APOD: Young Star Cluster NGC 346 (2023 Jan 13)

[APOD Robot]

Young Star Cluster NGC 346

Explanation: The most massive young star cluster in the Small Magellanic Cloud is NGC 346, embedded in our small satellite galaxy's largest star forming region some 210,000 light-years distant. Of course the massive stars of NGC 346 are short lived, but very energetic. Their winds and radiation sculpt the edges of the region's dusty molecular cloud triggering star-formation within. The star forming region also appears to contain a large population of infant stars. A mere 3 to 5 million years old and not yet burning hydrogen in their cores, the infant stars are strewn about the embedded star cluster. This spectacular infrared view of NGC 346 is from the James Webb Space Telescope's NIRcam. Emission from atomic hydrogen ionized by the massive stars' energetic radiation as well as and molecular hydrogen and dust in the star-forming molecular cloud is detailed in pink and orange hues. Webb's sharp image of the young star-forming region spans 240 light-years at the distance of the Small Magellanic Cloud.

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[bystander]

viewtopic.php?t=42877

[AVAO]

Young Star Cluster NGC 346

see more information:

slider HST/JWST: https://esawebb.org/images/comparisons/weic2301/
paper: https://arxiv.org/abs/2301.03932
zoom in: https://www.youtube.com/watch?v=msg13lHhbAI&t=3s
article: https://phys.org/news/2023-01-webb-unco ... pe=desktop
discussion: https://www.youtube.com/watch?v=CeRtJnbCBOw#t=17m10s

[Ann]

NGC 346 in infrared light by JWST.

NGC 346 in optical light. Credit: NASA, ESA and A. Nota

---

I found today's APOD confusing, and I had to put it next to an optical image of the same target to try to understand what I'm seeing.

The little galaxy, if that is what it is, was a nice find. The "pillar" had me scratching my head. What is that thing? And the bright red star, I guess, is an embedded infrared star. Oh well.

Note that the bright cluster of massive blue stars, that is so prominent in the Hubble image, is very "subdued" in the JWST image. By contrast, the rich cluster of old yellow stars at upper center right in the Hubble image is very visible in the portrait by JWST.

To me, by far the most interesting thing about today's APOD is how it reveals the filamentary structure of the dust (and gas, because the dust traces the gas) in NGC 346. Note how several filaments of gas and dust meet at the center of the image, where the brilliant cluster has formed.

However, to me today's APOD is a reminder of how weird it is to see how different stars look in optical and infrared light. The pictures below illustrate that weirdness perfectly.

Famous star clusters in infrared light. Credit: 2MASS.

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The same clusters in optical light. Do you recognize them? Credit: Andrew Cooper

---

Ann

[Ann]

Young Star Cluster NGC 346

see more information:

slider HST/JWST: https://esawebb.org/images/comparisons/weic2301/
paper: https://arxiv.org/abs/2301.03932
zoom in: https://www.youtube.com/watch?v=msg13lHhbAI&t=3s
article: https://phys.org/news/2023-01-webb-unco ... pe=desktop
discussion: https://www.youtube.com/watch?v=CeRtJnbCBOw#t=17m10s

Thanks, AVAO! The HST/JWST slider is great! I don't have time for the rest now, but will look at it later.

Ann

[bls0326]

Thanks, AVAO! I found the slider views quite interesting!

[orin stepanek]

NGC Star forming region in SMC! Beautiful! Looks almost like a fetus!

SMC! Amazing what these small galaxies have in them!

[AVAO]

Young Star Cluster NGC 346

Star or binary star system with jets?
Background galaxy with one or two cores?

[johnnydeep]

Young Star Cluster NGC 346

Star or binary star system with jets?
Background galaxy with one or two cores?

That is indeed one very nice looking - possibly two-cored - background galaxy! Nice spotting Ann and AVAO.

[johnnydeep]

Is it just me or does this "sculpt the edges" link from the text not point to anything in particular - https://hubblesite.org/contents/media/i ... Image.html ?

