Starship Asterisk*

Inside the Eagle Nebula

Explanation: In 1995, a now famous picture from the Hubble Space Telescope featured Pillars of Creation, star forming columns of cold gas and dust light-years long inside M16, the Eagle Nebula. This remarkable false-color composite image revisits the nearby stellar nursery with image data from the orbiting Herschel Space Observatory and XMM-Newton telescopes. Herschel's far infrared detectors record the emission from the region's cold dust directly, including the famous pillars and other structures near the center of the scene. Toward the other extreme of the electromagnetic spectrum, XMM-Newton's X-ray vision reveals the massive, hot stars of the nebula's embedded star cluster. Hidden from Hubble's view at optical wavelengths, the massive stars have a profound effect, sculpting and transforming the natal gas and dust structures with their energetic winds and radiation. In fact, the massive stars are short lived and astronomers have found evidence in the image data pointing to the remnant of a supernova explosion with an apparent age of 6,000 years. If true, the expanding shock waves would have destroyed the visible structures, including the famous pillars. But because the Eagle Nebula is some 6,500 light-years distant, their destruction won't be witnessed for hundreds of years.

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I like all the colors, even if they are false. In one link, it kinda looks like different kinds of beings jumping out and shedding the dust as they go. But i didn't notice anything that resembles an eagle. Maybe it's just to much of a close-up.

Beyond wrote:I like all the colors, even if they are false. In one link, it kinda looks like different kinds of beings jumping out and shedding the dust as they go. But i didn't notice anything that resembles an eagle. Maybe it's just to much of a close-up.

They aren't really false. Mapped would be a better term, especially in the case where some of the data isn't even in the visible spectrum at all.

Chris Peterson wrote:

Beyond wrote:I like all the colors, even if they are false. In one link, it kinda looks like different kinds of beings jumping out and shedding the dust as they go. But i didn't notice anything that resembles an eagle. Maybe it's just to much of a close-up.

They aren't really false. Mapped would be a better term, especially in the case where some of the data isn't even in the visible spectrum at all.

I suppose then, that someone should change the 3-rd word of the second sentence.

bystander wrote: http://asterisk.apod.com/viewtopic.php?f=31&t=26630

WHAT?? A super nova may have blown the Eagle to bits? Why, that's...that's terrible!

Help me add something up - "remnant of a supernova" indicates it happened before the "6000 years ago" statement. But for us to see it, it must have happened more than 6500 years ago. So the shockwave from the explosion isn't moving fast enough across the field of view to affect the 'pillars of creation'.

So - How wide is the field of view ? What speed does this/a supernova shockwave typically travel ?
(PS I want to know if it's worth staying alive 500 years to witness whether the author is right )

Today's APOD caption:

"...astronomers have found evidence in the image data pointing to the remnant of a supernova explosion with an apparent age of 6,000 years. If true, the expanding shock waves would have destroyed the visible structures, including the famous pillars. But because the Eagle Nebula is some 6,500 light-years distant, their destruction won't be witnessed for hundreds of years. "

Hasn't someone got their sums wrong here?

If the "evidence in the image data" shows a 6,000 year old supernova remnant, then since the light from that 6,000 year old event has taken 6,500 years to get to us, the actual (cosmic) age of the supernova is 12,500 years. Fine.

But when the article says "because the Eagle Nebula is some 6,500 light-years distant, their destruction won't be witnessed for hundreds of years", it now seems to be saying that the supernova occured 6,000 years ago is cosmic time, and it's light (as well as the light from the shock wave destruction of the pillars etc.) won't get to us for another 500 years. I think everyone can see the problem with that assertion! It's impossible to know about an event whose light signal is still en route to us. How could there be "evidence in the image data" for a supernova, whose light sphere won't even reach us for another 500 years?!!

Deus_ex_Mayma has a point. You see a supernova, so the light of the supernova has already reached us. The supernova destroyed the pillars, but we can't see this because the light of that event is still on route to earth. Ho do you know in the first place that the supernova has destroyed the pillars if we (still) can't see this? Maybe we can infer that the pillars are destroyed from the distance between de supernova and the pillars, and the speed of the shockwave of the supernova. Maybe the shockwave will need a few hunderd years to reach the pillars. In that case, te destruction wil occur a few centuries after the supernova. Because the distance of the Eagle nebula is 6500 light years, (travel time of the light) the destruction has already taken place but we won't witness this untill a few centuries in the future

Looks like a flower blooming.

:---[===] *

In the blue hollow it looks like a person praying!

I think the last two sentences of today's explanation require something further. If there is evidence today that a supernova explosion occurred 6000 years ago, we would have witnessed that explosion and its effects 6000 years ago (had we been alive), not in 500 years. We're not going to see it twice.

Paul White

There is a link in today's APOD text to a preprint of the research paper which discusses the possibility of a supernova explosion; I hope people will download and read it!

