APOD: Cosmic Crab Nebula (2014 Jul 25)

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APOD: Cosmic Crab Nebula (2014 Jul 25)

Post by APOD Robot » Fri Jul 25, 2014 4:05 am

Image Cosmic Crab Nebula

Explanation: The Crab Pulsar, a city-sized, magnetized neutron star spinning 30 times a second, lies at the center of this tantalizing wide-field image of the Crab Nebula. A spectacular picture of one of our Milky Way's supernova remnants, it combines optical survey data with X-ray data from the orbiting Chandra Observatory. The composite was created as part of a celebration of Chandra's 15 year long exploration of the high energy cosmos. Like a cosmic dynamo the pulsar powers the X-ray and optical emission from the nebula, accelerating charged particles to extreme energies to produce the jets and rings glowing in X-rays. The innermost ring structure is about a light-year across. With more mass than the Sun and the density of an atomic nucleus, the spinning pulsar is the collapsed core of the massive star that exploded, while the nebula is the expanding remnant of the star's outer layers. The supernova explosion was witnessed in the year 1054.

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Re: APOD: Cosmic Crab Nebula (2014 Jul 25)

Post by CURRAHEE CHRIS » Fri Jul 25, 2014 12:27 pm

Pretty cool- the picture looked like it has a 3D element on my screen. When they say it could be seen in 1054 does that mean the supernova event could be seen here on earth in 1054?? ie with the naked eye??

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Re: APOD: Cosmic Crab Nebula (2014 Jul 25)

Post by Chris Peterson » Fri Jul 25, 2014 1:37 pm

CURRAHEE CHRIS wrote:Pretty cool- the picture looked like it has a 3D element on my screen. When they say it could be seen in 1054 does that mean the supernova event could be seen here on earth in 1054?? ie with the naked eye??
Yes, the 1054 supernova was a naked eye event, recorded by several cultures for sure and possibly by others.
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Re: APOD: Cosmic Crab Nebula (2014 Jul 25)

Post by Psnarf » Fri Jul 25, 2014 3:44 pm

The badaboom was recorded by Chinese astronomers with buck-nekkid eyeballs. They wrote that it was visible for about a month.
http://chandra.harvard.edu/photo/2014/1 ... ear_lg.jpg brings out the two jets in detail. The front jet appears to shoot out a couple of light years, then pour into a bowl.
I don't understand what it is that is pulsing. The two jets appear to extend from the poles; the rings from the equator. Are there disturbances in the spinning rings that generate the pulses? Is the axis of rotation through the poles with the jets aimed pretty-much a constant location? Is the pulsar itself spinning along a different axis with the rings and jets a pretty-much static remnant?

We know from our lunar-distance measurements with lasers that even a coherent beam of photons will expand into a cone with a photon density growing more diffuse with the distance from the source. Is that the case with a pulsar? Do the pulses necessarily come from the poles with the axis of rotation along the equator as in the lighthouse analogy, or could there be jets escaping from holes much like the holes in the surface of the sun that emit particles that affect our magnetosphere? Are the pulses seen head on, or are we catching the edge of the two cones from polar jets? Just looking for other possible explanations of the observed phenomena.

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Re: APOD: Cosmic Crab Nebula (2014 Jul 25)

Post by hlwelborn » Fri Jul 25, 2014 4:35 pm

Tantalizing. Exactly so!

