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Astronomers discover an oceanic world comparable to the mass of Mars and in distance of “Goldilocks”

publicado a la‎(s)‎ 26 ago 2021, 9:07 por Plataforma Sites Dgac
A team of astronomers announced new findings about exoplanets around a nearby star, L 98-59, observed with the Very Large Telescope (VLT) of the European Southern Observatory in Chile.
An artist's depiction of one of the exoplanets around star L 98-59.

A scale of the size of the planets in the Solar System.
Among them is a planet with half the mass of Venus, an ocean world and a possible planet within the habitable zone, dubbed "Goldilocks". 

“Goldilocks” is a story about a girl named Goldilocks who does not like oatmeal flakes that are too sweet, like baby bear, or too salty, like papa bear. She does not like beds too soft or too hard. Instead, she likes things at their midpoint, like Mama Bear.

This story is used to illustrate the area around a star where the temperature is “just right” for water to exist. It is a place where the temperature is not too cold for the water to freeze, nor too hot for it to evaporate. These are also the right conditions for life as we know it to exist. 

This new world would be comparable to the approximate mass of the planet Mars with a gravity, also approximate, of about 3.7 m/s2. This means that, for example, a person who weighs 154 pounds on Earth, in that world would weigh around 57.3 pounds. 

“The planet in the habitable zone may have an atmosphere that could protect and support life,” said María Rosa Zapatero Osorio, an astronomer at the Centre for Astrobiology in Madrid, Spain, and one of the authors of the study published on August 5 in the journal Astronomy & Astrophysics. 

The orbits of the exoplanets of L 98-59 are 35 light years from Earth and it was found that they host rocky planets, such as Earth or Venus, that are close enough to the star to receive heat. 

Three planets with water inside 

ESO’s VLT telescope helped the team infer that three of the planets could contain water inside or in their atmospheres. The exoplanets closest to L 98-59 are probably dry, but could have small amounts of water, while around 30 percent of the mass of the third planet could be water, making it an ocean world. 

In addition, the team detected a fourth previously undiscovered exoplanet and suspect the existence of a fifth. Astronomers first detected the three planets of L 98-59 in 2019, using NASA’s TESS satellite.

“We have hints of the presence of a terrestrial planet in the habitable zone of this system,” explained Olivier Demangeon, a researcher at Instituto de Astrofísica e Ciências do Espaço, University of Porto in Portugal and lead author of the new study.

From a technical point of view, the study was a milestone because it allowed astronomers to determine —using the radial velocity method— that the innermost planet in the system has only half the mass of Venus. It is the lightest planet measured using this technique, which calculates the wobble of the star caused by the tiny gravitational pull of its orbiting planets.