Fingers, Loops and Bays in the Crab Nebula

November 6, 2008
Credit: NASA/CXC/SAO/F.Seward

(PhysOrg.com) -- This image gives the first clear view of the faint boundary of the Crab Nebula's X-ray-emitting pulsar wind nebula. The nebula is powered by a rapidly-rotating, highly-magnetized neutron star, or "pulsar" (white dot near the center).

The combination of rapid rotating and strong magnetic field generates an intense electromagnetic field that creates jets of matter and anti-matter moving away from the north and south poles of the pulsar, and an intense wind flowing out in the equatorial direction.

The inner X-ray ring is thought to be a shock wave that marks the boundary between the surrounding nebula and the flow of matter and antimatter particles from the pulsar. Energetic electrons and positrons (antielectrons) move outward from this ring to brighten the outer ring and produce an extended X-ray glow.

The fingers, loops, and bays in the image all indicate that the magnetic field of the nebula and filaments of cooler matter are controlling the motion of the electrons and positrons. The particles can move rapidly along the magnetic field and travel several light years before radiating away their energy. In contrast, they move much more slowly perpendicular to the magnetic field, and travel only a short distance before losing their energy.

This effect can explain the long, thin, fingers and loops, as well as the sharp boundaries of the bays. The conspicuous dark bays on the lower right and left are likely due to the effects of a toroidal magnetic field that is a relic of the progenitor star.

Provided by NASA

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8 comments

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Quantum_Conundrum
1 / 5 (2) Nov 06, 2008
Wow. Anyone else realize just how much conjecture is in this article?
SciTechdude
2.7 / 5 (3) Nov 06, 2008
Wow. Anyone else realize just how much conjecture is in this article?


Anyone else realize how hard it is to learn about things so far away that light from there started it's journey before the earth cooled?
manojendu
1 / 5 (1) Nov 07, 2008
But this is an old image. If I am correct this is a Chandra image many years old now!
Ivan2
2 / 5 (1) Nov 09, 2008
Speaking of conjecture, no one suspected it was moving downward because there is more "smoke" on the upper side?!
yyz
2.3 / 5 (3) Nov 10, 2008
@SciTechdude, the original SN explosion was first sighted from Earth in 1054 A.D. This date in addition to the estimated distance of M 1 at 6,500 light-years leaves the true date of the original SN event remotely separated in time from when the Earth cooled (approx. 4.5 billion years ago). Still, a remarkable image of a freash SNR relatively close to the Earth. @manojendu & Ivan2, this image is a composite of many Chandra images taken over the years and carefully calibrated to bring out both the inner active region in the vicinity of the resultant pulsar and the faint, wispy Xray tendrils at the edge of the Xray dominated emission at the edges of the field. As for the true space motion of the pulsar itself, I seem to recall that the measured motion is not in the 'downward' direction but rather in the 3 o'clock direction from its' present location. Also, the 'smoke' on the upper side of the image is Xray photons emitted from very hot gas heated by the emission from the pulsar and distorted by the immense magnetic field pervading the SNR.
Ivan2
3 / 5 (2) Nov 11, 2008
image is a composite of many Chandra images taken over the years and carefully calibrated

I was counting on it, yyz, I asked because I was comparing it with a NASA "Image of the day" number 27, a composite of the Cat's Eye nebula, also very ethereal though in a different way (http://www.nasa.g...otd.html but do download the big photo so you can see the beautiful detail... it's been my background picture for a few days now) where a possible direction of rotation could be infered from the veils of the two little tips of the "explosion", with the fine whisps of "smoke" that make it seem to have a tiny clockwise bias. But now you tell us this "smoke" really is x-ray and I don't know if it can be compared to the thin veil of "vapor" coming out of the two tips of the nebula. Would it make sense? Thanks.
yyz
2.3 / 5 (3) Nov 13, 2008
@ Ivan2, really a great question especially when comparing images of the two objects.Superficially the objects resemble each other rather closely, but in reality are two completely different types of objects. The Cat's Eye Nebula (NGC 6543) is an example of a planetary nebula, formed when a low mass star (like our sun) runs out of its primary fuel source, begins to shed its' outer layers, and leaves behind a dense, hot (tens of thousands degrees Kelvin) nucleus called a white dwarf, which radiates fiercely enough to cause the ejected outer layers to glow brightly in visible (& other)wavelengths. Hubble combined many visible light exposures to create this stunning color composite. The Crab Nebula , on the other hand, represents the leftover debris & radiation from a supernova explosion of a massive star. A superdense, superhot neutron star (radiating at millions of degrees Kelvin)forms the source of radiation from this object. Very high energy (Xray & gamma ray) photons are emitted by the neutron star, and it's this light(Xray in the case of the Chandra photo)that is being imaged. Superficially, the objects look similar, but comparing these objects is like comparing apples to oranges.Love that pic of the Cat's Eye though, and even the Crab Nebula Xray image has a haunting, fiery allure of its own.
Ivan2
not rated yet Nov 17, 2008
Superficially the objects resemble each other(...) Very high energy (Xray & gamma ray) photons are emitted by the neutron star (...) comparing these objects is like comparing apples to oranges.

So the little smoke "wisps" and filigree are light-years long!!!!!!!! Wow!

Thanks, yyz.

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