APOD: The Tadpoles of IC 410 (2014 Jan 09)

[APOD Robot]

The Tadpoles of IC 410

Explanation: This telescopic close-up shows off the otherwise faint emission nebula IC 410 in striking false-colors. It also features two remarkable inhabitants of the cosmic pond of gas and dust below and right of center, the tadpoles of IC 410. The picture is a composite of images taken through narrow band filters. The narrow band image data traces atoms in the nebula, with emission from sulfur atoms in red, hydrogen atoms in green, and oxygen in blue. Partly obscured by foreground dust, the nebula itself surrounds NGC 1893, a young galactic cluster of stars that energizes the glowing gas. Composed of denser cooler gas and dust the tadpoles are around 10 light-years long, potentially sites of ongoing star formation. Sculpted by wind and radiation from the cluster stars, their tails trail away from the cluster's central region. IC 410 lies some 12,000 light-years away, toward the constellation Auriga.

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[Nitpicker]

That's beautiful. It took me a while to get the orientation of this image (which for some reason I am always compelled to do). The tadpoles are very close to the backside of the galactic plane. They appear to be swimming south in galactic terms, or south-west in celestial terms. Looking back towards the galactic centre from there, I imagine we form part of a nice bit of foreground fluff, obscuring the view in some aesthetic way.

[tc3]

the tad poles are a nice part of this nebula ... but what I am most impressed with in the picture is near bottom left of center - a part of the nebula that looks like a twisted rope. Wondered if that section had been given a name like the tadpoles?

[Boomer12k]

Wonderful image...nice and sharp....Martin ROCKS!!!


I always go....."OXYGEN?!?!?!?!?"

Because oxygen is not something I always associate with a nebula....According to some science shows....OUR oxygen came about from bacteria releasing oxygen and took a very long time to build up....I wonder how much of the oxygen in the beginning was actually from Stellar forces, and like this, a nebula, when the Solar System began.... Probably none....but it is an interesting thought...as pretty much everything else we have here appears to come from Space....

:---[===] *

[Ann]

Oxygen, in fact, is formed in stars (and even in supernovae, I think). But our dear old Earthly O₂, which we breathe, is formed by green plants through photosynthesis. But those tadpoles don't get to breathe any of that. Lucky us, though!

Ann

[Chris Peterson]

Oxygen, in fact, is formed in stars (and even in supernovae, I think). But our dear old Earthly O₂, which we breathe, is formed by green plants through photosynthesis. But those tadpoles don't get to breathe any of that. Lucky us, though!

That's a somewhat confusing statement, with the word "form" being used in two different ways.

Oxygen is primarily created in the CNO hydrogen/helium fusion process. Some rarer isotopes are created in more energetic processes like supernovas.

Plants, of course, don't create oxygen at all, but separate it from CO₂ in the photosynthesis process, releasing free O₂. O₂ is the only highly stable molecule of oxygen, and it can certainly be produced by non-biological processes, as well.

[neufer]

Oxygen, in fact, is formed in stars (and even in supernovae, I think). But our dear old Earthly O₂, which we breathe, is formed by green plants through photosynthesis. But those tadpoles don't get to breathe any of that. Lucky us, though!

That's a somewhat confusing statement, with the word "form" being used in two different ways.
Oxygen is primarily created in the CNO hydrogen/helium fusion process.

The CNO hydrogen/helium fusion process mostly produces unstable oxygen isotopes
(or stable oxygen isotopes that quickly burn into fluorine by fusing with hydrogen).

Stable oxygen isotopes are primarily a byproduct of the triple-alpha process helium/carbon fusion process:

---

<<The triple-alpha process is a set of nuclear fusion reactions by which three helium-4 nuclei (alpha particles) are transformed into carbon.

Older stars start to accumulate helium produced by the proton–proton chain reaction and the carbon–nitrogen–oxygen cycle in their cores. The products of further nuclear fusion reactions of helium with hydrogen or another helium nucleus produce lithium-5 and beryllium-8 respectively, both of which are highly unstable and decay almost instantly back into smaller nuclei. When the star starts to run out of hydrogen to fuse, the core of the star begins to collapse until the central temperature rises to 108 K (8.6 keV). At this point helium nuclei are fusing together faster than their product, beryllium-8, decays back into two helium nuclei.

