APOD: LL Ori and the Orion Nebula (2013 Feb 03)

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APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby APOD Robot » Sun Feb 03, 2013 5:05 am

Image LL Ori and the Orion Nebula

Explanation: This esthetic close-up of cosmic clouds and stellar winds features LL Orionis, interacting with the Orion Nebula flow. Adrift in Orion's stellar nursery and still in its formative years, variable star LL Orionis produces a wind more energetic than the wind from our own middle-aged Sun. As the fast stellar wind runs into slow moving gas a shock front is formed, analogous to the bow wave of a boat moving through water or a plane traveling at supersonic speed. The small, arcing, graceful structure just above and left of center is LL Ori's cosmic bow shock, measuring about half a light-year across. The slower gas is flowing away from the Orion Nebula's hot central star cluster, the Trapezium, located off the upper left corner of the picture. In three dimensions, LL Ori's wrap-around shock front is shaped like a bowl that appears brightest when viewed along the "bottom" edge. The beautiful picture is part of a large mosaic view of the complex stellar nursery in Orion, filled with a myriad of fluid shapes associated with star formation.

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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby BDanielMayfield » Sun Feb 03, 2013 8:20 am

WHAT is centered at 1218, 246 ??? My guess is that it’s a Bok globule, but it sorta looks like a firefly! :D
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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby fausto.lubatti » Sun Feb 03, 2013 9:24 am

Great colors, indeed!

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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby MargaritaMc » Sun Feb 03, 2013 9:32 am

BDanielMayfield wrote:WHAT is centered at 1218, 246 ???


May I ask what the numbers refer to in the above post? :?

And, what are the other two bright, presumably, stars in this lovely image?

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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby MargaritaMc » Sun Feb 03, 2013 9:49 am

Visible slightly above left center is the star LL Orionis (LL Ori), originally release by the Hubble Heritage Project in 2002. The delicate bow shock that surrounds LL Ori points towards the stream of gas flowing slowly away from the center of the Orion Nebula, near the Trapezium stars located off the image to the upper left. Close examination of the ends of the bow shock show secondary shocks that are formed as a two-sided jet of gas flowing away from this forming star at high velocity strikes the stream of low velocity gas from the center. To the right of LL Ori, a ghostly veil of material hangs thick and dark, obscuring portions of the nebula behind it.

The bright star toward the lower left of the image, known as LP Orionis (LP Ori), is surrounded by a prominent reflection nebula. Astronomers believe the star is moving within another veil of material that lies in front of M42. The appearance of the bright rim above LP Ori indicates that the teardrop shaped dark region around the illuminating star must be a cavity formed as the star moves through the veil material, rather than being a dusty veil obscuring light behind it.

Object Names: Orion Nebula, M42, NGC 1976

http://hubblesite.org/newscenter/archive/releases/2006/01/image/i/



So I may have partly answered my own question. The bright star at the lower left is LP Orionis. But the Hubble information doesn't mention the star to the right of LL Orionis.
I am presuming that LL Orionis itself is the bright dot in the middle of the bow wave?

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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby Ann » Sun Feb 03, 2013 11:18 am

I was completely confused by the caption here, because I thought that the bluish star with the prominent blue bow shock was LL Orionis. But when I checked LL Orionis with my software, it turned out to have very red colors.

So the blue star with the blue bow shock is LP Orionis and not LL Orionis? That makes good sense, and my software describes LP Orionis as a star of spectral class B, with blue colors.

Margarita, I agree with you that LL Orionis is the orangish star with the prominent bow shock in the upper part of the picture.

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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby owlice » Sun Feb 03, 2013 11:40 am

The text states that the "small, arcing, graceful structure just above and left of center is LL Ori's cosmic bow shock."

The (excellent) paper available at the link for "the complex" in the last sentence of the explanation has more information and images.
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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby saturno2 » Sun Feb 03, 2013 2:13 pm

Orion Nebula
Variable Star LL Orionis produces a fast stellar wind and produces
a " bow wave" in the gas of Orion Nebula.
This " bow wave¨ is LL Ori´s cosmic bow shock

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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby Boomer12k » Sun Feb 03, 2013 2:23 pm

Lovely picture of one of my favorite areas.

Around the bright star in the lower left, is that not another bow shock, or it is just relfection?

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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby neufer » Sun Feb 03, 2013 2:41 pm



owlice wrote:
The text states that the "small, arcing, graceful structure just above and left of center is LL Ori's cosmic bow shock."

The (excellent) paper available at the link for "the complex" in the last sentence of the explanation has more information and images.
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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby Ann » Sun Feb 03, 2013 3:06 pm

Boomer12k wrote:Lovely picture of one of my favorite areas.

Around the bright star in the lower left, is that not another bow shock, or it is just relfection?

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That's definitely a bow shock.

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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby BDanielMayfield » Sun Feb 03, 2013 3:13 pm

MargaritaMc wrote:
BDanielMayfield wrote:WHAT is centered at 1218, 246 ???


