CATA researcher speaks at world astronomy summit on the relevance of the study of Red Dwarfs

Bárbara Rojas Ayala, as a world expert in M Dwarfs, developed her presentation on the characteristics, advances and difficulties in the study of these cool stars, to know their composition and that of their planets that could be candidates to harbor life.

M Dwarfs or Red Dwarfs are the coldest, smallest and most numerous stars in the universe, estimated to account for 70% of those in the Milky Way. They are also fundamental to understanding the processes that have governed the dynamics and chemical evolution of our galaxy.

Therefore, the importance of the plenary presentation that Bárbara Rojas Ayala, Associate Researcher at the Center for Astrophysics and Related Technologies (CATA), made on the study of these bodies at the “Cool Stars 22” conference organized by the University of California San Diego (UCSD) and San Diego State University (SDSU) on “Cool Stars, Solar Systems and the Sun”. This is the main event of its kind in the world and brought together leading astronomers and astronomers in San Diego, USA.

The meeting sought to place cool stars in the context of stellar systems. It included all aspects of the creation and interactions of cool stars: their fundamental properties, their multiplicity at large and small separations, their chemical abundances, their magnetic fields and their activity. The session also focused on cool stars as hosts of planetary systems and/or disks and their interactions.

“One striking aspect of M Dwarfs is that their life expectancy is much longer than the current age of the Universe. So, since they do not change and do not evolve, they are perfect for mapping the dynamics and chemical evolution of the Galaxy. Now, the problem we face is that, as they are small, since they have between 8% and 60% of the Sun’s mass, they are very faint and that makes it difficult to observe them”, explains the member of the Exoplanets and Astrobiology area of CATA.

His plenary presentation entitled “Unveiling the Stellar Properties of M-Dwarfs: Current Advances and Future Prospects” was among the highlights of the workshop and delved into the intricate task of unraveling the stellar properties of Red Dwarfs.

During the conference, the astronomer from the Universidad de Tarapacá also explained that the interest in these stars is due to the fact that it is easier to find small planets, mostly rocky, like the Earth.

The search for these bodies, which orbit M Dwarfs, has sparked renewed interest in their stellar characteristics, driving advances in observational techniques and theoretical models. Navigating through various methodologies employed to extract fundamental parameters of these low-mass stars, with special emphasis on the fundamental role played by binary/multiple systems and reference samples in understanding their nature.

“The only way to determine the masses of stars accurately is when they are in multiple systems, in binary systems. But, in addition, when they are in binaries composed of a star like the Sun and a secondary M Dwarf, we can use them to calibrate metallicity ratios with different indices and thus know, finally, how rich in metals they are. In addition, their study requires synthetic models that allow us to copy their spectra, which is difficult because their mass is very small, they are very cold and their atmospheres are complex, full of molecular absorption. Another difficulty is that, because they are faint, obtaining high signal-to-noise data requires more telescope time. However, now with the Large Surveys and Deep Surveys (catalogs of stars in wide and deep fields of view) we have observed enough of them in the optical and infrared,” says CATA Associate Researcher Bárbara Rojas Ayala.

In doing so, spectral parameters of Red Dwarfs such as effective temperature, metallicity and surface gravity are being determined using the same technique used decades ago on stars such as the Sun. But in this case, for example, in the near infrared, rather than in the optical.

Integrated work

The role played by CATA in the research carried out by Bárbara Rojas Ayala, which she presented at this conference in the United States, is fundamental. “There are colleagues at CATA who are in the Star and Planet Formation area who know young M Dwarfs quite well and we are contributing, together, to understanding what planet formation is like around these stars. In the literature it can be seen that there are controversies as to whether Red Dwarfs are good candidates to host life on any of their planets, and that is the research that I am carrying out together with James Jenkins (CATA-UDP), in the Exoplanets and Astrobiology area of CATA. In addition, together with Claudio Cáceres (CATA-UNAB), we are trying to observe cold disks around these stars that can tell us something about the formation of the planet”, says the astronomer.

Therefore, by working together, it is possible to bring together different CATA researchers with expertise in different techniques to find new ways to facilitate their study.

“Despite significant progress, challenges remain, especially in reconciling discrepancies between methodologies. However, it is precisely these challenges that motivate our collective efforts to overcome them in the near future. Interdisciplinary collaborations continue to propel us toward a holistic understanding of M-Dwarfs and their role as stellar hosts. This journey not only enriches our understanding of individual stars, but also deepens our knowledge of planetary systems and our Galaxy in general,” details Bárbara Rojas Ayala.

Among the remaining challenges, regarding the characterization and spectroscopy of M Dwarfs, is to achieve accurate measurements of their surface gravity. And this is specifically related to their mass and size, something absolutely necessary to characterize exoplanets.

Another of the things that need to be studied in depth is to ensure that the work with the optical and infrared telescopes is consistent. As well as extending all the calibration techniques to the smaller Red Dwarfs, bringing the techniques closer to Brown Dwarfs, stellar bodies that have no nuclear reactions in their interior.