Science & Technology

“Ultra-Hot Neptune,” new exoplanet 260 light years from Earth

Santiago, Sep 21 (efe-epa).- An investigation headed by Chilean scientists has discovered the first so-called “Ultra-Hot Neptune,” a type of exoplanet considered to be a “rare beast” and located 260 light years from Earth, a distance that is relatively close by in astronomical terms, even though it takes light from it 260 years to reach us.

The planet, which bears the scientific name LTT9779b, is a little larger than the seventh planet from the sun – Neptune, a gas giant – but it has twice the mass, a similar density and orbits so close to its star that its year lasts just 19 hours and the temperature of its atmosphere is greater than 1,700 degrees C (3,000-plus F).

The exoplanet orbits only about 5 percent of the distance from the Sun to Mercury, the hottest planet in the Solar System and the closest one to the sun.

According to the scientific paper published on Monday in the prestigious magazine Nature, the temperature of this newly discovered heavenly body provides scientists with a unique opportunity to study the atmospheres of planets outside the Solar System.

At a similar temperature, the heavy elements can be ionized in the atmosphere and the molecules broken down. This provides scientists with a unique laboratory for studying the chemistry of planets outside the Solar System, according to the leader of the investigation, James Jenkins, a professor with the Astronomy Department at the Physical Sciences and Mathematics Faculty of the state-run Universidad de Chile.

The exoplanet was detected by the Transiting Exoplanet Survey Satellite (TESS), which since its launch in April 2018 has been observing different sectors of the sky – 13 zones in the Southern Hemisphere during its first year in operation and then 13 zones in the Northern Hemisphere in its second year.

LTT9779b is located in the so-called Neptune Desert, an area in the radio and wavelength bands where Neptune-like worlds are rarely found, according to the Nature article.

The exoplanet is a “rare beast” because it exists in a zone of space that is sparsely populated by gas-giant planets of its kind – that is, the region very, very close to their parent stars – and finding such a world in that region is highly unusual, according to the investigation.

The parent star that the exoplanet orbits is about half the age of the Sun, that is to say about two billion years old, and given the intense radiation so close to it scientists did not expect to find a Neptune-like object there that has been able to hold on to its atmosphere for such a long time.

Normally, intense radiation of that kind would strip the atmosphere from any planet orbiting so close to its star.

LTT9779b has an atmosphere with a mass equivalent to three times the mass of Earth. However, because the planet is so close to the star, the radiation from the star should have destroyed it quickly. The question is “How could the exoplanet maintain its atmosphere for such a long time?” Jenkins said.

According to the publication, future studies of the exoplanet’s atmosphere could shed light on some of the current mysteries about how this kind of planet forms, how they evolve and the details of their composition.


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