[ EDIT: never mind - it works fine for me now! ]

[johnnydeep]

So where can I get a higher res version of this? I can't even find one here - https://webbtelescope.org/contents/news ... s-2023-101.

I know the APOD image is better, but where did that one come from?

[Joe Stieber]

So where can I get a higher res version of this? I can't even find one here - https://webbtelescope.org/contents/news ... s-2023-101.

I know the APOD image is better, but where did that one come from?

Scroll to the bottom of the page you linked, then under "Release Images," there's a pair of large thumbnails, one plain and one annotated. Click on either of them and scroll down to "Download Options" where they provide links to massive (nominal 100 MB) PNG and TIF files.

[Ann]

Young Star Cluster NGC 346

Star or binary star system with jets?
Background galaxy with one or two cores?

How strange! This is what the object looks like in the Hubble picture:

In the Hubble image, we can see one bright "nucleus"(?), and immediately to the right of it we can see one faint yellow "nucleus"(?). And to the right of the second nucleus is another, reasonably bright object.

It is possible that this is a double-nucleus galaxy, where one nucleus is more dust-enshrouded than the other. The third object could be a foreground star, or indeed, possibly a third galaxy interacting with the double-nucleus one.

The "arms" of this galaxy look like a cross between normal spiral arms and tidal tails to me. Note that they appear to be completely dust-free.

The Violin Clef galaxy. Credit: SDSS/Zooniverse.

---

For all of that, I'm not saying that the strange galaxy-like object can't be a binary star with jets. I just think it is more likely that the object is a galaxy. (Would the individual stars of an interacting binary pair in the Small Magellanic Cloud really be sufficiently far apart that even JWST could resolve them?)

Ann

[AVAO]

Young Star Cluster NGC 346

Star or binary star system with jets?
Background galaxy with one or two cores?

That is indeed one very nice looking - possibly two-cored - background galaxy! Nice spotting Ann and AVAO.

Click to view full size image 1 or image 2

Hmmm. I was unsure and have checked it again more detailed:
The "jets" or "arms" are invisible in the optical spectral range. The visible "arms" in the HST are probably from HST WFC F814W. The fact that the upper arm appears to be in front of the dust filament in the JWST image is therefore apparently a misleading effect resulting from the overlapping of the wavelengths. In the blue channel of the HST image, the arms are practically invisible. The "second" or "middle" galactic core only becomes visible in the infrared. But I'm still not 100% convinced, because the "main core" is also very good visible in the optical area and appears there as a "star". Unfortunately, the JWST data are not yet public, so that no more detailed analyzes are possible here.

Thanx Ann
Now our analyzes have overlapped in time. But it's nice that we get quite the same result

[AVAO]

"...And the bright red star, I guess, is an embedded infrared star...
Ann

The star is almost certainly Cl* NGC 346 MPG 454, a Herbig Ae/Be Star.
https://simbad.cds.unistra.fr/simbad/sim-basic?Ident=Cl*+NGC+346+MPG+454&submit=SIMBAD+search

"NGC 346 MPG 454 (SMC IRS 18) derives its name from the catalogue by Massey et al. (1989). It is located at the position of N66, an H ii region (Henize 1956). This source also occurs in the list of candidate PNe by Kamath et al. (2014). Chandra X-ray observations reveal that NGC 346 MPG 454 is one of the brightest blue stars in the NGC 346 cluster (Naz ́e et al. 2002)."
https://www.researchgate.net/publicatio ... anic_Cloud

[Ann]

Star or binary star system with jets?
Background galaxy with one or two cores?

That is indeed one very nice looking - possibly two-cored - background galaxy! Nice spotting Ann and AVAO.

Click to view full size image 1 or image 2

Hmmm. I was unsure and have checked it again more detailed:
The "jets" or "arms" are invisible in the optical spectral range. The visible "arms" in the HST are probably from HST WFC F814W. The fact that the upper arm appears to be in front of the dust filament in the JWST image is therefore apparently a misleading effect resulting from the overlapping of the wavelengths. In the blue channel of the HST image, the arms are practically invisible. The "second" or "middle" galactic core only becomes visible in the infrared. But I'm still not 100% convinced, because the "main core" is also very good visible in the optical area and appears there as a "star". Unfortunately, the JWST data are not yet public, so that no more detailed analyzes are possible here.

