Survey of the Galaxy M83

Using the 6.5-meter Magellan telescope at Las Campanas, we have mapped the galaxy M83 at unprecedented resolution. The seeing on the mountain was 0.4 arcseconds for most of the observing run, and with the light gathering power of the 6.5-meter telescope we were able to gather images comparable to those made with the Hubble Space Telescope. What Hubble gains in resolution, we gain in light gathering power. The result is a view of the galaxy M83 better than ever seen before. Dr. Barry Madore, Dr. Wendy Freedman, Ryan Quadri (Harvey Mudd) and Dr. Bryan Penprase have taken these images, and will study the images to look for evidence of asymptotic giant stars and Cepheids. The result will be an improved understanding of
the distance to the galaxy, and of the evolution of the halo population of stars within the galaxy.


To get a view of what the galaxy M83 looks like, below is a link to a full color image of the galaxy taken by Dr. Barry Madore at the 100" DuPont telescope. This is the view of the galaxy which an inhabitant of an orbiting globular cluster might see. You can click on this image to get a larger view.

One of our main projects was to get information on the population of stars at the edge of the galaxy. We used the 6.5-meter telescope to gather images at progressively greater distances from the core of the galaxy.

In the images below you can see a montage of several images which march out to greater distances from the center of the galaxy. At the edge is the image of the faint stars in the halo of the galaxy. The outer image was constructed using dozens of exposures with the 6.5-meter telescope to reveal stars and galaxies that nobody has ever seen before! All the images were made using the V and I filters -- we have mapped the V filter to the blue channel and the I filter to the R and G channels to simulate real color. The image below is reduced in size by half so you can see it in your browser. The amount of information in the image is staggering -- as is the dynamic range of the image which falls from very bright to nearly 26th magnitude. The sharp changes in colors of the stars within the galaxy is apparent, as the various stellar populations give light in blue or red light depending on their age and luminosity.
The bright blue dots in the picture correspond to individual O and B stars in this galaxy. All this at a distance of 7 Megaparsecs or over 22 million light years!   In the deepest image at the far right we are looking at other stars which have run out of Hydrogen fuel and have moved up the "asymptotic red giant branch". Our study will help us understand better the populations of the stars within this galaxy and how they appear to vary in brightness.



 

The observing run also produced some fantastic images of other galaxies. Have a look at our galaxy images!

Galaxy images taken during the March 2001 Las Campanas Observing run with Barry Madore, Wendy Freedman, Ryan Quadri, and Bryan Penprase