Friday, December 17, 2004

M1 The Crab Nebula

Click image for larger view.

A pulsar lurks

"Imagine our enormous Sun compressed down to a mere 18 1/2 miles (30 kilometers) across and ramped up to a rotational speed equal to that of your desktop computers power supply fan (1800 rpm) and you would have the Crab's central pulsar."

One of the reasons the Crab Nebula is such a notable object is that its sudden appearance took place only an eyeblink away at least on a 'cosmic' time scale. First discovered 950 years ago on July 4, 1054 AD by Chinese astronomers, this vast supernova explosion gained a brightness in the night sky at least four times that of Venus (-6 mag). It was visible for 23 days in daylight!

The nebula left over from the explosion is approximately 10 light years in diameter and is expanding at the rate of 1800 km/sec.

But what makes M1 so unusual is, in part, how it emits its light and the fact that it is really a nebula within a nebula. The outer nebula consists of the expanding gases and matter ejected by the supernova event. The inner nebula is the result of synchrotron radiation or polarized light created by a strong magnetic field filling the inner nebula. A magnetic field of this magnitude causes light waves to literally vibrate in the same uniform plane. The source of this radiation is none other than the source of the nebula itself. The star which went supernova in 1054 AD, has evolved into a rapidly rotating neutron star or pulsar and its gravity along with the magnetic field are pushing electrons to near light speed generating a very bright blue inner nebula core. And when I say bright, I mean bright because its overall luminosity in all spectral ranges has been estimated at 100,000 times that of our sun! It rotates or pulses at the rate of 30 times a second. Imagine our enormous Sun compressed down to a mere 18 1/2 miles (30 kilometers) across and ramped up to a rotational speed equal to that of your desktop computers power supply fan (1800 rpm) and you would have the Crab's central pulsar.

The pulsar can just be seen, in the negative image above with the two arrows pointing to it.

Techno Stuff: LX90, ATK-2HS, 0.6 FR, Baader IR, 10fps, 98 X 30 secs, Brightness 55%, Gamma 0%,Sat 50%, Gain 100%, White Balance nothing selected, Darks used Processed in K3ccdTools, Registax, Photoshop, Selective color added.

Thursday, December 16, 2004

M97 The Owl Nebula

         M97 reprocessed to show               Lord Rosse's 18th century
         the shell which surrounds               drawing of M97 - Now we
         the inner nebula.                             know why it's called the
                                                                 the Owl Nebula ....   :>)
M97, the Owl Nebula, is one of the more complex planetary nebulas in existance. It is actually composed of three shells - an inner nebula similar to the apple core shape of M27, the Dumbell Nebula [ M27 ] , a round outer shell and finally a somewhat elliptical whispy outer halo which is escaping the central hot white dwarf's gravitational hold. The outer halo was produced when the white dwarf first blew off its outer mass, the round shell was formed when the dwarf's stellar wind became a superwind causing a shockwave to slam into the outer halo, similar to what occured during the formation of the 'bubble' in the Bubble Nebula [ NGC7635 ], and finally the inner owl shape resulting from an even faster stellar wind which encountered the round shell.

The Owl is, in fact, a late stage planetary nebula that has begun its gradual dipersal back into the interstellar medium, as is the eventual fate of all matter in the universe. The recycling process of death and rebirth is never ending.

First discovered by Pierre M├ęchain in 1781 and later named by Lord Rosse in 1848 after viewing it in his giant (72 inch) reflecting telescope, the Owl, located on the bottom edge of the Big Dipper's bowl, is about 6000 years old and anywhere from 1,300 to 12,000 light years away. Distances to planetary nebula are particularly difficult to measure and sometimes the measurement errors are larger than the actual distance of the nebulas itself! At least we know the Owl is located within our own galaxy.

Techno Stuff: M97 - LX90, ATK-2HS, 0.6 FR, Baader IR
5fps, 139 X 40 secs, B 55%, G 0%, Sat 50%, Gain 80%,
WB nothing selected, Darks used, Processed in K3ccdTools,
Registax, Photoshop, Corel Draw, Selective color added.

Who says I don't have good taste in jewelry?
Scroll your mouse over the ring and watch it light up!