APOD: V838 Light Echo: The Movie (2014 Jun 17)

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APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby APOD Robot » Tue Jun 17, 2014 4:10 am

Image V838 Light Echo: The Movie

Explanation: What caused this outburst of V838 Mon? For reasons unknown, star V838 Mon suddenly became one of the brightest stars in the entire Milky Way Galaxy. Then, just a few months later, it faded. A stellar flash like this has never been seen before -- supernovas and novas expel a tremendous amount of matter out into space. Although the V838 Mon flash appeared to expel some material into space, what is seen in the above eight-frame movie, interpolated for smoothness, is actually an outwardly moving light echo of the flash. The actual time-span of the above movie is from 2002, when the flash was first recorded, to 2006. In a light echo, light from the flash is reflected by successively more distant ellipsoids in the complex array of ambient interstellar dust that already surrounded the star. Currently, the leading model for V838's outburst was the orbital decay and subsequent merging of two relatively normal stars. V838 Mon lies about 20,000 light years away toward the constellation of Monoceros, while the largest light echo above spans about six light years in diameter.

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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby Ann » Tue Jun 17, 2014 4:54 am

Interesting. Will we get a blue straggler out of this? :ssmile:

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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby Boomer12k » Tue Jun 17, 2014 6:21 am

It is kind of deceptive...in that...it looks like everything is pushed outward like roiling smoke...and not waves of light striking ever distant areas of dust....in the end it looks like cream that has been stirred in coffee a bit.
Unless, this is part of the material expelled with the flash...in which case, it looks like a planetary nebula, rather than an echo....this depiction is kind of confusing to me, the way it looks and moves as it has been smoothed with MORPHING.

If it is light, illuminating dust at different ranges....it should look different....like a lighthouse illuminating different ranges of scattered FOG.....it would not push anything away...just illuminate further out.

Since it is DUST....should it not RESEMBLE a Reflection Nebula?

Probably just me......

Still....a fascinating object and AWESOME VIEW!!!!

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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby Nitpicker » Tue Jun 17, 2014 7:52 am

It is quite difficult to visualise the shape the dust must form around the star, just by watching the video. But I suppose it is probably not too hard to build up a 3-D model from the sequence of frames.

If we imagine a perfectly spherical shell of dust with a radius of three light years, surrounding the central star as it brightened and faded over a period of months in 2002, then I would not expect to observe the furthest part of the illuminated shell (behind the star) until 2008, six years later. Over the course of those six years, I would expect to see a circle of illuminated dust expand from a dot in 2002 (in front of the star), up to a maximum circle of three light years radius in 2005, and then back down to a dot again in 2008.

I suppose what we are really observing in the video, is quite similar to a cross-section through the dust, moving from front to back. Sort of but not quite. Am I close?

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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby neufer » Tue Jun 17, 2014 9:52 am

Nitpicker wrote:
It is quite difficult to visualise the shape the dust must form around the star, just by watching the video. But I suppose it is probably not too hard to build up a 3-D model from the sequence of frames.

If we imagine a perfectly spherical shell of dust with a radius of three light years, surrounding the central star as it brightened and faded over a period of months in 2002, then I would not expect to observe the furthest part of the illuminated shell (behind the star) until 2008, six years later. Over the course of those six years, I would expect to see a circle of illuminated dust expand from a dot in 2002 (in front of the star), up to a maximum circle of three light years radius in 2005, and then back down to a dot again in 2008.

I suppose what we are really observing in the video, is quite similar to a cross-section through the dust, moving from front to back. Sort of but not quite. Am I close?
Image

Quite similar to cross-sections through your perfectly spherical shell of dust with a radius of three light years, moving from front to back... yes ...

But there are other spherical shells of dust with other radii as well ... which is why we never observe a simple circle at any given time.

:arrow: I prefer to think of it as expanding paraboliod cross-sections of a real 3-D dust structure (ignoring for absorption & multiple reflections of course).
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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby FloridaMike » Tue Jun 17, 2014 1:08 pm

I found a sequence of some of the stills. Even this depiction produces the illusion that material is moving but if you look closely you can see that it is not.
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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby zbvhs » Tue Jun 17, 2014 1:09 pm

I don't see it. The flash of light from the star would have been like a wave washing across a beach. What could be called echoes would be the the little ripples and splashes kicked up as the wave passed. We should be seeing a ring of light spreading out from the star and illuminating clumps of gas and dust as it passes. What is appearing is a lot of material being pushed away from the star and mixing with surrounding material. How is this considered an echo?
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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby C'est moi seul » Tue Jun 17, 2014 1:30 pm

The excess graphical manipulation and annoying music underscore the collapse of the real star of knowledge under the dust puffery of an entertainment production.

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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby Chris Peterson » Tue Jun 17, 2014 2:00 pm

zbvhs wrote:I don't see it. The flash of light from the star would have been like a wave washing across a beach. What could be called echoes would be the the little ripples and splashes kicked up as the wave passed. We should be seeing a ring of light spreading out from the star and illuminating clumps of gas and dust as it passes. What is appearing is a lot of material being pushed away from the star and mixing with surrounding material. How is this considered an echo?

Yes. That's because this is a terrible animation (and, IMO, a terrible choice for an APOD). The use of morphing software to smooth the transitions between just a handful of actual frames has totally distorted the reality of what's happening, and done so in a way that leads to a completely false view of what a light echo is. If you view the individual HST images, it's apparent that no material is moving outwards (that is, over the time range of the images, there isn't any obvious outward movement of gas or dust).
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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby rockymountaineer » Tue Jun 17, 2014 2:14 pm

Thanks for articulating that, Chris, I agree with your statement.

