Santa Cruz de Tenerife, 11 Mar. (Europa Press) –
An international team, spearheaded by a predoctoral researcher at the Institute of Astrophysics of the Canary Islands (IAC), has identified a super-Earth orbiting within the habitable zone of GJ 3998, a nearby red dwarf star located 59 light years from Earth. The newly discovered planet, designated GJ 3998 D, is the third planet identified within this system.
“GJ 3998 D is a welcomed addition to the planetary inventory of our cosmic vicinity,” remarked Atanas Stefanov, a PhD student funded by Fundación “La Caixa” at the IAC and the University of La Laguna (ULL), who is the lead author of the study published in Astronomy & Astrophysics.
Stefanov noted that this super-Earth appears to be situated in the habitable zone of one of the stars closest to our Sun, which reinforces the need to “continue searching for habitable planets.”
The recently discovered planet, GJ 3998 D, is a super-Earth with a mass that is six times that of Earth. It lies in the optimistic habitable zone of its star and completes an orbit every 41.8 days.
At this distance, GJ 3998 D receives only 20% more stellar radiation compared to what Earth experiences from the Sun. “GJ 3998 is considerably smaller and colder than the Sun, which results in the habitable zone being positioned closer to the star,” explained Alejandro Suárez Mascareño, a researcher at the IAC and co-author of the study.
“While it is undoubtedly different from Earth, if the planet has a rocky composition, it could potentially support liquid water on its surface, a key requirement for life,” added Jonay I. González Hernández, also a researcher at the IAC and co-author.
Potential for Atmospheric Analysis
The proximity of this system to the Sun renders GJ 3998 D a compelling candidate for atmospheric analysis.
“It should be feasible to confirm the existence of an atmosphere and search for oxygen using the forthcoming Andes spectrograph on the ESO’s Extremely Large Telescope (ELT). GJ 3998 D would also represent a good target for future investigations with the Exo Life Finder telescope,” noted Rebolo, an IAC researcher and co-author of the study.
This discovery is part of the Hades programme, an international initiative aimed at exploring planetary systems surrounding red dwarfs using the Nazionale Galileo Telescope (TNG) located at the Roque de los Muchachos Observatory on La Palma.
The IAC points out that red dwarfs are smaller and cooler than our Sun and account for nearly three-quarters of the stellar population in our galaxy. Their low mass and prevalence make them prime targets in the quest for low-density planets.
GJ 3998, one such red dwarf, has attracted significant interest due to its proximity (59 light years) and moderate stellar activity. By employing the HARPS-N spectrograph on the TNG telescope, the research team detected subtle oscillations in the star’s movement, attributed to the gravitational influence of the orbiting planets.
The research institution further notes that a previous study conducted in 2016 by the same team had already discovered two planets. The detection of an additional signal in the data prompted further observations and reanalysis of the data set. With three known planets now in the system, GJ 3998 illustrates how prevalent multi-planet systems are.
“Planets, particularly those of low density, seldom exist in isolation; they tend to prefer companions. Often, when we revisit a system with new measurements and methods, we uncover planets that were previously overlooked,” Stefanov concluded.
Nicola Nari, a doctoral student at the ULL, also contributed to this significant discovery.
