Starship Asterisk*

IC 1805: Light from the Heart

Explanation: Sprawling across almost 200 light-years, emission nebula IC 1805 is a mix of glowing interstellar gas and dark dust clouds about 7,500 light-years away in the Perseus spiral arm of our galaxy. Stars were born in this region whose nickname, the Heart Nebula, derives from its Valentine's-Day-appropriate shape. The clouds themselves are shaped by stellar winds and radiation from massive hot stars in the nebula's newborn star cluster Melotte 15 about 1.5 million years young. This deep telescopic image maps the pervasive light of narrow emission lines from atoms in the nebula to a color palette made popular in Hubble images of star forming regions. The field of view spans about two degrees on the sky or four times the diameter of a full moon. The cosmic heart is found in the constellation of Cassiopeia, the boastful mythical Queen of Aethiopia .

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Heart of the heart....a lovely depiction.


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This was a predictable choice for today. I think an image of colliding (or merging) galaxies would also be appropriate.

Todays APOD is an appropriate one for Valentines Day!

Compare today’s sharp view of the core of the Heart nebula with the wider view of the Heart and Soul nebulas of a few days back: http://apod.nasa.gov/apod/ap140211.html

Note how much more detail pops out from today’s view. Now pick any interesting detail you like from today’s image, and imagine being able to zoom in to see it with a like improvement in detail. There are now a few truly massive telescopes in the works that should make this possible, such as the TMT (Thirty Meter Telescope).

This illustrates why aperture fever is incurable. The desire for bigger and better telescopes is boundless.

Bruce

I love the fiddly bits. All hail Slartabartfast.

BDanielMayfield wrote:Compare today’s sharp view of the core of the Heart nebula with the wider view of the Heart and Soul nebulas of a few days back: http://apod.nasa.gov/apod/ap140211.html

Note how much more detail pops out from today’s view. Now pick any interesting detail you like from today’s image, and imagine being able to zoom in to see it with a like improvement in detail. There are now a few truly massive telescopes in the works that should make this possible, such as the TMT (Thirty Meter Telescope).

This illustrates why aperture fever is incurable. The desire for bigger and better telescopes is boundless.

Well, to a degree. But beyond a certain point- and it's not very large (well under a meter), aperture isn't usually about higher resolution, but about greater light collecting ability. The TMT isn't going to provide any higher resolution for wide angle shots than amateurs are getting every day. Large telescopes in space can do that, but not on the ground. Future images made from the ground won't be any more zoomable than existing images.

Beautiful image for those who celebrate the festivity(there are those who don't celebrate it, like myself, for having a pagan origin with a beginning in a pre-Roman celebration call it 'Lupercalia') but something that interested me was the link 'spiral arm' that explain the theory of the two spiral arms of our galaxy. I call it theory because, I think, the truth is that to know exactly how is our galaxy, first we should be out of it to view it from the outside. And I'm afraid that this will take a long time to achieve.

Chris Peterson wrote:Well, to a degree. But beyond a certain point- and it's not very large (well under a meter), aperture isn't usually about higher resolution, but about greater light collecting ability. The TMT isn't going to provide any higher resolution for wide angle shots than amateurs are getting every day. Large telescopes in space can do that, but not on the ground. Future images made from the ground won't be any more zoomable than existing images.

So, in your estimation, adaptive optics technology isn't going to improve?

jsanchezjr wrote:Beautiful image for those who celebrate the festivity(there are those who don't celebrate it, like myself, for having a pagan origin with a beginning in a pre-Roman celebration call it 'Lupercalia') but something that interested me was the link 'spiral arm' that explain the theory of the two spiral arms of our galaxy. I call it theory because, I think, the truth is that to know exactly how is our galaxy, first we should be out of it to view it from the outside. And I'm afraid that this will take a long time to achieve.