Once beryllium-8 is produced a little faster than it decays, the number of beryllium-8 nuclei in the stellar core increases to a large number. Then in its core there will be many beryllium-8 nuclei that can fuse with another helium nucleus to form carbon-12, which is stable:

Because the triple-alpha process is unlikely, it needs a long time to produce much carbon. One consequence of this is that no significant amount of carbon was produced in the Big Bang because within minutes after the Big Bang, the temperature fell below that necessary for nuclear fusion.

Ordinarily, the probability of the triple alpha process is extremely small. However, the beryllium-8 ground state has almost exactly the energy of two alpha particles. In the second step, 8Be + 4He has almost exactly the energy of an excited state of 12C. These resonances greatly increase the probability that an incoming alpha particle will combine with beryllium-8 to form carbon. The existence of this resonance was predicted by Fred Hoyle before its actual observation, based on the physical necessity for it to exist, in order for carbon to be formed in stars. In turn, prediction and then discovery of this energy resonance and process gave very significant support to Hoyle's hypothesis of stellar nucleosynthesis, which posited that all chemical elements had originally been formed from hydrogen, the true primordial substance.

As a side effect of the process, some carbon nuclei can fuse with additional helium to produce a stable isotope of oxygen and release energy:

• ¹²C + ⁴He → ¹⁶O + γ (+7.162 MeV)

This creates a situation in which stellar nucleosynthesis produces large amounts of carbon and oxygen but only a small fraction of these elements is converted into neon and heavier elements. Both oxygen and carbon make up the 'ash' of helium-4 burning. The anthropic principle has been controversially cited to explain the fact that nuclear resonances are sensitively arranged to create large amounts of carbon and oxygen in the Universe.

Fusion processes produce nuclides only up to nickel-56 (which decays later to iron); heavier elements (those beyond Ni) are created mainly by neutron capture. The slow capture of neutrons, the s-process, produces about half of these heavy elements. The other half are produced by rapid neutron capture, the r-process, which probably occurs in a core-collapse supernova.>>

[Ann]

Thanks for setting me straight, Chris.

Ann

[Chris Peterson]

Thanks for putting me straight, Chris.

I'm pretty sure you already knew that plants don't create oxygen! Just a matter of word choice. I wish I spoke Swedish as well as you do English.

[Chris Peterson]

The CNO hydrogen/helium fusion process mostly produces unstable oxygen isotopes
(or stable oxygen isotopes that quickly burn into fluorine by fusing with hydrogen).

Fair enough. The important point, however, remains the same: oxygen is created by nuclear processes, and converted to various molecular forms by chemical processes.

[MarkBour]

Tadpoles are amphibians. That's why this discussion is all about how they get oxygen.

If I understand the APOD's intro description, then the blue I am seeing all over the image is from oxygen being very prevalent in this area? I don't see any green and very little red. That confuses me, because I thought there'd be lots of hydrogen about. Is there something I'm not understanding here?

[neufer]

If I understand the APOD's intro description, then the blue I am seeing all over the image is from oxygen being very prevalent in this area? I don't see any green and very little red. That confuses me, because I thought there'd be lots of hydrogen about. Is there something I'm not understanding here?

The green blends in with the blue and is more noticeable in the bigger picture.

[Beyond]

Why is it that one always has to be able to see the bigger picture, before one can understand something of what one normally sees

[Boomer12k]

Why is it that one always has to be able to see the bigger picture, before one can understand something of what one normally sees

So a person "sees" things in the proper context....without which you would not have as complete, or clear, understanding of the small part you are focusing on....

:---[===] *

[Beyond]

Why is it that one always has to be able to see the bigger picture, before one can understand something of what one normally sees

So a person "sees" things in the proper context....without which you would not have as complete, or clear, understanding of the small part you are focusing on....

