APOD: Star Factory Messier 17 (2023 Sep 08)

Comments and questions about the APOD on the main view screen.
User avatar
APOD Robot
Otto Posterman
Posts: 5464
Joined: Fri Dec 04, 2009 3:27 am

APOD: Star Factory Messier 17 (2023 Sep 08)

Post by APOD Robot » Fri Sep 08, 2023 4:05 am

Image Star Factory Messier 17

Explanation: Sculpted by stellar winds and radiation, the star factory known as Messier 17 lies some 5,500 light-years away in the nebula-rich constellation Sagittarius. At that distance, this 1/3 degree wide field of view spans over 30 light-years. The sharp composite, color image highlights faint details of the region's gas and dust clouds against a backdrop of central Milky Way stars. Stellar winds and energetic light from hot, massive stars formed from M17's stock of cosmic gas and dust have slowly carved away at the remaining interstellar material, producing the cavernous appearance and undulating shapes. M17 is also known as the Omega Nebula or the Swan Nebula.

<< Previous APOD This Day in APOD Next APOD >>

User avatar
Ann
4725 Å
Posts: 13620
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Star Factory Messier 17 (2023 Sep 08)

Post by Ann » Fri Sep 08, 2023 5:25 am

OmegaNebulaGrandMesaObservatory2023_1024[1].jpg
Star Factory Messier 17.
Image Credit & Copyright: Kim Quick, Terry Hancock,
and Tom Masterson (Grand Mesa Observatory)

There is more than meets the eye in the M17 nebula. First of all, there is a champagne flow of gas coming out of this nebula! 🍾

Click to play embedded YouTube video.

NASA wrote:

This new image from NASA's Chandra X-ray Observatory reveals hot gas flowing away from massive young stars in the center of the Horseshoe Nebula (a.k.a. M17 or the Omega Nebula).
...
So, what's causing the glowing X-rays found by in this image? One possibility is high-speed winds of particles flowing away from the massive stars have slammed into each other, heating the gas. Or, the super-hot (up to 7 million degrees Fahrenheit) gas could be produced as these winds collide with cool clouds to form bubbles of hot gas.

Wherever it came from, this hot gas appears to be flowing out of the Horseshoe like champagne flows out of a bottle when the cork is removed, so it has been termed an "X-ray champagne flow."

Second of all (as Youtuber Anton Petrov would say), there is a very nice sequence of triggered star formation in M17.

Spitzer.catech.edu wrote:

A dragon-shaped cloud of dust seems to fly out from a bright explosion in this infrared light image from the Spitzer Space Telescope.

These views have revealed that this dark cloud, called M17 SWex, is forming stars at a furious rate but has not yet spawned the most massive type of stars, known as O stars. Such stellar behemoths, however, light up the M17 nebula at the image's center and have also blown a huge "bubble" in the gas and dust in M17 EB.

The stars and gas in this region are now passing though the Sagittarius spiral arm of the Milky Way (moving from right to left), touching off a galactic "domino effect." The youngest episode of star formation is playing out inside the dusty dragon as it enters the spiral arm. Over time this area will flare up like the bright M17 nebula, glowing in the light of young, massive stars. The remnants of an older burst of star formation blew the bubble in M17 EB to the left.
Wikipedia wrote:

(The Omega Nebula) is considered one of the brightest and most massive star-forming regions of our galaxy. Its local geometry is similar to the Orion Nebula except that it is viewed edge-on rather than face-on.

The open cluster NGC 6618 lies embedded in the nebulosity and causes the gases of the nebula to shine due to radiation from these hot, young stars; however, the actual number of stars in the nebula is much higher – up to 800, 100 of spectral type earlier than B9, and 9 of spectral type O,[citation needed] plus over a thousand stars in formation on its outer regions. It is also one of the youngest clusters known, with an age of just 1 million years.

So M17, the Omega Nebula, is like the Orion Nebula seen edge on! Yes, but there is no champagne flow in the Orion Nebula.

Cheers! 🥂

Ann
You do not have the required permissions to view the files attached to this post.
Color Commentator

SpookyAstro
Science Officer
Posts: 116
Joined: Sat Feb 07, 2015 7:38 pm

Re: APOD: Star Factory Messier 17 (2023 Sep 08)

Post by SpookyAstro » Fri Sep 08, 2023 5:54 am

Wow! Awesome info Ann!!!! Thank you!!

