My research interests lie in stellar populations with an emphasis on the use of variable stars to probe properties such as age, metallicity, and distances. Currently, my studies have focused on globular clusters and dwarf galaxies.
I am going to be starting a new postdoctoral position at Macalester College with Dr. Kim Venn. The research I will be working on there include analyses of blue supergiants in dwarf irregular galaxies and abundances from red giants in dwarf spheroidal galaxies. There is also a teaching component to my postdoc position.
I have also begun work on another project with Dr. Patricia Knezek examining
low surface brightness, very gas-rich dwarf galaxies in the Centaurus A
group. The goal of this study is to understand the properties of these
galaxies which have low stellar density and high gas content. HST/WFPC2
images have been obtained in order to determine the mean metallicities of
these galaxies and their star formation histories.
UPDATE! Here
is the poster that was presented at the 201st Meeting of the
American Stronomical Society displaying our results for the Centaurus A
dwarf galaxies surveyed in our project. We have also submitted a manuscript
to the Astrophysical
Journal Letters discussing the "unique" star formation history seen
in HIPASS 1321-31.
I am also researching two unusual, metal-rich globular clusters, NGC 6388 and
NGC 6441. For this project, I am collaborating with Drs.
Horace A. Smith,
Marcio Catelan, and Allen
Sweigart. Each cluster exhibits a blue extension to
the horizontal branch, unusual for clusters so metal-rich. These horizontal
branches also get brighter as one moves blueward. Models by Sweigart and
Catelan have shown that in explaining these effects, the horizontal branches
for these clusters would have to be unusually bright. Any RR Lyrae found in
these clusters would then have unusually long periods. As published in our
Astrophysical Journal Letter, this is
indeed the case in these clusters.
UPDATE! Here is
a more in-depth discussion on the research on NGC 6441 and NGC 6388 along with
links for relevant publications. We now include our recently accepted paper
discussing the variable stars found in our
HST snapshot survey of NGC 6441.
Previous to this research, I worked with Horace Smith in searching the Small
Magellanic Clouds for variables. For more information, please see a very nice
write-up done by
Michele Stark while she did her Research Experience for Undergraduates at
Michigan State University during the Summer of 1997. Michele continued this
work for the next year as she searched for periods and created light curves
for known and new variables. More recently,
Brian Sharpee worked
on analyzing the data.
A paper on the results
has been published by the Astronomical Journal.
I have also joined in a collaboration to study the Fornax dwarf spheroidal galaxy and its globular clusters. Extensive surveys are being carried out to look at their stellar and variable star populations.
Along with my collaborators that worked on NGC 6388 and NGC 6441, we have obtained time on the YALO 1m telescope to observe two metal-rich globular clusters NGC 6569 and NGC 6304. It is our hope to find any RR Lyrae variables that possibly exist in these clusters and if they exist, to determine if their properties match what has been found for other metal-rich globular clusters.
