María Teresa Ruiz González

Ruiz has proudly described herself as a daughter of Chilean public education. She studied at the Liceo 7 de Niñas in Santiago, began her university path in Chemical Engineering at the Universidad de Chile, and then found her natural language in astronomy.

In 1971 she obtained her degree in Astronomy from the Universidad de Chile and the Carnegie-Chile Fellowship to continue her studies in the United States. At Princeton she completed her master's in Astrophysics in 1973 and her doctorate in 1975, building a scientific base she would later put to use across Chile, Italy, Mexico and the United States.

Her time at Princeton was not just an academic credential. She was part of a generation of women scientists who had to establish a presence in spaces where there were almost no Latin American women. From there she returned to Chile with an international training she would put to the service of research, teaching and institution-building.

After completing her doctorate, Ruiz carried out postdoctoral research at the Astronomical Observatory of Trieste, Italy, where she deepened her work on the final stages of stellar evolution. She then worked as a visiting astronomer at the Institute of Astronomy of UNAM (Mexico's national autonomous university) and, in 1978, as a visiting scientist at NASA's Goddard Institute for Space Studies in New York.

That international path was key to her scientific maturity. When she joined the Universidad de Chile in full, she brought with her not only observation and research techniques, but a network of experience that helped project Chilean astronomy into a global conversation.

Her research focused on low-mass stars, brown dwarfs and the final stages of stellar evolution. Rather than chasing only the spectacular, Ruiz sharpened her eye to detect faint, difficult bodies — the kind that force a careful distinction between planet, star and something in between.

Kelu-1 was named with a Mapuche word for red, a fitting choice for a cold, faint and decisive object. Its discovery confirmed that the universe is full of bodies that do not fit comfortably into our initial categories.

The discovery was made at La Silla Observatory and became one of the first strong confirmations of free-floating brown dwarfs. These objects are neither ordinary planets nor full stars: they have intermediate masses and cannot sustain hydrogen fusion the way a stable star does.

From 1987 she carried out extensive academic work at the Universidad de Chile, training generations of astronomers. Her courses covered modern physics, general astronomy, intelligent life in the universe, extragalactic astronomy, gaseous nebulae and stellar populations.

She also chaired and drove key spaces for the development of national astronomy, including the Fundación para el Desarrollo de la Astronomía de Chile (the Foundation for the Development of Astronomy in Chile) and the Centro de Astrofísica y Tecnologías Afines (the Centre for Astrophysics and Related Technologies). Her work helped establish Chile as a country that not only hosts telescopes, but produces knowledge from them.

Her dream, repeated in interviews and outreach writing, was for science to find evidence of life beyond Earth. For Ruiz, the universe remained an open conversation: full of bodies invisible to the human eye, questions not yet asked, and worlds we may not yet know how to recognise.

The report also places her among the most influential women in Chile, not only for her discoveries, but for the way she opened up spaces of scientific authority for other women.

Her retirement in 2025, prompted by an eye condition that had progressively affected her sight, closed a chapter of active research, but not her influence. Every generation she trained, every outreach book, and every public conversation about Chilean astronomy carries part of that legacy.