APOD: South of Orion (2022 Jan 27)

[APOD Robot]

[img]https://apod.nasa.gov/apod/calendar/S_220127.jpg[/img] South of Orion

Explanation: South of the large star-forming region known as the Orion Nebula, lies bright blue reflection nebula NGC 1999. At the edge of the Orion molecular cloud complex some 1,500 light-years distant, NGC 1999's illumination is provided by the embedded variable star V380 Orionis. The nebula is marked with a dark sideways T-shape at center right in this telescopic vista that spans about two full moons on the sky. Its dark shape was once assumed to be an obscuring dust cloud seen in silhouette. But infrared data suggest the shape is likely a hole blown through the nebula itself by energetic young stars. In fact, this region abounds with energetic young stars producing jets and outflows with luminous shock waves. Cataloged as Herbig-Haro (HH) objects, named for astronomers George Herbig and Guillermo Haro, the shocks have intense reddish hues. HH1 and HH2 are just below and right of NGC 1999. HH222, also known as the Waterfall nebula, looks like a red gash near top right in the frame. To create the shocks stellar jets push through the surrounding material at speeds of hundreds of kilometers per second.

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[Ann]

Today's APOD is stunningly beautiful! Of course, the entire NGC 1999 is most fascinating, and Vikas Chanders' portrait is superb! Even so, I can't help comparing it with a picture of (more or less) the same area by Robert Gendler:

South of Orion. Image Credit & Copyright: Vikas Chander.

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The NGC 1999 region. Photo: Robert Gendler.

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Note near the lower right corner in the APOD a red circle with a dark hole inside. The same formation is near the center in Robert Gendler, just below NGC 1999, and to me this circle almost looks like a tiny caldera of a tall volcano, where lava is streaming down all around its sides. NGC 1999, just above this circular structure, appears in Gendler's image to be blowing out jet streams of gasses. You can also see the Waterfall Nebula near the top right corner in Gendler's image as well as in Chander's. To the lower right of the Waterfall Nebula in Gendler's image is a strange triangular formation.

Let's look at some details in Chander's picture:

Vikas Chander's image shows us many Herbig-Haro objects in bright red. These are tiny jets and outflows - well, comparatively tiny! - from young stars that are still accreting matter. The red color is hydrogen alpha caused by shock waves as the jets hit the surrounding medium and ionize small patches of hydrogen as a result.

I really like Chander's portrait of IC 428, which is an object that was totally unknown to me before, and I have found no useful information on it. Its color is strange. It is not at all blue, as it might be if a blue star was embedded, as in nebula NGC 6726. And it is not orange, as it might be if a star cluster was embedded and highly reddened by dust, like the Flame Nebula. (All right, the Flame Nebula is also being ionized by Orion's Belt star Alnitak, but...)

So my guess, for what it is worth, is that IC 428 just maybe possibly maybe might be a nebula surrounding a T Tauri star. A T Tauri star would be mature enough not to emit jets (and thus not ionize its surroundings and make them glow red), or so I think.

We have to take a closer look at NGC 1999 too, of course!

The cavity of NGC 1999. NASA and The Hubble Heritage Team (STScI)

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The location of NGC 1999 in Orion (red circle). Star map:ESO, IAU and Sky & Telescope

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It is so clear from the Hubble image that NGC 1999 is a cavity. The incredible void in it makes it a unique object, at least among objects so far catalogued by astronomers. Imagine the jet that punched through the rather thick nebula here and left this T-shaped scar! This "black hole", or "hole-y T", completely baffled astronomers when they first saw the Hubble image of NGC 1999 back in the year 2000, and they thought that the T was a dust cloud. Indeed, a Wikipedia page is still telling us it is a dust cloud!!! No no no, Wikipedia!!

Wikipedia wrote:

The WFPC2 image of NGC 1999 shows a remarkable jet-black cloud near its center, resembling a letter T tilted on its side, located just to the right and lower right of the bright star. This dark cloud is an example of a "Bok globule," named after the late University of Arizona astronomer Bart Bok. The globule is a cold cloud of gas, molecules, and cosmic dust, which is so dense it blocks all of the light behind it. In the Hubble image, the globule is seen silhouetted against the reflection nebula illuminated by V380 Orionis. Astronomers believe that new stars may be forming inside Bok globules, through the contraction of the dust and molecular gas under their own gravity.