Always a huge honor to have our image posted on APOD :D

If anyone is interested here's the tech info for this image:

Location: GrandMesaObservatory.com Purdy Mesa, Colorado

Captured over 4 nights in June, July and August 2023 for Total acquisition time of 14.3 hours.

RGB 858 min 143 x 360 sec
Camera: QHY294C one shot color CMOS
Filter Wheel: QHYCFW3 Medium
Gain 2850, Offset 76
Calibrated with dark, and dark Flat Frames

Optics: William Optics FLT 156mm F7.8 1228mm
Image Scale: 0.76 arcsec/pix
Field of View: 0.90 0.61
EQ Mount: Paramount ME
Image Acquisition software NINA Pre-Processing in PixInsight Post Processed in Photoshop CC

Christian G.
Science Officer
Posts: 193
Joined: Sat Apr 08, 2023 10:37 pm

Re: APOD: Star Factory Messier 17 (2023 Sep 08)

Post by Christian G. » Fri Sep 08, 2023 12:12 pm

Gorgeous dramatic colours!

De58te
Commander
Posts: 584
Joined: Mon Sep 30, 2013 6:35 pm

Re: APOD: Star Factory Messier 17 (2023 Sep 08)

Post by De58te » Fri Sep 08, 2023 12:28 pm

Is there an easy explanation I can tell my 7-year-old grandson explaining why the nebula is mostly 80% red but has a distinctive blue colored clock hand about at the 3 o'clock position? Here's what I know. The red is mostly hydrogen gas absorbing the red as absorbtion from the solar winds. The blue is actually oxygen reflecting the blue color like a mirror. So the boy asks, since the oxygen is located only in that one place, is that proof that there are life forms there around those planets such as here on the blue planet Earth?

User avatar
Cousin Ricky
Science Officer
Posts: 456
Joined: Mon Aug 26, 2013 4:08 pm
Location: St. Thomas, U.S. Virgin Islands (+18.3, -64.9)

Re: APOD: Star Factory Messier 17 (2023 Sep 08)

Post by Cousin Ricky » Fri Sep 08, 2023 2:16 pm

De58te wrote: Fri Sep 08, 2023 12:28 pm Is there an easy explanation I can tell my 7-year-old grandson explaining why the nebula is mostly 80% red but has a distinctive blue colored clock hand about at the 3 o'clock position? Here's what I know. The red is mostly hydrogen gas absorbing the red as absorbtion from the solar winds. The blue is actually oxygen reflecting the blue color like a mirror. So the boy asks, since the oxygen is located only in that one place, is that proof that there are life forms there around those planets such as here on the blue planet Earth?
First of all, the hydrogen is not absorbing red; it is absorbing UV and emitting red. Oxygen fluoresces a bluish green, but I suspect the blue in M17 comes mostly from reflection or scattering off dust. Chris Peterson probably knows more.

The answer to the boy’s question is no. We see free oxygen around planets as a sign of life because oxygen is a very reactive gas, and combines with other elements when it gets a chance. (Your grandson may know that oxygen is part of H2O, but you don’t see the oxygen there. In fact, oxygen is part of rust, wood, people, and most rocks. You don’t see it because it likes to combine with other elements and stay hidden.) This means that if we see free oxygen in a planet’s atmosphere, something has to be releasing it from those compounds and maintaining it there. On Earth, that something is plants and other photosynthesizing organisms.

But the oxygen in this nebula is in outer space. It is very thin, and doesn’t get much chance to combine with other elements. It’s like being in the wilderness versus being in a city. In a city you meet other people all the time, but you don’t get a chance to see many people in the wilderness. In outer space, oxygen doesn’t need a process to free it.

User avatar
Chris Peterson
Abominable Snowman
Posts: 18405
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Star Factory Messier 17 (2023 Sep 08)

Post by Chris Peterson » Fri Sep 08, 2023 2:31 pm

De58te wrote: Fri Sep 08, 2023 12:28 pm Is there an easy explanation I can tell my 7-year-old grandson explaining why the nebula is mostly 80% red but has a distinctive blue colored clock hand about at the 3 o'clock position? Here's what I know. The red is mostly hydrogen gas absorbing the red as absorbtion from the solar winds. The blue is actually oxygen reflecting the blue color like a mirror. So the boy asks, since the oxygen is located only in that one place, is that proof that there are life forms there around those planets such as here on the blue planet Earth?
This is a rich H II region. There is some ionized oxygen (an emitter, not a reflector), but the red of the H dominates. The colors we see in this image aren't very "true". They have been very emphasized, very saturated. That section seen as blue here is seen as desaturated red in most images. That's because it's a very bright area, and scattered white light from the stars in that region somewhat wash out the hydrogen emissions. We usually only see the oxygen in this region when a narrowband filter is used to isolate it, which is not the case here. Here's what I'd consider a more "natural" indication of the colors in this nebula (although with a much less deep image).
_
M17_rgb.jpg
You do not have the required permissions to view the files attached to this post.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
https://www.cloudbait.com

