NGC 7331 Galaxy looks bent (APOD 22 Oct 2008)

[adrianxw]

This galaxy look deformed to me. The centre section seems tilted relative to the outer lying blue spiral arms.

Are there other galaxies in the neighbourhood that could have peturbed it?

[emc]

This galaxy look deformed to me. The centre section seems tilted relative to the outer lying blue spiral arms.

Are there other galaxies in the neighbourhood that could have peturbed it?

Hi adrianxw,

Happy anniversary with APOD!

I see your point, but I wonder if it is an optical illusion based in the spiral structures?

What a beautiful image... a model picture of outer space!

BTW - I'm getting an error message trying to access the higher resolution image.

[bystander]

This galaxy look deformed to me. The centre section seems tilted relative to the outer lying blue spiral arms.

Are there other galaxies in the neighbourhood that could have peturbed it?

I thought the same thing. There's a smudge at 7 o'clock that may be a companion dwarf galaxy, but I have no comfirmation of that.

There was a similar discussion on an earlier APOD, NGC 7331 Wheels within wheels (APOD 12 Jul 2008). See more APOD images of NGC 7331 here.

[Sputnick]

The caption says 'the image is based on information' .. so it's not a photograph, and to me it was obvious at first glance that it was not a photograph .. but I read the caption just to confirm. I see no reason some galaxies should not be bent .. creation seems infinite in compositions.

[bystander]

The caption says 'the image is based on information' .. so it's not a photograph, and to me it was obvious at first glance that it was not a photograph .. but I read the caption just to confirm.

The caption actually says "... This striking image ... was produced using data ..." All "digital images" are produced from "data", even "digital camera photographs". So what's your point?

[emc]

The highest resolution image is working now…

Besides the prominent galaxy in the foreground the three distant galaxies are also intriguing. Especially the three or four armed barred one with what looks like a baby alligator swimming around the bar (in the detail view). The swimming alligator looking shape must be a fourth arm that is developing differently from the other three. And the bar must be many light years across… it looks HUGE!

http://en.wikipedia.org/wiki/Barred_spi ... y#The_bars
<<"The creation of the bar is generally thought to be the result of a density wave radiating from the center of the galaxy whose effects reshape the orbits of the inner stars. This effect builds over time to stars orbiting further out, which creates a self-perpetuating bar structure.[4] Another possible cause of bar creation is tidal disruptions between galaxies.[citation needed]

Bars are thought to be a temporary phenomenon in the life of spiral galaxies, the bar structure decaying over time, transforming the galaxy from a barred spiral to a "regular" spiral pattern. Past a certain size the accumulated mass of the bar compromises the stability of the overall bar structure. Barred spiral galaxies with high mass accumulated in their center tend to have short, stubby bars.">>

So the prominent bar tell us that the distant "alligator" galaxy is younger than the one in the foreground?

[Sputnick]

The caption says 'the image is based on information' .. so it's not a photograph, and to me it was obvious at first glance that it was not a photograph .. but I read the caption just to confirm.

The caption actually says "... This striking image ... was produced using data ..." All "digital images" are produced from "data", even "digital camera photographs". So what's your point?

Bystander .. I just wish a photograph was a photograph instead of an artist's conception, which this one obviously is.

[bystander]

http://en.wikipedia.org/wiki/Barred_spi ... y#The_bars

So the prominent bar tell us that the distant "alligator" galaxy is younger than the one in the foreground?

Alternatively, since the foreground galaxy is closer, it must be younger. To add to the confusion, the next paragraph in the wiki article you quoted begins with:

Recent studies have confirmed the idea that bars are a sign of galaxies reaching full maturity as the "formative years" end.

Anyway, what I originally thought could be a dwarf is obviously an even more distant spiral. However, there are two smudges to the top left of NGC 7331 (one left of your "alligator", the other below that) that could be companions, as well as what looks like could be star streams.

[bystander]

I just wish a photograph was a photograph instead of an artist's conception, which this one obviously is.

I hope your not implying the image is falsified in some way. Most (if not all) color images of the cosmos are enhanced is some way. The fact that they are color is an attribute of that enhancement (the originals are B&W or grayscale). Most enhancements are chosen to reveal some detail. It appears the attempt here was to reveal in sharp detail the features of this spiral galaxy. The explanation is here.

