Exercise 1 - Measuring the Distance to Supernova 1987A
The geometry of the nearest ring around Supernova
1987A (SN1987A) is introduced. We then define the scale of the Hubble
image of the supernova so that the angular diameter of the ring
and also the inclination of the ring relative to the plane of the
sky can be found. Observations from Earth show how light from the
supernova reached the different parts of the ring. Using light intensity
measurements and the speed of light, the physical dimensions of
the ring can be found. Once both the angular and the physical size
of the ring have been determined, we can determine the distance
to SN1987A itself.
The first three tasks contain a picture, that includes a measuring rod. To
perform the required measurements use the rod and drag its endpoints to the
appropriate place on the image. The fourth applet has a vertical line, that
can be dragged by the mouse. The applet will then calculate the value on the
x-axis, which represents a number of days.
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