APOD: M8: The Lagoon Nebula (2013 Aug 17)

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APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by APOD Robot » Sat Aug 17, 2013 4:09 am

Image M8: The Lagoon Nebula

Explanation: This beautiful cosmic cloud is a popular stop on telescopic tours of the constellation Sagittarius. Eighteenth century cosmic tourist Charles Messier cataloged the bright nebula as M8. Modern day astronomers recognize the Lagoon Nebula as an active stellar nursery about 5,000 light-years distant, in the direction of the center of our Milky Way Galaxy. Hot stars in the embedded open star cluster NGC 6530 power the nebular glow. Remarkable features can be traced through this sharp picture, showing off the Lagoon's filaments of glowing gas and dark dust clouds. Twisting near the center of the Lagoon, the small, bright hourglass shape is the turbulent result of extreme stellar winds and intense starlight. The alluring color view was captured with a telescope and digital camera while M8 was high in dark, rural Argentina skies. At the nebula's estimated distance, the picture spans over 60 light-years.

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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by Ann » Sat Aug 17, 2013 7:34 am

This is a very beautiful picture of a much-photographed object.

I checked out the imaging data of the picture and was a bit confused. As far as I could understand, today's APOD is not an RGB image, photographed through red, green and blue filters. It is also not an image which has been enhanced with extra Ha data. I would assume, therefore, that this is an image whose colors do not depend on filters. Clearly it is not a mapped color image, either. The colors in this image are unusually delicate.

The Lagoon Nebula shows a progression of star formation going from left to right. Clearly the youngest object here is the star illuminating the Hourglass Nebula, the small bright whitish object at center right. To the left of the Hourglass Nebula is a bright blue star, 9 Sagittarius, the brightest star inside the Lagoon Nebula. (The bright yellow-white star at two o'clock is a foreground object.) Blue 9 Sagittarius is a very hot and bright O-type star. Today's APOD shows that 9 Sgr interacts with the gas and dust in the Lagoon Nebula: there is a suggestion of a cavity around the star, and the dust in its vicinity has a bluish tinge. This probably means that the star is in the process of blowing the gas and dust away from itself with its strong stellar wind, but there is still dust not too far from it. This dust faintly reflects the star's blue light, creating a faint blue reflection nebula mixed with the larger nebula's overall red Ha light. 9 Sagittarius appears to be at a similar evolutionary stage as S Monocerotis.

To me, the long curving dust lane that gives the Lagoon Nebula its name can be thought of as partly created by 9 Sagittarius. But there are bright stars on the other side of that prominent dust lane, too. There is a slight similarity between this dust lane dividing groups of bright stars in the Lagoon Nebula and the dust lane dividing groups of bright stars in IC 1805.

The group of stars on the other side of the dust lane in the Lagoon Nebula belong to cluster NGC 6530. These stars don't seem to interact with the nebulosity of the Lagoon Nebula in the same way as 9 Sagittarius, although the curving red ridge below the cluster may have something to do with these stars. At least some of that red ridge may have been created by 9 Sagittarius and the star in the Hourglass Nebula, however. There is a light-colored "extension downward" of the dark dust lane of the Lagoon Nebula, and this light-colored extension may well have been created by 9 Sagittarius but not by cluster NGC 6530. In other words: the stars of NGC 6530 are older than 9 Sagittarius, and 9 Sagittarius is older than the star in the Hourglass Nebula.

We are watching star formation in progress.

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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by saturno2 » Sat Aug 17, 2013 10:36 am

This image is very interesting

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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by neufer » Sat Aug 17, 2013 11:32 am

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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by ignacio_db » Sat Aug 17, 2013 11:35 am

Ann wrote:This is a very beautiful picture of a much-photographed object.

I checked out the imaging data of the picture and was a bit confused. As far as I could understand, today's APOD is not an RGB image, photographed through red, green and blue filters. It is also not an image which has been enhanced with extra Ha data. I would assume, therefore, that this is an image whose colors do not depend on filters. Clearly it is not a mapped color image, either. The colors in this image are unusually delicate.

Ann
Hi Ann,
Just to clarify, this is an RGB image, taken with a standard digital reflex camera with its IR filter removed (so that H-alfa radiaton gets thru). It is a one-shot-color camera, that uses a Bayer matrix filter to sample RGB colors in each exposure. The stacked image in its linear form was color balanced, so that the combined or average radiation of all stars in the field looks white.