A Bok globule, now called a Thackeray globule, is indeed a dust cloud being evaporated by the ultraviolet light of hot stars:

This intriguing new view of a spectacular stellar nursery IC 2944 is being released to celebrate a milestone: 15 years of ESO’s Very Large Telescope. This image also shows a group of thick clouds of dust known as the Thackeray globules silhouetted against the pale pink glowing gas of the nebula. These globules are under fierce bombardment from the ultraviolet radiation from nearby hot young stars. They are both being eroded away and also fragmenting, rather like lumps of butter dropped onto a hot frying pan. It is likely that Thackeray’s globules will be destroyed before they can collapse and form new stars. Photo: ESO.

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So all in all, the NGC 1999 region is a treasure trove of fantastic formations. Thank you for the image, Vikas Chander!

Ann

[XgeoX]

Wow Ann, the cavity of NGC 1999 is exceptionally beautiful! I can’t really even describe why I find it so attractive but it seems to be so many things at once.
Well, sorry I’m getting so mystical here! Lol

Eric

[orin stepanek]

I like this view; nice and clean!!

Annotated; beautifully done!

Looks like a guy walking in a fog!

[neufer]

It is so clear from the Hubble image that NGC 1999 is a cavity.

The incredible void in it makes it a unique object, at least among objects so far catalogued by astronomers. Imagine the jet that punched through the rather thick nebula here and left this T-shaped scar! This "black hole", or "hole-y T", completely baffled astronomers when they first saw the Hubble image of NGC 1999 back in the year 2000, and they thought that the T was a dust cloud.

"Hole-y T", Batman, how could those Hubble scientists have been so blind
as to not immediately realize that NGC 1999 is a cavity (or rather a eunuch object?)
---------------------------------------------------------------
. . . King Lear : Act I, scene I
.
KENT: My life I never held but as a pawn (♟)
. To wage against thy enemies; nor fear to lose it,
. Thy safety being the motive.
.
KING LEAR: Out of my sight!
---------------------------------------------------------------

Indeed, a Wikipedia page is still telling us it is a dust cloud!!! No no no, Wikipedia!!

David Lynch quote: “Keep your eye on the doughnut, not on the hole.”

<<NGC 1999 is a dust-filled bright nebula with a vast hole of empty space represented by a black patch of sky, as can be seen in the photograph. It is a reflection nebula, and shines from the light of the variable star V380 Orionis.

It was previously believed that the black patch was a dense cloud of dust and gas which blocked light that would normally pass through, called a dark nebula. Analysis of this patch by the infrared telescope Herschel (October 9, 2009), which has the capability of penetrating such dense cloud material, resulted in continued black space. This led to the belief that either the cloud material was immensely dense or that an unexplained phenomenon had been detected.

With support from ground-based observations done using the submillimeter bolometer cameras on the Atacama Pathfinder Experiment radio telescope (November 29, 2009) and the Mayall (Kitt Peak) and Magellan telescopes (December 4, 2009), it was determined that the patch looks black not because it is an extremely dense pocket of gas, but because it is truly empty. The exact cause of this phenomenon is still being investigated, although it has been hypothesized that narrow jets of gas from some of the young stars in the region punctured the sheet of dust and gas, as well as, powerful radiation from a nearby mature star may have helped to create the hole. Researchers believe this discovery should lead to a better understanding of the entire star forming process.>>

[Chris Peterson]

It is so clear from the Hubble image that NGC 1999 is a cavity. The incredible void in it makes it a unique object, at least among objects so far catalogued by astronomers. Imagine the jet that punched through the rather thick nebula here and left this T-shaped scar! This "black hole", or "hole-y T", completely baffled astronomers when they first saw the Hubble image of NGC 1999 back in the year 2000, and they thought that the T was a dust cloud. Indeed, a Wikipedia page is still telling us it is a dust cloud!!! No no no, Wikipedia!!

The Wikipedia entry sounds perfectly correct. NGC 1999 is not a cavity. It is a dusty reflection nebula with a cavity in its center.

