Lumnance Frame - Consists of 5 15-minute images
Designations: M1, NGC 1952
Object Type: Supernova Remnant
Constellation: Taurus
RA: 5h 34.5m
Dec: 22 deg 01min
Visual
Magnitude: 8.4; 8.0 (O'Meara)
Size: 6 min X 4 min
Distance: ~6,500 light
years
Discoverer: John Bevis, 1731
Visual Description: Messier had no
idea his first catalogued object would be among the most intriguing in the
heavens. M1, the Crab Nebula, is one of 100 or more known supernova remnants in
our galaxy - a corpse of a star that experienced a fast life and a violent
death. A supernova explosion is the final stage in the life of a star some 15
times more massive than our sun. Such a red supergiant star (like Betelgeuse, in
the shoulder of Orion) voraciously consumes its nuclear fuel in about 10 million
years (100 times faster than the sun). When the star's thermonuclear energy is
exhausted, its earth size core collapses under the force of gravity and, within
seconds, shrinks until the core's density equals that of an atomic nucleus.
Unable to contract further, infalling gas rebounds off the resistant core. A
quarter-second later, the star ends its life in a fantastic explosion, the peak
energy of which can rival that of its host galaxy. The Crab is the remains of a
cataclysmic stellar explosion that occurred in our Milky Way galaxy in A.D.
1054. So powerful and so close (approximately 6,500 light years) was the blast
that Chinese sky-watchers described it as a "guest star" in the annals of the
Sung dynasty. It shined as bright as Venus in the daytime sky, appeared reddish
white, and was observed for 23 days. As the only supernova Remnant in Messier's
catalogue, M1 warrants special attention. In small telescopes it is a 6 min X 4
min irregular patch of nebulosity situated a little more than 1 degree northwest
of the 3rd-magnitude star Zeta Tauri, a hot, blue subgiant star. The nebula is
surprisingly easy to see with 7X35 binoculars (amazing, if you consider that
nearly two millennia have passed since the explosion). Curiously, most
catalogues fail to provide a precise visual-magnitude estimate for this very
famous object in the Messier Album, Mallas and Kreimer give it a magnitude of "8
or 9"; Burnham says "about 9." Jones, in his work Messier's Nebulae and Star
Clusters, gives it a more precise magnitude, 8.4. All these estimates seem a
trifle too faint.
At 23X the Crab Nebula shares the field with Zeta
Tauri, and the nebulous glow looks much like the ghost image of that star. But
the nebula, which measures roughly 11 light years by 7 1/2 light years , is so
much more enormous. It is composed of three parts: a 16th-magnitude pulsar (a
rotating neutron sta), an inner bubble of material (a powerful wind of radiating
particles bound to the object's magnetic field), and an outer shell of dense
material released in the supernova explosion.
Seeing Conditions: 85%
Telescope: Meade 10" LX200 Optical Tube
Assembly
Focal
Length: 1575 mm ( f10 2500 mm OTA
with a f6.3 focal reducer)
Mount: Takahashi NJP 160
Camera: Starlight XPress
MX916
Exposure:
The color M1 image
consists of lo-res color images (red green and blue) and a hi-res luminance
image. Each color image consist of 2-20 minute exposures stacked (added). The
resulting colors were then combined to form an RGB image. The hi-res luminance
image consists of 5-15 minute exposures stacked (added). The hi-res images were
taken about a week after the color images. The low resolution RGB image was then
combined with a high resolution luminance image using photoshop to give greater
detail. .
Other: S.T.A.R 2000 Autoguider
Image Processing: hi-pass filter used to sharpen
The Visual description of the Crab Nebula was writen by Steven James O'Meara in the book "The Messier Objects" by Stephen James O'Meara. Page. 39. ISBN number 0-521-55332-6.
Copyright(c) 2007 Doug Sanqunetti. All rights reserved