Thanks for your interesting note.

Regards,
Ignacio

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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by orin stepanek » Sat Aug 17, 2013 11:49 am

I always like the Lagoon Nebula! 8-) :D
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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by Galaxian » Sat Aug 17, 2013 1:28 pm

APOD Robot wrote: Twisting near the center of the Lagoon, the small, bright hourglass shape is the turbulent result of extreme stellar winds and intense starlight.

"Hourglass shape"? I can see a dark, demented, rabid meerkat off to the right and a dark sidewinder to left of centre but no hourglass. Is my pareidolonics broken again?
APOD Robot wrote: The alluring color view was captured with a telescope and digital camera while M8 was high in dark, rural Argentina skies. At the nebula's estimated distance, the picture spans over 60 light-years.]
It's a truly lovely image, very beautifully done, but at 60 LYs across I doubt if it would be visible to the human eye if we could even get closer [to do which, we need starships, of course]. Too vast, too faint, not enough colour photons per square radian. Does anyone know if I'm right in thinking that, like a thin mist on Earth, this is one of those things best seen from a vast distance and quite undetectable if you lived inside it?

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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by Galaxian » Sat Aug 17, 2013 1:29 pm


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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by Adolfo Domínguez » Sat Aug 17, 2013 7:49 pm

It's really a interesting image what you've posted. But, what means this image slipping to right and left?

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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by Chris Peterson » Sat Aug 17, 2013 8:00 pm

Adolfo Domínguez wrote:It's really a interesting image what you've posted. But, what means this image slipping to right and left?
The image is a fantasy. It is misleading, and IMO doesn't belong in a science forum like this without a good deal of qualification. It was created by inventing a 3D structure that doesn't represent reality, and mapping an astroimage into it. The result gives a sense of what the 3D structure of a nebula might look like, but does not represent the physical reality of this particular nebula at all.

We can't generate a true 3D image of a structure like this because we only observe it from a single viewpoint, and we have only limited and crude information about the distance to any part of it, or its surrounds.
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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by Ann » Sat Aug 17, 2013 8:16 pm

Image
Galaxian wrote:
APOD Robot wrote: Twisting near the center of the Lagoon, the small, bright hourglass shape is the turbulent result of extreme stellar winds and intense starlight.

"Hourglass shape"? I can see a dark, demented, rabid meerkat off to the right and a dark sidewinder to left of centre but no hourglass. Is my pareidolonics broken again?


The Hourglass Nebula is the brightest part of the Lagoon Nebula. It shows up well in this Anglo-Australian Observatory photo. A Hubble picture of the Hourglass Nebula can be seen here.
Galaxian wrote:
APOD Robot wrote: The alluring color view was captured with a telescope and digital camera while M8 was high in dark, rural Argentina skies. At the nebula's estimated distance, the picture spans over 60 light-years.]
It's a truly lovely image, very beautifully done, but at 60 LYs across I doubt if it would be visible to the human eye if we could even get closer [to do which, we need starships, of course]. Too vast, too faint, not enough colour photons per square radian. Does anyone know if I'm right in thinking that, like a thin mist on Earth, this is one of those things best seen from a vast distance and quite undetectable if you lived inside it?
I'm sure you are right that we wouldn't see much (or any) of the nebulosity if we lived inside the Lagoon Nebula. Oh, correction: I think we might see parts of the Hourglass Nebula. Though perhaps we would have to look at it the same way as we look at the solar corona: by blotting out the brilliant disk of the star which is creating the nebula.

I think it would be quite unhealthy to live inside the Lagoon Nebula. All those hot stars ionizing the Nebula would produce would produce a lot of nasty radiation. And one of those stars could just pop one day as a supernova.

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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by Chris Peterson » Sat Aug 17, 2013 9:02 pm

Ann wrote:It's a truly lovely image, very beautifully done, but at 60 LYs across I doubt if it would be visible to the human eye if we could even get closer [to do which, we need starships, of course]. Too vast, too faint, not enough colour photons per square radian. Does anyone know if I'm right in thinking that, like a thin mist on Earth, this is one of those things best seen from a vast distance and quite undetectable if you lived inside it?
The brightness doesn't change with distance. So if you were inside this nebula, you'd see what you see visually through a telescope- a faint gray background. From some distance, you can see shape and structure, since there is contrast against areas without it. From inside, it would simply present as a faint gray glow that pervades the sky. Depending on your location inside, you might see a bit of structure, but it would be very broad and subtle, like some of the variation we see in the Milky Way.
Chris

