Education Activities To Accompany
Chandra Data Analysis Software
Cas-A
Activity 1: Pixels, Pixels, Everywhere
1. To see the astonishing detail in
this picture, play with the contrast/bias control by right clicking
anywhere in the image and dragging the mouse around (while still
holding the button down). This is fun! Try to obtain the most
detail possible in the picture.
2. Select the "he" color map. Go to
Color-->contrast/bias, and set the pointers at contrast
6.7 and bias 0.06. This viewpoint is extremely instructive. First,
you see a rotated square which shows you the extent of the satellite's
field of view. Also, you see a very bright (almost white) lumpy,
but somewhat circular region surrounding the central pulsar.
Outside the lumpy region, we see a fainter, more wispy region.
What is all this telling us?
We have pieced together the
following story....
About 300 years ago, the star that is now the central object
exploded. Remarkably, it was not seen by anyone, apparently,
even though these explosions, as we have seen, are usually large
enough so that the radiation can provide enough light for reading
at midnight. How, then, do we know when it happened? Optical
data shows material (via the Doppler effect) streaming outward
from the object at thousands of kilometers/sec. If we run this
expansion backwards, the material would get back to the center
in about 350 years. Thus, the object should have been visible
around 1650 AD.
