NOAO

Well, this blog's off to a limping start. Fortunately, my New Year's resolution was "to blog more!"[1].

I am now an employee of the National Optical Astronomy Observatory (NOAO), where I will continue my work for the SAGE project. I've been kind of a loner in that project, working on my classification of protostellar objects in the vicinity of a star-forming region with little interaction with the larger team. I hope that will change now that I am at NOAO, working with Bob and Knut. My focus will change a bit as well, as I'll probably start working mostly on AGB stars and other evolved stellar populations. Exciting times.

[1]: Not really...but I will try to post more often

Observing at Magellan

I'm currently in the observing room of my favorite telescope, Magellan. It's good to be back in Chile again (this is my second trip this year, and my first trip to Magellan since last October). I will be taking spectra of red giant stars in star clusters of the Magellanic Clouds, in order to determine their chemical abundances. I'm using MIKE+Fibers, which is scheduled in a rather unique way. All MIKE+Fibers proposals are scheduled concurrently, and then the observers split the total block of observing time and execute a mini-queue to obtain everyone's data.

This is the third night of the MIKE+Fibers block, and my first night of observing. Right now, I'm just watching the other observers, remembering the ropes of the instrument. Probably tomorrow, I'll start actually pulling my weight.

Interesting non-science developments at LCO since my last visit: the observers' workstations are now Mac Mini's, rather than Linux boxen. And the Magellan kitchen now has an espresso machine (and there was much rejoicing).

I'll try to post some images of the telescope and instrument later.

UPDATE: Here are some images.

Hmm. I can't seem to get the image uploader to work, so here are *links* to images:

Here's a good overview shot of the MIKE+Fibers system. The whole assembly sits on the nasmyth platform of the telescope, the spectrograph itself is off to the left; it is connected to the telescope by hundreds of optical fibers (the red and blue cables), each of which will transmit the light from a single star in the focal plane of the telescope (off-image to the right) to the input slit of the spectrograph.

The fibers need to be placed very precisely in order to receive the light from stars (or galaxies) scattered across a particular field. This is achieved by designing plug-plates well in advance for a particular place in the sky. The plug-plate is a curved sheet of metal, like a large dinner plate. Hundreds of holes are drilled into the plate at the precise locations where the target stars will be when the telescope is positioned correctly. It's amazing that it works, but it really does. Here is an image showing a plate that has been plugged with fibers. The fibers need to be plugged into their holes manually; it takes about 30 minutes.

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.

Abstract

Hello, Jason here.

I'm an astronomer at the University of Arizona, studying star formation and stellar populations in nearby galaxies, particularly in the Magellanic Clouds.

This blog will serve as a journal of my research activities, and commentary on developments in science (not only in astronomy; I am also interested in other areas of physics, evolutionary biology and many other fields). I will try not to talk about politics this time, unless it intersects with the world of science.

I really enjoy being an astronomer. I usually have three or four lines of research going at once, which is never boring, but it can be a challenge to make progress on all fronts. I'm hoping that by blogging frequently I can improve my discipline in this regard.

So, welcome, non-existent readers!