:---[===] *

Actually, that was a rhetorical question. ... So, what is the proper context in which to see the universe and all that is in it? Is the universe all that there is... anywhere, ... or perhaps just an itty-bitty part of something bigger, like say, a cell is to a human body, important, but lost in the crowd.

[Ann]

Tadpoles are amphibians. That's why this discussion is all about how they get oxygen.

If I understand the APOD's intro description, then the blue I am seeing all over the image is from oxygen being very prevalent in this area? I don't see any green and very little red. That confuses me, because I thought there'd be lots of hydrogen about. Is there something I'm not understanding here?

In an RGB image, the entire "pond" of IC 410 would be red from hydrogen emission. There is no shortage of hydrogen emission here. The reason why people photograph nebulae in narrowband is to see what other ionized gases are there, apart from the ubiquitous hydrogen.

Take a look at this 600 kb pixel image of IC 410 (on the left) and its elongated "neighbor", IC 405. IN RGB, both nebulae look equally red. But in this narrowband image, IC 410 is seen to be blue in the center from oxygen emission, while IC 405 lacks any ionized oxygen (except perhaps a hint of it nestling inside its bright "D" shape).

The intensely blue color of IC 410 in today's APOD doesn't mean that there is a shortage of hydrogen there. It means, rather, that this is nebula contains a hot and powerful cluster, which emits enough ultraviolet light to ionize not only hydrogen, but oxygen, too.

Ann

[Chris Peterson]

If I understand the APOD's intro description, then the blue I am seeing all over the image is from oxygen being very prevalent in this area? I don't see any green and very little red. That confuses me, because I thought there'd be lots of hydrogen about. Is there something I'm not understanding here?

You don't see these colors discretely because all the gases are mixed, forming different colors. First of all, you aren't seeing much blue in this image. What you're seeing is closer to cyan- a mix of green and blue showing the mix of hydrogen and oxygen. Compare the original image to the same thing with the green (hydrogen) removed:

The effect of the ubiquitous green hydrogen is to make the blue oxygen regions look more cyan, and the red sulfur regions to look more orange.

We can also take away the blue (oxygen) and red (sulfur), leaving just the hydrogen:

If you were looking at a natural color image of this nebula, both the sulfur and hydrogen would be captured in the red channel, the oxygen in the green channel, and continnum in all channels. The result would be that you'd see a pinkish-magenta color over much of the region. You would not see red, unless the color balance was very distorted.

[Ann]

Chris Peterson wrote:
First of all, you aren't seeing much blue in this image. What you're seeing is closer to cyan- a mix of green and blue showing the mix of hydrogen and oxygen.

I'd like to (politely) disagree, Chris. If you compare wikipedia's definition of cyan with wikipedia's definition of blue, I'd say that the central parts of IC 410 look more blue than cyan. Of course that's a question of how we define blue and cyan. I certainly don't question the fact that both hydrogen and oxygen are present in the inner parts of IC 410. The final color balance of the picture is a matter of processing, judgment and aesthetics, and it is harder to know what a mapped-color image "should" look like compared with a "natural-color" one.

It is true, however, that most emission nebula look reddish-pink in most RGB images. Admittedly many RGB images make emission nebulae look light pink, light yellow or almost white in their centers.

Ann

[geckzilla]

You could argue left and right about whether that color is blue or cyan but mathematically it is somewhere between pure blue and pure cyan.
https://en.wikipedia.org/wiki/Cerulean_blue

Cerulean, also spelled caerulean, is a color term that may be applied to certain colors with the hue ranging roughly between blue and cyan, overlapping with both.

Color has got to be one of the most annoyingly subjective things that we keep discussing at this forum as if there is some kind of authoritative way to describe it that nearly everyone can agree with.

[Chris Peterson]

You could argue left and right about whether that color is blue or cyan but mathematically it is somewhere between pure blue and pure cyan.

Correct. In the standard RGB image processing environment nearly everyone uses, there are 8 rigorously defined colors: black, white, red, green, blue, cyan, magenta, yellow. Anything else is a matter of opinion and non-standardized conventions.

