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Astr111 Photography Projects, Fall 2005

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Crab Nebula, Maggie Jo Pettinga

Crab Nebula

This nebula is an expanded cloud of gas from a supernova that exploded in 1054AD. The Crab Nebula was discovered in 1731 by John Bevis, an amateur British astronomer. However, the supernova that created the gas in this nebula, was first seen by the Anasazi Indians in present day New Mexico. The spot the Crab Nebula was first seen is very near to where the Calvin telescope is in New Mexico, so this picture is from the same place the supernova was discovered.

As you can see in the image, the Crab Nebula has a higher concentration of gas near the center of the nebula. This is exemplifided by how bright the stars behind the nebula look on the thinner, outer edge of the Nebula. The red color of the Nebula is caused by the large amounts of hydrogen in the nebula. When hydrogen is heated to a high temperature, it emits red light. The hydrogen in this nebula is from the explosion of the supernova that produced the gas that formed as the Crab Nebula. The redish tint of the Crab Nebula shows it is hot, especially on the outer edge.

Looking at the picture above, you notice there is no red hydrogen in the center of the nebula. This is because the Crab Nebula is the only object we can see with our eyes that emits Synchrotron radiation. The Synchrotron radiation spins the electons in the center of the nebula along a magnetic field so fast they stream out toward the edges of the nebula. This is why the nebula looks like it was created starting in the center then working out to the edges, and it also explains why there is no color in the center. The electrons are simply moving too fast.

The angular size of the Crab Nebula is 4.0645 arc minutes.

References:

Messier Objects
http://www.seds.org/messier/m/m001.html

Right Ascension (J2000) 05:34:30
Declination (J2000) +22:01:00
Filters used blue(B), green(V), red(R), and clear(C)
Exposure time per filter 5x60 seconds in C,B,V,R
Date observed

October 6 (C)
October 7 (VR)

October 19 (B)