Star Light Simulator illuminates the search for life around the most common stars in the Milky Way

Star Light Simulator (left) and luminous (right). It has 25 channels in total, emitting light from 365nm (ultraviolet light) to 940nm (infrared light). Credit: La Rocca et al.

Europlanet Science Conference

Italian researchers have experimentally demonstrated for the first time that microorganisms can photosynthesise using infrared-dominated light emitted by the most common type of star in the Milky Way.

Results from the Star Light Simulator, presented at the Europlanet Science Conference (EPSC) 2022, suggest that life could evolve around stars different from our Sun and produce habitable oxygen-rich worlds by more complex organisms.

Most stars in our Milky Way galaxy are the smallest type of star that burns hydrogen, known as M red dwarfs. They are cooler and less bright than our Sun and emit mainly light in the infrared and far infrared, with very low emissions at visible wavelengths . Due to the abundance of these planets, many exoplanets have been found around M dwarfs. However, whether or not these planets are capable of supporting life has been the subject of much debate in recent years.

The Star Light Simulator, created through the collaboration of teams from the National Institute of Astrophysics (INAF), the Institute of Photonics and Nanotechnology (IFN-CNR) and the Department of Biology in Padua, can generate light intensities and spectra in different ranges to reproduce the light of any star. For this experimental setup, the team recreated the light emitted by the M-dwarf along with an atmospheric simulation chamber that replicated an artificial planetary environment.

“We initially focused on cyanobacteria because they have extraordinary abilities to withstand every environment on Earth, as well as their ability to survive in near-infrared light,” said Professor Nicoletta La Roca of the University of Padua, who led the study. “When these acclimatized to the simulated environment, we extended our testing to algae and various types of red and green microalgae.”

All experiments were successful, as all microorganisms proved that they can grow and photosynthesize under M-dwarf light.

Professor Larocca commented: “Life as we know it depends on liquid water, so this is one of the main criteria for an exoplanet to be considered habitable. More complex terrestrial life forms also depend on oxygen. On Earth, cyanobacteria have played a vital role in the oxidation of our atmosphere. atmospheric. The new experimental results expand our knowledge of potentially habitable environments and, therefore, where we might expect to find a planet harboring complex life.”

Sun-like stars versus M dwarfs for life and habitability: M dwarf stars display a very different set of characteristics compared to Sun-like stars, affecting the potential for life on planets orbiting those stars. Credit: Thibaut Roger – Europlanet 2024 RI

More information

The results have been presented for publication in a special issue of the open-access journal Life in the special issue “Frontiers in Extremophiles: From Life at the Edges on Earth to Space Exploration”.

La Rocca, N., Battistuzzi, M., Claudi, R., Cocola, L., and Poletto, L: Reactions of eukaryotic photosynthetic organisms to M-dwarf starlight simulation. , Europlanet Science Conference 2022, Granada, Spain, September 18-23, 2022, EPSC2022-495, 2022.