APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Comments and questions about the APOD on the main view screen.
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APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by APOD Robot » Tue Nov 11, 2014 5:07 am

Image Orion in Gas, Dust, and Stars

Explanation: The constellation of Orion holds much more than three stars in a row. A deep exposure shows everything from dark nebula to star clusters, all embedded in an extended patch of gaseous wisps in the greater Orion Molecular Cloud Complex. The brightest three stars on the far left are indeed the famous three stars that make up the belt of Orion. Just below Alnitak, the lowest of the three belt stars, is the Flame Nebula, glowing with excited hydrogen gas and immersed in filaments of dark brown dust. Below and left of the frame center and just to the right of Alnitak lies the Horsehead Nebula, a dark indentation of dense dust that has perhaps the most recognized nebular shapes on the sky. On the upper right lies M42, the Orion Nebula, an energetic caldron of tumultuous gas, visible to the unaided eye, that is giving birth to a new open cluster of stars. Immediately to the left of M42 is a prominent bluish reflection nebula sometimes called the Running Man that houses many bright blue stars. The featured image covers an area with objects that are roughly 1,500 light years away and spans about 75 light years.

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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by BDanielMayfield » Tue Nov 11, 2014 5:27 am

This is arguably one of the most interesting neighborhoods on the entire sky. Great image.
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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by Nitpicker » Tue Nov 11, 2014 7:32 am

I'm probably in an ignorant minority here, but I do sometimes wonder how much (near-vacuum) fluffy stuff I can cope with in an astro-image, whilst still thinking I vaguely understand what I'm looking at. After my initial "ooh ahh", the first thing I noticed was that the Trapezium Cluster in M42, seems to have been almost processed out of existence. Is this the only region to get such special treatment?

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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by Ann » Tue Nov 11, 2014 8:29 am

What a great image! I love it! :D

An image like this can't be "true", however. There are so many objects here of wildly different brightnesses that if you want to see tham all, the brightest ones have to be suppressed and the faintest enhanced.

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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by Nitpicker » Tue Nov 11, 2014 8:47 am

Ann wrote:What a great image! I love it! :D

An image like this can't be "true", however. There are so many objects here of wildly different brightnesses that if you want to see tham all, the brightest ones have to be suppressed and the faintest enhanced.

Ann
Whilst I agree with that, it all becomes rather arbitrary when two areas of comparable brightness are adjusted by different amounts such that they are no longer comparable.

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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by Ann » Tue Nov 11, 2014 10:56 am

This picture is a lot "truer". Still, we can't really tell from this picture that the Orion Nebula is so much brighter than the Flame Nebula.

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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by Nitpicker » Tue Nov 11, 2014 12:04 pm

Ann wrote:This picture is a lot "truer". Still, we can't really tell from this picture that the Orion Nebula is so much brighter than the Flame Nebula.

Ann
In "truth", the area around the Trapezium is much, much brighter than the Running Man, like in this example: Image Link: http://astro.primozcigler.net/media/gal ... /m42-2.jpg

Whilst I can see the benefit of the extensive HDR-like techniques applied to make this APOD, a lot of "true" information has been lost in the process.

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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by rgendler » Tue Nov 11, 2014 12:45 pm

Although I'm credited this image is mostly Roberto Colombari's work. I donated my 2006 version of this field which he combined with DSS data. Of course natural luminosity gradients are violated in almost all images of this region.
My 2006 version is below
http://www.robgendlerastropics.com/ODFNM.html

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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by BDanielMayfield » Tue Nov 11, 2014 12:53 pm