[Sputnick]

I just wish a photograph was a photograph instead of an artist's conception, which this one obviously is.

I hope your not implying the image is falsified in some way. Most (if not all) color images of the cosmos are enhanced is some way. The fact that they are color is an attribute of that enhancement (the originals are B&W or grayscale). Most enhancements are chosen to reveal some detail. It appears the attempt here was to reveal in sharp detail the features of this spiral galaxy. The explanation is here.

Falsified? Your reference merely repeated that 'information' was used to construct the image. Yes .. in my not humble opinion the image is not a photograph, and is obviously not a photograph.

[adrianxw]

Er? A photograph is an image formed by light falling on a light sensitive surface. Since the raw data of the image under discussion was obtained by light falling on a light sensitive surface, it is a photograph by definition. It has been processed to bring out existing detail in the photograph to better present it. It is still a photograph.

Your message, created in your mind, was converted to information, and has been through any number of encoding/decoding processes before it was displayed on my monitor.

Experience, however, tells me that these sort of arguments are futile and detract from the original purpose of the thread. Trolls are trolls.

And yes! My word, it is my APOD anniversary today. I hadn't noticed.

[bystander]

Falsified? Your reference merely repeated that 'information' was used to construct the image. Yes .. in my not humble opinion the image is not a photograph, and is obviously not a photograph.

I still don't get your point. I suspect that very few APOD images meet your definition of a photograph.

Here's the original release from Calar Alto.

[Sputnick]

A photograph is a picture taken with an optical camera. I suspect the image we are discussing was perhaps constructed with radio telescope information .. but it's definitely not an optical image, not that this is important to any but us purists.

[bystander]

A photograph is a picture taken with an optical camera. I suspect the image we are discussing was perhaps constructed with radio telescope information .. but it's definitely not an optical image, not that this is important to any but us purists.

Nope, all visible wave lengths. Data was captured thru a 3.5 m optical telescope at Calar Alto in the mountains of southern Spain. No radio telescopes used. But by your definition, images captured by digital cameras are not photographs. I still don't see your point.

[vperis]

I just wish a photograph was a photograph instead of an artist's conception, which this one obviously is.

I hope your not implying the image is falsified in some way. Most (if not all) color images of the cosmos are enhanced is some way. The fact that they are color is an attribute of that enhancement (the originals are B&W or grayscale). Most enhancements are chosen to reveal some detail. It appears the attempt here was to reveal in sharp detail the features of this spiral galaxy. The explanation is here.

Falsified? Your reference merely repeated that 'information' was used to construct the image. Yes .. in my not humble opinion the image is not a photograph, and is obviously not a photograph.

Hello all,

after reading this thread, I think I must write a short note here about the image.

Sputnick, this photo is as real as your face. The data is real: the telescope has been acquiring real photons during several hours. And I apply processes that can be applied to daylight photos. The only difference from daylight photography is that, being documental photography, if you want to show all the features of the objects being photographed, you must push up a bit more the processes you apply.

Said this, this photograh is NOT a painting. Please, be sure you are able to make a statement before making it.

Best regards,
Vicent.

[vperis]

A photograph is a picture taken with an optical camera. I suspect the image we are discussing was perhaps constructed with radio telescope information .. but it's definitely not an optical image, not that this is important to any but us purists.

FYI, this are the transmission curves of the filters used to make the photo:




Regards,
Vicent.

[bystander]

Hello all,

after reading this thread, I think I must write a short note here about the image.

Sputnick, this photo is as real as your face. The data is real: the telescope has been acquiring real photons during several hours. And I apply processes that can be applied to daylight photos. The only difference from daylight photography is that, being documental photography, if you want to show all the features of the objects being photographed, you must push up a bit more the processes you apply.

Said this, this photograh is NOT a painting. Please, be sure you are able to make a statement before making it.

Best regards,
Vicent.

Thanks, Vicent. Welcome to Asterisk and congratulations on your APOD. Great work, I hope to see more of it.

btw, you now share an anniversary with adrianxw.