The music is also awful, like "V838: The Game Show"

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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby starsurfer » Tue Jun 17, 2014 2:43 pm

C'est moi seul wrote:The excess graphical manipulation and annoying music underscore the collapse of the real star of knowledge under the dust puffery of an entertainment production.

Just watch it without the sound.

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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby starsurfer » Tue Jun 17, 2014 2:44 pm

Ann wrote:Interesting. Will we get a blue straggler out of this? :ssmile:

Ann

Maybe we could call it Ann's Star? :D

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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby Tink » Tue Jun 17, 2014 2:52 pm

I would suggest, with the utmost respect, that an added musical underscore is never needed, and nearly always annoying.

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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby Chris Peterson » Tue Jun 17, 2014 2:59 pm

Tink wrote:I would suggest, with the utmost respect, that an added musical underscore is never needed, and nearly always annoying.

Music is subjective, and a matter of the tastes of the author. It can always be turned off. In this case we have an image that is presenting bad science. Music I can live with. Bad data, not so much.
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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby Ron-Astro Pharmacist » Tue Jun 17, 2014 3:54 pm

If this video isn't up to standards - the concept is. It may not be too impressive for a few thousand years while we gather data that represents the change we will view. I suspect time dimensioned astronomy will eventually better satisfy our video cravings.

After all – our star so bright we can see it during the day.

That echoes with the previous sentiment to state the obvious. It points out that many of us need information so graphic that it slaps us in the face. Today's APOD works for me – if only to perceive what's self-evident to those with a better eye and the imagination to share it properly.

So why is it night when so many suns are shinning? Guess that's just a perception we've gotten use to.
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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby Jim Armstrong » Tue Jun 17, 2014 4:07 pm

For two days in a row (perhaps a lamentable record) the APOD has been very difficult for users of dial-up modems to access.
The increase, and it is growing, in such material is matched by a decrease in my long time interest in this website.
I guess that is progress.

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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby geckzilla » Tue Jun 17, 2014 4:10 pm

Ron-Astro Pharmacist wrote:So why is it night when so many suns are shinning? Guess that's just a perception we've gotten use to.

https://en.wikipedia.org/wiki/Inverse-square_law
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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby ninjan33r » Tue Jun 17, 2014 4:50 pm

It seems like such an event would be a good way to calibrate astronomical distances.

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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby Chris Peterson » Tue Jun 17, 2014 5:28 pm

Ron-Astro Pharmacist wrote:If this video isn't up to standards - the concept is. It may not be too impressive for a few thousand years while we gather data that represents the change we will view.

And I'd argue, based on what you say, that the concept itself is flawed. Because the idea here isn't to show the time evolution of the nebula (which seems to be how you're seeing it), but a light echo. And this does neither. As a sort of simulated time progression, it's not accurate, and in terms of showing a light echo it's even worse.

Today's APOD works for me – if only to perceive what's self-evident to those with a better eye and the imagination to share it properly.

No, it's showing something totally different than reality. Unless you already know exactly what a light echo is and what it looks like, there's no way to view this video without ending up with misinformation. This very obviously shows clouds of gas and dust expanding radially, and that's not happening.
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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby hlwelborn » Tue Jun 17, 2014 5:30 pm

With all the shortcomings of this particular presentation, the reality it is meant to illuminate is Magnificent. How thrilling to have captured this celestial event. If it was just recorded in 2002, when did it actually happen?

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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby Chris Peterson » Tue Jun 17, 2014 5:36 pm

hlwelborn wrote:With all the shortcomings of this particular presentation, the reality it is meant to illuminate is Magnificent. How thrilling to have captured this celestial event. If it was just recorded in 2002, when did it actually happen?

In 2002.

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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby Chris Peterson » Tue Jun 17, 2014 5:58 pm

Jim Armstrong wrote:For two days in a row (perhaps a lamentable record) the APOD has been very difficult for users of dial-up modems to access.
The increase, and it is growing, in such material is matched by a decrease in my long time interest in this website.
I guess that is progress.

It is progress. With more than 80% of Internet users in the major APOD market (developed countries) having at least low-end broadband access, either fixed or mobile, nobody designs for dial-up performance anymore. A few people who may be stuck with that technology suffer, but the vast majority of people get a much richer experience.
Chris

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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby Sinan İpek » Tue Jun 17, 2014 6:30 pm

This movie made me think a lot. I wondered actually how much of a planetary nebula is the material expelled from the explosion of its star and how much of it is just the interstellar dust already was there?

Maybe, we should reconsider those well-known nebulae images. What do you think?
Last edited by Sinan İpek on Tue Jun 17, 2014 6:57 pm, edited 1 time in total.

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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby Chris Peterson » Tue Jun 17, 2014 6:45 pm

Sinan İpek wrote:This movie made me think a lot. I wondered actually how much of a planetary nebulae is the material expelled from the explosion of its star and how much of it is just the interstellar dust already was there?

It's likely that all the material we see in this nebula was ejected from the progenitor star.
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Re: APOD: V838 Light Echo: The Movie (2014 Jun 17)

Postby Sinan İpek » Tue Jun 17, 2014 6:59 pm

Chris Peterson wrote:
Sinan İpek wrote:This movie made me think a lot. I wondered actually how much of a planetary nebulae is the material expelled from the explosion of its star and how much of it is just the interstellar dust already was there?

It's likely that all the material we see in this nebula was ejected from the progenitor star.

But then, those material should travel faster than light, because it seems to have been already there.


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