Nitpicker wrote:I'm probably in an ignorant minority here, but I do sometimes wonder how much (near-vacuum) fluffy stuff I can cope with in an astro-image, whilst still thinking I vaguely understand what I'm looking at. After my initial "ooh ahh", the first thing I noticed was that the Trapezium Cluster in M42, seems to have been almost processed out of existence. Is this the only region to get such special treatment?
The star Alnitak right above the Flame nebula has been quite notably dimmed. It's really about as bright as the other two belt stars, but here it's so dim it doesn't stand out at all.
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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by Nitpicker » Tue Nov 11, 2014 12:58 pm

rgendler wrote:Although I'm credited this image is mostly Roberto Colombari's work. I donated my 2006 version of this field which he combined with DSS data. Of course natural luminosity gradients are violated in almost all images of this region.
My 2006 version is below
http://www.robgendlerastropics.com/ODFNM.html
Thank you Mr Gendler. Whilst your 2006 version (which is impressive just for being eight years old) shows slightly less structural detail than the APOD, it seems like you violated the natural luminosity gradients in a more natural way. :ssmile:

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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by BDanielMayfield » Tue Nov 11, 2014 1:06 pm

rgendler wrote:Although I'm credited this image is mostly Roberto Colombari's work. I donated my 2006 version of this field which he combined with DSS data. Of course natural luminosity gradients are violated in almost all images of this region.
My 2006 version is below
http://www.robgendlerastropics.com/ODFNM.html
Thanks for what you and the other contributors do Robert. Please don't be offend. Producing these images is an art form, not just or even primarily science.
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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by Boomer12k » Tue Nov 11, 2014 1:55 pm

Probably my favorite nebula, and area....and sooo much going on.

We shall have to evolve better eyes so we can see all the Glory, without photography... :D

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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by mikey » Tue Nov 11, 2014 1:58 pm

Orion consists of 7 stars, so the opening line should have read "The belt of Orion holds much more than three stars in a row."

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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by Chris Peterson » Tue Nov 11, 2014 2:29 pm

Nitpicker wrote:Whilst I agree with that, it all becomes rather arbitrary when two areas of comparable brightness are adjusted by different amounts such that they are no longer comparable.
If the intent is purely to highlight structure, or purely to produce an aesthetic image, it doesn't really matter.

An image like this has far more dynamic range than can be presented linearly. For me, what is important is how the contrast stretching is performed. It can be uniform over the entire image- a huge compression, for instance, but two objects of the same true intensity will be presented with the same transformed intensity. That's how I process images, and that's what I like to see. But images can also be selectively stretched, using masking and other tools. As a rule, I don't like it when that is done (subject to the exceptions above). Not because information is lost, but because reality is genuinely misrepresented.
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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by MarkBour » Tue Nov 11, 2014 4:34 pm

I think an image such as this (however thoroughly processed) puts a critical nail in the coffin of Olber's paradox.
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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by Cousin Ricky » Tue Nov 11, 2014 7:02 pm

mikey wrote:Orion consists of 7 stars, so the opening line should have read "The belt of Orion holds much more than three stars in a row."
Time to put on my pedantic hat.

Orion consists of a whole lot more than 7 stars. Orion is a mathematically defined wedge of the universe, which contains dozens of stars visible to the naked eye, perhaps billions of stars within the Milky Way, and an unknown number of stars beyond the Milky Way. In addition to stars, Orion holds a lot of dust, glowing gas, dark matter, et al.

I'm sure that the description is simply alluding to the most common instruction to beginners on how to recognize Orion, so as such, calling attention to the belt would be superfluous. It would also be wrong, as M42 and the Running Man, major stars of this show, are not in the belt region.
Last edited by Cousin Ricky on Wed Nov 12, 2014 2:24 am, edited 3 times in total.

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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by Cousin Ricky » Tue Nov 11, 2014 7:05 pm

I'm surprised no one has mentioned M78, peeking in from the lower left corner of the image. M78 is the lonely one out in Orion; it must surely know how it feels to be M92.

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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by ta152h0 » Tue Nov 11, 2014 7:09 pm

Cosmic cylinder of a high compression engine at the moment of ignition
edited in honor of my English teacher so long ago
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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by alino » Tue Nov 11, 2014 7:25 pm

09-20-2009 is the same picture and comment.

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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by Chris Peterson » Tue Nov 11, 2014 7:43 pm

Cousin Ricky wrote:Time to put on my pedantic hat.

