Abhijit Chakraborty of PRL, spotted the planet orbiting a star that is around 1.5 times the mass of our sun and is located 725 light-years away.

An artist’s impression of a hot-Jupiter exoplanet.
An artist’s impression of a hot-Jupiter exoplanet. C. Carreau / ESA

“This discovery is made using PRL Advanced Radial-velocity Abu-sky Search (PARAS) optical fiber-fed spectrograph, the first of its kind in India, on the 1.2-meter Telescope of PRL at its Mt. Abu Observatory,” the Indian space agency ISRO writes. “These measurements were carried out between December 2020 and March 2021. Further follow-up measurements were also obtained from TCES spectrograph from Germany in April 2021, and also independent photometric observations from the PRL’s 43-centimeter telescope at Mt. Abu.”

The planet, called TOI 1789b or HD 82139b, is around 1.4 times the size of Jupiter, with around 70% of its mass. It also orbits its host star in just 3.2 days, meaning it is extremely close to the star — at a distance of just 0.05 times the distance between the Earth and the sun. That makes it a type of planet called a hot Jupiter.

As the planet is so close to the star, it experiences extremely high temperatures of up to 2000 K (3140 Fahrenheit or 1727 Celsius), which is hot enough to melt iron. The planet is also inflated, making it very low density, so it’s puffy and larger than Jupiter even though it has less mass.

Similar hot Jupiter planets have been discovered using other instruments like exoplanet NGTS-10b, discovered as part of the Next-Generation Transit Survey (NGTS), or the famous KELT-9b, the hottest exoplanet known with a surface temperature of up to 7,800 degrees Fahrenheit which was discovered using the Kilodegree Extremely Little Telescope.

Studying hot Jupiters can help astronomers understand how planetary systems form and evolve, as they are extreme outcomes and give rise to questions about how planets could have ended up so close to their stars. “The detection of such system enhances our understanding of various mechanisms responsible for inflation in hot Jupiters and the formation and evolution of planetary systems around evolving and aging stars,” the ISRO wrote.

The research is published in the journal Monthly Notices of the Royal Astronomical Society.

Editors' Recommendations

Georgina Torbet
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
Astronomers find remnants of planets around 10 billion-year-old stars
Artist’s impression of the old white dwarfs WDJ2147-4035 and WDJ1922+0233 surrounded by orbiting planetary debris, which will accrete onto the stars and pollute their atmospheres. WDJ2147-4035 is extremely red and dim, while WDJ1922+0233 is unusually blue.

Far away in the depths of the Milky Way lie two small, dim stars that are in the final stage of their life. At over 10 billion years old, white dwarfs WDJ2147-4035 and WDJ1922+0233 are among the oldest stars in our galaxy, and recently, astronomers discovered something special orbiting around them: the remains of planets, making this one of the oldest known rocky planetary systems.

Astronomers used data from GAIA, the Dark Energy Survey, and the X-Shooter instrument at the European Southern Observatory to peer at this system. They identified debris from orbiting planetesimals, which are globs of dust and rock which are created during planetary formation. The researchers used spectroscopy to look at the light coming from the two white dwarf stars and break it down into different wavelengths, which can show what materials the stars and the surrounding matter are made of.

Read more
This month, get a great view of Jupiter as it comes its closest in 70 years
This photo of Jupiter, taken from the Hubble Space Telescope on June 27, 2019, features the Giant Red Spot, a storm the size of Earth that has been raging for hundreds of years.

Widely considered our solar system's most beautiful planet, Jupiter will reach opposition this month. That means Jupiter will be at its closest point to Earth, offering excellent views of this natural wonder. Jupiter's opposition happens every 13 months, but this opposition is a special one as the planet will make its closest approach to Earth in 70 years.

When looking from Earth at a planet like Jupiter, the distance between the two planets will be shortest when the planets are in opposition. This means that Earth is directly between the sun and Jupiter, so as the sun sets in the west, Jupiter rises in the east. That's the 13-month cycle of a typical opposition, but this opposition is unusual.

Read more
Researchers discover planet in the habitable zone of an ultra-cool star
The telescopes of the SPECULOOS Southern Observatory gaze out into the stunning night sky over the Atacama Desert, Chile.

Even though we've discovered over 5,000 exoplanets, or planets outside of our solar system, most of these aren't very Earth-like. They're often much bigger than Earth, being more like gas giants Saturn and Jupiter than small and rocky, and relatively few are located in the habitable zone where liquid water could exist on their surface. That's why it's exciting when a planet comparable to Earth is discovered in its habitable zone -- as one such recently discovered planet is.

Researchers looked at a planet called LP 890-9b or TOI-4306b, previously discovered by NASA's Transiting Exoplanet Survey Satellite. Using a ground-based telescope called SPECULOOS (Search for habitable Planets EClipsing ULtra-cOOl Stars), they studied the planet which is around 30% larger than Earth and orbits extremely close to its star, with a year lasting just 2.7 days.

Read more