APOD: The Galactic Core in Infrared (2015 Jan 18)

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APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by APOD Robot » Sun Jan 18, 2015 5:10 am

Image The Galactic Core in Infrared

Explanation: What's happening at the center of our Milky Way Galaxy? To help find out, the orbiting Hubble and Spitzer space telescopes have combined their efforts to survey the region in unprecedented detail in infrared light. Infrared light is particularly useful for probing the Milky Way's center because visible light is more greatly obscured by dust. The above image encompasses over 2,000 images from the Hubble Space Telescope's NICMOS taken in 2008. The image spans 300 by 115 light years with such high resolution that structures only 20 times the size of our own Solar System are discernable. Clouds of glowing gas and dark dust as well as three large star clusters are visible. Magnetic fields may be channeling plasma along the upper left near the Arches Cluster, while energetic stellar winds are carving pillars near the Quintuplet Cluster on the lower left. The massive Central Cluster of stars surrounding Sagittarius A* is visible on the lower right. Why several central, bright, massive stars appear to be unassociated with these star clusters is not yet understood.

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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by Guest » Sun Jan 18, 2015 6:13 am

You need to fix the start of the third sentence: the HTML code is mangled with the text.

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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by geckzilla » Sun Jan 18, 2015 6:16 am

Guest wrote:You need to fix the start of the third sentence: the HTML code is mangled with the text.
bystander emailed the editors about this a few hours ago.
Just call me "geck" because "zilla" is like a last name.

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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by JohnD » Sun Jan 18, 2015 9:21 am

What are the false colours?
Red=glowing, white=white hot, dark=cold?

There is what looks like a window lower left, into a 'normal' star field, so a cold area, with symmetrically opposite, lower right, a white hot object. Reminiscent of the hot and cold spots in the cosmic background radiation.
We're not seeing some artifact of wide field observations, are we?

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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by Ann » Sun Jan 18, 2015 9:53 am

I love this image. The central cluster of stars looks amazing. I can imagine that our galaxy would be seen to have a small, white core when seen from the outside. A shorter exposure would reveal a ring of mostly hot blue stars probably surrounding a small, brilliant, possibly yellowish center housing the invisible supermassive black hole of our galaxy.

Wowsers! This is what infrared astrophotography should be doing! :D

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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by Chris Peterson » Sun Jan 18, 2015 7:25 pm

JohnD wrote:What are the false colours?
Red=glowing, white=white hot, dark=cold?
It's hard to make a clear correlation because so much data is combined here. Roughly, I think the luminance is representative of temperature, with white being hottest. Within that, blues are hottest (~500° C), then greens (~400° C), then oranges (~200°C), and coolest are reds (<100°C). Stars are showing up mainly in the NICMOS data (luminance only, capturing ~900-2600° C), and are uniformly white.

Infrared is actually used to capture very cool objects in terms of the astronomical temperatures we usually think of. Visible light and shorter is used for high temperature objects.
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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by geckzilla » Sun Jan 18, 2015 9:08 pm

I think that there is the general idea that infrared corresponds directly and linearly to temperature. I don't think that's the case. Just like visible light, different sections of it can say different things. It's not just for measuring temperature. There are narrowband emissions in infrared, too.
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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by Chris Peterson » Sun Jan 18, 2015 10:45 pm

geckzilla wrote:I think that there is the general idea that infrared corresponds directly and linearly to temperature. I don't think that's the case. Just like visible light, different sections of it can say different things. It's not just for measuring temperature. There are narrowband emissions in infrared, too.
That's true. Certainly, the NICMOS instrument has a lot of narrowband IR filters. Of course, this is in near infrared where we see the same sort of emissions that we do in visible, associated with various ionized species. But in the far IR, the situation is different. Instruments designed for that part of the spectrum (like IRAC) typically utilize broadband detectors, and are intended mainly for making measurements of thermal radiation. All the color in today's image is broadband middle IR and is primarily useful for providing information about the blackbody characteristics of dust- that is, temperature.
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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by Ann » Mon Jan 19, 2015 12:08 am

JohnD wrote:
There is what looks like a window lower left
That is a cleared-out "bubble" that has been cleared of dust by the fierce winds of the hot massive stars of the so called Quintuplet Cluster. One star is surrounded by a yellowish nebula. That is the so called Pistol Star.

