Temperate super-earth Gliese 48 b orbits near the edge of its star's habitable zone

Gliese 48 b is a newly characterized super-Earth orbiting a red dwarf star. Located in a temperate region where temperatures could potentially support liquid water, the planet has a mass roughly eight times that of Earth. While it does not pass in front of its star from our viewpoint, its orbital behavior and stable signal make it a significant target for understanding planetary systems around smaller stars.

Star system: Gliese 48 | Distance from the Sun: 26.9 light years

Gliese 48 b is a massive, temperate planet known as a super-Earth that orbits a red dwarf star. The planet follows an orbital path that takes approximately 39.6 days to complete. It receives an amount of light and heat from its host star very similar to the energy Earth receives from the Sun. Because of this positioning, the planet sits within the optimistic habitable zone, which is the region around a star where conditions might allow for the existence of liquid water on a planetary surface.

To identify this planet, researchers analyzed radial velocity data, which measures the subtle wobbles of a star caused by the gravitational tug of an orbiting body. By combining decade-long measurements from the HIRES instrument and data from the CARMENES spectrograph, they confirmed the planetary signal remained consistent over a 15-year period. Furthermore, the team examined light data from the TESS space telescope to determine if the planet passes directly in front of its star. They found no evidence of such transits and determined that the planet's orbital angle prevents it from blocking the star's light from our perspective.

Because the planet does not transit its star, its exact size remains unknown. However, the data confirms it has a minimum mass of approximately 8.1 times that of Earth. Its host star, Gliese 48, is an active red dwarf with a rotation period of 51.5 days. The stability of the planetary signal and its temperate nature mark Gliese 48 b as an important candidate for further study regarding the development of planets around low-mass stars.

Key findings
Gliese 48 b has a minimum mass of 8.11 Earth masses.
The planet completes one orbit every 39.63 days.
The planet does not transit its star, indicating an orbital inclination of less than 89.3 degrees.
It receives 0.889 times the stellar flux that Earth receives from the Sun.
The planet is located within the optimistic habitable zone of its host star.

Scientific study

Detection and characterization of the temperate super-earth Gliese 48 b (external link)