APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

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APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

Postby APOD Robot » Fri Dec 28, 2012 5:08 am

Image NGC 6188 and NGC 6164

Explanation: Fantastic shapes lurk in clouds of glowing hydrogen gas in NGC 6188, about 4,000 light-years away. The emission nebula is found near the edge of a large molecular cloud unseen at visible wavelengths, in the southern constellation Ara. Massive, young stars of the embedded Ara OB1 association were formed in that region only a few million years ago, sculpting the dark shapes and powering the nebular glow with stellar winds and intense ultraviolet radiation. The recent star formation itself was likely triggered by winds and supernova explosions, from previous generations of massive stars, that swept up and compressed the molecular gas. Joining NGC 6188 on this cosmic canvas is rare emission nebula NGC 6164, also created by one of the region's massive O-type stars. Similar in appearance to many planetary nebulae, NGC 6164's striking, symmetric gaseous shroud and faint halo surround its bright central star at the lower right. The field of view spans about two full Moons, corresponding to 70 light years at the estimated distance of NGC 6188.

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Re: APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

Postby Ann » Fri Dec 28, 2012 6:46 am

Today's APOD is a wonderful portrait of the roiling gas and dust in the red emission nebula NGC 6188. A blue reflection nebula can also be seen, as well as scattered blue starlight. As for the star HD 148937, the one that is surrounded by planetary nebula-like two-lobed nebulosity, this still very hot star must be in the beginnings of its death throes. I haven't found any confirmation that HD 148937 is a Wolf-Rayet star, which is a stage in the life of a very hot and massive star when the star sheds massive amounts of its outer envelope due to its own incredible stellar wind. Gamma Velorum is such a star. It is seen at lower right in the image by Robert Gendler.

So HD 148937 is not a Wolf-Rayet star. Possibly, then, it might be a little brother of Eta Carina. This Hubble image of Eta Carina shows a morphology similar to that of HD 148937: There is a two-lobed bright inner nebula, surrounded by an outer shell.

As for the great nebula NGC 6188, it is powered by a truly great star, HD 150136. At least one source claims that HD 150136 is the nearest of all O3 stars. The spectral classification of O3 is used for the most massive, hottest normal stars, although I believe that a classification of O2 might have been used in a very few cases.

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Re: APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

Postby biddie67 » Fri Dec 28, 2012 1:34 pm

Ann ~~ thanks for taking the time to research and provide the info above. I was still in my "double wow" response to the photo when I came over here. I'm always amazed how much work is being done to understand what is out there ...

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Re: APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

Postby neufer » Fri Dec 28, 2012 1:55 pm

------------------------------------------------
    . Cymbeline Act 5, Scene 5
CYMBELINE: Let's quit this ground,
. And *SMOKE* the temple with our sacrifices.

------------------------------------------------
    . Titus Andronicus Act 1, Scene 1
LUCIUS: See, lord and father, how we have perform'd
. Our Roman rites: Alarbus' limbs are lopp'd,
. And entrails feed the sacrificing fire,
. Whose *SMOKE*, like incense, doth perfume the sky.

------------------------------------------------
    . King Henry VI, Part i Act 2, Scene 2
BURGUNDY: Myself, as far as I could well discern
. For *SMOKE* and dusky vapours of the night,
. Am sure I scared the Dauphin and his trull,

------------------------------------------------
    . Macbeth Act 1, Scene 5
LADY MACBETH: Come, thick night,
. And pall thee in the dunnest *SMOKE* of hell,
. That my keen knife see not the wound it makes,
. Nor heaven peep through the blanket of the dark,
. To cry 'Hold, hold!'

------------------------------------------------
    . The Rape of Lucrece Stanza 115
'O Night, thou furnace of foul-reeking *SMOKE*,
Let not the jealous Day behold that face
Which underneath thy black all-hiding cloak
Immodestly lies martyr'd with disgrace!

------------------------------------------------
    . Romeo and Juliet Act 1, Scene 1
ROMEO: Mis-shapen chaos of well-seeming forms!
. Feather of lead, bright *SMOKE*, cold fire, sick health!