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Re: APOD: Cosmic Crab Nebula (2014 Jul 25)

Post by Chris Peterson » Fri Jul 25, 2014 4:52 pm

Psnarf wrote:I don't understand what it is that is pulsing. The two jets appear to extend from the poles; the rings from the equator. Are there disturbances in the spinning rings that generate the pulses? Is the axis of rotation through the poles with the jets aimed pretty-much a constant location? Is the pulsar itself spinning along a different axis with the rings and jets a pretty-much static remnant?
The pulsation is caused by a beam emitted along the polar axis of the neutron star's magnetic field, which is tipped from its axis of rotation. The visible jets in the nebula structure must be related, but are quite different from the rapidly rotating beam of radiation.
We know from our lunar-distance measurements with lasers that even a coherent beam of photons will expand into a cone with a photon density growing more diffuse with the distance from the source. Is that the case with a pulsar?
All radiation falls of with the inverse square of distance, collimated or not, coherent or not. The pulsar is no different.
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Re: APOD: Cosmic Crab Nebula (2014 Jul 25)

Post by Ron-Astro Pharmacist » Fri Jul 25, 2014 5:15 pm

The idea that all space is expanding leads me to want to understand more about expansion's effect on matter. That gravity can locally overwhelm the universe-wide expansion of space itself seems obvious enough. It does makes me wonder, when these extremes of gravity occur, why often these jet-like structures form. Almost as if it's compensatory. Is it conceivable that all matter is expanding with the rest of the universe until an intense gravitational environment reverses the process? A sort of "reached the tipping point" occurs and the process results in these types of objects. I know it's though that matter is size-static in space while space itself is expanding the rest of the universe but if all matter is expanding, as into a hyper-space in uniform reference, how would we know?

Nice way to tantalize us with quite the thought-provoking image today. :clap:
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Re: APOD: Cosmic Crab Nebula (2014 Jul 25)

Post by Ron-Astro Pharmacist » Fri Jul 25, 2014 5:50 pm

I mean I know it's "thought"... I can never write a comment without a typo. :oops:
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Re: APOD: Cosmic Crab Nebula (2014 Jul 25)

Post by starsurfer » Fri Jul 25, 2014 6:37 pm

CURRAHEE CHRIS wrote:ie with the naked eye??
Naked eyes are beautiful. :wink:

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Re: APOD: Cosmic Crab Nebula (2014 Jul 25)

Post by Ann » Fri Jul 25, 2014 6:49 pm

CURRAHEE CHRIS wrote:Pretty cool- the picture looked like it has a 3D element on my screen. When they say it could be seen in 1054 does that mean the supernova event could be seen here on earth in 1054?? ie with the naked eye??
Certainly. There were no telescopes back then, you know!

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Re: APOD: Cosmic Crab Nebula (2014 Jul 25)

Post by Chris Peterson » Fri Jul 25, 2014 8:48 pm

Ron-Astro Pharmacist wrote:The idea that all space is expanding leads me to want to understand more about expansion's effect on matter. That gravity can locally overwhelm the universe-wide expansion of space itself seems obvious enough. It does makes me wonder, when these extremes of gravity occur, why often these jet-like structures form.
There's nothing special about gravity in cases like this. It's simply the source of energy that resulted in a collapsed object with a high spin rate. Combine rapid rotation with a magnetic field, and you get the recipe for jets- both relativistic jets which transport material, and jets which primarily manifest as EM beams due to synchrotron radiation or other mechanisms. It's not a particularly mysterious phenomenon, and generally models well, suggesting we do have a reasonable understanding of what's going on. It has no connection to the metric expansion of the Universe.
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Re: APOD: Cosmic Crab Nebula (2014 Jul 25)

Post by distefanom » Fri Jul 25, 2014 10:00 pm

some years ago I've seen a time-lapse sequence of images that mimics a pulsating nucleus in there...
It was a HST image sequence.
I've seen in that video, that the sorrounding was "moving" a bit according with the pulsation....
I wonder: is that "movement" the indication of the time-space deformation in some way?
Is that a "hint" of what the "space" in the (almost) immediate surroundings would appear to a daring observer that could coast those endangering places?
https://www.youtube.com/watch?v=XtENfctmiVM
Anyone has an idea of this?