[vperis]

Thanks, Vicent. Welcome to Asterisk and congratulations on your APOD. Great work, I hope to see more of it.

btw, you now share an anniversary with adrianxw.

Thanks for your wellcomming messaje. And happy birthday adrianxw!

[pat-on-mars]

Hi and welcome to Vicent. This is a great example of a processed digital image that winds up so dreamy-looking that it might be classified as a work of art.

The original question does remain though. My screen is too small to see the entire large format picture at once, but it seems if I trace out the dust lanes in the galaxy, they do appear to give a "spinning plate" appearance to the object. As the plate spins down and wobbles, that is. The edges are asymmetrical in a 3 dimensional way, which is certainly hard to prove on a photo like this.

Any input from the pros?

And as for gleaning hard and fast astronomy from Wikipedia - please remember that it is a committee document. Anyone can add content to the various articles. A barred spiral is a barred spiral. Cause unknown so far, just a bunch of theories.

[bystander]

For comparison to Vicent's graph - The Visible Spectrum

http://upload.wikimedia.org/wikipedia/c ... ectrum.png

[vperis]

Hi and welcome to Vicent. This is a great example of a processed digital image that winds up so dreamy-looking that it might be classified as a work of art.

The original question does remain though. My screen is too small to see the entire large format picture at once, but it seems if I trace out the dust lanes in the galaxy, they do appear to give a "spinning plate" appearance to the object. As the plate spins down and wobbles, that is. The edges are asymmetrical in a 3 dimensional way, which is certainly hard to prove on a photo like this.

Any input from the pros?

And as for gleaning hard and fast astronomy from Wikipedia - please remember that it is a committee document. Anyone can add content to the various articles. A barred spiral is a barred spiral. Cause unknown so far, just a bunch of theories.

Hi,

I will do a search for papers regarding your question... I think there's something in the literature.


V

[Sputnick]

If it's so photographically photgraphic how come it looks so phonily phoney? And, how does a "processed digital image" differ from a photograph?

[psyched]

I love these images of spiral galaxies. They indeed are almost works of art. It is mind-boggling to imagine the vast dimensions of space pictured. The first thing that strikes me when I see one of these images is that the sky does not look like that when I look at it. Of course I don't have telescopic eyes.

And I do not view the image as being false in any way. Digital and analogue photography are not really that different, though one can argue about various features of each, such as the fineness of the texture.

It is analogous to audio recording, where some people feel that analogue recordings sound better than digital ones, and may even claim that the sampling rate of the digital recording is low enough that they can hear the difference.

[Sputnick]

I guess then, Psyched, you'd enjoy hearing "the music of the spheres" spoken of in the bible.

[Nereid]

If it's so photographically photgraphic how come it looks so phonily phoney?

It has to do with how the 'input' fluxes in the filters are mapped to 'output' intensities of each R, G, and B pixel; the mapping differs from that of the human eye-brain visual system.

Do you have any experience with image processing software, such as Photoshop? It's pretty easy to explain using that paradigm. Ditto if you are familiar with hue, saturation, and brightness/value/intensity/lightness, etc. If not, then perhaps a few links to reference material on chromaticity, colours, etc would help you.

And, how does a "processed digital image" differ from a photograph?

In the usual meaning, a 'photograph' is an image recorded on a light-sensitive film or plate; in astronomy these are usually glass plates coated with a gelatin emulsion in which small crystals of (one or more) silver halides are suspended (in most popular photography, including astrophotography, polyester or acetate film is used instead of glass).

In astronomy 'colour' was observed, using photographic plates, by a combination of filters and different emulsions.

Photographic plates do not have a linear response curve (the amount of silver - which becomes the 'black' in a photograph - is not a linear function of the incident light, even within a narrow wavelength), but neither does the human eye-brain visual system.

Modern detectors used in astronomy - CCDs for example (they're also found in most modern digital cameras) - are digital devices: light falling on them produces a charge, which is 'read out' by electronics on (or close by) the chips and converted to a digital signal (crudely, long strings of zeros and ones). An image from such a device is 'just' data, which can be 'processed' by image processing software such as Photoshop. Broadly speaking, CCDs have linear response curves, which greatly simplifies processing.