------------------------------------------------
Ben Jonson: the influence of humor, which ... hurles
. FOORTH *NOTHING but SMOOKE* and congested vapours.
Art Neuendorffer

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Re: APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

Postby dbooksta » Fri Dec 28, 2012 2:10 pm

What wavelengths were mapped to what colors in this image?

And why isn't this information provided for all false-color images?

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Re: APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

Postby Ann » Fri Dec 28, 2012 2:31 pm

dbooksta wrote:What wavelengths were mapped to what colors in this image?

And why isn't this information provided for all false-color images?


If you follow the link called this cosmic canvas, you come to the photographer's own page. Here you can find the following information:

HA-RGB image
Ha - 60 min
RGB 20 minutes per channel

So it is a normal RGB (red, green, blue) image, combined with a Ha exposure in order to bring out as much red nebulosity as possible. We may therefore assume that whatever is red in this image is probably all red Ha emission. Personally I don't see anything in the image which is bright red and is not likely to be Ha. Certainly, however, the stars in the image emit some red light, and the dust is going to redden some light that filters through the dust. Nothing is bright green in the image, but the stars certainly all emit some green light, and the blue nebulosity contains some green light, too. Also, in fact, the red Ha light is mixed with some blue-green Hβ emission.

Whatever is blue in the image is likely to be "really" blue, although the image may have been processed in such as way as to enhance the blue color. There are definitely stars here that are much bluer than the Sun.

Ann

P.S. Biddie67, you are welcome! :D
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Re: APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

Postby Chris Peterson » Fri Dec 28, 2012 4:12 pm

Ann wrote:If you follow the link called this cosmic canvas, you come to the photographer's own page. Here you can find the following information:

HA-RGB image
Ha - 60 min
RGB 20 minutes per channel

So it is a normal RGB (red, green, blue) image, combined with a Ha exposure in order to bring out as much red nebulosity as possible.

To be clear, when these types of images are made the Ha is not typically mapped to red, but to the luminance channel. So the Ha isn't actually providing any color, but rather is providing the high resolution structure that we see in the nebula. The red color is presumably coming only from the red filter channel.
Chris

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Re: APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

Postby Ron-Astro Pharmacist » Fri Dec 28, 2012 4:59 pm

Has APOD ever considered indicating where and what size the picture is within its noted position in the sky? In this case we are referred to the constellation Ara. It would be interesting to place a box within the constellation indicating its position and size. My learning curve is steep and a landmark as indicated would add a depth of understanding. :idea: Ron

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Re: APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

Postby ta152h0 » Fri Dec 28, 2012 5:13 pm

and you have now entered Zeus empire and ooops, the door locked behind you. So much to see and so much to decipher, it will take a lifetime.
Wolf Kotenberg

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Re: APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

Postby Ann » Fri Dec 28, 2012 5:46 pm

Ron-Astro Pharmacist wrote:Has APOD ever considered indicating where and what size the picture is within its noted position in the sky? In this case we are referred to the constellation Ara. It would be interesting to place a box within the constellation indicating its position and size. My learning curve is steep and a landmark as indicated would add a depth of understanding. :idea: Ron


Check out this picture by Akira Fuji. In the "upper right quadrant" you can see the lower part of Scorpius. Note the two blue stars at top center: they are Lambda and Upsilon Scorpii. Note, at about 2 o'clock, the characteristic curving shape made up of, from bottom to top, Zeta Scorpii, star cluster NGC 6231, and the red nebulosity possibly called IC 4628.

You can see a dark "ridge" running downwards and to the right in the image. That is actually the major dust lane of the Milky Way. At about 4 o'clock there is a large bright patch containing several small bright spots, the largest and brightest of which is cluster NGC 6067. We are now in constellation Norma.

Constellation Ara is between the lower part of Scorpius and constellation Norma. Can you see a somewhat large but slightly faint pink patch at about 3 o'clock? Maybe you can see that a dark ridge appears to run below this pink patch, and something that looks like a small elongated bright patch inside it?

That pink patch is today's APOD, NGC 6188. And the elongated small bright patch inside it is the cluster NGC 6193 which ionizes the nebula and makes it glow.

