Earth-sized planets commonly found around smallest stars reveals CARMENES data

Earth-sized planets commonly found around smallest stars reveals CARMENES data
by Robert Schreiber
Berlin, Germany (SPX) Jun 30, 2025

Astronomers at Heidelberg University's Konigstuhl Observatory have found that Earth-sized planets are particularly prevalent around low-mass stars, according to new findings from the CARMENES project. The study led to the discovery of four new exoplanets and offers compelling evidence that stars with less than one-sixth the mass of our Sun frequently host terrestrial worlds.

The observations were conducted using the CARMENES spectrograph at the Calar Alto Observatory in Spain. Developed at the Konigstuhl Observatory, the instrument targets M-dwarfs-stars with between one-tenth and one-half the Sun's mass. These small stars dominate the galaxy in number and exhibit minute wobbles due to the gravitational pull of orbiting planets, which CARMENES detects via radial velocity measurements.

Researchers focused on 15 M-dwarfs selected from a broader catalog of 2,200 stars monitored by the program. By studying their spectral data, they identified four new planets. One has a mass about 14 times that of Earth and circles its star every 3.3 years. The remaining three are between 1.03 and 1.52 Earth masses, with orbital periods ranging from 1.43 to 5.45 days.

Statistical modeling indicates that stars with less than 0.16 solar masses typically host two planets each with masses under three times that of Earth. "It is quite remarkable how often small planets occur around very low-mass stars," said Dr Adrian Kaminski, who led the research at Heidelberg's Centre for Astronomy. In contrast, larger planets were found to be significantly less common. "This suggests that low-mass stars tend to form smaller planets in close orbits," he added.

Although no known exoplanet exactly mirrors Earth in all characteristics-mass, size, temperature, and stellar type-the newly found planets fulfill at least the first three criteria. "Small, rocky planets in the so-called habitable zone - the area around a star where water could exist in liquid form - are potential candidates for habitable worlds," explained Prof. Dr Andreas Quirrenbach, the observatory's director. He noted that the stability and abundance of M-dwarfs make them promising targets in the ongoing search for life-supporting environments beyond our solar system.

Research Report:The CARMENES search for exoplanets around M dwarfs. Occurrence rates of Earth-like planets around very low-mass stars