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Old 01-18-2012, 09:02 AM
 
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I've been studying a region just to the west of what we think of as the great Orion Nebula (but is actually part of that star-forming region but is almost never included in images of it) for the past few months, and have taken a series of images of the region that didn't turn out well enough to share with anyone. I haven't given up on obtaining a good image and hope to do so before Orion gives way to the spring constellations. Having said that, I will first present a contextual image of the region (taken by well known amateur astronomer Robert Gendler in 2006), and then present images of objects embedded within it in order to explain why I think this is such a fascinating region, and very weird as well.



This young star-forming region includes many strange and fascinating objects, including NGC 1999, IC 427, IC 428, HH1, HH2, HH34, a mysterious emission nebula called the waterfall (HH 222), and some other objects whose names I have yet to discover.



NGC 1999

Located about 2 degrees south of the Orion Nebula is NGC 1999, a classic reflection nebula illuminated by the lone star, V380 Orionis. The nebula lies in the Orion "A" molecular cloud complex and is notable for what has historically been considered to be a dark T-shaped Bok globule (which is a condensing cloud of gas and dust that will eventually form a star) that was thought to lie in the foreground to the nebula, about 20 arc seconds southwest of V380 Orionis. The problem is that every recent study done on this dark 'object', by the Hubble, Spitzer, Chandra telescopes has found that the dark region is completely void of anything - no dust, no gas, no star. As far as they can tell, it is completely empty space right in the middle of a dense gas and dust cloud. I have found no compelling hypotheses as to why this region is so completely empty One candidate is that a supernova ripped a hole in the surrounding gas and dust cloud. This seems to me to be the most plausible explanation, though all known supernovae leave a stellar corpse behind, while none has been found in this void.

The spectrum of the central star and the nebula are identical which tells us that what we see is truly reflected starlight. At visual wavelengths the blue light we see is scattered by microscopic dust grains as small as 0.2 to 0.5 microns. The blue light has a similar wavelength as the dust particles and is scattered more efficiently than the longer wavelengths of light. The reflected starlight therefore produces the optical appearance of a brilliant blue nebula.



HH1 and HH2

Two bright Herbig-Haro objects exist nearby to NGC 1999. They are designated HH-1 and HH-2 and represent the first of these objects recognized by Guillermo Haro and George Herbig around 1950. The nature of these objects was unknown to Herbig and Haro at the time they first catalogued them. We now know they are shock excited nebulae. The small glowing clouds are the result of energetic outflows ejected from low mass protostars hidden from view by thick clouds of dust. The outflows from these infant stars power shock fronts that collide with the ambient gases and dust at speeds exceeding 100,000 miles per hour. The heated ambient gases then release the newly acquired energy in the visual wavelengths and appear as a deep and eerie red glow. Herbig-Haro objects are found most often in areas of active star formation. HH1 and HH2, although catalogued separately, are really part of the same structure, being opposite ends of a bipolar jet of superheated plasma ejected from a single low mass protostar.



IC 427

IC 427 is located near the center of the first image of the region. It is a large dim blue reflection nebula that is lit up by a star(s) hidden from view behind a veil of dark dust and hydrogen gas that is dimly ionized, causing the slight reddish glow.



IC 428

At the top center edge of the first photograph is located IC 428. It is another dim blue reflection nebula lit up by the large foreground star.



The Waterfall Nebula (HH 222) and HH 34

In the upper right hand corner of the first images are objects called the Waterfall (HH 222) and HH 34, below it. What created the Waterfall Nebula? No one knows. The structure seen in the region of NGC 1999 in the Great Orion Molecular Cloud complex is one of the more mysterious structures yet found on the sky. Designated HH-222, the elongated gaseous stream stretches about ten light years and emits an unusual array of colors. One hypothesis is that the gas filament results from the wind from a young star impacting a nearby molecular cloud. That would not explain, however, why the Waterfall and fainter streams all appear to converge on a bright but unusual non thermal radio source located toward the upper left of the curving structure. Another hypothesis is that the unusual radio source originates from a binary system containing a hot white dwarf, neutron star, or black hole, and that the Waterfall is just a jet from this energetic system. Such systems, though, are typically strong X-rays emitters, and no X-rays have been detected. For now, this case remains unsolved. Perhaps well-chosen future observations and clever deductive reasoning will unlock the true origin of this enigmatic wisp in the future.


