APOD: The Southern Cliff in the Lagoon (2021 May 15)

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APOD: The Southern Cliff in the Lagoon (2021 May 15)

Post by APOD Robot » Sat May 15, 2021 4:07 am

Image The Southern Cliff in the Lagoon

Explanation: Undulating bright ridges and dusty clouds cross this close-up of the nearby star forming region M8, also known as the Lagoon Nebula. A sharp, false-color composite of narrow band visible and broad band near-infrared data from the 8-meter Gemini South Telescope, the entire view spans about 20 light-years through a region of the nebula sometimes called the Southern Cliff. The highly detailed image explores the association of many newborn stars imbedded in the tips of the bright-rimmed clouds and Herbig-Haro objects. Abundant in star-forming regions, Herbig-Haro objects are produced as powerful jets emitted by young stars in the process of formation heat the surrounding clouds of gas and dust. The cosmic Lagoon is found some 5,000 light-years away toward the constellation Sagittarius and the center of our Milky Way Galaxy. (For location and scale, check out this image superimposing the close-up of the Southern Cliff within the larger Lagoon Nebula. The scale image is courtesy R. Barba'.)

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Re: APOD: The Southern Cliff in the Lagoon (2021 May 15)

Post by Ann » Sat May 15, 2021 6:53 am

I expect the people who love mapped color nebula images to do the gushing!

Anyway...

Southern Cliff in the Lagoon Nebula annotated .png
The Lagoon Nebula with the southern cliff annotated in yellow,
and arrowed blue-looking but non-blue star. Image: ESO/VPHAS+ team.

I've posted a picture of the Lagoon Nebula in RGB and shown the Southern Cliff in yellow. A blue arrow points at a star that looks very blue in the APOD, but it is really a non-blue star, HD 164948, of spectral class F8.

Go figure.

Ann
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Re: APOD: The Southern Cliff in the Lagoon (2021 May 15)

Post by heehaw » Sat May 15, 2021 9:40 am

Gush! I love it, Ann!

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Re: APOD: The Southern Cliff in the Lagoon (2021 May 15)

Post by VictorBorun » Sat May 15, 2021 10:46 am

to switch between the two I posted them in Facebook. A dusty lane in the foreground sort of jump at you in the center of the picture when you switch to natural colors.

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Re: APOD: The Southern Cliff in the Lagoon (2021 May 15)

Post by E Fish » Sat May 15, 2021 1:01 pm

I will gush a bit. I love the details that come out in these mapped color images. I know they're not the real colors, but all the ridges and beautiful patterns of the nebulae are so much more obvious in these.

I love the other ones, too, but I'm not too picky on my astronomy pics.

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Re: APOD: The Southern Cliff in the Lagoon (2021 May 15)

Post by Chris Peterson » Sat May 15, 2021 1:30 pm

E Fish wrote:
Sat May 15, 2021 1:01 pm
I will gush a bit. I love the details that come out in these mapped color images. I know they're not the real colors, but all the ridges and beautiful patterns of the nebulae are so much more obvious in these.

I love the other ones, too, but I'm not too picky on my astronomy pics.
There's more to it than just the choice of colors. There's the fact that this is imaged partly in wavelengths that our eyes can't see. If this were in "real colors" much of it would be invisible!
Chris

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Re: APOD: The Southern Cliff in the Lagoon (2021 May 15)

Post by orin stepanek » Sat May 15, 2021 2:19 pm

M8_rim2geminicrop600.jpg

I love the photo; I most confess; to me it looks like rats peeking over
the top! :mrgreen:

M8_rim2geminicrop600.jpg
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Last edited by orin stepanek on Sat May 15, 2021 2:48 pm, edited 1 time in total.
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Re: APOD: The Southern Cliff in the Lagoon (2021 May 15)

Post by De58te » Sat May 15, 2021 2:48 pm

I have a curious question about the object behind the bright star on the right side of the Lagoon Nebula in the comparison photo for scale and location. What is that straight orange line behind the blue star at about 3:00 o'clock? If today's APOD spans about 20 light years then in comparison that straight line must be at least 4 to 5 light years long? I don't think it is star spikes since star spikes are usually the same color as the star. (It doesn't show up in Ann's photo. but her photo does have star spikes. Nowhere near as long though.)