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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by neufer » Sun Aug 18, 2013 12:17 am

Chris Peterson wrote:
Adolfo Domínguez wrote:
It's really a interesting image what you've posted. But, what means this image slipping to right and left?
The image is a fantasy. It is misleading, and IMO doesn't belong in a science forum like this without a good deal of qualification. It was created by inventing a 3D structure that doesn't represent reality, and mapping an astroimage into it. The result gives a sense of what the 3D structure of a nebula might look like, but does not represent the physical reality of this particular nebula at all. We can't generate a true 3D image of a structure like this because we only observe it from a single viewpoint, and we have only limited and crude information about the distance to any part of it, or its surrounds.
  • Actually, the CIA has just released this photo from Area 51.

    "That which we do not understand sometimes causes apprehension."
http://en.wikipedia.org/wiki/Science_Fiction_Theatre wrote:
Science Fiction Theatre, December 31, 1955 : Are We Invaded?

<<"That which we do not understand sometimes causes apprehension." A reporter and the daughter of a respected astronomer, watching the stars one evening from their parked car, see what they consider a flying saucer. A stranger appears at the door of the car saying he too saw the light in the sky, and asks if he can be given a lift down the hill into town. Later, the astronomer refuses to believe the couple saw anything more than an optical illusion. To prove the existence of UFOs, the reporter films a documentary of witnesses, while the astronomer promptly demonstrates scientific explanations for each witness's sightings. But the mysterious stranger has dropped off a photograph at the astronomer's lab- a photograph of our solar system taken from deep space. The stranger has disappeared, but left a forwarding address: Alpha Centauri, 4.5 light years from Earth.>>
Art Neuendorffer

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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by Billsey » Sun Aug 18, 2013 12:46 am

I regard it as unfortunate that this nebula already has a popular name, because in this image, to me, it looks for all the world like a tunnel rather than a lagoon.

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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by orin stepanek » Sun Aug 18, 2013 1:17 am

Billsey wrote:I regard it as unfortunate that this nebula already has a popular name, because in this image, to me, it looks for all the world like a tunnel rather than a lagoon.
Tunnel?
:?: Lagoon? To me Lagoon fits quite nicely! 8-)
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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by Boomer12k » Sun Aug 18, 2013 1:52 am

Always beautiful, like a large, open, Clam Shell....

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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by Galaxian » Sun Aug 18, 2013 1:06 pm

Ann wrote: The Hourglass Nebula is the brightest part of the Lagoon Nebula. It shows up well in this Anglo-Australian Observatory photo. A Hubble picture of the Hourglass Nebula can be seen here.
Galaxian wrote:
APOD Robot wrote: The alluring color view was captured with a telescope and digital camera while M8 was high in dark, rural Argentina skies. At the nebula's estimated distance, the picture spans over 60 light-years.]
It's a truly lovely image, very beautifully done, but at 60 LYs across I doubt if it would be visible to the human eye if we could even get closer [to do which, we need starships, of course]. Too vast, too faint, not enough colour photons per square radian. Does anyone know if I'm right in thinking that, like a thin mist on Earth, this is one of those things best seen from a vast distance and quite undetectable if you lived inside it?
I'm sure you are right that we wouldn't see much (or any) of the nebulosity if we lived inside the Lagoon Nebula. Oh, correction: I think we might see parts of the Hourglass Nebula. Though perhaps we would have to look at it the same way as we look at the solar corona: by blotting out the brilliant disk of the star which is creating the nebula.

I think it would be quite unhealthy to live inside the Lagoon Nebula. All those hot stars ionizing the Nebula would produce would produce a lot of nasty radiation. And one of those stars could just pop one day as a supernova.

Ann

Hmmm, thank you, but still no "hourglass". The brightest patch looks like an angelic lady in the image you posted from AAO and like Jodrell Bank or Parks radio telescope in the Hubbley image. It's lovely, but it's not symmetrical enough to be a timepiece.

I'm not so sure it would be unhealthy to live in the Lagoon, or even on Io or in the accretion disk of a magnetar. Like the life that got pushed into living near black smokers I suspect that anything that evolved there would think our calm, placid, weakly irradiated space is unsurvivable. Life adapts. It's like the theoretical Martian microbes, if there ever were any they would have survived Mars changing and the planet would be lousy with them.
Were there alien bugs on a world in the smoke at the glowing core of the Lagoon at least some of them would evolve to eat hard radiation somehow. Cadmium-protein complexes in their midicloriens?
Anyway, I still think my pareidolonics are out of alignment. Thank you for trying.