User avatar
orin stepanek
Plutopian
Posts: 8200
Joined: Wed Jul 27, 2005 3:41 pm
Location: Nebraska

Re: APOD: Star Factory Messier 17 (2023 Sep 08)

Post by orin stepanek » Fri Sep 08, 2023 4:26 pm

m17close_hst_c1.jpg
M17 also known as the Omega or Swan Nebula; 8-) a very nice photo!
Kind of likes like a saint is looking over the nebula! Upper left part of
photo! :D
You do not have the required permissions to view the files attached to this post.
Orin

Smile today; tomorrow's another day!

SpookyAstro
Science Officer
Posts: 116
Joined: Sat Feb 07, 2015 7:38 pm

Re: APOD: Star Factory Messier 17 (2023 Sep 08)

Post by SpookyAstro » Fri Sep 08, 2023 8:56 pm

De58te wrote: Fri Sep 08, 2023 12:28 pm Is there an easy explanation I can tell my 7-year-old grandson explaining why the nebula is mostly 80% red but has a distinctive blue colored clock hand about at the 3 o'clock position? Here's what I know. The red is mostly hydrogen gas absorbing the red as absorbtion from the solar winds. The blue is actually oxygen reflecting the blue color like a mirror. So the boy asks, since the oxygen is located only in that one place, is that proof that there are life forms there around those planets such as here on the blue planet Earth?
Great question and discussion! I would say that what Chris said is pretty accurate, that this area is generally blown out and usually more white in most images I've seen or a more saturated red. We used a HDR technique when processing this image which I think contributed to getting the resulting color, that is to say we combined three different stretched images; one low intensity, one medium intensity and one high intensity to get the resulting image. While there are a lot of images that mostly show a red or red/white color hue of this area there are some that do however capture some bluish hues such as these images: https://apod.nasa.gov/apod/ap140527.html, https://apod.nasa.gov/apod/ap170824.html.

When processing images we don't add anything into the image that isn't already there so this color is more a result of trying to tone down the overblown white area and drawing out the color that was there which in this case had a blue hue to it and I rather liked it so we kept it in the image. I could have desaturated it but chose not to. I've seen quite a few OIII images on the internet so there is that present and it is in the area where the bluish hue is in this image however this was a RGB image from a one shot color CMOS camera without OIII added to it so the resulting color is broad-spectrum instead of narrowband. I would also add that it is an artistic interpretation of this area that isn't intended to be scientific, this image was a product of what the camera recorded and then emphasized to get this result :D

-Tom

User avatar
Ann
4725 Å
Posts: 13620
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Star Factory Messier 17 (2023 Sep 08)

Post by Ann » Sat Sep 09, 2023 5:04 am

SpookyAstro wrote: Fri Sep 08, 2023 8:56 pm
De58te wrote: Fri Sep 08, 2023 12:28 pm Is there an easy explanation I can tell my 7-year-old grandson explaining why the nebula is mostly 80% red but has a distinctive blue colored clock hand about at the 3 o'clock position? Here's what I know. The red is mostly hydrogen gas absorbing the red as absorbtion from the solar winds. The blue is actually oxygen reflecting the blue color like a mirror. So the boy asks, since the oxygen is located only in that one place, is that proof that there are life forms there around those planets such as here on the blue planet Earth?
Great question and discussion! I would say that what Chris said is pretty accurate, that this area is generally blown out and usually more white in most images I've seen or a more saturated red. We used a HDR technique when processing this image which I think contributed to getting the resulting color, that is to say we combined three different stretched images; one low intensity, one medium intensity and one high intensity to get the resulting image. While there are a lot of images that mostly show a red or red/white color hue of this area there are some that do however capture some bluish hues such as these images: https://apod.nasa.gov/apod/ap140527.html, https://apod.nasa.gov/apod/ap170824.html.

