Scientists have discovered a new planet that breaks all heat records. The boiling gas planet was discovered using a homemade, unassuming telescope. A scorching hot new world was discovered.
The planet KELT-9b breaks all records with its scorching temperature of as much as 4.6 thousand Kelvin (approximately 4 327 degrees Celsius).
“It is over a thousand degrees hotter than the hottest planet known. So it's much hotter than other planets,”says Lars Buhhave, lecturer at the Niels Bohr Institute at Copenhagen University.
He is part of a group of scientists who discovered a hot planet, described in the latest issue of the famous scientific publication Nature.
Molecules burst
This newly discovered planet can be compared to another gas giant - Jupiter. Jupiter is the largest planet in our solar system, but KELT-9b is 1.9 times larger, 2.9 times heavier and many times hotter.
“You can't even think of any life on this planet. It is so hot that you cannot even count on maintaining molecular bonds. They break apart, so that the gas on the planet's surface is made up mostly of individual atoms,”says Lars Buchhave.
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How hot the stars are
Mia Lundkvist of Aarhus University is also studying hot planets and stars, and she finds the new study "very interesting."
“It is always very interesting when planets with extreme characteristics are discovered - planets that are not like others. KELT-9b is such an extreme planet, much hotter than any other,”says Mia Lundqvist, a postdoctoral fellow at the Institute of Physics and Astronomy, who was not involved in the new study.
The parent star KELT-9b, the star around which the planet orbits, is also extremely hot: as much as 10,170 Kelvin (9,897 degrees Celsius), twice as hot as our own parent star, the Sun.
“The idea that this planet receives about 45 thousand times more light and heat than what we get about the Sun here on Earth is mesmerizing,” says Mia Lundqvist.
The intense heat emanating from the parent star is just one of the reasons for KELT-9b's record temperature. Another reason is that the planet is very close to its star. While the Earth takes a year to revolve around the Sun, KELT-9b is so close to the parent star that it only takes a day and a half to complete its circular path.
Record hot
One side of the planet KELT-9b is hotter than the other.
The fact is that the planet is always turned by the same side to its star - just as the Moon is always turned with one side to the Earth.
On the hot side of KELT-9b, the temperature is about 4.6 thousand Kelvin (4 327 degrees Celsius).
Until now, the temperature record for the planet was 3.3 thousand Kelvin (3027 degrees Celsius)
The planet may have a tail
“When KELT-9b hovers around its star, it may have a tail of matter, just like comets is known to have,” says Lars Buhhave.
“The planet is so close to the star that it is bombarded with radiation. This can lead to the evaporation of matter from the planet, resulting in a comet-like tail. This is not uncommon for planets that are close to their parent stars. But we do not yet know if this happens in this case. At the moment we have just discovered the planet itself,”says Lars Buhhave.
The calculations of the new study indicate that ultraviolet radiation (UV radiation) from the parent star is so great that the entire atmosphere of the planet could evaporate during the lifetime of the star, notes Mia Lundqvist.
“But this estimate is inaccurate, as evaporation is a complex process that we do not fully understand yet. So it's great to discover planets like KELT-9b to try to figure out how rare or common they are,”says Mia Lundqvist.
How temperature is determined
Scientists can (to simplify) calculate the temperature of a planet and its star based on the type of radiation emitted by the star. For example, the color of the radiation indicates the temperature of a star.
When the temperature of a star is known, scientists can calculate the temperature of a planet based on knowledge of the distance between the star and the planet.
The hottest star with a planet
In recent years, scientists have discovered thousands of exoplanets - that is, planets that, like KELT-9b, revolve around stars other than the Sun. Only six of the currently known exoplanets revolve around a very hot type of star called class A stars, and no planets have ever been found in an even hotter type B star.
The parent star KELT-9bs sits on the class A and class B boundary, and is therefore hotter than all other open stars that have an exoplanet.
“Planets are difficult to detect in hot, and therefore larger, stars, so there are significantly fewer planets that belong to hot stars than those that belong to colder types. These planets are harder to find, but that doesn't mean they're not there. Anyway, this planet is proof that planets can exist around very hot stars,”says Lars Buhhave.
How planets are found
Exoplanets are harder to spot in hot giant stars, and this affects the way scientists search for them.
After all, one cannot directly see such planets. They are only discovered because they obscure the mother star, explains Lars Buhhave.
“When a planet passes in front of its star, there is a dip in the star's light curve. When passing in front of a larger star, the dip in the light curve is small, which is why it is more difficult to detect planets orbiting large, hot stars,”says Lars Buhhave.
Discovered with a small telescope
Despite these difficulties, the new planet was not discovered using the most advanced scientific equipment. On the contrary, KELT-9b was discovered with a small telescope, which, compared to many of its giant brethren, seems almost "substandard".
The planet was first spotted by the Kilodegree Extremely Little Telescope (KELT) North at the Wiener Observatory in Arizona in 2014.
The KELT telescope is designed to observe bright, highly luminous stars, while other telescopes are usually designed to study distant stars that are difficult to see,”explains Lars Buhave.
“The telescope was designed by the folks at Ohio University. They bought completely standard lenses and regular mass-produced telescopes, so the price was very different from that of giant ultra-expensive telescopes,”says Lars Buchhave, mentioning that the largest telescope on Earth is the European Extremely Large Telescope, which is now planned to be built, will cost more than one billion euros.
“It is possible to build 13,000 observatories with KELT telescopes for the money that would be spent on the European extremely large telescope. It's funny: astronomy usually moves towards ever larger telescopes, but this case shows that there is always room for new discoveries, even if you have a relatively small budget."
Lise Brix