Spectral observations of Dwarf Elliptical Galaxies

I have been involved in spectral observations of Dwarf Elliptical Galaxies using the Double Spectrograph at the Palomar Observatory, California. These observations are part of the work of Liese van Zee, a former graduate student of my advisor and now an Assistant Professer at Indianna University. I have been on two observing runs as part of this project, in September 2001 and April 2002.

• The September 2001 run was spent looking for the signature of rotation in three of the dwarf elliptical companions of the Andromeda galaxy. Dwarf elliptical galaxies (like their giant counterparts) are not supposed to rotate according to accepted knowledge, but in March 2001 (in the first observing run for this project) Liese and Martha found evidence that at least some in the Virgo Cluster do. The observations we did in September were designed to test whether or not dEs in a much lower density environment than the Virgo Cluster also rotate.
• The first night the April 2002 run was devoted to taking high resolution spectra of UCGA 292, the third lowest metallicity galaxy known (discovery paper). The spectra were taken with the aim of calculating a helium abundance for this galaxy. A measurement of this would be really useful in the determination of the primodial helium abundance. A common way to measure this is to use abundances from several galaxies of different metallicities and extrapolating down to zero. This means that low metallicity data points, like 1 Zwicky 18 (the lowest known metallicity galaxy) and UGCA 292 are very important.
• The other 5 nights of the April 2002 run were marked down for more rotation studies of dEs in the Virgo cluster. Unfortunately we lost the first 2 nights as we were sitting in a cloud bank unable to open the dome. We collected data for the remaining 3 nights from dEs in various groups onf the Virgo cluster with the aim of searching for environmental effects in their kinematics.