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Astr110 Photography Projects, Spring 2006

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Crab Nebula, Stephen Disselkoen

Crab Nebula

The Crab Nebula (also known as Messier Object 1, M1 or NGC 1952) is a gaseous diffuse nebula in the constellation Taurus. It is the remnant of a supernova that was recorded by Chinese and Arab astronomers in 1054 as being visible during daylight for 23 days. Located at a distance of about 6500 ly from Earth, it has a diameter of 6 ly and is expanding at a rate of 1000 km per second. A neutron star in the center of the nebula rotates 30 times per second. At the center of the nebula is the Crab Pulsar, also known as PSR B0531+21, a neutron star remnant of the supernova which is roughly 10 km in diameter. It was discovered in 1968, and this was the first observation of an association between supernova remnants and pulsars, a key discovery in establishing the interpretation of pulsars as neutron stars. The Crab Pulsar rotates once every 33 milliseconds, or 30 times each second, and the beams of radiation it emits interact with the nebular gases to produce complex patterns of wind and fluorescence. The most dynamic feature in the inner part of the nebula is the point where one of the pulsar's polar jets slams into the surrounding material forming a shock front. The shape and position of this feature shifts rapidly, with the equatorial wind appearing as a series of wisp-like features that steepen, brighten, then fade as they move away from the pulsar to well out into the main body of the nebula. The emission from the Crab Pulsar is also detected throughout the whole electromagnetic spectrum, from radio band to high energy gamma-rays. (Wikipedia) The supernova that created the Crab Nebula was observed in 1054 by Chinese astronomers and was the first supernova observation ever recorded. The event was linked to the Crab Nebula in the 1930s when modern studies of supernovae were starting to take off. The Crab nebula is about 6500 light years away. The magnitude system had been invented when the supernova was observed (it was invented by Hipparcos, a Greek astronomer). However the Chinese Astronomers that observed the supernova made no estimate of the magnitude. It must have been bright though, as they did record that it was visible during the day for 3 weeks!( Curious )

As seen in the image, the Crab Nebula is absolutely beautiful! The Crab Pulsar can be seen in the center of the image when observed closely but stronger telescopes than the one used at Calvin College would reveal it more clearly. The stars are white in the image so it can be reasonably stated that the image colors are relatively accurate; the magnificent red and yellow clouds of weaving mystery gasses can be observed all around the nebula. The size of this nebula, using the small angle formula, is roughly 13 ly (S=6500ly x (7arc minutes/3400mins in a radian)=13.3835). There can be no doubt that "things" such as these reflect and boast the glory of our mighty and creative God.

References:
Listed via Hyperlink within the text. Curious/wikipedia/TheSky software as a general reference for orientation

Right Ascension (J2000) 5:34:00
Declination (J2000) +22:01:00
Filters used blue(B), green(V), red(R), and clear(C)
Exposure time per filter 1x60 seconds in C, 60 seconds in BVR
Date observed

March 21, 2006 (C)
March 13 (RV), 15(B)