May I ask what the numbers refer to in the above post? :?

You certainly may ask. I had to ask a similar question myself about 6 months ago Margarita. The numbers are pixel coordinates, with 1,1 being on the top left corner of the image. If you view this image in a photo editor you should see at the bottom counters as you move your mouse across the image. The first number is the pixel count to the right from the left side while the second is the count down from the top. As the entire image is about 4800 x 3360 pixels large the object I was pointing out is about 1/4th of the way from the left side and about 1/14th of the way down from the top.

There you will find a very dark object that at some magnifications looks rather unnatural. (To be clear, I don’t actually believe it to be some sort of artifact, but … )
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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby Ann » Sun Feb 03, 2013 3:35 pm

BDanielMayfield wrote:
There you will find a very dark object that at some magnifications looks rather unnatural. (To be clear, I don’t actually believe it to be some sort of artifact, but … )


I believe that that is a cavity that has been "blown" in the nebulosity by the wind and radiation from the hot B-type star, LP Orionis.

A slightly similar cavity can be seen in this Hubble image of nebula NGC 1999 in Orion. The dark shape was first believed to be a very dark and thick cloud, a so-called Bok globule, but now I think that astronomers believe that it is simply a cavity, blown by the wind of the late B-type star right next to it.


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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby neufer » Sun Feb 03, 2013 3:40 pm

Click to play embedded YouTube video.

It's shaped like a huge cigar :!:
BDanielMayfield wrote:
The numbers are pixel coordinates, with 1,1 being on the top left corner of the image. If you view this image in a photo editor you should see at the bottom counters as you move your mouse across the image. The first number is the pixel count to the right from the left side while the second is the count down from the top. As the entire image is about 4800 x 3360 pixels large the object I was pointing out is about 1/4th of the way from the left side and about 1/14th of the way down from the top.

There you will find a very dark object that at some magnifications looks rather unnatural. (To be clear, I don’t actually believe it to be some sort of artifact, but … )

Your guess is as good as mine, Bruce.
Last edited by neufer on Sun Feb 03, 2013 3:44 pm, edited 1 time in total.
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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby MargaritaMc » Sun Feb 03, 2013 3:41 pm

BDanielMayfield wrote:
MargaritaMc wrote:
BDanielMayfield wrote:WHAT is centered at 1218, 246 ???


May I ask what the numbers refer to in the above post? :?

You certainly may ask. I had to ask a similar question myself about 6 months ago Margarita. The numbers are pixel coordinates, with 1,1 being on the top left corner of the image. If you view this image in a photo editor you should see at the bottom counters as you move your mouse across the image. The first number is the pixel count to the right from the left side while the second is the count down from the top. As the entire image is about 4800 x 3360 pixels large the object I was pointing out is about 1/4th of the way from the left side and about 1/14th of the way down from the top.

There you will find a very dark object that at some magnifications looks rather unnatural. (To be clear, I don’t actually believe it to be some sort of artifact, but … )


Ah ha! Many thanks. I don't have a photo Editor, but it is useful to know this.
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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby bystander » Sun Feb 03, 2013 4:12 pm

LLOri_hubble_cut.jpg

BDanielMayfield wrote:WHAT is centered at 1218, 246 ???
BDanielMayfield wrote:There you will find a very dark object that at some magnifications looks rather unnatural.)
Ann wrote:I believe that that is a cavity that has been "blown" in the nebulosity by the wind and radiation from the hot B-type star, LP Orionis.

    It's not anywhere close to LP Ori. I believe this is the object to which Daniel refers ...
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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby Ann » Sun Feb 03, 2013 4:17 pm

bystander wrote:
BDanielMayfield wrote:WHAT is centered at 1218, 246 ???
BDanielMayfield wrote:There you will find a very dark object that at some magnifications looks rather unnatural.)
Ann wrote:I believe that that is a cavity that has been "blown" in the nebulosity by the wind and radiation from the hot B-type star, LP Orionis.

It's not anywhere close to LP Ori. I believe this is the object to which Daniel refers ...

LLOri_hubble_cut.jpg


Sorry! Well, I think that is a proplyd, a protoplanetary disk. It is most likely a solar system in the making. The disk appears to be very thick, dark and massive.

Similar proplyds can be seen here.

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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby Chris Peterson » Sun Feb 03, 2013 4:21 pm

BDanielMayfield wrote:The numbers are pixel coordinates, with 1,1 being on the top left corner of the image.

This convention is a technical curiosity, a consequence of the fact that the first television displays constructed their images by sweeping a raster from the upper left corner of the screen. Since the first digital display devices used television technology for their displays, the memory buffers that mapped to the image treated the upper left as the origin. Otherwise, we'd probably use the more reasonable first quadrant, with the bottom left being the origin. So now we're left with needing to reflect all the standard equations for rotation and translation when doing image processing. (BTW, the origin pixel in the upper left is normally (0,0), not (1,1) - does your image processing software actually show it as the latter? That would be odd.)