[Ann]

It is so clear from the Hubble image that NGC 1999 is a cavity. The incredible void in it makes it a unique object, at least among objects so far catalogued by astronomers. Imagine the jet that punched through the rather thick nebula here and left this T-shaped scar! This "black hole", or "hole-y T", completely baffled astronomers when they first saw the Hubble image of NGC 1999 back in the year 2000, and they thought that the T was a dust cloud. Indeed, a Wikipedia page is still telling us it is a dust cloud!!! No no no, Wikipedia!!

The Wikipedia entry sounds perfectly correct. NGC 1999 is not a cavity. It is a dusty reflection nebula with a cavity in its center.

You and I are reading that Wikipedia entry differently, Chris.

Ann

[Chris Peterson]

It is so clear from the Hubble image that NGC 1999 is a cavity. The incredible void in it makes it a unique object, at least among objects so far catalogued by astronomers. Imagine the jet that punched through the rather thick nebula here and left this T-shaped scar! This "black hole", or "hole-y T", completely baffled astronomers when they first saw the Hubble image of NGC 1999 back in the year 2000, and they thought that the T was a dust cloud. Indeed, a Wikipedia page is still telling us it is a dust cloud!!! No no no, Wikipedia!!

The Wikipedia entry sounds perfectly correct. NGC 1999 is not a cavity. It is a dusty reflection nebula with a cavity in its center.

You and I are reading that Wikipedia entry differently, Chris. :wink:

Hmm: "NGC 1999 is a dust-filled bright nebula with a vast hole of empty space represented by a black patch of sky, as can be seen in the photograph. It is a reflection nebula, and shines from the light of the variable star V380 Orionis." I don't see how many ways that can be read. I don't see how it is in any way inaccurate.

NGC 1999 is most certainly not the cavity. We don't name cavities this way. This object is a structure that contains a cavity. Every authoritative reference defines it as a reflection nebula.

[Tekija]

The Wikipedia entry sounds perfectly correct. NGC 1999 is not a cavity. It is a dusty reflection nebula with a cavity in its center.

You and I are reading that Wikipedia entry differently, Chris.

Hmm: "NGC 1999 is a dust-filled bright nebula with a vast hole of empty space represented by a black patch of sky, as can be seen in the photograph. It is a reflection nebula, and shines from the light of the variable star V380 Orionis." I don't see how many ways that can be read. I don't see how it is in any way inaccurate.

NGC 1999 is most certainly not the cavity. We don't name cavities this way. This object is a structure that contains a cavity. Every authoritative reference defines it as a reflection nebula.

Ann was misled by the caption of the Wikipedia image in Wikimedia Commons that, as it should, cites the original HHT caption? The text on the Wikipedia, on the other hand, was corrected to refer to a hole on 16 May 2010, according to the page edit history. And Chris perhaps did not notice that Ann had cited the old image caption, not current text? Hence the apparent disagreement?

[Chris Peterson]

You and I are reading that Wikipedia entry differently, Chris. :wink:

Hmm: "NGC 1999 is a dust-filled bright nebula with a vast hole of empty space represented by a black patch of sky, as can be seen in the photograph. It is a reflection nebula, and shines from the light of the variable star V380 Orionis." I don't see how many ways that can be read. I don't see how it is in any way inaccurate.

NGC 1999 is most certainly not the cavity. We don't name cavities this way. This object is a structure that contains a cavity. Every authoritative reference defines it as a reflection nebula.

Ann was misled by the caption of the Wikipedia image in Wikimedia Commons that, as it should, cites the original HHT caption? The text on the Wikipedia, on the other hand, was corrected to refer to a hole on 16 May 2010, according to the page edit history. And Chris perhaps did not notice that Ann had cited the old image caption, not current text? Hence the apparent disagreement?

I'm mainly responding to her claim "It is so clear from the Hubble image that NGC 1999 is a cavity." I guess that is subject to interpretation. If she means it as "the dark region in NGC 1999 is a cavity, not a dust cloud", then there is no disagreement. In any case, however, Wikipedia has it right. As Wikipedia nearly always does.

