One of the lightest exoplanets ever found has a year that lasts a little less than eight hours. Called GJ 367b, the planet zips around a dim red dwarf star that is located fairly close to us at a distance of just 31 light-years away.
The planet was found by experts looking through data that was collected by NASA’s Transiting Exoplanet Survey Satellite (TESS). It was then analyzed in further detail with the High Accuracy Radial Velocity Planet Searcher (HARPS) that is on the European Southern Observatory's 3.6-meter telescope in Chile. The researchers found that GJ 367b is approximately 70% as big as our planet and 55% of its mass. It is considered an “ultra-short period” (USP) planet as it takes just 7.7 hours to orbit its host star.
Because of the close proximity to its star, there is no possibility that GJ 367b could have any life as it receives approximately 500 times more stellar radiation than Earth gets from our sun. It is more than probably tidally locked with only one side of the planet facing the star at all times. The sun-facing side would have temperatures as hot as 2,700 degrees Fahrenheit (almost 1,500 degrees Celsius).
It’s possible that it was once a much larger planet but the radiation from the star (or perhaps a massive impact with another object) took away a lot of its mass.
Szilárd Csizmadia, who is from the Institute of Planetary Research at the German Aerospace Center (also known as DLR), went into further details about the planet, “The high density indicates the planet is dominated by an iron core.” “These properties are similar to those of Mercury, with its disproportionately large iron and nickel core that differentiates it from other terrestrial bodies in the solar system.”
Since the system is decently close to us, scientists will be able to study it further and get a better understanding of it as stated by TESS team member Natalia Guerrero who is an astrophysics PhD student at the University of Florida but was not involved with the study, “Understanding how these planets get so close to their host stars is a bit of a detective story.” “How did it move close in? Was this process peaceful or violent? Hopefully this system will give us a little more insight,” she said in a statement provided by the Massachusetts Institute of Technology (MIT).
In the same statement, George Ricker, who is a senior research scientist at MIT's Kavli Institute for Astrophysics and Space Research, noted, “For this class of star, the habitable zone would be somewhere between a two-to-three-week orbit,” adding, “Since this star is so close by, and so bright, we have a good chance of seeing other planets in this system.” Their study was published in the journal Science.
An artist’s impression of GJ 367b can be viewed here.