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M87's Jet is 5,000 LY long. In a story today, HST watched it brighten, dim and brighten again in only 7 years?
How is that possible if the speed of light is truly the ultimate speed limit?
Even the smaller area of brightening is over 100 light years across.
The bright spot on the left is the core of the galaxy. The seven year brightening is 247 ly from the core. I extrapilated the diameter of the brightening from the fact provided that the two bright spots were 247 ly apart.
In this case, this is not a problem with perspective. We know that a pressure wave or electrical charge or some other initiating signal had to spread across the entire length of the brightening area in the time it took to brighten. How would you explain that? Either the initiator went down the jet OR the jet went thru a special area of space. Either way, lots more than seven light years of length was spanned in far less time than it would take light to cover the same distance in empty space.
Thanks to all the brave souls that answer this question.
Oops the two bright spots are 214 ly apart. Here is the quote from a related story.
The Chandra X-ray Observatory was the first to report the brightening in 2000. HST-1 was first discovered and named by Hubble astronomers in 1999. The gas knot is 214 light-years from the galaxy's core.
For those who suggested a huge perpendicular beam that caused the brightening:
1.) beams aren't broad, they are point sources that spread in a pressure wave that is something like spherical. This would cause the beam of electron or photons to spread at something less than the speed of light. How could a beam be parallel and be lightyears across? It would take years for the beam to start and years for it to stop, not to mention a mechinism or natural emitter of laser like beam light years across. A good thought experiment, but nothing exists like that in nature.
2..) the source of the beam would be visible from the visible or ultraviolet radiation that would accompany the emission of the electrons.
Good try, but I doubt you could point to any real source in nature that acts like this giant perpendicular beam.
6 Answers
- Anonymous1 decade agoFavorite Answer
"Among the consequences of these near light-speed or relativistic jets are flashlightlike beams of high-energy x-rays and gamma rays as well as the illusion of superluminal (faster-than-light) speeds when viewed straight on..."
http://www.sciam.com/article.cfm?id=black-hole-pla...
"Sequence of Hubble images showing apparent motion at six times the speed of light in the galaxy M87" (in 1997 photos)
Source(s): forty-five years of reading astronomy magazines. - JeffLv 51 decade ago
I think that's a really good question. In that picture, the area of brightening looks pretty small, though. I don't know where you get that the area of brightening is 100 LY across--the article doesn't say anything about the size of the brightened area. It's a pretty fuzzy photo, so I'm guessing that the actual bright event is much smaller and it is just blurred out.
It is possible, however, for certain events to appear faster than the speed of light without anything breaking any laws of physics. For example, imagine that I shine a very bright light at a disk of dust that is 100LY wide. if things are oriented right, the entire disc may light up at approximately the same time--within a few years, and much faster than 100 years, since the light is hitting the whole surface at about the same time. That could be what's happening in a cloud outside of M87. As another example, I could train a big line of fireflies to all light up at exactly the same time, hundreds of years from now. I set them all out in a line 100 light years long (which will take me at least 100 years to set up), and then I travel far away and look at it--depending on how I programmed the fireflies ahead of time, you could have the whole thing light up at once, or go from one side to the other much faster than the speed of light. The fireflies and the light are not going faster, just the phenomenon is moving faster than light.
- supastremphLv 61 decade ago
I'm not even going to pretend that I can shed any light on what is happening in the jet. But a mechanism to produce these kinds of effects are far from impossible.
Imagine an immense 2-D sheet of water. light years in size. Now let an equally immense plane wave burst of electrons travelling at .99c impinge on the slab along the normal of the sheet. If you are very far away, you will see the entire slab illuminate uniformly from Cerenkov radiation, then become dark, regardless of how far apart the pieces of it are.
In contrast, if you were actually on the sheet, you would see the immediate area around you light up, then the sheet's illumination would move away from you at c. Something more similar to what you were expecting?
- Anonymous1 decade ago
Ok, from reading the article, it is clear that what is brightening and dimming is "a clump of matter embedded in the jet", not the entire jet.
I can think of a few things that might explain that (the jet is running into something, like some interstellar gas, for example) but the article seems to make it clear to me that it is *not* the entire jet that is flaring, but rather a clump of matter in a specific part of it.
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- VyaardLv 71 decade ago
I'm guessin that it could be an "optical illusion"...
1) The flare doesn't has to come from a single-point-event (like a supernova event), so it could actually be happening in a large area at te same time...
2) ... But we're observing it from far enough to percieve it as almost a single-point-event.
I think it's an excellent question anyway. Cheers.
- DLMLv 71 decade ago
Hmmm.
I haven't looked into this particular "jet," but it's possible that this jet is roughly parallel to your field of view, and the distance from one end of it to another is negligible in distance from us (on an intergalacticlevel) and so light from one end reached us at the same time light from the other end reaches us.
Kind of like a long truck that is one mile away from you, and positioned so that you are looking at it in "profile." The rear bumber and front bumper are both about the same distance from you, as oppossed to if you were looking at it "head on" or "rear on" and the front bumper and rear bumper would differ in distance from you by about sixty feet.
I'll look into that particular "jet" though and see if I can confirm this possibility.
