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Page 1 of 5Astronomy 101 Lab 7(Modified from University of Michigan Astronomy Activities: The Crab Nebula)The Crab NebulaOverview and Objectives●Explore the death of a high mass star●Measure the expansion rate of a supernova●Explore some of the difficulties on observational astronomyIntroductionBefore you begin, you will need to print out or open the following images. Note that if you printthem out, you can work with a ruler. If you are unable to print them, you make makemeasurements off of a computer screen provided you do not change the screen size betweenmeasurements:Crab Nebula in 1973()Crab Nebula in 2000()One of the most fascinating objects in the winter night sky is the famous Crab nebula, locatednear the tip of one of Taurus the Bull's horns. The nebula was discovered by the well knownFrench astronomer, Charles Messier, in 1758. It is the first object in his catalog of fuzzy objectsin the night sky that he began compiling in 1764. The Crab nebula is in fact the remnants of the bright supernova of 1054.This supernova was recorded by Chinese astronomers. Their records indicate it was visibleduring the dayfor 23 days andin the nighttime sky for two years.In 1968, radio astronomers Staelin and Reifenstein found the tiny stellar remnant at the core of the nebula - a neutron star!This neutron star spins on its axis 30 times a second. The star's magnetic field causes it to emit beams of light from itsmagnetic poles. These twin spotlight beams sweep by the earth, causing the neutron star to appear to blink on and off.Because of this flickering, the neutron star is also called a "pulsar."Since the crab nebula is the result of a star exploding, it continues to expand. We can measure that expansion to learnmore about the crab nebula, and supernovas and their remnants in general. To do that, we need to identify landmarkswithin the nebula that don’t change significantly over the decades, but do expand with the nebula. This can be tricky,since most of the nebula is thin gas and dust, so there aren’t a lot of features to match.In the infrared and visible lightimages above, you can see that the gas and dust often clump together in lines or streamers calledfilaments. Where those