Astronomers have discovered a “super-Earth” orbiting a red dwarf star just 37 light-years from our solar system.
The exoplanet Ross 508 b touches the so-called habitable zone of its parent star, the zone in which surface temperatures are adapted to allow the existence of liquid water, a key ingredient of life. The newly discovered exoplanet is about four times the mass of Earth and was discovered using a new infrared monitoring technique. This super-Earth’s proximity to our planet means it’s ripe for atmospheric investigation, which could help researchers determine if life could exist around a low-mass planet. stars.
“The fact that the very first planet discovered by this new method is so close to the habitable zone seems too good to be true and bodes well for future discoveries,” said Bun’ei Sato, team leader and professor at Tokyo Institute of Technology. in a report.
Red dwarfs like Ross 508, which has about one-fifth the mass of the sun, are small stars that make up about three-quarters of all the stars in our galaxy, the Milky Way. These stars are particularly abundant in the region around our solar system, making red dwarf stars and their systems ideal targets for searching for planets outside the solar system. solar system and the investigation of possible life elsewhere in the universe.
The fact that red dwarfs are small means that they are cool, with temperatures between 2,000 and 3,500 Kelvin. Their relatively low temperatures make them dim in visible light, unlike larger stars, and mean astronomers must study them in the infrared.
To do this, the Astrobiology Center in Japan has developed an infrared observing instrument called the InfraRed Doppler (IRD) instrument to mount on the Subaru Telescope in Hawai’i. With this instrument – the world’s first high-precision infrared spectrograph for an 8-meter class telescope – astronomers set out to search for signs of planets around red dwarf stars.
Specifically, the researchers looked for the telltale “wobble” that an exoplanet causes in the orbit of its parent star; the wobble registers as a small shift in the wavelength of starlight as it approaches and moves away from Earth.
The discovery of Ross 508B marks the first success of the project, officially named IRD Subaru Strategic Program (IRD-SSP).
“It’s been 14 years since IRD’s development began,” Sato said. “We continued our development and research in hopes of finding a planet exactly like Ross 508 b.”
Ross 508 b, the third planet to orbit such a low-mass star, has an average distance from its parent star of just one-twentieth the distance between earth and sun. The astronomers who discovered it believe that the planet’s highly elliptical orbit carries it into Ross 508’s habitable zone every 11 days.
“Ross 508 b is the first successful detection of a super-Earth using only near-infrared spectroscopy,” Subaru Telescope researcher Hiroki Harakawa said in the release. “Before that, in the detection of low-mass planets such as super-Earths, near-infrared observations alone were not accurate enough, and verification by high-precision line-of-sight velocity measurements in visible light was necessary.” (Although super-Earths are larger than our own planet, most exoplanets scientists are currently detecting are much larger.)
Harakawa added that the study, of which he was lead author, shows that even when acting alone, the IRD-SSP is able to detect planets. He said the work particularly demonstrates the advantage of IRD-SSP in its ability to detect planets with high accuracy, even around late-type red dwarfs that are too faint to observe with visible light.
The team’s research was published June 30 in the journal Publication of the Astronomical Society of Japan (PASJ).