[Edited to correct sources of images, sorry.]

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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by Chris Peterson » Sun Aug 18, 2013 2:01 pm

Galaxian wrote:I'm not so sure it would be unhealthy to live in the Lagoon, or even on Io or in the accretion disk of a magnetar. Like the life that got pushed into living near black smokers I suspect that anything that evolved there would think our calm, placid, weakly irradiated space is unsurvivable. Life adapts.
Life adapts, but it takes time, and it probably requires that change doesn't happen too fast. I don't think the radiation environment in general would make a place like the Lagoon inhospitable to life. But the supernova problem that Ann refers to probably is a big problem. Having a number of stars quite close to each other is also a problem, because it's likely to make planetary systems unstable.

In an environment like the Lagoon, I can easily imagine life developing. But I don't think you'll have planetary systems stable enough, or a space environment stable enough, to allow the necessary time for it to evolve to anything very complex before it gets toasted or frozen.
Chris

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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by neufer » Sun Aug 18, 2013 2:20 pm

Galaxian wrote:
I'm not so sure it would be unhealthy to live in the Lagoon, or even on Io or in the accretion disk of a magnetar. Like the life that got pushed into living near black smokers I suspect that anything that evolved there would think our calm, placid, weakly irradiated space is unsurvivable. Life adapts.
Click to play embedded YouTube video.
Chris Peterson wrote:
Life adapts, but it takes time, and it probably requires that change doesn't happen too fast. I don't think the radiation environment in general would make a place like the Lagoon inhospitable to life. But the supernova problem that Ann refers to probably is a big problem. Having a number of stars quite close to each other is also a problem, because it's likely to make planetary systems unstable.

In an environment like the Lagoon, I can easily imagine life developing. But I don't think you'll have planetary systems stable enough, or a space environment stable enough, to allow the necessary time for it to evolve to anything very complex before it gets toasted or frozen.
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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by DavidLeodis » Sun Aug 18, 2013 5:39 pm

It is a very nice image. :)

As I like to know the date when an image was taken I found that in the information brought up through the "The alluring color view" link it stated 2013-07-05, which (based on dates with other images in the website) will be 2013 July 5. However, in the image's Exif information it stated the create date (which I assume is the date it was taken) was August 7 2013. I wonder therefore which is the correct date when it was taken :?:

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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by Chris Peterson » Sun Aug 18, 2013 5:51 pm

DavidLeodis wrote:It is a very nice image. :)

As I like to know the date when an image was taken I found that in the information brought up through the "The alluring color view" link it stated 2013-07-05, which (based on dates with other images in the website) will be 2013 July 5. However, in the image's Exif information it stated the create date (which I assume is the date it was taken) was August 7 2013. I wonder therefore which is the correct date when it was taken :?:
Given that this isn't a single image, but a stack made from raw images that don't even include EXIF data in the first place, I'd be inclined to use the information on the imager's website for the date, and assume whatever is in the EXIF of the released JPEG is related to the processing software, not the camera.
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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by ignacio_db » Sun Aug 18, 2013 6:08 pm

Chris Peterson wrote:
DavidLeodis wrote:It is a very nice image. :)

As I like to know the date when an image was taken I found that in the information brought up through the "The alluring color view" link it stated 2013-07-05, which (based on dates with other images in the website) will be 2013 July 5. However, in the image's Exif information it stated the create date (which I assume is the date it was taken) was August 7 2013. I wonder therefore which is the correct date when it was taken :?:
Given that this isn't a single image, but a stack made from raw images that don't even include EXIF data in the first place, I'd be inclined to use the information on the imager's website for the date, and assume whatever is in the EXIF of the released JPEG is related to the processing software, not the camera.
That is exactly right. Thanks for pointing it out. The EXIF data marks the date the processed final image was created for publication. It's done automatically by the processing software used, and never paid too much attention to it. Sorry for the confusion.

Ignacio

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Re: APOD: M8: The Lagoon Nebula (2013 Aug 17)

Post by DavidLeodis » Sun Aug 18, 2013 6:16 pm

Thanks Chris and Ignacio. Your help is much appreciated. :)