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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by DavidLeodis » Mon Jan 19, 2015 1:12 pm

I am wondering if the APOD image area covers all of the galactic core or not, as the "these star clusters" link brings up a wider field-of-view image in which the APOD image only covers the left half (the same wider field-of-view image is also in the information brought up through the fast facts in the "above image" link). If the APOD does cover the left half of the galactic core then it seems odd (well it does to me!) that there seems to be much more 'going on' in the left half of the galactic core than in the right! I hope that makes sense :).

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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by HellCat » Mon Jan 19, 2015 2:27 pm

spellchecker here - shouldn't it be "discernible?"

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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by Chris Peterson » Mon Jan 19, 2015 2:49 pm

HellCat wrote:spellchecker here - shouldn't it be "discernible?"
Both are acceptable spellings.
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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by JohnD » Mon Jan 19, 2015 6:22 pm

Ann wrote:
JohnD wrote:
There is what looks like a window lower left
That is a cleared-out "bubble" that has been cleared of dust by the fierce winds of the hot massive stars of the so called Quintuplet Cluster. One star is surrounded by a yellowish nebula. That is the so called Pistol Star.
Ann
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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by pete xyz » Mon Jan 19, 2015 6:46 pm

What is it that looks like Saturn about a third of the way from the the Quintuplet Cluster to Sagittarius-A?

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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by Ann » Tue Jan 20, 2015 12:41 am

DavidLeodis wrote:I am wondering if the APOD image area covers all of the galactic core or not, as the "these star clusters" link brings up a wider field-of-view image in which the APOD image only covers the left half (the same wider field-of-view image is also in the information brought up through the fast facts in the "above image" link). If the APOD does cover the left half of the galactic core then it seems odd (well it does to me!) that there seems to be much more 'going on' in the left half of the galactic core than in the right! I hope that makes sense :).
It could well be that one "side" of the galactic core is busier than the other. Galaxies are often asymmetric when it comes to how many clusters it churns out, and where those clusters are located.

This is a large (708.44 KB) Hubble image of the inner bulge and core region of galaxy NGC 5248. You can see that the star clusters are not evenly distributed.

Another interestingly "star formation-asymmetric" galaxy is NGC 4450. In this Adam Block image, you can see that the galaxy is making a respectable amount of blue clusters and pink nebulas at the inner end of a long winding dust lane, but apart from that, there is not a lot of star formation going on.

And in this old Adam Block picture of galaxy M58, you can see one tiny, brilliant blue "dot" that looks like a foreground star or possibly a supernova superimposed on one of the thick spiral arms. Actually, it is the one bright cluster of M58.

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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by Ann » Tue Jan 20, 2015 1:04 am

pete xyz wrote:What is it that looks like Saturn about a third of the way from the the Quintuplet Cluster to Sagittarius-A?
I'm not sure what object you refer to, but there is a star rather close to the Quintuplet cluster that has shed a lot of mass, which forms a ring (more likely a sphere) around it. This is almost certainly a massive star that has lost a lot of mass through a fierce stellar wind.

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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by pete xyz » Tue Jan 20, 2015 2:23 pm

Hi Ann, it is a little farther to the right of that star. It is only discernable at highest magnification. probably some artifact....

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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by DavidLeodis » Tue Jan 20, 2015 3:19 pm

Thanks Ann for your help regarding my query. :)

In regard to pete xyz's query I think the Saturn-like object may be that to the right of this section that I have taken from an enlargement of the APOD image. :saturn:
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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by Ann » Wed Jan 21, 2015 2:58 am

DavidLeodis wrote:Thanks Ann for your help regarding my query. :)

In regard to pete xyz's query I think the Saturn-like object may be that to the right of this section that I have taken from an enlargement of the APOD image. :saturn:
To me that looks like a background galaxy. Amazingly, but yes, it does.

What it really is, I can't say.

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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by geckzilla » Wed Jan 21, 2015 4:19 am

Ann wrote:
DavidLeodis wrote:Thanks Ann for your help regarding my query. :)

In regard to pete xyz's query I think the Saturn-like object may be that to the right of this section that I have taken from an enlargement of the APOD image. :saturn:
To me that looks like a background galaxy. Amazingly, but yes, it does.