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Re: APOD: The Southern Cliff in the Lagoon (2021 May 15)

Post by Chris Peterson » Sat May 15, 2021 2:54 pm

De58te wrote:
Sat May 15, 2021 2:48 pm
I have a curious question about the object behind the bright star on the right side of the Lagoon Nebula in the comparison photo for scale and location. What is that straight orange line behind the blue star at about 3:00 o'clock? If today's APOD spans about 20 light years then in comparison that straight line must be at least 4 to 5 light years long? I don't think it is star spikes since star spikes are usually the same color as the star. (It doesn't show up in Ann's photo. but her photo does have star spikes. Nowhere near as long though.)
CCD blooming. It's a consequence of how charge spills into adjacent pixels on the sensor. You can see it on other bright stars in the image as well, just not quite as long. The color is determined by which channel (or channels) had blooming.
Chris

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Re: APOD: The Southern Cliff in the Lagoon (2021 May 15)

Post by Guest » Sat May 15, 2021 3:33 pm

Is today's false-color key written about anywhere? I'm curious to know what colors mean what.

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Re: APOD: The Southern Cliff in the Lagoon (2021 May 15)

Post by Chris Peterson » Sat May 15, 2021 3:37 pm

Guest wrote:
Sat May 15, 2021 3:33 pm
Is today's false-color key written about anywhere? I'm curious to know what colors mean what.
It sounds like they mapped H-alpha to red, S II to green, and broadband near IR to blue.
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Re: APOD: The Southern Cliff in the Lagoon (2021 May 15)

Post by Ann » Sat May 15, 2021 5:49 pm

Chris Peterson wrote:
Sat May 15, 2021 3:37 pm
Guest wrote:
Sat May 15, 2021 3:33 pm
Is today's false-color key written about anywhere? I'm curious to know what colors mean what.
It sounds like they mapped H-alpha to red, S II to green, and broadband near IR to blue.
Thanks. It would explain why the most non-blue (and most IR-bright) of the prominent stars in the picture would look the bluest.

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Re: APOD: The Southern Cliff in the Lagoon (2021 May 15)

Post by E Fish » Sun May 16, 2021 2:47 pm

Chris Peterson wrote:
Sat May 15, 2021 1:30 pm
E Fish wrote:
Sat May 15, 2021 1:01 pm
I will gush a bit. I love the details that come out in these mapped color images. I know they're not the real colors, but all the ridges and beautiful patterns of the nebulae are so much more obvious in these.

I love the other ones, too, but I'm not too picky on my astronomy pics.
There's more to it than just the choice of colors. There's the fact that this is imaged partly in wavelengths that our eyes can't see. If this were in "real colors" much of it would be invisible!
Oh, I understand that (although I didn't convey it well :) ). That's what I love about these false colors images. I was just explaining this to one of my friends the other day because she didn't understand how we use x-rays and infrared and all that in astronomy.

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Re: APOD: The Southern Cliff in the Lagoon (2021 May 15)

Post by VictorBorun » Sun May 16, 2021 6:31 pm

Chris Peterson wrote:
Sat May 15, 2021 3:37 pm
It sounds like they mapped H-alpha to red, S II to green, and broadband near IR to blue.
It's incorrect order:

656.28 nm (H-alpha) to red
560.62 nm (S II) to green
1000 nm (broadband near IR) to blue

and it fails to represent the hot/cool stars.
What can we do to mend it?
There are two things we want to present as red: H-alpha and IR
Let's make them red-green (yellow) and red-blue (purple) respectively.
And make S II green-blue (cyan). Here:

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Re: APOD: The Southern Cliff in the Lagoon (2021 May 15)

Post by Chris Peterson » Sun May 16, 2021 7:58 pm

VictorBorun wrote:
Sun May 16, 2021 6:31 pm
Chris Peterson wrote:
Sat May 15, 2021 3:37 pm
It sounds like they mapped H-alpha to red, S II to green, and broadband near IR to blue.
It's incorrect order:

656.28 nm (H-alpha) to red
560.62 nm (S II) to green
1000 nm (broadband near IR) to blue

and it fails to represent the hot/cool stars.
What can we do to mend it?
There are two things we want to present as red: H-alpha and IR
Let's make them red-green (yellow) and red-blue (purple) respectively.
And make S II green-blue (cyan).
There is, however, more to choosing a false color palette than simply ordering the wavelengths. Personally, I find the mapping that was used to present more information to my eyes than the one you suggest.
Chris

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Re: APOD: The Southern Cliff in the Lagoon (2021 May 15)

Post by VictorBorun » Mon May 17, 2021 6:33 am

I wanted too much.
If we have just one goal, the correct order, we must map:
1000 nm (broadband near IR) to blue -----> to red
656.28 nm (H-alpha) to red-----------------> to green
560.62 nm (S II) to green-------------------> to blue

All we have to do is shift the "hue" of the posted RGB picture by +120° [/img2]

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Re: APOD: The Southern Cliff in the Lagoon (2021 May 15)

Post by VictorBorun » Mon May 17, 2021 12:25 pm

but an interactive multy-wavelength viewer would be better.
Like Jupiter in IR and visible or in visible and UV

Have seen here