APOD: The Horsehead Nebula (2019 Dec 17)

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APOD: The Horsehead Nebula (2019 Dec 17)

Post by APOD Robot » Tue Dec 17, 2019 5:06 am

Image The Horsehead Nebula

Explanation: Sculpted by stellar winds and radiation, a magnificent interstellar dust cloud by chance has assumed this recognizable shape. Fittingly named the Horsehead Nebula, it is some 1,500 light-years distant, embedded in the vast Orion cloud complex. About five light-years "tall", the dark cloud is cataloged as Barnard 33 and is visible only because its obscuring dust is silhouetted against the glowing red emission nebula IC 434. Stars are forming within the dark cloud. Contrasting blue reflection nebula NGC 2023, surrounding a hot, young star, is at the lower left of the full image. The featured gorgeous color image combines both narrowband and broadband images recorded using several different telescopes.

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Ann
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Re: APOD: The Horsehead Nebula (2019 Dec 17)

Post by Ann » Tue Dec 17, 2019 5:31 am

Cropped image of Horsehead region.
Mark Hanson & Martin Pugh, SSRO, PROMPT, CTIO, NSF
Uncropped image of Horsehead region.
Mark Hanson & Martin Pugh, SSRO, PROMPT, CTIO, NSF





















Today's APOD is a cropped version of the gorgeous Horsehead/NGC 2023 image that Mark Hanson posted in the Latest Submissions thread on December 7, 2019. I much prefer the uncropped version, which also shows us the stunning blue and pink NGC 2023 reflection nebula (lower left in the picture at right).

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Alex_g444

Re: APOD: The Horsehead Nebula (2019 Dec 17)

Post by Alex_g444 » Tue Dec 17, 2019 7:51 am

It looks like there are some striations in the red area around the horsehead. Magnetic field ?

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Re: APOD: The Horsehead Nebula (2019 Dec 17)

Post by orin stepanek » Tue Dec 17, 2019 1:21 pm

I guess I never thought of the Horsehead as a star factory! :D Ed would love this! (emc)
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Re: APOD: The Horsehead Nebula (2019 Dec 17)

Post by Chris Peterson » Tue Dec 17, 2019 2:22 pm

Alex_g444 wrote:
Tue Dec 17, 2019 7:51 am
It looks like there are some striations in the red area around the horsehead. Magnetic field ?
Unlikely. Interstellar magnetic fields are extremely weak, and there's no clear mechanism that could produce structure this strong in this hot, dense, turbulent environment. This is a region dominated by gravity, radiation pressure, and shock fronts.
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BDanielMayfield
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Re: APOD: The Horsehead Nebula (2019 Dec 17)

Post by BDanielMayfield » Tue Dec 17, 2019 3:24 pm

Chris Peterson wrote:
Tue Dec 17, 2019 2:22 pm
Alex_g444 wrote:
Tue Dec 17, 2019 7:51 am
It looks like there are some striations in the red area around the horsehead. Magnetic field ?
Unlikely. Interstellar magnetic fields are extremely weak, and there's no clear mechanism that could produce structure this strong in this hot, dense, turbulent environment. This is a region dominated by gravity, radiation pressure, and shock fronts.
Seeing that interstellar magnetic fields are so weak, wouldn't intergalactic fields be even weaker?
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Chris Peterson
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Re: APOD: The Horsehead Nebula (2019 Dec 17)

Post by Chris Peterson » Tue Dec 17, 2019 3:31 pm

BDanielMayfield wrote:
Tue Dec 17, 2019 3:24 pm
Chris Peterson wrote:
Tue Dec 17, 2019 2:22 pm
Alex_g444 wrote:
Tue Dec 17, 2019 7:51 am
It looks like there are some striations in the red area around the horsehead. Magnetic field ?
Unlikely. Interstellar magnetic fields are extremely weak, and there's no clear mechanism that could produce structure this strong in this hot, dense, turbulent environment. This is a region dominated by gravity, radiation pressure, and shock fronts.
Seeing that interstellar magnetic fields are so weak, wouldn't intergalactic fields be even weaker?
Not sure. Both are extremely weak. But intergalactic fields operate over very large distances where other forces are extremely weak, as well, allowing for subtle (VERY subtle) structure to form, if you know how to look for it.
Chris

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DL MARTIN

Re: APOD: The Horsehead Nebula (2019 Dec 17)

Post by DL MARTIN » Tue Dec 17, 2019 4:19 pm

If what we are seeing is 1500 iight years distant then it is 1500 years in the past. By failing to account for this 'then and now' time difference are we not dismissing 1500 years of changes in the subject? Again, if I take a photo of a 10 year old and it takes 10 years for the picture to arrive elsewhere, the person seeing the photo understands that the subject is now 20 years old and not the 10 year old portrayed.
Does this not constitute an element of misrepresentation ?