You may also want to check out this picture of the Milky Way. The brightest star at about 8 o'clock is Altair in the constellation Aquila, the southernmost star in the well-known Summer Triangle. You can see the brightest part of the Milky Way in constellation Sagittarius. Upper Scorpius rises above the disk of the Milky Way almost vertically above the bright yellow bulge in Sagittarius. Can you see Antares, surrounded by a yellow reflection nebula?

Now follow the major dust lane to the upper right in the picture. Can you see the characteristic curving shape made up of Zeta Scorpii, cluster NGC 6231 and nebulosity IC 4628?

If you have found this characteristic Scorpius "hook", then move right just a little bit. You'll come to a small brightening in the dust lane, a brightening that seems to trail a long dark train of dust below and to the left of it. This brightening is Ara, and the brightest part is nebulosity NGC 6188 and cluster NGC 6193.

Ann
Last edited by Ann on Fri Dec 28, 2012 6:42 pm, edited 1 time in total.
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Re: APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

Postby LocalColor » Fri Dec 28, 2012 6:10 pm

Stunning image and interesting discussion. Thank you.

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Re: APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

Postby Anthony Barreiro » Fri Dec 28, 2012 7:06 pm

Ron-Astro Pharmacist wrote:Has APOD ever considered indicating where and what size the picture is within its noted position in the sky? In this case we are referred to the constellation Ara. It would be interesting to place a box within the constellation indicating its position and size. My learning curve is steep and a landmark as indicated would add a depth of understanding. :idea: Ron

Hi Ron. I can relate to the steep learning curve! The universe is pretty big, and the closer you look at anything the more complex it becomes!

To get oriented and find your way around, you need a good sky atlas. I'm an old dinosaur who still uses printed atlases. The Sky and Telescope Pocket Sky Atlas or the Cambridge Star Atlas (fourth edition) are both excellent for beginners and will remain faithful companions as your knowledge grows. There are a number of desktop computer planetarium programs that provide charts of the sky and much additional information. Stellarium is free, open-source, and available for Linux, Windows, Macintosh, and Ubuntu (what the heck is Ubuntu?). If you use a tablet computer or a smart phone, there are a lot of mobile applications for skywatching. My favorites are SkySafari Plus and Pocket Sky Atlas.

Happy hunting!
May all beings be happy, peaceful, and free.

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Re: APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

Postby Case » Fri Dec 28, 2012 7:07 pm

Ron-Astro Pharmacist wrote:Has APOD ever considered indicating where and what size the picture is within its noted position in the sky? In this case we are referred to the constellation Ara. It would be interesting to place a box within the constellation indicating its position and size.

Here’s a view with the horizon, looking south from Namibia, where the image was taken, in June. Ara is about 60° up around midnight.
Image

Here is a closer view of Ara. “The field of view [of the APOD] spans about two full Moons” -- or about 1°, a little bit more than the distance between β Ara and γ Ara (0.85°). The APOD image is the small patch in the upper right corner.
Image
(Images are (edited) screenshots from Stellarium.)

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Re: APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

Postby neufer » Fri Dec 28, 2012 10:12 pm

.


So the APOD FOV is spilling
over onto Norma:

Image
Norma Jeane Mortenson
Case wrote:
Here is a closer view of Ara. “The field of view [of the APOD] spans about two full Moons”
-- or about 1°, a little bit more than the distance between β Ara and γ Ara (0.85°).
    The APOD image is the small patch in the upper right corner.
Image
(Images are (edited) screenshots from Stellarium.)
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Re: APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

Postby Boomer12k » Sat Dec 29, 2012 1:00 am

Neufer and Case. Thank you for the Star maps. Very interesting. Ara looks like Orion without the belt and sword.
Very helpful for someone who is not familiar with the Southern Skies.

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Re: APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

Postby neufer » Sat Dec 29, 2012 3:20 am

Art Neuendorffer

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Re: APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

Postby Case » Sat Dec 29, 2012 8:06 am

neufer wrote:So the APOD FOV is spilling over onto Norma

More precisely, Friday’s companion NGC 6164 is within Norma’s boundaries. NGC 6164 is one of John Herschel’s discoveries (1834). [Yes, son of William Herschel.]