Orion consists of a whole lot more than 7 stars. Orion is a mathematically defined wedge of the universe, which contains dozens of stars visible to the naked eye, perhaps billions of stars within the Milky Way, and an unknown number of stars beyond the Milky Way.
Even in discussing the asterism, it seldom includes just seven stars. Almost always the shield and bow are included, as well.
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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by bystander » Tue Nov 11, 2014 7:44 pm

alino wrote:09-20-2009 is the same picture and comment.
Actually it is 09-29-2009, and it is not the same image.
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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by Nitpicker » Tue Nov 11, 2014 9:58 pm

Chris Peterson wrote:
Nitpicker wrote:Whilst I agree with that, it all becomes rather arbitrary when two areas of comparable brightness are adjusted by different amounts such that they are no longer comparable.
If the intent is purely to highlight structure, or purely to produce an aesthetic image, it doesn't really matter.

An image like this has far more dynamic range than can be presented linearly. For me, what is important is how the contrast stretching is performed. It can be uniform over the entire image- a huge compression, for instance, but two objects of the same true intensity will be presented with the same transformed intensity. That's how I process images, and that's what I like to see. But images can also be selectively stretched, using masking and other tools. As a rule, I don't like it when that is done (subject to the exceptions above). Not because information is lost, but because reality is genuinely misrepresented.
Yes, I think that better expresses my thoughts as well. I just needed to talk it out.

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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by Ann » Wed Nov 12, 2014 12:57 am

Nitpicker wrote:
rgendler wrote:Although I'm credited this image is mostly Roberto Colombari's work. I donated my 2006 version of this field which he combined with DSS data. Of course natural luminosity gradients are violated in almost all images of this region.
My 2006 version is below
http://www.robgendlerastropics.com/ODFNM.html
Thank you Mr Gendler. Whilst your 2006 version (which is impressive just for being eight years old) shows slightly less structural detail than the APOD, it seems like you violated the natural luminosity gradients in a more natural way. :ssmile:
That's a really great image, Rob, and to me the luminosity gradients in it are very satisfactory.

But luminosity gradients are always a problem, and it is easy to forget that practically all astronomical nebula images misrepresent the brightness of the nearby stars. Here is a (1 102,8 KB) image of the Rosette Nebula, showing mostly the stars. In visible light, that is surely what the Rosette Nebula and its ionizing cluster NGC 2244 "really" looks like.

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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by Nitpicker » Wed Nov 12, 2014 2:04 am

Ann, we are talking about two different things. Contrast stretching is a great tool and is almost always applied to deep sky astrophotographs (except for a few scientific applications). But in most cases, the stretching scheme is applied in the same way across the whole image, so that any two stars of the same brightness, say, still appear to be as bright as each other after stretching, however much they've been stretched.

However, in this APOD, there are regions which we know to be of similar brightness, yet they appear in the image to have quite different brightness, so the stretching scheme has not been applied in the same way across the whole image. I was not actually attempting to find fault with the APOD, but I was trying to discuss this aspect of the APOD, and the fact that it makes a significant difference (to me at least).

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Re: APOD: Orion in Gas, Dust, and Stars (2014 Nov 11)

Post by Ann » Wed Nov 12, 2014 3:01 am

Nitpicker wrote:Ann, we are talking about two different things. Contrast stretching is a great tool and is almost always applied to deep sky astrophotographs (except for a few scientific applications). But in most cases, the stretching scheme is applied in the same way across the whole image, so that any two stars of the same brightness, say, still appear to be as bright as each other after stretching, however much they've been stretched.

However, in this APOD, there are regions which we know to be of similar brightness, yet they appear in the image to have quite different brightness, so the stretching scheme has not been applied in the same way across the whole image. I was not actually attempting to find fault with the APOD, but I was trying to discuss this aspect of the APOD, and the fact that it makes a significant difference (to me at least).
I see your point. I really do.

But for me, a lover of stars, I often feel that the stars are treated very strangely in astronomical imagery. For example, as Bruce wrote:
BDanielMayfield wrote:
The star Alnitak right above the Flame nebula has been quite notably dimmed. It's really about as bright as the other two belt stars, but here it's so dim it doesn't stand out at all.
That phenomenon is extremely common in images focusing on the Horsehead region, if they also include Orion's Belt.

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