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Designations:
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M1, NGC 1952
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Object Type:
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Constellation:
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Taurus
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5h 34.5m
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+22 deg 01 min
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8.4; 8.0 (O'Meara)
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Size:
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6 X 4 arcminutes
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Distance:
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~6,500 light years
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Discoverer:
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John Bevis, 1731
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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, in falling 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 sub-giant 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. |
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Telescope:
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Meade 10" LX200 Optical Tube Assembly
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Focal Length:
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1575 mm ( f10 2500 mm OTA with a f6.3 focal reducer)
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Mount:
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Camera
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Starlight XPress MX916
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Guider:
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Starligt XPress S.T.A.R 2000 Autoguider
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Exposures:
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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
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Location:
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Cicero, IN
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Software:
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