Norma is a ‘modern’ constellation, the name ‘l’Equerre et la Regle’ being introduced in 1751-52 by Nicolas Louis de Lacaille. (He named 14 constellations!) It is often depicted as a draughtsman’s set-square and rule. The right angle (90°) of the set-square refers to ‘normal’, which inspired the latinized constellation name of Norma in 1763.

The brightest stars of Norma are of only fourth magnitude and none have names. Because of changes in the constellation’s boundaries since Lacaille’s time, Norma no longer has stars labelled Alpha or Beta. The stars that Lacaille designated Alpha and Beta Normae are now part of Scorpius, where they are known as N and H Scorpii respectively. Incidentally, Norma shares this distinction with Puppis and Vela, both of which lack stars labelled Alpha and Beta because they were once part of a much larger constellation, in their case Argo Navis; when Argo was split into three by Lacaille, the stars Alpha and Beta ended up in the third subdivision, Carina.

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Re: APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

Postby Ann » Sat Dec 29, 2012 8:31 am

Thank you very much for that map, Case! I am quite unable to produce such things.

And thanks for your associations, Art. Indeed, Norma is the located next to Ara.

I'd like to return to astronomy and to associations that can be traced to today's APOD in a more astronomical way. As Case's map shows so clearly, emission nebula 6188, as large and impressive as it is, is only a very small part of constellation Ara.

Pictures of emission nebulae are astronomical favorites. Check out the homepages of astrophotographers like Robert Gendler or Adam Block, and see how many pictures of emission nebulae they have produced. And yet, when you look at wide-angle pictures of the Milky Way, the emission nebulae are so small, few and far between.

Check out this picture of the Milky Way. A good thing about it is that you can clearly see many emission nebulae because of their pink color. Let's try to identify them!

At far left, as far left as you can go, you have IC 405 and IC 410, with a stellar asterism, "The Leaping Minnow", running between them.

The next pink nebula is located below the plane of the Milky Way, above the Pleiades. It's the California Nebula.

The next two nebulae are the Heart and Soul nebulae, IC 1805 and IC 1848.

The tiny round nebula hanging somewhat below th eplane of the Milky Way is the Pacman Nebula, NGC 281.

Next we come to the faint NGC 7822, which looks mostly like a line of reddened star located in a really dark patch of the Milky Way dust lane.

Next we come to IC 1396, with the Elephant Trunk nebula and the remarkable reddish Garnet Star, Mu Cephei, apparently sitting on the edge of it.

The next two nebulae are the well-known North America and Pelican Nebulae. Note in the large Milky Way picture that you can see some nebulosity to the lower left of the North America nebula. You can see it in the link I've provided here, too. To my knowledge this nebulosity hasn't got a name, but it is centered on, and ionized by, the magnificent runaway O8-type star, 68 Cygni or HD 203064.

By the way, shouldn't the Cocoon nebula be here somewhere, too? Absolutely, but I can't find it in the Milky Way picture. It's too tiny.

The next nebulosity, instead, is a lot of scattered nebulosity which I choose to just call the Gamma Cygni nebulosity.

Now you come to a long stretch of nebula-free Milky Way. We first come to a nebula whose name I haven't managed to figure out. It is centered on cluster NGC 6604, and parts of the nebula are called Lynd's Bright Nebula 71 and Lynd's Bright Nebula 72. It's a quite large nebula, but faint. In this link, the large faint nebula centered on cluster NGC 6604 is at top right, and well-known M16, the Eagle Nebula, is below it.

M16 deserves another link too, of course. This false-color image shows off the inner structure of M16 very well.

After M16 we have M17, the Swan Nebula. It is the site of fantastic star formation. This image shows the "champagne flow" of M17, as the tremendous stellar winds of all the newborn O stars inside force huge amounts of gas out of "openings" in the nebula in the same way as champagne is forced out of the bottle when the cork has been removed.

The next nebula is the large, faint nebula Sharpless 2-27 around runaway star Zeta Ophiuchi. It is seen at the very top of the image, above the plane of the Milky Way. There is apparently a meteor in the picture, too.

Almost directly below Sharpless 2-27 is M8, the Lagoon Nebula. In this picture you can see the Lagoon nebula on the left and the Trifid Nebula on the right. I can see the Trifid Nebula in the Milky Way picture, but I can't see its pink color. It is probably too tiny.