DL MARTIN

Re: APOD: The Horsehead Nebula (2019 Dec 17)

Post by DL MARTIN » Tue Dec 17, 2019 4:50 pm

If what we are seeing is 1500 iight years distant then it is 1500 years in the past. By failing to account for this 'then and now' time difference are we not dismissing 1500 years of changes in the subject? Again, if I take a photo of a 10 year old and it takes 10 years for the picture to arrive elsewhere, the person seeing the photo understands that the subject is now 20 years old and not the 10 year old portrayed.
Does this not constitute an element of misrepresentation ?

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Re: APOD: The Horsehead Nebula (2019 Dec 17)

Post by Chris Peterson » Tue Dec 17, 2019 5:01 pm

DL MARTIN wrote:
Tue Dec 17, 2019 4:19 pm
If what we are seeing is 1500 iight years distant then it is 1500 years in the past. By failing to account for this 'then and now' time difference are we not dismissing 1500 years of changes in the subject? Again, if I take a photo of a 10 year old and it takes 10 years for the picture to arrive elsewhere, the person seeing the photo understands that the subject is now 20 years old and not the 10 year old portrayed.
Does this not constitute an element of misrepresentation ?
What value is there in looking at an old photograph in light of the fact that the person in that photograph is now older? Is there an iota of additional information you can get from that photo by knowing that?

Likewise for astronomical images. What value is there in knowing that something is older in some sense "now" than it was "then"? Until you can answer that question, your complaint makes no sense.
Chris

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sillyworm 2

Re: APOD: The Horsehead Nebula (2019 Dec 17)

Post by sillyworm 2 » Tue Dec 17, 2019 9:23 pm

I no longer see a horsehead..looks more like a frog headed creature approaching a giant snail

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Re: APOD: The Horsehead Nebula (2019 Dec 17)

Post by Chris Peterson » Tue Dec 17, 2019 9:29 pm

sillyworm 2 wrote:
Tue Dec 17, 2019 9:23 pm
I no longer see a horsehead..looks more like a frog headed creature approaching a giant snail
Warning. Once seen, cannot be unseen.
_
hh-ass.jpg
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Re: APOD: The Horsehead Nebula (2019 Dec 17)

Post by Arcturus » Wed Dec 18, 2019 7:37 am

Alex_g444 wrote:
Tue Dec 17, 2019 7:51 am
It looks like there are some striations in the red area around the horsehead. Magnetic field ?
Magnetic fields effects are more "local", I'd rather say radiation.

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Re: APOD: The Horsehead Nebula (2019 Dec 17)

Post by TheZuke! » Wed Dec 18, 2019 2:47 pm

Chris Peterson wrote:
Tue Dec 17, 2019 9:29 pm

Warning. Once seen, cannot be unseen.
Actually, I think that is a better way of looking at it.

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Re: APOD: The Horsehead Nebula (2019 Dec 17)

Post by neufer » Wed Dec 18, 2019 7:08 pm

TheZuke! wrote:
Wed Dec 18, 2019 2:47 pm
Chris Peterson wrote:
Tue Dec 17, 2019 9:29 pm

Warning. Once seen, cannot be unseen.
Actually, I think that is a better way of looking at it.
I always think of the chess piece.
https://en.wikipedia.org/wiki/Chess#Prohibition_in_Islam wrote:
<<In 1979 in Islamic Republic of Iran, Grand Ayatollah Ruhollah Khomeini issued a religious fatwa ruling against chess on the grounds that it "excessively fatigues the brain" and constitutes gambling. Grand Ayatollah Ali al-Sistani of Iraq, issued multiple fatwas against chess and backgammon ruling that playing both “is absolutely forbidden even without placing a bet”. In 2016 in Saudi Arabia, Grand Mufti Abdul-Aziz ibn Abdullah Al ash-Sheikh issued a religious fatwa ruling that chess is forbidden in Islam because it constitutes gambling, stating "chess is a waste of time and an opportunity to squander money. It causes enmity and hatred between people.">>
Art Neuendorffer