My Research

Since this blog will mostly be about my research, I thought I would start by telling a bit about what I work on.

The one-sentence version is, I study star formation in nearby galaxies: the physical processes which ignite, sustain and extinguish star formation on a galactic scale. One of the best ways to study these processes is by reconstructing the star formation histories of galaxies. By measuring the brightnesses and colors of many thousands of stars, it is possible to infer their distribution of ages (and thus, to determine how the galaxy formed stars throughout its history). In this sense, a galaxy's present stellar population is like a "fossil record" of its past star-formation activity, hence the title of this blog.

Primarily, I work on the Magellanic Clouds, two satellite galaxies of the Milky Way. I am involved in both optical and infrared surveys of the Large and Small Magellanic Clouds. I am using the optical data to reconstruct the star formation histories of these two galaxies in unprecedented detail. The infrared data provide a critical complement: the present-day star formation activity.

I'm also determining star formation histories of other dwarf galaxies in the Local Group, including some that have only been discovered in the past couple of years.

In addition to star formation histories, I have also become interested in galactic chemistry. There is a life cycle of baryonic matter in galaxies: star form from dusty gas clouds, and as they evolve and die, they usually inject some of their material back into this interstellar medium (ISM) of gas and dust. But here's the thing: while that stuff was in the star, nuclear fusion was happening. Nuclear fusion is a natural alchemy that sustains (almost) all stars in the Universe), so the mix of elements that went into the star is different from the mix of elements it returns to the ISM. In particular, the stars produce heavier elements from light ones (you may have heard the factoid that all atoms in the Universe heavier than beryllium were once burned inside a star). Thus, the life-cycle of material in galaxies involves an inevitable "self-enrichment", whereby each generation of stars has more heavy elements than the previous generation (caveats: particularly violent episodes of star formation can cause the galaxy to erupt like a volcano, which results in most of the enriched material flying off into intergalactic space; also, it's possible for a galaxy to accrete material that has very low enrichment, which would reduce the overall fraction of heavy elements).

I am interested in examining this self-enrichment process in nearby galaxies by measuring the chemical abundances in their stars, using spectroscopy.