Astronomers have discovered an Earth-size planet that is covered in volcanoes and is about 90 light-years away. This exoplanet was found and studied using data from Nasa’s TESS (Transiting Exoplanet Survey Satellite) and retired Spitzer Space Telescope, along with some ground-based observatories, according to the US space agency.
This planet, called LP 791-18 d, orbits a small red dwarf star in the southern constellation Crater. The research team, led by Merrin Peterson, a graduate of the Trottier Institute for Research on Exoplanets (iREx) based at the University of Montreal, published a paper on the discovery in the journal Nature. According to Nasa, the team estimates that this new planet is slightly larger and has more mass than Earth.
“LP 791-18 d is tidally locked, which means the same side constantly faces its star,” said Björn Benneke, a co-author and astronomy professor at iREx who planned and supervised the study, in a statement by Nasa. “The day side would probably be too hot for liquid water to exist on the surface. But the amount of volcanic activity we suspect occurs all over the planet could sustain an atmosphere, which may allow water to condense on the night side.”
LP 791-18 d orbits a small red dwarf star, LP 791-18, in the southern constellation Crater. The star is 14% of the mass and 17% of the radius of the Sun. In 2019, astronomers discovered two other worlds in the system, LP 791-18 b and c. The former is about 20% bigger than Earth while the latter is 2.5 times Earth’s size and more than seven times its mass, according to Nasa.
As the dwarf star is one of the coolest known to host exoplanets, a team led by Peterson used the infrared Spitzer Space Telescope to take 127 hours' worth of near-continuous observations of it, according to a report in Science Alert. During the observations, they found the presence of a previously unknown world, now called LP 791-18 d. This exoplanet is in the dwarf star's habitable zone. Hence, theoretically, there could be liquid water on the surface and the surface is neither so hot that the water boils off, nor cold enough for it to freeze.
So, have we found a new Earth? Well, not exactly. The exoplanet’s same side always faces the star, which means there is extremely hot daylight on one side while it is constantly nighttime on the other side, the Science Alert report adds. Moreover, as LP 791-18d’s distance from the star changes, gravity stretches and compresses the planet, heating it from within.
This internal heating could trigger volcanic activity which could create a thick atmosphere. Examining this with an observatory like the James Webb Space Telescope could help us understand how planets like Earth or Venus, which are volcanically active, but have different evolutionary paths, are so different from each other, according to the Science Alert report.
"A big question in astrobiology, the field that broadly studies the origins of life on Earth and beyond, is if tectonic or volcanic activity is necessary for life," astrophysicist Jessie Christiansen of the California Institute of Technology explains in the statement. According to the Science Alert report, the discovery of the new exoplanet shows how complex habitability can be, and why it is important to understand each planetary system holistically.
Earlier this week, an international team of scientists led by Abhijit Chakraborty at the Exoplanet Research Group of the Physical Research Laboratory (PRL), Ahmedabad discovered another exoplanet whose size is similar to Jupiter but its mass is 13 times more, as reported by the Indian Space Research Organisation.