Low-Mass Stars: Most Common yet Least Understood, says Columbia Astronomy Professor

August 06, 2019

Marcel Agüeros, Professor of Astronomy and Founding Director of Columbia University's Bridge to PhD Program in STEM, an initiative aimed at increasing the participation of students from underrepresented groups in Ph.D. programs in STEM disciplines, gave a colloquium end-May at Universidad Católica’s Institute of Astrophysics.

The presentation was on Agüeros’s area of specialization: low-mass stars, or stars that have about the same mass as the sun or a fraction of that.

“One of the primary reasons for this interest is that they are among the most common in our galaxy, but they’re the ones about which we know the least. Even their fundamental properties: mass radius relation, how they lose momentum, how magnetically active they are, are not very well understood,” he said in an interview following the colloquium. “If you’re interested in exoplanets and planets around the stars, the places we’re most intensely looking now for planets like Earth, are around low-mass stars. If we want to see how those planets evolved, what the conditions are like now, whether they would be able to harbor life, we really need to better understand the fundamental properties of those stars.”

Up until the 1990s, humans knew of about a dozen M-dwarf stars, despite the fact that these represent 85-90% of the 100 billion stars in the Milky Way, Agüeros noted. However, “technology has been transformative over the last ten years or so – space-based missions, multi-object spectrographs, have made it easier to identify, examine and understand ensembles of these low-mass stars in ways that were not possible a decade ago. Today, people increasingly understand that these are fundamental building blocks for all kinds of areas of astrophysics, and if we want to do precision astrophysics, we need to understand the ‘brick’ much better.”

Both Columbia and Universidad Católica have a long-standing relationship in Astrophysics, which has included more than seven student exchange programs in the last three years.

The relationship with Chile “is an opportunity for Columbia students to work in a cutting edge department that is in many ways similar to ours, about the same size, similar interests, but it’s also very different – it’s in a different hemisphere, less undergraduate focus, with more post-docs, and Chile is an astronomy country,” he added. “So it’s very obvious that there are benefits here. Those are the best contacts that you can make - to develop human capital.”