Beyond wrote:

Chris Peterson wrote:They aren't really false. Mapped would be a better term, especially in the case where some of the data isn't even in the visible spectrum at all.

I suppose then, that someone should change the 3-rd word of the second sentence. :yes: :mrgreen:

The terminology isn't wrong, it just seems to create confusion. Somebody made a list recently of lots of words used by scientists (without problem) that cause confusion among non-scientists... technical jargon, if you like. This is one of those.

Originally, "false color" meant converting a grayscale image to color by mapping intensities to colors. But with time, it has drifted in meaning, and is now commonly used to refer to any image that is represented in colors different from how an ideal human eye would perceive things. That's fine, but "false" carries a lot of baggage with it in terms of its many meanings... in particular there is a strong negative connotation that something underhanded was done.

That's why I prefer "mapped color", and it also more accurately describes what is being done.

pgwhite wrote:
I think the last two sentences of today's explanation require something further. If there is evidence today that a supernova explosion occurred 6000 years ago, we would have witnessed that explosion and its effects 6000 years ago (had we been alive), not in 500 years. We're not going to see it twice.

Let's just talk for the moment about time as we observe it here on Earth: X-ray & IR instruments show evidence for a fairly recent (i.e., less than a hundred year old) supernova... a supernova that could never have been observed visually because it took place in an extremely dusty region. The shock wave from that recent supernova will probably destroy the nearby "Pillars of Creation" in about 500 years in the future.

However, since the "Pillars of Creation" are 6,500 light years away they, in fact,
have already been destroyed 6,000 years ago by a supernova that took place ~6,500 years ago.

http://scienceblogs.com/startswithabang/2012/01/learning_all_about_the_eagle_a.php wrote:
<<Could there have been a recent supernova at the center? To be honest, they don't know, yet! What you'd look for is faint and diffuse X-ray emission, and you'd see how far it extends around the interior regions of the nebula. If XMM-Newton sees too much of it, it would invalidate this theory, but a small (but non-zero) amount would support it. The work is still being done, but this is the current working theory, and it's consistent with what Chandra (X-ray) and Spitzer (infrared) have seen in their previous observations.>>

Deus_Ex_Mamiya wrote:But when the article says "because the Eagle Nebula is some 6,500 light-years distant, their destruction won't be witnessed for hundreds of years", it now seems to be saying that the supernova occured 6,000 years ago is cosmic time, and it's light (as well as the light from the shock wave destruction of the pillars etc.) won't get to us for another 500 years. I think everyone can see the problem with that assertion! It's impossible to know about an event whose light signal is still en route to us. How could there be "evidence in the image data" for a supernova, whose light sphere won't even reach us for another 500 years?!!

It's just not very well written, and shows what happens when you try to make "cosmic time" mean anything. It really doesn't.

The sloppy language keeps getting repeated, derived from what a researcher said about five years ago when this bubble was first observed, and hypothesized to be a supernova remnant (which isn't certain).

The correct way to visualize this is as a supernova (maybe) that occurred within the last few hundred years, and has produced a shock wave that will cross the Pillars of Creation region of the nebula in another few hundred years, probably tearing it apart. The distance between us and the Eagle Nebula is irrelevant, and changes nothing about the timing.

orin stepanek wrote:In the blue hollow it looks like a person praying!

That's the Pillars of Creation. See here.

Distance from Earth to Eagle Nebula 12,500 light-years.
Distance from Earth to Supernova 6,000 light-years.
The explosion of Supernova will can to destroy structures of Eagle Nebula in 500 years or more.
The energy has that to travel many years for to arrive Eagle Nebula.

orin stepanek wrote:In the blue hollow it looks like a person praying!

That's the first thing I thought, too.

bystander wrote:

orin stepanek wrote:In the blue hollow it looks like a person praying!

That's the Pillars of Creation. See here.

Thanks!! That's even *more* far out.

Ann wrote:Isn't it sloppy language to claim that there is an embedded star cluster of massive hot stars in the Eagle Nebula that is hidden from Hubble's view at optical wavelengths?

Why? Am I missing something here? That seems like a perfectly reasonable assertion.

saturn2 wrote:Distance from Earth to Eagle Nebula 12,500 light-years.
Distance from Earth to Supernova 6,000 light-years.
The explosion of Supernova will can to destroy structures of Eagle Nebula in 500 years or more.
The energy has that to travel many years for to arrive Eagle Nebula.

Nope. The supernova (if that's what it is) is inside the Eagle Nebula, so both are about the same distance from Earth, ~6500 ly.

Dont all readings (Xray, IR, etc) have the same look-back time as visual time (lightspeed)? It sounds like they are trying to say this supernova explosion is 6,000 years old, 500 years less than the current look-back time that we see M16.