Chilean researcher Bárbara Rojas-Ayala found a way to measure the “metallicity” of M dwarf (red dwarf) stars which in turn could help science to better understand how planets, stars and galaxies form.
Rojas-Ayala, an associate professor at the University of Tarapaca and a researcher at Center of Astrophysics and Tecnologías Afines in Chile, says that M dwarfs are the tiniest hydrogen-burning starsabout 0.08 to 0.6 times the size of Earth’s sun.
“They are very faint because of their small sizes and low temperatures compared to the sun, so dim that we cannot see any of them at night with just our eyes, however, they compose more than 70% of the stars in the Milky Way! ” she says, adding that the closest star to our solar system, Próxima Centauri is this kind of star.
“They represent the large majority of stars; hence, knowing their characteristics is fundamental for our complete understanding of stellar astrophysics, planet formation and evolution, and Galaxy,” she says.
Rojas-Ayala developed a method to estimate the amount of elements heavier than hydrogen and helium (“metals”) in the photospheres of M dwarfs, known as the “metallicity” of a star.
“It is the result of stellar nucleosynthesis and the metal enrichment of the interstellar medium by stellar winds and supernovae, that provides recycling materials for the birth of new stars,” she says, “Younger stars are more metal-rich than older stars.”
Rojas-Ayala says before there wasn’t a reliable method to estimate their metallicities and meanwhile, planets were being found around red dwarfs.
“In solar-type stars, the presence and characteristics of planets seemed to be linked to the star’s metallicity, a concept known as the planet-metallicity correlation,” she says, “We wanted to get reliable metallicities for M dwarfs to see if they followed the planet-metallicity correlation or if there were differences in the way planets were formed.”
From Aspiring Lawyer to Astronomer
Rojas-Ayala was born and grew up in Santiago, Chile and initially aspired to a legal career.
“Since I was about 10 years old, I had decided to become a lawyer… It never crossed my mind that I could be an astronomer!” she says, adding that she had never met an astronomer and thought it was a hobby, not a career path.
“When I was in my last year in high school, I realized that I had an idealized view of what a lawyer did,” Rojas-Ayala says.
She would then go on to study at an engineering school as that would give her two more years to choose a degree.
“However, trying to skip some of the physics labs, I took an astronomy course. I thought it was fascinating to study such distant celestial objects just with the light that reaches us from them… and I was hooked!” Rojas-Ayala says, adding that she applied and got accepted into a summer undergrad program at the Cerro Tololo International Observatory (CTIO) in Chile.
She would then move to Ithaca, NY, to start graduate school at Cornell, then New York and then Portugal, before returning to Chile about 8 years ago.
Rojas-Ayala says Chile has become a relevant place globally for optical, near-infrared, and sub-millimeter astronomy.
“It is excellent to see Chilean researchers involved in great projects that aim to understand our origins and the mysteries of the universe and that their international colleagues value their contributions and participation,” she says.
Another female astronomer from Latin America is Sofía Rojas Ruiz.
She will be using the James Webb Space Telescope (JWST) to study the first-born bright galaxies and quasars that contributed to the process of illuminating the universe from complete darkness about 13 billion years ago.