[Tekija]

And Ann did not by my reading intentionally confuse the hole with the nebula but thought the hole was still referred to as Bok globule.

[Chris Peterson]

And Ann did not by my reading intentionally confuse the hole with the nebula but thought the hole was still referred to as Bok globule.

Certainly possible.

[neufer]

Click to play embedded YouTube video.

Ann was misled by the caption of the Wikipedia image in Wikimedia Commons that, as it should, cites the original HHT caption? The text on the Wikipedia, on the other hand, was corrected to refer to a hole on 16 May 2010, according to the page edit history. And Chris perhaps did not notice that Ann had cited the old image caption, not current text? Hence the apparent disagreement?

I'm mainly responding to her claim "It is so clear from the Hubble image that NGC 1999 is a cavity." I guess that is subject to interpretation. If she means it as "the dark region in NGC 1999 is a cavity, not a dust cloud", then there is no disagreement.

[Ann]

Hmm: "NGC 1999 is a dust-filled bright nebula with a vast hole of empty space represented by a black patch of sky, as can be seen in the photograph. It is a reflection nebula, and shines from the light of the variable star V380 Orionis." I don't see how many ways that can be read. I don't see how it is in any way inaccurate.

NGC 1999 is most certainly not the cavity. We don't name cavities this way. This object is a structure that contains a cavity. Every authoritative reference defines it as a reflection nebula.

Ann was misled by the caption of the Wikipedia image in Wikimedia Commons that, as it should, cites the original HHT caption? The text on the Wikipedia, on the other hand, was corrected to refer to a hole on 16 May 2010, according to the page edit history. And Chris perhaps did not notice that Ann had cited the old image caption, not current text? Hence the apparent disagreement?

I'm mainly responding to her claim "It is so clear from the Hubble image that NGC 1999 is a cavity." I guess that is subject to interpretation. If she means it as "the dark region in NGC 1999 is a cavity, not a dust cloud", then there is no disagreement. In any case, however, Wikipedia has it right. As Wikipedia nearly always does.

Yes, Chris, that is obviously what I meant, namely, that the dark region in the center of NGC 1999 is a cavity, not that NGC 1999 itself is a cavity rather than a dusty nebula. After all, what NGC designation could possibly refer to a cavity only, or any pitch-black region only???

Could there be an NGC object there?

But my point was that the astronomers who first took a look at the Hubble image of NGC 1999 couldn't quite believe that the dark object in the center of this dusty nebula was a cavity.

And I want to thank Tekija for noticing that I was quoting the caption of the Wikipedia image in Wikimedia Commons, which indeed still claims that the dark "T" in NGC 1999 is a dark Bok globule. Thank you, Tekija!

Ann

[Chris Peterson]

Ann was misled by the caption of the Wikipedia image in Wikimedia Commons that, as it should, cites the original HHT caption? The text on the Wikipedia, on the other hand, was corrected to refer to a hole on 16 May 2010, according to the page edit history. And Chris perhaps did not notice that Ann had cited the old image caption, not current text? Hence the apparent disagreement?

I'm mainly responding to her claim "It is so clear from the Hubble image that NGC 1999 is a cavity." I guess that is subject to interpretation. If she means it as "the dark region in NGC 1999 is a cavity, not a dust cloud", then there is no disagreement. In any case, however, Wikipedia has it right. As Wikipedia nearly always does.

Yes, Chris, that is obviously what I meant, namely, that the dark object in the center of NGC 1999 is a cavity, not that NGC 1999 itself is a cavity rather than a dusty nebula. After all, what NGC designation could possibly refer to a cavity only, or any old pitch-black object only??? But my point was that the astronomers who first took a look at the Hubble image of NGC 1999 couldn't quite believe that the dark object in the center of this dusty nebula was a cavity.

And I want to thank Tekija for noticing that I was quoting the caption of the Wikipedia image in Wikimedia Commons, which indeed still claims that the dark "T" in NGC 1999 is a dark Bok globule. Thank you, Tekija! :D

Ann

Hmm. One person's "obvious"...