While it's truly a theory, it's one which is very well supported by observational evidence. You don't have to outside the galaxy to make excellent measurements of its structure. With radio and IR we can see great distances, and there are methods of estimating the distance to stars and other structures. If you know the coordinates and the distance, you can make a structural model.

That the Milky Way is a spiral galaxy is known beyond reasonable doubt. The details still being worked out have to do with whether there are two or four arms, whether there's a bar, and the like. These things can be tricky to decide even when looking at other galaxies.

Chris Peterson wrote:

jsanchezjr wrote:Beautiful image for those who celebrate the festivity(there are those who don't celebrate it, like myself, for having a pagan origin with a beginning in a pre-Roman celebration call it 'Lupercalia') but something that interested me was the link 'spiral arm' that explain the theory of the two spiral arms of our galaxy. I call it theory because, I think, the truth is that to know exactly how is our galaxy, first we should be out of it to view it from the outside. And I'm afraid that this will take a long time to achieve.

While it's truly a theory, it's one which is very well supported by observational evidence. You don't have to outside the galaxy to make excellent measurements of its structure. With radio and IR we can see great distances, and there are methods of estimating the distance to stars and other structures. If you know the coordinates and the distance, you can make a structural model.

That the Milky Way is a spiral galaxy is known beyond reasonable doubt. The details still being worked out have to do with whether there are two or four arms, whether there's a bar, and the like. These things can be tricky to decide even when looking at other galaxies.

Thanks for clarifying this points, this is very interesting for me. And totally agree that our milky way is a spiral galaxy. Also I understand that looking on the structure, composition and size of others galaxies that behave like our milky way allows a very accurate idea of how is our galaxy(correct me if I'm wrong). Only, I think, that in the same way we could certify without a doubt how is our planet when seen from space for the first time, we also know without a doubt how is our galaxy when we can watched from the outside, sure, if ever possible.

jsanchezjr wrote:.... we also know without a doubt how is our galaxy when we can watched from the outside, sure, if ever possible.

Yes, we are awaiting the return of V'ger to confirm this.

FloridaMike wrote:

jsanchezjr wrote:.... we also know without a doubt how is our galaxy when we can watched from the outside, sure, if ever possible.

Yes, we are awaiting the return of V'ger to confirm this.

I don’t think I’ll wait up for that to happen, but I’ll leave a light on anyway.

Mactavish wrote:

FloridaMike wrote:

jsanchezjr wrote:.... we also know without a doubt how is our galaxy when we can watched from the outside, sure, if ever possible.

Yes, we are awaiting the return of V'ger to confirm this.

I don’t think I’ll wait up for that to happen, but I’ll leave a light on anyway.

At least then, we'd be safe from the Klingons.

The heart appears wounded. Is there an Arrow Nebula in the neighborhood? Happy Valentines Day!!

The more pictures of nebulae I see in shades of brown, the more I like that palette. Somehow I find it easier to see depth and structure in brown clouds than pink clouds. (And I don't know if I could stomach a pink apod on Valentine's day! )

Anthony Barreiro wrote:The more pictures of nebulae I see in shades of brown, the more I like that palette. Somehow I find it easier to see depth and structure in brown clouds than pink clouds. (And I don't know if I could stomach a pink apod on Valentine's day! )

That's because it takes all three color channels to create brown, which means you've got more photons being sent to your eyes. It's much brighter than red alone, which requires green and blue to be significantly subdued to look vibrant and red. Despite being darker, red tends to be more eye-catching. It's an aesthetic trade-off either way.

geckzilla wrote:

Anthony Barreiro wrote:The more pictures of nebulae I see in shades of brown, the more I like that palette. Somehow I find it easier to see depth and structure in brown clouds than pink clouds. (And I don't know if I could stomach a pink apod on Valentine's day! :lol2: )

That's because it takes all three color channels to create brown, which means you've got more photons being sent to your eyes. It's much brighter than red alone, which requires green and blue to be significantly subdued to look vibrant and red. Despite being darker, red tends to be more eye-catching. It's an aesthetic trade-off either way.