HH 34 is located below the Waterfall. It is a classic Herbig-Haro object, the nature of which can be better seen in this National Optical Astronomy Observatory image:



The protostar in the center is jetting plasma in opposite directions to form the excited shocked regions at the top and bottom of the image. The lower jet is very noticable in this image. The upper jet is believed to be hidden behind dust and gas. These jets are believed to originate at the poles of the star and are iguided by the strong magnetic fields the star emits.

There are several other objects of note in this interesting region, including a possible HH object to the lower right of IC 427, a large H2 region of dust and gas that forms a kind of right-pointing chevron shape below HH 34, along the right edge of the first photograph, and another possible elongated gaseous stream located long the left margin of the first image.

All in all, I think this is one of the most interesting, and weird regions of our Milky Way galaxy. A guy could spend a lifetime studying it.
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Old 02-13-2013, 08:42 AM
 
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Default My Image Of This Region

See if you can find the objects discussed above on my image, below.



I took this image on November 5, 2011, and just now got it looking remotely decent, which goes to show how difficult processing these images can be.
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Old 02-13-2013, 05:04 PM
 
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Default Close Up Of The NGC 1999 and IC 427 Regions with HH-1 and H-2

NGC 1999, IC 427, HH-1 and HH-2 (two baby stars just forming). Have a peek at it here:



Image (cropped):
...
12x300sec= 60 minutes total exposure at ISO 800

Taken with my equipment at the LAS observatory on November, 5, 2011, in Curby, Indiana

Enjoy,

Last edited by orogenicman; 02-13-2013 at 05:54 PM..
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Old 02-13-2013, 10:02 PM
 
Location: Wasilla, Alaska
17,825 posts, read 20,496,555 times
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Quote:
Originally Posted by orogenicman View Post
I've been studying a region just to the west of what we think of as the great Orion Nebula (but is actually part of that star-forming region but is almost never included in images of it) for the past few months, and have taken a series of images of the region that didn't turn out well enough to share with anyone. I haven't given up on obtaining a good image and hope to do so before Orion gives way to the spring constellations. Having said that, I will first present a contextual image of the region (taken by well known amateur astronomer Robert Gendler in 2006), and then present images of objects embedded within it in order to explain why I think this is such a fascinating region, and very weird as well.

This young star-forming region includes many strange and fascinating objects, including NGC 1999, IC 427, IC 428, HH1, HH2, HH34, a mysterious emission nebula called the waterfall (HH 222), and some other objects whose names I have yet to discover.

NGC 1999

Located about 2 degrees south of the Orion Nebula is NGC 1999, a classic reflection nebula illuminated by the lone star, V380 Orionis. The nebula lies in the Orion "A" molecular cloud complex and is notable for what has historically been considered to be a dark T-shaped Bok globule (which is a condensing cloud of gas and dust that will eventually form a star) that was thought to lie in the foreground to the nebula, about 20 arc seconds southwest of V380 Orionis. The problem is that every recent study done on this dark 'object', by the Hubble, Spitzer, Chandra telescopes has found that the dark region is completely void of anything - no dust, no gas, no star. As far as they can tell, it is completely empty space right in the middle of a dense gas and dust cloud. I have found no compelling hypotheses as to why this region is so completely empty One candidate is that a supernova ripped a hole in the surrounding gas and dust cloud. This seems to me to be the most plausible explanation, though all known supernovae leave a stellar corpse behind, while none has been found in this void.

The spectrum of the central star and the nebula are identical which tells us that what we see is truly reflected starlight. At visual wavelengths the blue light we see is scattered by microscopic dust grains as small as 0.2 to 0.5 microns. The blue light has a similar wavelength as the dust particles and is scattered more efficiently than the longer wavelengths of light. The reflected starlight therefore produces the optical appearance of a brilliant blue nebula.
Great photos, thanks!

Here is a larger image of NGC1999:



According to JPL, V380 Orionis is actually a triple-star system, and "one of these three stars appears to have launched a jet that helped clear the hole, as well as other jets and stellar radiation."

Source: Catalog Page for PIA13109

I understand why JPL is calling it a "hole" rather than a dark nebulae, like those in IC 2944. In the visual wavelength it looks like a hole, and they were surprised to find that even in the infrared wavelength it still appears as a hole, when infrared should have been able to see through the dust. If it was truly like a dark nebulae, then it would be an active star forming region, and heat would have been detected even through the dust. But that is not the case.

However, I am a bit leery of their explanation for how the "hole" came to be. To me it seems like speculation because they have no evidence of any jets from any of the three stars in any wavelength. While a strong stellar jet is certainly a plausible explanation, it does not match our current observation.