What it really is, I can't say.
Ok, when you said background galaxy I had to take a closer look because it's nearly impossible to see background galaxies through the galactic core. The stars are just waaaaay too bright and drown out fainter objects. But it is interesting! It actually looks a lot like a planetary nebula. It's ionized gas and shows that classic bipolar shape. I don't know exactly what hydrogen emission is at 1.87 microns but a google search reveals it referred to as a Paschen-alpha emission line. If I had to guess I'd say it's something like H-alpha's infrared cousin.

Here's a picture of it at 200% zoom. Note the nebula appears blue denoting its brightness at 1.87 microns and near absence at 1.90 microns.
266.512487_-28.879461.jpg
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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by starsurfer » Wed Jan 21, 2015 10:24 am

geckzilla wrote:I think that there is the general idea that infrared corresponds directly and linearly to temperature. I don't think that's the case. Just like visible light, different sections of it can say different things. It's not just for measuring temperature. There are narrowband emissions in infrared, too.
Isn't H2 one?

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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by starsurfer » Wed Jan 21, 2015 10:28 am

geckzilla wrote:
Ann wrote:
DavidLeodis wrote:Thanks Ann for your help regarding my query. :)

In regard to pete xyz's query I think the Saturn-like object may be that to the right of this section that I have taken from an enlargement of the APOD image. :saturn:
To me that looks like a background galaxy. Amazingly, but yes, it does.

What it really is, I can't say.
Ok, when you said background galaxy I had to take a closer look because it's nearly impossible to see background galaxies through the galactic core. The stars are just waaaaay too bright and drown out fainter objects. But it is interesting! It actually looks a lot like a planetary nebula. It's ionized gas and shows that classic bipolar shape. I don't know exactly what hydrogen emission is at 1.87 microns but a google search reveals it referred to as a Paschen-alpha emission line. If I had to guess I'd say it's something like H-alpha's infrared cousin.

Here's a picture of it at 200% zoom. Note the nebula appears blue denoting its brightness at 1.87 microns and near absence at 1.90 microns.
266.512487_-28.879461.jpg
Wow that looks amazing! I admire your talent and skills, I think you're quite rather wonderful!
A number of optically invisible planetary nebulae have been found in infrared, I guess these are heavily obscured by dust.
Hvae you thought of submitting it to a professional? Maybe it is uncatalogued and completely known and you could be credited with its discovery?!
I suggest a possible popular name, Topaz Nebula? Another idea is Schmidt's Blue Wisp?

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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by Chris Peterson » Wed Jan 21, 2015 2:53 pm

starsurfer wrote:
geckzilla wrote:I think that there is the general idea that infrared corresponds directly and linearly to temperature. I don't think that's the case. Just like visible light, different sections of it can say different things. It's not just for measuring temperature. There are narrowband emissions in infrared, too.
Isn't H2 one?
What do you mean by "H2"? H II? H2? Your notation is ambiguous.
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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by geckzilla » Wed Jan 21, 2015 2:55 pm

starsurfer wrote:Hvae you thought of submitting it to a professional? Maybe it is uncatalogued and completely known and you could be credited with its discovery?!
I suggest a possible popular name, Topaz Nebula? Another idea is Schmidt's Blue Wisp?
I used it as an excuse to email Bruce Balick. But I couldn't take discovery. I mean, pete xyz pointed it out. I'd call it the APOD nebula or something ambiguous if it were up to me.
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Re: APOD: The Galactic Core in Infrared (2015 Jan 18)

Post by starsurfer » Thu Jan 22, 2015 8:46 pm

Chris Peterson wrote:
starsurfer wrote:
geckzilla wrote:I think that there is the general idea that infrared corresponds directly and linearly to temperature. I don't think that's the case. Just like visible light, different sections of it can say different things. It's not just for measuring temperature. There are narrowband emissions in infrared, too.
Isn't H2 one?
What do you mean by "H2"? H II? H2? Your notation is ambiguous.
I meant H2. If I had meant HII, I would have said HII.
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