APOD: Horsehead and Orion Nebulas (2024 Sep 10)

[APOD Robot]

Horsehead and Orion Nebulas

Explanation: The dark Horsehead Nebula and the glowing Orion Nebula are contrasting cosmic vistas. Adrift 1,500 light-years away in one of the night sky's most recognizable constellations, they appear in opposite corners of the above stunning mosaic. The familiar Horsehead nebula appears as a dark cloud, a small silhouette notched against the long glow of hydrogen -- here shown in gold -- at the lower left. Alnitak is the easternmost star in Orion's belt and is seen as the brightest star just below and to the left of the Horsehead. To the left of Alnitak is the Flame Nebula, with clouds of bright emission and dramatic dark dust lanes. The magnificent emission region, the Orion Nebula (aka M42), lies at the upper right. Immediately to its left is a prominent reflection nebula sometimes called the Running Man. Pervasive tendrils of glowing hydrogen gas are easily traced throughout the region.

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[ozalba]

The brightest star below-left of the Horsehead is HD 37903; Alnitak is just above the Flame Nebula, in this image.

[Ann]

What I like about this APOD is all the details in the surrounding dust.

Horsehead and Orion Nebulas. Image Credit & Copyright: Antoine & Dalia Grelin

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Note the "pillars" pointing at Sigma Orionis.
The Horsehead Nebula is one of those pillars.

What I specifically like about the APOD is all the "pillars" pointing at Sigma Orionis. Sigma Orionis is a hot O-type star, which, because of its harsh stellar wind and intense ultraviolet light, has cleared a "bubble" around itself. But at the margins of this bubble, "pillars" of gas and dust remain standing, pointing at Sigma Orionis. The Horsehead Nebula is just one of those pillars.

(And I know that Chris insists that the Horsehead Nebula is really the, well, Horse-backside Nebula. How about providing an illustration, Chris?)


Let's take a look at a few of the sights. Let's start with the Horsehead (or the Equine Rear):

The Horsehead.

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Let's move on reflection nebula NGC 2023:

NGC 2023. It is illuminated by hot B-type star HD 37903, as was pointed out in the post above mine. Credit: Cosmotography.

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Let's look at the Flame Nebula in different wavelengths:

The Flame Nebula in visual light. Credit: Adam Block/Mount Lemmon SkyCenter/University of Arizona

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The Flame Nebula in X-rays and infrared, revealing the star cluster inside. Credit: X-ray: NASA/CXC/PSU/K.Getman, E.Feigelson, M.Kuhn & the MYStIX team; Infrared: NASA/JPL-Caltech

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There is a small round nebula near the Flame Nebula, IC 432, that we can take a look at:

IC 432 (left) and IC 431. Credit: Rick J at Cloudy Nights.

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The interesting little nebula NGC 1999 is at far right in the APOD. Maybe you want to read abut it here.

A wide field image centered on NGC 1999. Image: ESO/Digitized Sky Survey 2

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NGC 1999 (top). The red objects are Herbig Haro objects, outbursts from yung stars in the process of forming. Credit: Science Photo Library/Subaru 8.2 meter Telescope.

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The Running Man Nebula can be found practicing for the Olympics at the other side of the Orion Nebula:

The Running Man Nebula. Credit: Bernard Miller.

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As for the Orion Nebula, this famous picture by Hubble looks good:

The Orion Nebula, also known as M42. The adjacent nebula M43 is at upper left. Credit: NASA, ESA, M. Robberto (Space Telescope Science Institute/ESA) and the Hubble Space Telescope Orion Treasury Project Team

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Let's have a look at Sigma Orionis:

Sigma Orionis with surrounding stars and the Horsehead Nebula at far left. Credit: Lithopsian .

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And here is a nice picture of Orion's Belt with Alnitak, Alnilam and Mintaka:

Orion's Belt. The stars are, from lower right to upper left,
Alnitak, Alnilam and Mintaka. Credit: Mohammad Nouroozi

And let's have two more pictures of the Horsehead Nebula and surroundings, shall we?

The Horsehead Nebula is seen against a red background. The yellow Flame nebula is at far left. Reflection nebula NGC 2023 is just to the lower left of the Horsehead. Bright star Alnitak is to the upper right of the Flame Nebula. Sigma Orionis is at top. Credit: Rafael Compassi, Presidente Lucena, Brazil.

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Bright star Alnitak (top left), Sigma Orionis (top right), NGC 2023 (just below center left), the Flame Nebula (far left) and the Horsehead Nebula (just below center right). Credit: Mark Casto, Halesworth, Suffolk, UK.

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I really recommend this page if you want to see a ton of Horsehead Nebula pictures!


And now I want a hot dog. The deep yellow color of the APOD gave me a craving for mustard!

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Ann

[FLPhotoCatcher]

There is a nebulous area that actually looks like a skull and crossbones. The running man and the Orion nebula are the two eyes.

[Christian G.]

What I specifically like about the APOD is all the "pillars" pointing at Sigma Orionis. Sigma Orionis is a hot O-type star, which, because of its harsh stellar wind and intense ultraviolet light, has cleared a "bubble" around itself. But at the margins of this bubble, "pillars" of gas and dust remain standing, pointing at Sigma Orionis. The Horsehead Nebula is just one of those pillars.

Why does it seem that, unlike Sigma Orionis with the Horsehead Nebula, the equally hot Alnitak isn't really "carving" anything in the Flame Nebula? The dark dust pillars or lanes in its center aren't pointing in any way towards it, or am I misinterpreting what I'm seeing?

