Assignment 2: The Andromeda Galaxy

Due Friday, Dec 15, 2000, at 3 PM

Your job this week is to examine the Andromeda Galaxy, M31, using different wavelengths of light, and draw conclusions about the galaxy's properties.

Go to the SkyView site:

http://skyview.gsfc.nasa.gov/cgi-bin/skvbasic.pl

This site allows you to make maps of any portion of the sky, as seen from many different wavelengths. It contains a huge archive of data collected from many different surveys and space missions.

Preferred Java method

First, click on the word Java near the top of the screen. This will create a Java applet. Pick

Coordinates or name: M31
Size in degrees: 3
Pixel size: X 300 Y 300

Then click Submit. A new window should eventually pop up with the image you select. The image will have a nice greyscale colormap.

Deprecated HTML form method

This method is less desireable, because the images it returns have a confusing yellow-blue-red colormap. But it will work even if your browser doesn't support Java.

Set coordinates to the coordinates of the Andromeda galaxy:

      00 42 00, +41 00 00

Down in the Optional Parameters section of the form, select Image size of 3 degrees.

Selecting images in different wavelengths

Now, one at a time, choose the following from the Surveys menu item (or section of the form), and then press the Submit button.

Optical: Digitized Sky Survey
Infrared: IRAS 12 micron (near infrared)
The diagonal striping in this image is an artifact of the IRAS satellite's observing technique: it scanned long, thin sections of the sky.
Infrared: IRAS 100 micron (far infrared)
Radio: 0408 MHz -- 73 cm radio waves
Radio: VLA NVSS (1.4 GHz) -- 21 cm radio waves
X-rays: PSPC 1.0 Deg-Inten
The ROSAT satellite had a circular field of view of about 0.75 degrees, too small to cover the entire Andromeda galaxy at once. It was pointed at several different locations to make a mosaic of the galaxy, but, as the image shows, it didn't cover an entire 3-degree field around the galaxy. There is no information in X-rays in the outer portions of the image.

Write a short sentence or two which describes the contents of the galaxy (gas? dust? stars? spiral arms? bulge? etc.) based on each of the images.

Based on all the information you can glean from the different images, explain where (if anywhere) one should look to find recent star formation in the Andromeda Galaxy.

Last modified by MWR, Dec 20, 2000