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Re: APOD: Cosmic Crab Nebula (2014 Jul 25)

Post by Ron-Astro Pharmacist » Fri Jul 25, 2014 10:05 pm

Chris Peterson wrote:
Ron-Astro Pharmacist wrote:The idea that all space is expanding leads me to want to understand more about expansion's effect on matter. That gravity can locally overwhelm the universe-wide expansion of space itself seems obvious enough. It does makes me wonder, when these extremes of gravity occur, why often these jet-like structures form.
There's nothing special about gravity in cases like this. It's simply the source of energy that resulted in a collapsed object with a high spin rate. Combine rapid rotation with a magnetic field, and you get the recipe for jets- both relativistic jets which transport material, and jets which primarily manifest as EM beams due to synchrotron radiation or other mechanisms. It's not a particularly mysterious phenomenon, and generally models well, suggesting we do have a reasonable understanding of what's going on. It has no connection to the metric expansion of the Universe.
My lack of in depth of understanding of what is known often leads to a metaphysical interpretation of how the universe might appear. It's a challenge (but fun and rewarding) to present them in a way that others might grasp, gasp or laugh. Where else can non-professionals share an arena to question contemporary science with those much more highly qualified to nudge one back to a more mainstream viewpoint. It's quite an uncommon opportunity.

Thanks Chris & APOD staff for what you do (and for sparing the gaff) :) Ron
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Re: APOD: Cosmic Crab Nebula (2014 Jul 25)

Post by Chris Peterson » Fri Jul 25, 2014 10:11 pm

distefanom wrote:some years ago I've seen a time-lapse sequence of images that mimics a pulsating nucleus in there...
It was a HST image sequence.
I've seen in that video, that the sorrounding was "moving" a bit according with the pulsation....
I wonder: is that "movement" the indication of the time-space deformation in some way?
Is that a "hint" of what the "space" in the (almost) immediate surroundings would appear to a daring observer that could coast those endangering places?
https://www.youtube.com/watch?v=XtENfctmiVM
Anyone has an idea of this?
You might be confusing several things. The pulsation is a brightness change we see at 30 Hz caused by the rotation of the remnant neutron star. This is a bit too fast to see visually, but is easily isolated with fast video imaging or with stroboscopic imaging (using a camera behind a rotating shutter). I've seen several videos showing this fast pulsation.

Separately, because the supernova was recent and the nebula small, images made over a period of just a few years show structural changes and ongoing expansion. Images of these have been combined into time-lapse videos.

Neither of these things is related in any way to time-space deformation. That effect is trivially small within the Crab Nebula, and would only be weakly detectable very near the surface of the neutron star itself. You could safely sail right through the Crab Nebula (and you might well be unaware you were even in a nebula at all).
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Re: APOD: Cosmic Crab Nebula (2014 Jul 25)

Post by grump » Sat Jul 26, 2014 3:49 am

What do you make of the faint green line or streak at about 11o'clock (upper left) from the nebula? Looking carefully it seems to continue down past the LHS of the nebula.

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Re: APOD: Cosmic Crab Nebula (2014 Jul 25)

Post by geckzilla » Sat Jul 26, 2014 5:07 am

grump wrote:What do you make of the faint green line or streak at about 11o'clock (upper left) from the nebula? Looking carefully it seems to continue down past the LHS of the nebula.
I'm going with satellite trail.
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Re: APOD: Cosmic Crab Nebula (2014 Jul 25)

Post by Boomer12k » Sat Jul 26, 2014 5:43 am

Had not seen the "inner disc" and jets before. REMINDS me of a black hole... I guess something spinning that fast...just can't help it...


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Re: APOD: Cosmic Crab Nebula (2014 Jul 25)

Post by CURRAHEE CHRIS » Mon Jul 28, 2014 3:34 pm

Ann wrote:
CURRAHEE CHRIS wrote:Pretty cool- the picture looked like it has a 3D element on my screen. When they say it could be seen in 1054 does that mean the supernova event could be seen here on earth in 1054?? ie with the naked eye??
Certainly. There were no telescopes back then, you know!

Ann
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