When processing images we don't add anything into the image that isn't already there so this color is more a result of trying to tone down the overblown white area and drawing out the color that was there which in this case had a blue hue to it and I rather liked it so we kept it in the image. I could have desaturated it but chose not to. I've seen quite a few OIII images on the internet so there is that present and it is in the area where the bluish hue is in this image however this was a RGB image from a one shot color CMOS camera without OIII added to it so the resulting color is broad-spectrum instead of narrowband. I would also add that it is an artistic interpretation of this area that isn't intended to be scientific, this image was a product of what the camera recorded and then emphasized to get this result :D

-Tom
I agree with both Chris Peterson and Tom Masterson here. Yes, M17 is mostly red. Yes, the bright middle part contains an important component of red, and it is also brighter than the rest of the nebula, so that it can get a bit overexposed, which can make it look white.

However, I really believe that there is a blue component here, too. Yes, the blue is mostly from oxygen, but I believe that there is actually scattered blue starlight, too. I remember that astrophotographer David Malin, who was so careful with his colors, once showed that there is a blue rim around parts of the Lagoon Nebula. In other words, blue light from the brilliant blue stars inside the nebula had scattered outside of the red nebula. You can see the hints of blue along the north and south rim of the Lagoon Nebula in the picture below by Andreas Papp:


I think Andras Papp has made his image in such a way as to emphasize the blue component of the Lagoon Nebula. Nevertheless, that doesn't mean that the hints of blue along the northern and southern edges of the Lagoon Nebula aren't there.

I found a hugely interesting LRGB picture of M16 and M17 that shows a hint of blue outside the "bow shock" of M17:

M16 Eagle Nebula and M17 Swan Nebula in LRGB johnnywang astrobin.png
M16 (top) and M17 (bottom) by johnnywang at Astrobin.

You can see what looks like part of a blue rim along the edge of the red "bow shock" of M17. Yes, that could just be reflection nebulosity from stars located along the rim of that bow shock, but I can't shake the suspicion that it might also have something to do with reflection of blue starlight from the brilliant hot stars deep inside M17.

Let's compare the "all broadband" LRGB picture by johnnywang with an "all narrowband" picture of M16 and M17 by Emilio Castillo:


M16 and M17 in Hubble palette by Emilio Castillo.png
M16 (top) and M17 (bottom) in Hubble palette. Credit: Emilio Castillo.

In the Hubble palette, narrowband greenish cyan OIII is mapped as blue, red hydrogen alpha is mapped as green, and red ionized sulfur is shown as red. Note that in Emilio Castillo's image, OIII dominates in M17, but hydrogen alpha and ionized sulfur dominate in M16. I would in fact argue that based on johnnywang's and Emilio Castillo's images, M17 is indeed a little bluer than M16.

I agree with Chris that most RGB images show the bright center of M17 as either white or as a "nonsaturated shade of red", but there are some LRGB pictures by respected astrophotographers that do show the inner bright part of M17 as faintly bluish.

Ann
You do not have the required permissions to view the files attached to this post.
Color Commentator

SpookyAstro
Science Officer
Posts: 116
Joined: Sat Feb 07, 2015 7:38 pm

Re: APOD: Star Factory Messier 17 (2023 Sep 08)

Post by SpookyAstro » Sat Sep 09, 2023 8:01 pm

Great points Ann, your analysis is always much appreciated! :D

I think you may be onto something with the very energetic type O stars in this area putting out massive amounts of bluish light and that light scattering in this area, of course this is only my very amateur opinion and I in no way consider myself to be an expert in the how/why of the objects in my images 8-) I think what really helped to bring out not only the detail in the area but also the color was the HDR composite technique used when processing this image. If the object is stretched all at once you are going to deal with overblown areas and difficulty bringing out the faint outer areas, using the HDR toning technique I think it better approximates the overall brightness of the image and gives you a unique view of the object.

Here are the three stretches I used to create the final image, now keep in mind that these images were not color balanced yet and when we stack the individual images the result always turns out greenish with the setup of the bayer matrix for this camera. To me in the first one or the low stretch I can see the faint blue that is more accentuated in the final image.

Low:
Image

Medium:
Image

High:
Image

Of course I have to add a caveat once again that I in no way intend for this to be a 'scientific' or 'super realistic' interpretation of this area. For that I would honestly ask what the realistic measure actually is seeing as how nobody's eyeballs could really 'see' this and everyone's eyes are different not to mention those with color blindness etc and that this image was captured with a CMOS image sensor that works in a pretty different way than our eyes do, but that is a completely different discussion for another time :D

-Tom