A newly discovered exoplanet may be worth seeking out signs of life. Analysis by a team led by astronomer Diana Kossakowsky of the Max Planck Institute for Astronomy identifies a planet in the habitable zone orbiting its host star, red dwarf Wolf 1069. This region includes distances around the star where liquid water can be found on the planet’s surface. Also, a planet named Wolf 1069 b has the mass of the Earth. This planet is likely to be rocky, which may also have an atmosphere. This makes the planet one of the few promising targets for searching for signs of life-friendly conditions and biosignatures.

When astronomers look for planets outside our solar system, they are particularly interested in Earth-like planets. Of the more than 5,000 exoplanets they’ve discovered so far, only about a dozen have an Earth-like mass and live in the habitable zone, the region of the planetary system where water can remain liquid on the planet’s surface. With Wolf 1069 b, the number of such exoplanets capable of developing life has increased by one candidate.

A planet with endless night and day

Detecting such low-mass planets is still a major challenge. Diana Kossakowski and her team at the Max Planck Institute for Astronomy in Heidelberg took up this task. As part of the Carmenes project, a tool was developed specifically to search for potentially habitable worlds. The Carmenes team uses this device at the Calar Alto Observatory in Spain. “When we analyzed data from the star Kurt 1069, we found a clear, low-amplitude signal that looked like a planet with roughly the mass of Earth,” says Diana Kossakowsky. The research results are published in the journal “The orbit of the star in 15.6 days, a distance equivalent to one-fifteenth the distance between the Earth and the Sun.” Astronomy and Astrophysics.

According to the study, the surface of the dwarf star is relatively cold and therefore appears orange-reddish. “As a result, the so-called enclave is shifting inward,” Kossakovski said. Despite its proximity to the central star, planet Wolf 1069 b receives only about 65 percent of the incoming radiation power that Earth receives from the Sun. These special conditions make planets around red dwarfs like Wolf 1069 potentially suitable for life. Also, they can all have special features. Presumably, their rotation depends on the orbit of the host star. In other words, the star always faces one side of the planet. That is, there is eternal day, and on the other hand, there is always night. This is why we always stand on one side of the moon.

Climate modeling for exoplanets

Assuming Wolf 1069 b is a bare, rocky planet, even on its star-facing side the average temperature would be only minus 23 degrees Celsius. However, according to current information, it is possible for Wolf 1069 b to form an atmosphere. Under such an assumption, its temperature could rise to plus 13 degrees Celsius, as climate models and computer simulations show. Under these conditions, water remains liquid and conditions favorable to life prevail because life as we know it depends on water.

The atmosphere is not only a prerequisite for the emergence of life from a climatic point of view. It would also protect Wolf 1069 b from high-energy electromagnetic radiation and particles that could potentially disrupt biomolecules. Radiation and particles originate either from interstellar space or from the central star. If the star’s radiation is too intense, it can also release the planet’s atmosphere, as on Mars. But as a red dwarf, Wolf 1069 emits only relatively weak radiation. Thus, the atmosphere may have been preserved on the newly discovered planet. It is even possible that the planet has a magnetic field that protects it from charged particles of the stellar wind. Many rocky planets have a liquid core, similar to planet Earth, that creates a magnetic field under the dynamo effect.

Hard search for exoplanets with Earth mass

The search for exoplanets has made tremendous progress since the first of its kind was discovered 30 years ago. Still, the signatures that astronomers look for to detect planets with Earth masses and diameters are relatively weak and difficult to extract from data. Carmenes’ team looks for small periodic frequency shifts in stellar spectra. These shifts are expected to occur when the companion’s parent star pulls and oscillates under its own gravity. In conclusion. The frequency of light measured on Earth changes due to the Doppler effect. In the case of Wolf 1069 and its recently discovered planet, these fluctuations are large enough to be measured. One reason is that the difference in mass between star and planet is relatively small, causing the star to oscillate more prominently than others around a common center of mass. The mass of the planet can also be estimated from the periodic signal.

Only a few candidates to characterize future exoplanet

At 31 light-years away, Wolf 1069 b is the sixth-closest planet to Earth by mass in the habitable zone around its star. It belongs to a small group of objects such as Proxima Centauri b and Trappist-1 e that are candidates for searching for biosignatures. However, such observations are currently outside the scope of astronomical research. “We’ll probably have to wait another decade for that,” says Kossakovsky. The Extremely Large Telescope (ELT), currently under construction in Chile, could study the composition of these planets’ atmospheres and perhaps even detect molecular evidence of life.