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Astr111 Photography Projects, Fall 2009

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M1 Crab Nebula, Jessica Nieboer

Crab Nebula

The Crab Nebula is a supernova remnant, which is defined as "an expanding cloud of debris from an exploded star" (Bennett 561). Supernovas form when a star 'explodes'. This is a process that starts when a star accumulates large amounts of iron in its core, which cannot generate energy through fusion. There is degeneracy pressure that supports the core, up to a certain point. Once it reaches this point, the pressure collapses, and the gravitational pull causes the core to collapse into a ball of neutrons. This process releases a huge amount of energy, driving the former outer layers of the star out into space. The heat and energy from the explosion expands and dazzles in the form of brightly colored gas clouds (Bennett 562).Some exploded stars are referred to as pulsars, meaning that they are rapidly rotating (Frommert).

The Crab Nebula, also called M1, or the Crab Pulsar, (pictured above) is an example of a supernova remnant as described above; it is in fact the first of its kind to be discovered. Right now, it has an angular size of 232 arc seconds and it is estimated to be about 6.97 light years in diameter, but research has shown that it is expanding at a rate of about 1,800 kilometers per second. It is spinning at a rate of thirty revolutions per second (Frommert). Estimated to be about 6.2 kilo-light years away from us. In the photo, note the bright circular object in the middle, right next to the brightest region of the cloud. This is the high density neutron core around which the cloud is rotating. Also see the red, string-like pieces inside the cloud. These are gas filaments and remnants from the exploded star, possibly even the outer layer of the star before the explosion. Hydrogen gas gives them their red color (Frommert). It was discovered that the Crab Nebula is actually four times brighter than Venus. This nebula's brightness comes from electrons that are caught in the strong magnetic field of the pulsar. Because they are spinning so rapidly, they produce an energy called synchron radiation, that we see in the form of bright light. It is said to emit an electromagnetic pulse from almost every part of the spectrum (Frommert).

References:

Bennett, Jeffrey , Megan Donahue, Nicholas Schneider, and Mark Voit. The Cosmic Perspective. Fourth ed. San Francisco: Pearson Education, Inc., 2007. 561-64. Print.

Frommert, Hartmut and Kronberg, Christine. "Messier Object 1." Students for the Exploration and Development of Space. <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, 20x10 seconds in Blue, 20x5 seconds in Red and Green
Date observed

November 8, 2009 (CBVR)