Thanx Ann
Now our analyzes have overlapped in time. But it's nice that we get quite the same result

I think that maybe, maybe, the galaxy(?) seen in the picture of NGC 346 is a second cousin of the merging galaxies, IC 1178 and IC 1181, in the Perseus Cluster of galaxies:

Dry merger in the Perseus Cluster.
Credit: Detlef Hartmann.

IC 1178 and IC 1181 are two elliptical or lenticular galaxies in the Perseus Cluster of galaxies. IC 1178 and IC 1181 contain no "concentrated dust clouds of dust lanes" at all, and no concentrated gas clouds. As they merge, they produce no new stars at all (which is why it is called a dry merger), but they produce two tidal tails of flung-out old stars. The tidal tails are reminiscent of spiral arms.

Let's assume that the object that resembles a galaxy in the picture of NGC 346 really is a galaxy. Is it strange that we only detect it in infrared light?

I think not. If this galaxy, like IC 1178 and IC 1181, is made up almost exclusively of old stars, then the light that it emits will be intrinsically yellow. Let's assume, too, that the galaxy is sufficiently distant to be appreciably reddened by cosmological redshift. On top of that, let's assume that the galaxy is quite dust-reddened by all the dust that is present in and near NGC 346.

These three factors combined make it quite reasonable to assume that the galaxy (or at least the faint arms) will only be visible in infrared light.

Ann

[johnnydeep]

So where can I get a higher res version of this? I can't even find one here - https://webbtelescope.org/contents/news ... s-2023-101.

I know the APOD image is better, but where did that one come from?

Scroll to the bottom of the page you linked, then under "Release Images," there's a pair of large thumbnails, one plain and one annotated. Click on either of them and scroll down to "Download Options" where they provide links to massive (nominal 100 MB) PNG and TIF files.

Thanks. Strange that I still can't get a closeup of the mystery background galaxy that looks as good as AVAO's pics. [ Aside: why the heck won't my browser display a .tif file on Windows? It ALWAYS wants to save it to a file no matter how hard I try to make it open it! ]

[Chris Peterson]

So where can I get a higher res version of this? I can't even find one here - https://webbtelescope.org/contents/news ... s-2023-101.

I know the APOD image is better, but where did that one come from?

Scroll to the bottom of the page you linked, then under "Release Images," there's a pair of large thumbnails, one plain and one annotated. Click on either of them and scroll down to "Download Options" where they provide links to massive (nominal 100 MB) PNG and TIF files.

Thanks. Strange that I still can't get a closeup of the mystery background galaxy that looks as good as AVAO's pics. [ Aside: why the heck won't my browser display a .tif file on Windows? It ALWAYS wants to save it to a file no matter how hard I try to make it open it! ]

The TIFF file format is complex, supporting layers, many different bit depths (including floating point values), rich metadata, and much more. Displaying a TIFF file properly is best left to specialized image viewers and editors.

[johnnydeep]

Hey, did anyone notice the OTHER galaxy that looks quite similar to the possibly double nucleated one being discussed above? It's a ways down and to the right:

[johnnydeep]

Scroll to the bottom of the page you linked, then under "Release Images," there's a pair of large thumbnails, one plain and one annotated. Click on either of them and scroll down to "Download Options" where they provide links to massive (nominal 100 MB) PNG and TIF files.

Thanks. Strange that I still can't get a closeup of the mystery background galaxy that looks as good as AVAO's pics. [ Aside: why the heck won't my browser display a .tif file on Windows? It ALWAYS wants to save it to a file no matter how hard I try to make it open it! ]

The TIFF file format is complex, supporting layers, many different bit depths (including floating point values), rich metadata, and much more. Displaying a TIFF file properly is best left to specialized image viewers and editors.