[neufer]

Ann was misled by the caption of the Wikipedia image in Wikimedia Commons that, as it should, cites the original HHT caption? The text on the Wikipedia, on the other hand, was corrected to refer to a hole on 16 May 2010, according to the page edit history. And Chris perhaps did not notice that Ann had cited the old image caption, not current text? Hence the apparent disagreement?

I'm mainly responding to her claim "It is so clear from the Hubble image that NGC 1999 is a cavity." I guess that is subject to interpretation. If she means it as "the dark region in NGC 1999 is a cavity, not a dust cloud", then there is no disagreement. In any case, however, Wikipedia has it right. As Wikipedia nearly always does.

Yes, Chris, that is obviously what I meant, namely, that the dark object in the center of NGC 1999 is a cavity, not that NGC 1999 itself is a cavity rather than a dusty nebula.

Hmm. One person's "obvious"...

Obviously, what Ann meant to say was: “Yes, Chris, that is obliviously what I meant,”

After all, what NGC designation could possibly refer to a cavity only, or any old pitch-black object only??? But my point was that the astronomers who first took a look at the Hubble image of NGC 1999 couldn't quite believe that the dark object in the center of this dusty nebula was a cavity.

“Then you should say what you mean,” the March Hare went on.

“I do,” Alice hastily replied; “at least—at least I mean what I say—that’s the same thing, you know.”

“Not the same thing a bit!” said the Hatter. “You might just as well say that ‘I see what I eat’ is the same thing as ‘I eat what I see’!”

“You might just as well say,” added the March Hare, “that ‘I like what I get’ is the same thing as ‘I get what I like’!”

“You might just as well say,” added the Dormouse, who seemed to be talking in his sleep, “that ‘I breathe when I sleep’ is the same thing as ‘I sleep when I breathe’!”

“It is the same thing with you,” said the Hatter, and here the conversation dropped, and the party sat silent for a minute, while Alice thought over all she could remember about ravens and writing-desks, which wasn’t much.

And I want to thank Tekija for noticing that I was quoting the caption of the Wikipedia image in Wikimedia Commons, which indeed still claims that the dark "T" in NGC 1999 is a dark Bok globule.

Why not just complain to NASA directly:

Click to play embedded YouTube video.

<<The WFPC2 image of NGC 1999 shows a remarkable jet-black cloud near its center, resembling a letter T tilted on its side, located just to the right and lower right of the bright star. This dark cloud is an example of a "Bok globule," named after the late University of Arizona astronomer Bart Bok. The globule is a cold cloud of gas, molecules, and cosmic dust, which is so dense it blocks all of the light behind it. In the Hubble image, the globule is seen silhouetted against the reflection nebula illuminated by V380 Orionis. Astronomers believe that new stars may be forming inside Bok globules, through the contraction of the dust and molecular gas under their own gravity.>>

[Ann]

I'm mainly responding to her claim "It is so clear from the Hubble image that NGC 1999 is a cavity." I guess that is subject to interpretation. If she means it as "the dark region in NGC 1999 is a cavity, not a dust cloud", then there is no disagreement. In any case, however, Wikipedia has it right. As Wikipedia nearly always does.

Yes, Chris, that is obviously what I meant, namely, that the dark object in the center of NGC 1999 is a cavity, not that NGC 1999 itself is a cavity rather than a dusty nebula. After all, what NGC designation could possibly refer to a cavity only, or any old pitch-black object only??? But my point was that the astronomers who first took a look at the Hubble image of NGC 1999 couldn't quite believe that the dark object in the center of this dusty nebula was a cavity.

And I want to thank Tekija for noticing that I was quoting the caption of the Wikipedia image in Wikimedia Commons, which indeed still claims that the dark "T" in NGC 1999 is a dark Bok globule. Thank you, Tekija!

Ann

Hmm. One person's "obvious"...

---

This is Ann.


She has made 11737 posts at Starship Asterisk*, and she still believes that "NGC" means "Nothing! Gluck! Cluck!". (And she can't spell, either!)


(And she is wearing a blue dress, too. Or a blue something. She isn't too sartorially gifted.)


(But those pearls must be her mother's. They are not Ann's. Or maybe they are stars that Ann picked from the sky? Maybe some of the pearls are Orion's Belt, because the name of one of the stars there - Alnilam? - means "A string of pearls". Maybe Orion is missing his belt tonight? Maybe the nothingness where Orion's Belt used to be is the new NGC object in the sky? Nothing gluck cluck! says Ann.)


