I study our own Milky Way galaxy to find out how and why it evolved to what it is today. The evidence is that our Galaxy is a fairly typical spiral galaxy. That means that by studying our home in the universe, we can learn a lot about the evolution of other spiral galaxies like it. We can also use the story of our own Galaxy to help interpret observations at high redshift, where we can catch galaxies in the process of forming.
There are lots of observational and theoretical reasons why we think Galaxies like the Milky Way are created through merging and accretion of smaller systems. We can use the Milky Way to help answer some basic questions about how that process works.
We know that most of the matter in our Galaxy isn't gas or stars, but rather something we can't see at all called Dark Matter. But we know it is there because we can observe its gravitational pull on the stars. SEGUE is finding stars as far away in our Galaxy as we can so that we can weigh the Galaxy and find out how much dark matter there is, and where it is. We can also use the motions of those stars to learn how the Galaxy is still growing by accreting new stars and dark matter today.
Because we live in the middle of it, we see stars in the Galaxy spread over the whole sky. You can see that for yourself when you look at the Milky Way stretched across the sky on a clear night. What you are looking at is the disk of our Galaxy, edge-on, from the sun's position near one edge. So if we want a big-picture view of the Galaxy, we need large-area surveys that cover an appreciable fraction of the sky.Two such surveys I have worked on and with are the Sloan Digital Sky Survey (SDSS) and SEGUE, the Sloan Extension for Galactic Understanding and Exploration. Both of these use imaging in five filters and moderate-resolution spectroscopy to map out the structure (where the stars are) and stellar population content (where stars of different ages and metal-content are located). The SDSS was designed primarily to map the local universe, so it looked up out of the plane of the Galaxy. In the process of doing that extragalactic survey, it mapped about one quarter of the sky around the North Galactic pole. SEGUE is designed specifically to cover a larger range in Galactic latitude, reaching much closer to the plane of the Galaxy, in order study the Milky Way. You can learn more about the SDSS and SEGUE and get the data for yourself here.
In order for the SDSS and SEGUE surveys, or any other astronomical observations, to happen, we first need to have instruments that can see fainter objects and over a larger range in wavelength than our eyes can see.
A description of the imaging camera for the SDSS, which I helped design and build as graduate student (and sometimes have to fix), is here. This is a picture of us putting the front window of the camera, which is also the last corrector plate of the survey telescope, into its cell (very carefully!) The colored glass squares are the filters, one for each CCD.
The SDSS spectrographs, which also take the stellar spectra for SEGUE.
The LRIS spectrograph, new red CCD dewar commissioned December 2nd, 2010 (photo coming soon)
The ARC Echelle spectrograph, on the 3.5m telescope at Apache Point Observatory, is described here.
Before coming to Santa Cruz, I was a Hubble Postdoctoral Fellow
in the University of Washington, Seattle Astronomy Department
Apache Point Observatory, where the SDSS and SEGUE surveys happen.
Lick Observatory on Mt. Hamilton, where I hope to do some adaptive optics observations this coming semester.
W. M. Keck Observatory, where I have observed on the HIRES and ESI spectrographs.
The Thirty Meter Telescope, a future giant telescope project worked on by people at Santa Cruz and elsewhere.