[RJN]

The star Alnitak was incorrectly identified in the original APOD text. The text has now been corrected on the main NASA APOD. We apologize for the mistake. - RJN

[Ann]

What I specifically like about the APOD is all the "pillars" pointing at Sigma Orionis. Sigma Orionis is a hot O-type star, which, because of its harsh stellar wind and intense ultraviolet light, has cleared a "bubble" around itself. But at the margins of this bubble, "pillars" of gas and dust remain standing, pointing at Sigma Orionis. The Horsehead Nebula is just one of those pillars.

Why does it seem that, unlike Sigma Orionis with the Horsehead Nebula, the equally hot Alnitak isn't really "carving" anything in the Flame Nebula? The dark dust pillars or lanes in its center aren't pointing in any way towards it, or am I misinterpreting what I'm seeing?

Good question. Indeed, a very good question. It took me a long time to accept that Alnitak had anything to do with the Flame Nebula, because I couldn't see any visual signs that the Flame Nebula was being affected by the hot bright star in any way.

The Horsehead, Flame Nebula, Alnitak and Sigma Orionis region. Credit: Hypatia Alexandria

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As you can see in Hypatia Alexandria's image, there are no obvious "pillars" at all that are pointing at Alnitak. Also note that the color of the Flame Nebula is different than the color of red nebula behind the Horsehead Nebula. The color difference is not so great in Hypatia Alexandria's image, but in other images, the color difference is striking. Because of that, I used to think that the Flame Nebula was not being ionized from outside at all, and that all the light coming from this nebula was highly reddened starlight from young blue stars inside.

And you know what? I just now checked the Wikipedia entry on the Flame Nebula, and it would seem that I was right!!! Wikipedia said that Alnitak and the Flame Nebula really have nothing to do with one another!!! Fancy that!!!

Wikipedia wrote:

The bright star Alnitak (ζ Ori), the easternmost star in the Belt of Orion, appears very close to the Flame Nebula in the sky. But the star and nebula are not physically associated with one another. The Flame Nebula contains a young cluster of stars which includes at least one hot, luminous O-type star labeled IRS 2b. The dense gas and dust in the foreground of the nebula heavily obscures the star cluster inside the nebula, making studies at infrared wavelengths most useful.

Really and honestly, fancy that!!!

Ann

[Christian G.]

What I specifically like about the APOD is all the "pillars" pointing at Sigma Orionis. Sigma Orionis is a hot O-type star, which, because of its harsh stellar wind and intense ultraviolet light, has cleared a "bubble" around itself. But at the margins of this bubble, "pillars" of gas and dust remain standing, pointing at Sigma Orionis. The Horsehead Nebula is just one of those pillars.

Why does it seem that, unlike Sigma Orionis with the Horsehead Nebula, the equally hot Alnitak isn't really "carving" anything in the Flame Nebula? The dark dust pillars or lanes in its center aren't pointing in any way towards it, or am I misinterpreting what I'm seeing?

Good question. Indeed, a very good question. It took me a long time to accept that Alnitak had anything to do with the Flame Nebula, because I couldn't see any visual signs that the Flame Nebula was being affected by the hot bright star in any way.

The Horsehead, Flame Nebula, Alnitak and Sigma Orionis region. Credit: Hypatia Alexandria

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As you can see in Hypatia Alexandria's image, there are no obvious "pillars" at all that are pointing at Alnitak. Also note that the color of the Flame Nebula is different than the color of red nebula behind the Horsehead Nebula. The color difference is not so great in Hypatia Alexandria's image, but in other images, the color difference is striking. Because of that, I used to think that the Flame Nebula was not being ionized from outside at all, and that all the light coming from this nebula was highly reddened starlight from young blue stars inside.

And you know what? I just now checked the Wikipedia entry on the Flame Nebula, and it would seem that I was right!!! Wikipedia said that Alnitak and the Flame Nebula really have nothing to do with one another!!! Fancy that!!!

Wikipedia wrote:

The bright star Alnitak (ζ Ori), the easternmost star in the Belt of Orion, appears very close to the Flame Nebula in the sky. But the star and nebula are not physically associated with one another. The Flame Nebula contains a young cluster of stars which includes at least one hot, luminous O-type star labeled IRS 2b. The dense gas and dust in the foreground of the nebula heavily obscures the star cluster inside the nebula, making studies at infrared wavelengths most useful.

Really and honestly, fancy that!!!

Ann

Good to know! Alnitak's status as blistering O-type supergiant that would burn through any cloud near it is preserved!

[Chris Peterson]

What I like about this APOD is all the details in the surrounding dust.

I don't think we see much dust in this narrowband image. Most of the surrounding structure appears to be ionized hydrogen.

[Ann]

What I like about this APOD is all the details in the surrounding dust.

I don't think we see much dust in this narrowband image. Most of the surrounding structure appears to be ionized hydrogen.

All right - all the details in the surrounding chaotic gas, then?

Or maybe the gas is not even chaotic, just turbulent?

Ann

[bls0326]

Ann: Thanks for labels on the APOD picture. Sure helped me identify stuff in this busy area.

Brian

[AVAO]

What I like about this APOD is all the details in the surrounding dust.

I don't think we see much dust in this narrowband image. Most of the surrounding structure appears to be ionized hydrogen.

All right - all the details in the surrounding chaotic gas, then?

Or maybe the gas is not even chaotic, just turbulent?

Ann

Well...quite colorfull making of...
https://youtu.be/rnf226cdFJc?t=587

[Ann]

I don't think we see much dust in this narrowband image. Most of the surrounding structure appears to be ionized hydrogen.

All right - all the details in the surrounding chaotic gas, then?

Or maybe the gas is not even chaotic, just turbulent?

Ann

Well...quite colorfull making of...
https://youtu.be/rnf226cdFJc?t=587

Oh yuck!!! Horrible!

You can't use narrowband imagery to create good-looking and at least reasonably accurate color images of nebulas!

Ann