I'd say brown requires two channels- red and green. Brown is low intensity orange, so you have about twice as much red as green, and no blue.

Low to middle saturation reds and pinks tend to use high levels of all three primaries. In most cases, you have more photons coming off the screen with pink than brown.

I think the greater apparent dynamic range has more to do with how the light and dark points are set with browns than with absolute intensity.

geckzilla wrote:

Anthony Barreiro wrote:The more pictures of nebulae I see in shades of brown, the more I like that palette. Somehow I find it easier to see depth and structure in brown clouds than pink clouds. (And I don't know if I could stomach a pink apod on Valentine's day! )

That's because it takes all three color channels to create brown, which means you've got more photons being sent to your eyes. It's much brighter than red alone, which requires green and blue to be significantly subdued to look vibrant and red. Despite being darker, red tends to be more eye-catching. It's an aesthetic trade-off either way.

Thanks. Brown usually seems darker than red. I know, I should process some astronomical images and then I'll realize how completely ignorant I am about cumulative photon flux and other such elementary phenomena!

Chris Peterson wrote:I'd say brown requires two channels- red and green. Brown is low intensity orange, so you have about twice as much red as green, and no blue.

I wonder if that's why the blue reflection nebulae stand out in clear contrast in this image?

Chris Peterson wrote:Low to middle saturation reds and pinks tend to use high levels of all three primaries. In most cases, you have more photons coming off the screen with pink than brown.

I think the greater apparent dynamic range has more to do with how the light and dark points are set with browns than with absolute intensity.

I don't have a clue what this means, and that's okay. You all keep making the pretty pictures and I'll keep looking at them.

Chris Peterson wrote:I'd say brown requires two channels- red and green. Brown is low intensity orange, so you have about twice as much red as green, and no blue.

How do you propose to bring the intensity of that orange down without blue?

geckzilla wrote:

Chris Peterson wrote:I'd say brown requires two channels- red and green. Brown is low intensity orange, so you have about twice as much red as green, and no blue.

How do you propose to bring the intensity of that orange down without blue?

By reducing the intensity of the red and green. How does adding blue turn orange into brown? That will shift the hue on an axis between orange and a sort of magenta.

Saturated orange: 255, 128, 0
Brown: 128, 64, 0

If you want a less saturated brown you could start increasing the blue, but you'd need to increase the green also, with the limit (complete desaturation) having all three channels at 128.

You can completely turn off the blue channel in today's image and most of the colors only shift a little. Try that with the red or green channels, though, and the result is radical. Or sample the colors in the brown areas of the image. Not much blue in there.

Your definition is fine for the dark areas but at medium and lighter values brown (or tan, if you prefer) is no longer brown without blue. It's not crucial in some sense but it's necessary for natural looking browns and other subtle variations. Turning off the blue channel shifts it terribly yellow as one would expect so I disagree with you on that last statement.

geckzilla wrote:Your definition is fine for the dark areas but at medium and lighter values brown (or tan, if you prefer) is no longer brown without blue. It's not crucial in some sense but it's necessary for natural looking browns and other subtle variations. Turning off the blue channel shifts it terribly yellow as one would expect so I disagree with you on that last statement.

True, but the light areas are substantially unsaturated. They're similar in color and intensity to what we'd see with a redder palette, as well. At that point color is just a cast. The brightest areas in any image tend to be white.

That's what brown traditionally is, though. It's a special name we have for a desaturated zone of red and orange. It's the only desaturated color we have that is considered discreet. All others are recognized as pastel or drab versions of their saturated basic colors. It's very interesting to me that this happened. If you explain this to someone unfamiliar with color they will be incredulous that brown is related to red or orange at all.

I agree your 128,64,0 brown is brown but it is an exceptional and mathematically ideal state of brown that is at once saturated and yet still looks brown even against a black background instead of dark orange or dark yellow.