Too the upper right of the Lagoon Nebula is a faint pink nebula. It is centered on a magnificent and very distant O-type star, HD 162978. You can just barely spot the large, faint nebula in this image at four o'clock.

The next nebula is another large, faint nebula centered on an amazing O-type star. This nebula is located to the right of M6, the Butterfly Cluster, as seen in the Milky Way picture and in this image. Please note that the nebula is nowhere near as bright as it appears to be here!

Then we have NGC 6357, the War and Peace Nebula, and NGC 6334. the Cat's Paw Nebula.

Above them, above the plane of the Milky Way, is the large, faint nebula surrounding hot star Tau Scorpii. Unfortunately this was the best picture I could find! Tau Scorpii is almost smack in the middle of the picture. To the right of Tau Scorpii is Sigma Scorpii, which is surrounded by a much smaller but actually brighter nebula. At upper right in the picture you can see the nebula around Zeta Ophiuchi. At 4 and 5 o'clock you can see the faint nebulosity around stars Pi and Rho Scorpii. In the middle of the plane of the Milky Way, as seen in this picture, is NGC 6357 and NGC 6334, the War and Peace and Cat's Paw nebulae.

In the Stephane Guisard picture, you can see a ring apparently surrounding a small cluster, The cluster is NGC 6281, and it beats me, frankly, why there would be a ring of nebulosity around it. It looks like an unremarkable cluster, probably at least a hundred million years old. In this picture, you can see the cluster at about 8 o'clock, and a large, faint ring surrounding it.

More importantly, in the same picture you can see what I call "The Hook of Scorpius". In the middle of this picture you can see the red nebulosity, IC 2648, that makes up one end of the Hook. Then there is a scattered group and then line of stars, ending in the compact, remarkable cluster NGC 6231. Then there is a triangle of stars, the brightest of which is a reddish star which is a foreground object. The other two stars, at least one of them, is probably at the same distance from us as NGC 6231. The two brightest of these three stars are called Zeta Scorpii. The faint red arc in the right part if the picture is almost certainly caused by the mighty stellar wind of cluster NGC 6231.

Okay, and what is the next nebula? Why, it is NGC 6188 in Ara, of course!

Now we come to a long stretch of nebula-free Milky Way. The next important nebula is the Lambda Centauri Nebula. The most important part of the nebula, IC 2948, is centered around a group of O-type stars which ionize the nebula.

The next nebula is the great nebula of Carina!

The next nebula is the incredibly large Gum 12 nebula in constellations Vela, Puppis and Carina. This extremely large nebula may have been cause by a supernova, which compressed a lot of gas and pushed it outwards. The faint red arc above the plane of the Milky Way just above Gum 12 may be connected to Gum 12 and may have been caused by the same supernova. At least that's my guess. This APOD helps you locate various nebulae embedded in the Gum nebula.

There is a faint nebula to the right of the Gum nebula which I don't recognize. However, it appears to be centered on the great Tau Canis Majoris cluster. That makes sense. Tau Canis Majoris is a great O star, and there is another O star, 29 Canis Majoris, located relatively close by. Together these two great O stars would definitely blow out a cavity around themselves and compress the gas they have sent flying into a glowing red ring.

The next nebula is the Seagull Nebula.

Now I'm sure you can see Orion with all its nebulae hanging below the plane of the Milky Way.

The small bright round nebula in the plane of the Milky Way is the Rosette Nebula.

The much fainter nebula to the upper right of the Rosette nebula is the NGC 2264 cluster, with the Cone Nebula and the Christmas Tree cluster. Here you can see a picture of Rosette Nebula on the right and the Cone and Christmas Tree cluster nebula on the left. You can see how much brighter the Rosette Nebula is than the Cone and Christmas Tree cluster nebula. But the latter is surrounded by a large, faint nebula.

Phew! I'm done! But if you bear in mind that I looked up all the obvious nebula in that Milky Way image, you have to admit that the nebulae in the Milky Way are pretty small, few and far between.

Ann
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Re: APOD: NGC 6188 and NGC 6164 (2012 Dec 28)

Postby Ron-Astro Pharmacist » Mon Dec 31, 2012 8:27 pm

A large Muchas Gracias for all of your replies. :) Ron


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