November 19, 2004
Cassiopeia
Cassiopeia is a very prominent
constellation in the high northern skies these nights. Will
Rutherford, a student in Contemporary Astronomy at Warren Wilson
College photographed the constellation with a digital camera by taking
many 15 second exposures while the camera was mounted "piggy-back" on a
telescope equipped with a clock drive, so that the constellation was in
the same place in the camera field of view as the earth rotated during
the 10 minutes of picture taking. The camera was looking directly at
the sky, not through the telescope. The frames were further
aligned and digitally added by Physics Assistant Dan Sockwell.
The "co-adding" increases the visibility of faint stars. Notice
how many faint stars are visible using this technique. Cassiopeia
is also in the Milky Way - a part of the sky which is quite rich in
numbers of stars.
The
asterism of Cassiopeia is the familiar "W" formation made by the bright
stars as shown in the image at left. The color and contrast of
the stars in these images have been enhanced to exaggerate the various
colors. Notice that most of the bright stars are quite blue -
indicating that they are extremly hot - about 4 times hotter than the
sun. On the other hand, the bright star in the lowest part of
the "W" is yellowish, indicating it is about 2/3 the temperature of the
sun. Look for Cassiopeia next time the stars are
visible! More information about the stars in Cassiopeia may
be found at the SEDS web site: