APOD: The Elephant's Trunk Nebula in Cepheus (2017 Jan 19)

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APOD: The Elephant's Trunk Nebula in Cepheus (2017 Jan 19)

Post by APOD Robot » Thu Jan 19, 2017 5:06 am

Image The Elephant's Trunk Nebula in Cepheus

Explanation: Like an illustration in a galactic Just So Story, the Elephant's Trunk Nebula winds through the emission nebula and young star cluster complex IC 1396, in the high and far off constellation of Cepheus. Also known as vdB 142, the cosmic elephant's trunk is over 20 light-years long. This colorful close-up view includes image data from a narrow band filter that transmits the light from ionized hydrogen atoms in the region. The resulting composite highlights the bright swept-back ridges that outline pockets of cool interstellar dust and gas. Such embedded, dark, tendril-shaped clouds contain the raw material for star formation and hide protostars within. Nearly 3,000 light-years distant, the relatively faint IC 1396 complex covers a large region on the sky, spanning over 5 degrees. This dramatic scene spans a 1 degree wide field, about the size of 2 Full Moons.

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Re: APOD: The Elephant's Trunk Nebula in Cepheus (2017 Jan 19)

Post by yasgur » Thu Jan 19, 2017 12:00 pm

I looks like it's extending out from a face on the right side of the shot. A badly deformed Pinocchio nose? :D

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Re: APOD: The Elephant's Trunk Nebula in Cepheus (2017 Jan 19)

Post by neufer » Thu Jan 19, 2017 1:58 pm

yasgur wrote:
I looks like it's extending out from a face on the right side of the shot.

A badly deformed Pinocchio nose? :D
Elephants, Pinocchios and Just So Stories all have a lot in common.
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Re: APOD: The Elephant's Trunk Nebula in Cepheus (2017 Jan 19)

Post by moconnor » Thu Jan 19, 2017 2:22 pm

When I think about dust, I think about the handful of bunnies below my bed or behind my computer. If I collect and compress all of them, they consume less than a thimble and weigh less than a gram. But this Elephant's trunk is 20 light years long! It's hard for me to imagine that much dust. Does that much dust weigh more than the Earth? Jupiter? the Sun? Also, if I were to collect a sample of that dust and analyse it, what would it be made of? Sodium? Chlorine? Carbon? Gold?

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Re: APOD: The Elephant's Trunk Nebula in Cepheus (2017 Jan 19)

Post by Ann » Thu Jan 19, 2017 2:34 pm

You should ask Chris. But I think that cosmic dust is mostly made of various ices, water ice, ammonium ice, perhaps carbon dioxide ice, some hydrocarbons and some silicon.

Oh, wait...
A cosmic dust grain. Photo: R. Jay GaBany.
Cosmotography.com wrote:
Cosmic dust is comprised of carbon compounds and additional materials that include silicon, oxygen, nitrogen, nickel and, most likely, other heavy elements. Because of its carbon content, this cosmic fluff has been compared to diamond dust- it stretches the imagination, but the universe is, in fact, filled with this stuff!
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Re: APOD: The Elephant's Trunk Nebula in Cepheus (2017 Jan 19)

Post by Chris Peterson » Thu Jan 19, 2017 3:27 pm

moconnor wrote:When I think about dust, I think about the handful of bunnies below my bed or behind my computer. If I collect and compress all of them, they consume less than a thimble and weigh less than a gram. But this Elephant's trunk is 20 light years long! It's hard for me to imagine that much dust. Does that much dust weigh more than the Earth? Jupiter? the Sun?
A nebula like this has many, many solar masses. That's how come they are able to produce stars. Keep in mind, however, that this is basically a gas nebula, most of which is invisible. The dust only represents one or two percent of the total, the majority of which is hydrogen. And even though the total mass is hundreds of solar masses or more, that's distributed over many cubic light years, so the density of the entire thing is still lower than what we'd call a hard vacuum. It's massive only because it's huge, not because it's dense.
Also, if I were to collect a sample of that dust and analyse it, what would it be made of? Sodium? Chlorine? Carbon? Gold?
Cosmic dust is the main source of all the heavy elements when it comes to building new stellar systems. So you find in it all elements. But it is substantially made of silicates and carbonates, not all that different from the plain old dust that settles on your windowsill.
Chris

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Re: APOD: The Elephant's nose in Cepheus (2017 Jan 19)

Post by dlw » Thu Jan 19, 2017 5:02 pm

Can someone say more about the small red spot in the elephant's nostril area? It looks like the cavity is formed by strong radiation winds but the red spot seems unusual.

Thanks.
Elephant's nose.png
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Re: APOD: The Elephant's nose in Cepheus (2017 Jan 19)

Post by Chris Peterson » Thu Jan 19, 2017 5:18 pm

dlw wrote:Can someone say more about the small red spot in the elephant's nostril area? It looks like the cavity is formed by strong radiation winds but the red spot seems unusual.
My impression is that we're seeing through a blown-out channel to the glowing hydrogen that is behind the dusty region.
Chris

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heehaw

Re: APOD: The Elephant's Trunk Nebula in Cepheus (2017 Jan 19)

Post by heehaw » Thu Jan 19, 2017 9:59 pm

vdB 142 (I guess) is Sidney van den Bergh, who was my Masters thesis advisor: https://en.wikipedia.org/wiki/Sidney_van_den_Bergh


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Re: APOD: The Elephant's Trunk Nebula in Cepheus (2017 Jan 19)

Post by ta152h0 » Thu Jan 19, 2017 11:16 pm

may i drift off topic for a few lines and congratulate the team that put together the color map of Pluto I just saw at nasa.gov site. I really hope in the upcoming governance, exceptionalism at NASA continues to be the norm.
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Re: APOD: The Elephant's Trunk Nebula in Cepheus (2017 Jan 19)

Post by Guest » Fri Jan 20, 2017 3:56 pm

The obvious question inquiring minds want to know is, 'How do scientists KNOW the hydrogen clouds are hiding 'protostars'?' :roll:

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Re: APOD: The Elephant's Trunk Nebula in Cepheus (2017 Jan 19)

Post by Chris Peterson » Fri Jan 20, 2017 4:24 pm

Guest wrote:The obvious question inquiring minds want to know is, 'How do scientists KNOW the hydrogen clouds are hiding 'protostars'?' :roll:
Because we can also image them in infrared light, which allows us to see through the dust and view the protostars directly. (Although the nebula is mostly hydrogen gas, it is the dust, not the hydrogen, that hides the protostars in visible light.)
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Re: APOD: The Elephant's Trunk Nebula in Cepheus (2017 Jan 19)

Post by Ann » Fri Jan 20, 2017 4:44 pm

Here are two images of the Orion Nebula and the Trapezium Cluster. One of the images shows the Nebula and the cluster in visible light, and the other shows them in infrared light.

As you can see, many more stars are visible in infrared than in visible light.

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