(And Ann seems to have stolen Crux, too, and now she is wearing Crux as an ear ring. And look at those spiral swirls on various parts of her body. Surely they are galaxies? What galaxies have Ann stolen, I wonder?)


Ann

[Ann]

Grumpy woman.png (158.21 KiB) Viewed 10654 times

Grumpy woman speaks (in a loud voice:

Chris, you should check Ann's quote before asserting that Wikipedia doesn't say what she claims it is saying! Go to https://en.wikipedia.org/wiki/NGC_1999, click on the top image, and note that the caption that appears as the new page opens is exactly the one she quoted!

Ann, you should realize that not everyone knows what "NGC" means (New General Catalogue), or that it lists only bright objects. Not everyone understands that a dark object can't be an NGC object, so it was wrong of you to say that "NGC 1999 is a cavity", when it is really the name of a bright reflection nebula (with a cavity in its center)!

Ann

[Chris Peterson]

Grumpy woman.png

Grumpy woman speaks (in a loud voice:

Chris, you should check Ann's quote before asserting that Wikipedia doesn't say what she claims it is saying! Go to https://en.wikipedia.org/wiki/NGC_1999, click on the top image, and note that the caption that appears as the new page opens is exactly the one she quoted!

Ann, you should realize that not everyone knows what "NGC" means (New General Catalogue), or that it lists only bright objects. Not everyone understands that a dark object can't be an NGC object, so it was wrong of you to say that "NGC 1999 is a cavity", when it is really the name of a bright reflection nebula (with a cavity in its center)!

Ann

Find something wrong in a Wikipedia article? Fix it! That's how the system works. It depends upon community input and correction.

[bystander]

Find something wrong in a Wikipedia article? Fix it! That's how the system works. It depends upon community input and correction.

The error wasn't in the wikipedia article NGC 1999, but in the text accompanying the image File:Ngc1999.jpg which was taken from HubbleSite. It's a little harder to correct STScI and NASA.

[Chris Peterson]

Find something wrong in a Wikipedia article? Fix it! That's how the system works. It depends upon community input and correction.

The error wasn't in the wikipedia article NGC 1999, but in the text accompanying the image File:Ngc1999.jpg which was taken from HubbleSite. It's a little harder to correct STScI and NASA.

Directly, yes. Indirectly? We'll see. I sent a message through their contact page suggesting they review the content on that 22 year old page.

[Tom Glenn]

FYI the discussion link for today's APOD (January 28) still directs to this page, and the date on the APOD landing page above the image is incorrect (still says January 27). This glitch also causes the APOD for the 27th to be skipped if you click "<" to see the previous APOD.

[dlmartin7@cogeco.ca]

With Ann and Peterson sparing, one can only conclude that this discussion is one for the ages.

[Tekija]

This is the link to discuss today’s image:

http://asterisk.apod.com/viewtopic.php?t=42178

[neufer]

With Ann and Peterson sparing, one can only conclude that this discussion is one for the ages.

spare (v.) Old English sparian "to refrain from harming, be indulgent to, allow to go free; use sparingly," from the source of Old English spær "sparing, frugal," from Proto-Germanic *sparaz (source also of Old Saxon sparon, Old Frisian sparia, Old Norse spara, Dutch sparen, Old High German sparon, German sparen "to spare"). Meaning "to dispense from one's own stock, give or yield up," is recorded from early 13c. Related: Spared; sparing.
----------------------------------------------------------------------------------
spar (v.) late 14c., "go quickly, rush, dart, spring;" c. 1400, "to strike or thrust," perhaps from French esparer "to kick" (Modern French éparer), from Italian sparare "to fling," from Latin ex- (see ex-) + parare "make ready, prepare," hence "ward off, parry." Used in 17c. in reference to preliminary actions in a cock fight; figurative sense of "to dispute, bandy with words" is from 1690s. Extension to humans, in a literal sense, with meaning "to engage in or practice boxing" is attested from 1755. Related: Sparred; sparring.