Thanks. I figured all modern browsers would have been capable of opening TIFF files, but I guess not. At least Firefox gives me a message that "the associated helper application doesn't exist", whereas Vivaldi (Chromium based) does not.

[Chris Peterson]

Thanks. Strange that I still can't get a closeup of the mystery background galaxy that looks as good as AVAO's pics. [ Aside: why the heck won't my browser display a .tif file on Windows? It ALWAYS wants to save it to a file no matter how hard I try to make it open it! ]

The TIFF file format is complex, supporting layers, many different bit depths (including floating point values), rich metadata, and much more. Displaying a TIFF file properly is best left to specialized image viewers and editors.

Thanks. I figured all modern browsers would have been capable of opening TIFF files, but I guess not. At least Firefox gives me a message that "the associated helper application doesn't exist", whereas Vivaldi (Chromium based) does not.

Keep in mind that the Web was designed to deal with low bandwidth data. Which is why the native image formats that browsers support are all centered on significant compression (GIF, JPEG, PNG). As broadband has become common, people pay less attention to that, but the standards are still based on that idea, are probably should be. A website that used TIFF images in a page would be a bad design, even if browsers increasingly opted to support that format.

[johnnydeep]

The TIFF file format is complex, supporting layers, many different bit depths (including floating point values), rich metadata, and much more. Displaying a TIFF file properly is best left to specialized image viewers and editors.

Thanks. I figured all modern browsers would have been capable of opening TIFF files, but I guess not. At least Firefox gives me a message that "the associated helper application doesn't exist", whereas Vivaldi (Chromium based) does not.

Keep in mind that the Web was designed to deal with low bandwidth data. Which is why the native image formats that browsers support are all centered on significant compression (GIF, JPEG, PNG). As broadband has become common, people pay less attention to that, but the standards are still based on that idea, are probably should be. A website that used TIFF images in a page would be a bad design, even if browsers increasingly opted to support that format.

Yeah. I was going to quip that there ARE compressed TIFF formats, but even the LZW compression used in the JWST TIFF file produces that 97 MB result.

[Chris Peterson]

Thanks. I figured all modern browsers would have been capable of opening TIFF files, but I guess not. At least Firefox gives me a message that "the associated helper application doesn't exist", whereas Vivaldi (Chromium based) does not.

Keep in mind that the Web was designed to deal with low bandwidth data. Which is why the native image formats that browsers support are all centered on significant compression (GIF, JPEG, PNG). As broadband has become common, people pay less attention to that, but the standards are still based on that idea, are probably should be. A website that used TIFF images in a page would be a bad design, even if browsers increasingly opted to support that format.

Yeah. I was going to quip that there ARE compressed TIFF formats, but even the LZW compression used in the JWST TIFF file produces that 97 MB result.

Yeah, LZW is lossless, and lossless formats seldom provide much compression for most images. Web browsers are designed to show inline images, and those are small enough that the compression can be very lossy and still result in little visual degradation.

[johnnydeep]

Keep in mind that the Web was designed to deal with low bandwidth data. Which is why the native image formats that browsers support are all centered on significant compression (GIF, JPEG, PNG). As broadband has become common, people pay less attention to that, but the standards are still based on that idea, are probably should be. A website that used TIFF images in a page would be a bad design, even if browsers increasingly opted to support that format.

Yeah. I was going to quip that there ARE compressed TIFF formats, but even the LZW compression used in the JWST TIFF file produces that 97 MB result.

Yeah, LZW is lossless, and lossless formats seldom provide much compression for most images. Web browsers are designed to show inline images, and those are small enough that the compression can be very lossy and still result in little visual degradation.

At least it's better than using "none" for the compression algorithm in GIMP, which results in a 260 MB file!

[Ann]

Hey, did anyone notice the OTHER galaxy that looks quite similar to the possibly double nucleated one being discussed above? It's a ways down and to the right:

Click to view full size image

Great find, Johnny! Your "other" galaxy is definitely a real spiral galaxy, and it is interacting with a smaller galaxy as well.

Ann