M33, the Pinwheel Galaxy, is a Sc/Scd Spiral Galaxy. It rotates
clockwise, with the northern arm moving slowly west. Its rotational period
has been determined to be about 200 million years. It was probably first
found by Hodierna before 1654, but was rediscovered by Charles Messier in
1764. It is about 3,000,000 light-years from earth. It covers an area of
73x45 arc minutes. Besides Andromeda (M31), it is the nearest spiral galaxy.
Despite it’s proximity, it is very hard to observe because of its
low surface brightness. Many amateur observers often set cannot find it
because they are looking for a smaller, brighter object. It covers an area
four times that of a full moon. Several supernovae remnants and 112 variable
objects including 4 novae and 25 Cepheids, have been found within M33. M33
is one of only a few that does not show a redshift, it is approaching us
at 7 miles per second.
The light emitted from M33
comes mostly from main sequence stars especially in the thin disk, large
HII regions also contribute to the general light production. Most of the
light from the spiral arms comes from blue supergiants, because of the
higher amount of thes b-type supergiants, M33 seems “bluer”
than most galaxies. The total integrated sprectral type is A7.
Our group set out to collect a light profile of M33 and to determine whether
it fit well or poorly to theory. This was an interesting and challenging
project because M33 is both large in the sky and fairly faint, but despite
that we were able to create a light curve which was able to confirm that
our original images were almost certainly of the bulge and that the disk
must then extend off the scale of our original images.
Because M33 is so faint we were forced to be innovative in out methods.
After a few false starts the method we ended up using was fairly simple.
We used a piece of Astronomical software called DS9 to automatically generate
two graphs of brightness per pixel along vertical and horizontal lines
in our best image after rotating the image so that these lines didn’t
pass through any stars and centering the crosshairs on M33. Then we printed
those graphs and imported the best one into excel manually using rulers
and our knowledge of proportions. Once we had this data into excel we
converted pixels into kiloparsecs by using our knowledge of our original
image and the distance to M33. Then we made several plots of this data
to determine whether our theoretical model of the disk or the bulge fit
better. As it turned out after looking at our data the bulge model fit
extremely well, with a good value for the expected radius and a very good
correlation to the linear fit we expected. Attached to this report you
can see both our original image and two plots that show the light profile
to the left and right of M33’s center with the linear trendlines
we fitted to the data.
This image is a combination of 80 images, each 20 seconds in exposure
length. They were obtained on the 10th of October 2002 between the hours
of 1:00am and 2:21am or 0500 and 0621 UT. The raw images had dark and
flat field corrections applied to them and were aligned and then combined
using the CCDSoft program by Software Bisque. The combination was done
using an averaging algorithm which took the average of the aligned images
thus enhancing the data and canceling out much of the noise. All of the
exposures were taken with a clear filter maximizing the signal to noise
Orientation and Scale:
North is up and East is to the left. The binning for the exposures was
set to 2x2 and the angular diameter of the image is 7.2x5.2 arcminutes.
The galaxy core ahs celestial coordinates 01h 34m 01s +30º 40’
37” (epoch 2000) which is 14.78 degrees South East of Andromeda
Ammar, David Bytwerk and Jason Kornas