Perhaps it is the close proximity of the ternary system that is causing a collision of very energetic solar winds that created a hole in NGC1999. Or is it even a hole? If it was a hole in NGC1999 we should be able to see objects through that hole, right?

According to SIMBAD they list V380 Orionis spectral type A1e. Which would put its age at ~3 million years. Aladin Sky Atlas has a nice black and white negative image of NGC1999 and the triple-star system. Aladin also considers the "hole" as a dark nebulae.

Source:
SIMBAD query result
Aladin sky atlas

I am going to have to get back to you on the other wonderful objects you are interested in exploring, because that is all the time I have for tonight. Thanks again for the photos.
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Old 02-14-2013, 02:27 AM
 
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Stellar jets, which usually occur at or immediately after star birth, are fleeting phenomenon during the evolution of stars, so one would not necessarily expect to see them in or near this hole - the system could be advanced enough that the jets have already turned off; considering that V380 Orionis is a baby star system, I think the explanation that stellar jets created the hole is very plausible. When you consider the fact that this entire region contains several HH objects with stellar jets, two of which are in proximity to NGC 1999, then I think the stellar jet hypothesis becomes compelling. In fact, it is the only explanation I've seen to date that makes any sense.
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Old 02-14-2013, 06:38 AM
 
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By the way, thanks, Glitch.
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Old 02-14-2013, 12:54 PM
 
Location: Wasilla, Alaska
17,825 posts, read 20,496,555 times
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Quote:
Originally Posted by orogenicman View Post
Stellar jets, which usually occur at or immediately after star birth, are fleeting phenomenon during the evolution of stars, so one would not necessarily expect to see them in or near this hole - the system could be advanced enough that the jets have already turned off; considering that V380 Orionis is a baby star system, I think the explanation that stellar jets created the hole is very plausible. When you consider the fact that this entire region contains several HH objects with stellar jets, two of which are in proximity to NGC 1999, then I think the stellar jet hypothesis becomes compelling. In fact, it is the only explanation I've seen to date that makes any sense.
True, I had not considered that possibility.

Considering its size, V380 Orionis would have produced massive jets during its protostar phase. Once it reached 18 million K, the newly formed star would have blown all the dust and gas away with its solar winds, and the jets would have stopped.
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Old 02-17-2013, 06:36 AM
 
Location: Wasilla, Alaska
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Quote:
Originally Posted by orogenicman View Post
I have found no compelling hypotheses as to why this region is so completely empty One candidate is that a supernova ripped a hole in the surrounding gas and dust cloud. This seems to me to be the most plausible explanation, though all known supernovae leave a stellar corpse behind, while none has been found in this void.
There is one type of supernova that leaves no stellar corpse behind. It is called a pair instability supernova. Only stars that are between 130 and 250 solar masses die in this manner, leaving nothing but its outer shell behind.

Pair-instability supernova - Wikipedia, the free encyclopedia
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Old 02-17-2013, 06:48 AM
 
Location: Wasilla, Alaska
17,825 posts, read 20,496,555 times
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Quote:
Originally Posted by orogenicman View Post
HH 34 is located below the Waterfall. It is a classic Herbig-Haro object, the nature of which can be better seen in this National Optical Astronomy Observatory image:

The protostar in the center is jetting plasma in opposite directions to form the excited shocked regions at the top and bottom of the image. The lower jet is very noticable in this image. The upper jet is believed to be hidden behind dust and gas. These jets are believed to originate at the poles of the star and are iguided by the strong magnetic fields the star emits.

There are several other objects of note in this interesting region, including a possible HH object to the lower right of IC 427, a large H2 region of dust and gas that forms a kind of right-pointing chevron shape below HH 34, along the right edge of the first photograph, and another possible elongated gaseous stream located long the left margin of the first image.

All in all, I think this is one of the most interesting, and weird regions of our Milky Way galaxy. A guy could spend a lifetime studying it.
By protostar, I envision a newly formed star whose core that is greater than 2 million degrees Kelvin and less than 18 million degrees Kelvin. The size of those jets would seem to indicate a large amount of gas and debris is orbiting that protostar. We could be looking at the very early stages of a new solar system. Way cool!
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Old 02-17-2013, 09:03 AM
 
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Quote:
Originally Posted by Glitch View Post
By protostar, I envision a newly formed star whose core that is greater than 2 million degrees Kelvin and less than 18 million degrees Kelvin. The size of those jets would seem to indicate a large amount of gas and debris is orbiting that protostar. We could be looking at the very early stages of a new solar system. Way cool!
In most cases, that it probably true.
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