Be sure to click on the images below to view the hi-res versions.
Mid-Infrared Imaging from the Spitzer Space Telescope
"Centaurus A" Peculiar Lenticular Galaxy
This is a close-up image of a fairly nearby galaxy named NGC 5128 or "Centaurus A" (this second name actually refers to the radio source at the center). The light captured in the three images (blue, red & green of the color composite) was emitted in the mid-infrared. The cyan, yellow and red circles highlight globular clusters associated with the galaxy. You can see three of these in the panels on the upper right. I modeled the light of these globular clusters and subtracted it from the image to produce the lower right panel. You can read about this interesting, but challenging dataset here.
Galaxies in the NGC 1407 Group
Confirmed galaxy members on the Suprime-cam Moasaic
A year 10 work experience student, Joanna, created color images of NGC 1407 group galaxies and put them onto this website.
Joanna also discovered some background (unconfirmed) galaxies that struck her fancy. She put images of these onto a myspace page located over here.
Globular Clusters in the Giant Elliptical NGC 1407
Subaru/Suprime-Camera Mosaic
This is two views of the same image. The one one the right is the original. I modeled the light of the two elliptical galaxies (NGC 1407 center; NGC 1400 upper right) and subtracted it from the original to produce the image on the left. Click on the image to see a hi-res view.
Detail
This is a close-up of the latest dataset I've worked with. It is the result of a successful telescope proposal to use the Suprime-cam imager on the 8-m Subaru telescope in Hawaii. While the quality of this web image doesn't give the real data justice, you can still see globular clusters in the galaxy NGC 1407 (big source of light on the left) as the faint, bluish dots on this image. Please click on the image to get a closer look!
Location of the Globular Clusters (~30x20arcmin ~180x120kpc)
Plotted in green, on a very rough version Subaru mosaic are the brightest globular cluster candidates. It is pretty obvious they tend to concentrate near the center of NGC1407 (center) and another smaller galaxy NGC1400 (lower right). The globular cluster system of NGC1407 likely extends almost to the edge of this mosaic. Diffuse galaxy light from NGC 1407 extending approximately to the radius of NGC 1400 was removed for this image.
Finding the Globular Cluster Candidates
In the color-color plot above, point-source objects found on the Subaru mosaic are given. Globular clusters are known to occupy this region in color-color space. Most of the dots indeed form a line: there are a lot of globs in this field. Three separate mosaics were needed (which were combined to form the color image at the top) for this color-color selection. Exposures totaling 9 hour were taken. Only half of this imaging data was used for this rough reduction.
Zoomed region on the Subaru Mosaic
For this figure I've combined all available data. The mean seeing (blurring from the atmosphere) was 0.5 arcseconds. Under such conditions the detailed morphological structure of background galaxies is easily determined. This makes distinguishing globular clusters from background galaxies (which are contamination for me) much easier. The green ellipses are the estimated isophotal structure of the objects, as determined by SExtractor. Notice how badly some of the ellipses fit the dwarf galaxies on the image: this is a 'first-look' analysis.
HST Imaging of the Sombrero Galaxy Globular Cluster System
The Sombrero Galaxy
Locations of globular cluster candidates are highlighted with the blue and red symbols, corresponding to metal-poor and metal-rich globulars, respectively. The metal-rich ones tend to be found near the centers of galaxies.
A Single Globular Cluster
This is a color-composite image of a globular cluster we found on a Hubble Space Telescope ACS field near the Sombrero Galaxy. In space, without a blurring atmosphere, the resolution is trivially high, thus globular clusters are partially resolved (you can measure their sizes) at the distance of this galaxy.