Astronomers from the CARMENES (Calar Alto high-Resolution search for M dwarfs with Exoearths with Near-infrared and optical Échelle Spectrographs) consortium have detected a short-period rocky planet orbiting the red dwarf Gliese 486.
An artist’s impression of the super-Earth Gliese 486b and its red dwarf star. Image credit: RenderArea, https://renderarea.com.
Also known as GJ 486, Wolf 437, LHS 341, and HIC 62452, the star is much fainter and cooler than the Sun.
The newfound planet orbits the star once every 1.5 days at a distance of 2.5 million km.
Designated Gliese 486b, it belongs to a class of exoplanets called super-Earths.
It has a radius of 1.31 Earth radii, a mass 2.8 times that of our home planet, but has a similar density.
Its composition is not its only distinguishing feature — its relative closeness to Earth makes it an ideal candidate for observations with the next generation of astronomical technology.
An artist’s impression of the surface of Gliese 486b. Image credit: RenderArea, https://renderarea.com.
“The proximity of this exoplanet is exciting because it will be possible to study it in more detail with powerful telescopes such as the upcoming James Webb Space Telescope and the various Extremely Large Telescopes such as the GMT and TMT,” said Dr. Trifon Trifonov, an astronomer at the Max-Planck-Institut für Astronomie.
“Within the next few years, we hope to use transit spectroscopy to search for signs of an atmosphere and possibly determine this planet’s surface composition.”
With an equilibrium surface temperature of 700 K (427 degrees Celsius, 801 degrees Fahrenheit), Gliese 486b is too hot to support life as we know it.
“You wouldn’t be able to go outside without some kind of spacesuit,” said Dr. Ben Montet, an astronomer in the School of Physics at the University of New South Wales.
“The gravity is also 70% stronger than on Earth, making it harder to walk and jump. Someone who weighed 50 kg on Earth would feel like they weighed 85 kg on Gliese 486b.”
“If it had been around a hundred degrees hotter all its surface would be lava, and its atmosphere would be vaporized rock,” said Dr. José Antonio Caballero, an astronomer at the Astrobiology Centre (CAB, CSIC-INTA).
“On the other hand, if Gliese 486b had been around a hundred degrees cooler, it would not have been suitable for the follow-up observations.”
The astronomers detected Gliese 486b using data from NASA’s Transiting Exoplanet Survey Satellite (TESS) and ground-based telescopes in Spain, the United States, Chile and Hawaii.
“This is the kind of planet we’ve been dreaming about for decades,” Dr. Montet said.
“We’ve known for a long time that rocky super-Earths must exist around the nearby stars, but we haven’t had the technology to search for them until recently.”
The discovery is reported in a paper published this week in the journal Science.
T. Trifonov et al. 2021. A nearby transiting rocky exoplanet that is suitable for atmospheric investigation. Science 371 (6533): 1038-1041; doi: 10.1126/science.abd7645