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The ESA/ESO Astronomy Exercise Series
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Exercises

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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Exercise 1 PDF files