[Chris Peterson]

Chris Peterson wrote:
First of all, you aren't seeing much blue in this image. What you're seeing is closer to cyan- a mix of green and blue showing the mix of hydrogen and oxygen.

I'd like to (politely) disagree, Chris. If you compare wikipedia's definition of cyan with wikipedia's definition of blue, I'd say that the central parts of IC 410 look more blue than cyan. Of course that's a question of how we define blue and cyan.

Blue and cyan are rigorously defined. I did not identify the central region as cyan, but as "closer to cyan". Regardless of what colors you see with your eyes, you can measure the channel values. Averaging 10 zones all in the "blue" central region yields an average of 20% red, 32% green, 48% blue. That is not blue, but it can reasonably be described as closer to cyan (with a little magenta cast).

The same regions with the green channel removed (as in my second image) are much better described as blue (although the weak red signal lends a cast towards magenta).

The point of my comment was very simple: the central region is not blue. Thinking of it as blue is what led to the confusion that hydrogen is somehow absent in this image.

[MarkBour]

Thanks to all of you. I think this was a very very brief intro to the apparently very involved topic the processing of astronomical images.

[Anthony Barreiro]

That's beautiful. It took me a while to get the orientation of this image (which for some reason I am always compelled to do). The tadpoles are very close to the backside of the galactic plane. They appear to be swimming south in galactic terms, or south-west in celestial terms. Looking back towards the galactic centre from there, I imagine we form part of a nice bit of foreground fluff, obscuring the view in some aesthetic way.

I'm a few days late getting through some recent apod discussions.

Nitpicker, I think it's a great habit to orient an image in the sky and in space, and I love your suggestion of imagining how we look from way out in the galactic boondocks. It will be a while until we get a probe out there to send us a picture, so all we can do for now is imagine.

IC 410 is a remarkable nebula. Although it lies in the galactic plane, and at about 12,000 light years it's pretty far away from us, you can see it faintly through 10x50 binoculars in a dark sky. Because it lies in an outer arm of our Milky Way galaxy, there's not too much dust and gas between IC 410 and us, so its light is less attenuated than light coming from sources closer to the galactic center. IC 410 forms the western point of a nearly equilateral triangle about two degrees on a side with the much brighter open clusters M38 and M36. As seem from Brisbane, Australia IC 410 culminates around 30 degrees above the northern horizon, so you might be able to see it!

[Nitpicker]

IC 410 is a remarkable nebula. Although it lies in the galactic plane, and at about 12,000 light years it's pretty far away from us, you can see it faintly through 10x50 binoculars in a dark sky. Because it lies in an outer arm of our Milky Way galaxy, there's not too much dust and gas between IC 410 and us, so its light is less attenuated than light coming from sources closer to the galactic center. IC 410 forms the western point of a nearly equilateral triangle about two degrees on a side with the much brighter open clusters M38 and M36. As seem from Brisbane, Australia IC 410 culminates around 30 degrees above the northern horizon, so you might be able to see it!

With my scope in my back yard, I'm sure I could capture NGC1893, M38 and M36 with my camera, or get a greatly diminished view of them through the eyepiece. I think I'd have to drive for an hour or so to have a hope of IC410. I've not been to truly dark skies since I developed a real interest in learning the sky. I fear I would quickly get lost in the dazzle.

[Anthony Barreiro]

With my scope in my back yard, I'm sure I could capture NGC1893, M38 and M36 with my camera, or get a greatly diminished view of them through the eyepiece. I think I'd have to drive for an hour or so to have a hope of IC410. I've not been to truly dark skies since I developed a real interest in learning the sky. I fear I would quickly get lost in the dazzle.

I expect you might have the opposite experience. With more stars the constellations are fuller figures, rather than sparse connect-the-dots outlines. And faint extended objects that you have to strain to see in an eyepiece through light pollution jump right out at you. I'll never forget when I saw M33 naked-eye in a very dark, very clear, moonless sky. Or the times I mistook the milky way for cloud cover. If you can get to a dark location with an hour's drive, I have only one word of advice: go.