There you will find a very dark object that at some magnifications looks rather unnatural. (To be clear, I don’t actually believe it to be some sort of artifact, but … )

apod_detail.jpg
Ann might well be correct that this is a region hollowed out by stellar winds. I'm more inclined to go with your guess, however, that it's a dust globule of some sort. It looks to me like a star is being occluded, which wouldn't be the case if this was a cavity. If it's a dust globule, it could be coincidentally in front of a star, although it seems more likely it would be associated with that star in some way- part of a protostellar structure, perhaps.
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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby Ron-Astro Pharmacist » Sun Feb 03, 2013 5:38 pm

Sure looks like previous pictures (sorry I can't give specifics) that are described as a possible new solar system in the process of formation. A few days ago when Anthony had described protuberances as new star formation (in the APOD "Trifid Nebula") and the new star was leaving trailing a dust cloud. Is this just a newer version? In that it just hasn't had time to leave a protuberance/dust cloud. :?:
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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby BDanielMayfield » Sun Feb 03, 2013 5:50 pm

Yes, Art, bystander and Chris have all found the object to which I was referring.

Ann, the pawn picture you posted is beautiful. Thanks.

Chris, I checked and yes, my software does show the very top left corner as (0,0), and thanks for the interesting details. If this object is as we suspect a solar system in the making about how long in au might it be?

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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby neufer » Sun Feb 03, 2013 5:50 pm

Chris Peterson wrote:
BDanielMayfield wrote:
The numbers are pixel coordinates, with 1,1 being on the top left corner of the image.

This convention is a technical curiosity, a consequence of the fact that the first television displays constructed their images by sweeping a raster from the upper left corner of the screen. Since the first digital display devices used television technology for their displays, the memory buffers that mapped to the image treated the upper left as the origin. Otherwise, we'd probably use the more reasonable first quadrant, with the bottom left being the origin.
http://en.wikipedia.org/wiki/Mechanical_television wrote:
<<Mechanical television (also called televisor) was a broadcast television system that used mechanical or electromechanical devices to capture and display video images. However, the images themselves were usually transmitted electronically and via radio waves. The reason for the dual nature of mechanical television lay in the history of technology.

The earliest mechanical television components originated with 19th-century inventors, with 20th-century inventors later adding electronic components as they were created. Mechanical systems were used in television broadcasting from 1925 to 1939, overlapping the all-electronic television era by three years. The essential mechanical component usually consisted of a Nipkow disk, which has a series of holes in a spiral pattern. In the camera, the disk had a light-detecting device, usually a photoelectric cell, behind it. In the reproducer (the display), a modulated light source, usually used a neon tube, replacing the light detector. As each hole flew by, it produced a scan line. An AM radio wave or closed circuit then carried the scan line to the TV reproducer.>>
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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby Pkhabu » Sun Feb 03, 2013 6:44 pm

I am not an astronomer, so my first thought on seeing the object referred to by Chris Peterson was, a man-made satellite.
It does appear to be partially blocking a bright area, giving the object a pinched waist.
I suppose it would be visible in other space photos of the region if the object is stellar rather than man made.

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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby Chris Peterson » Sun Feb 03, 2013 7:02 pm

Pkhabu wrote:I am not an astronomer, so my first thought on seeing the object referred to by Chris Peterson was, a man-made satellite.
It does appear to be partially blocking a bright area, giving the object a pinched waist.
I suppose it would be visible in other space photos of the region if the object is stellar rather than man made.

Keep in mind that this image was made by the Hubble Telescope, in orbit around the Earth, and is an exposure with a length of many minutes or even hours. So there's no way any nearby object could be imaged.
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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby Chris Peterson » Sun Feb 03, 2013 7:04 pm

BDanielMayfield wrote:If this object is as we suspect a solar system in the making about how long in au might it be?

By my calculation, the image scale here is 0.1 arcseconds per pixel. The structure therefore subtends 2.56 arcseconds, which assuming a distance of 1500 ly means its physical size (along the long axis) is about 1200 AU. That does sound pretty reasonable for a protostellar system.
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Re: APOD: LL Ori and the Orion Nebula (2013 Feb 03)

Postby Ann » Mon Feb 04, 2013 12:56 am

To be clear, I really do believe that the object in question is a protoplanetary disk. I googled the expression, protoplanetary disk, and I actually found this very object, although the colors are different. Here is a page which describes this very object as a protoplanetary disk.

What we are seeing is likely a thick disk seen from the side. Here you can see an artist's conception of a similar object, and you can read about it, too.

Ron-Astro Pharmacist wrote:
Sure looks like previous pictures (sorry I can't give specifics) that are described as a possible new solar system in the process of formation. A few days ago when Anthony had described protuberances as new star formation (in the APOD "Trifid Nebula") and the new star was leaving trailing a dust cloud. Is this just a newer version? In that it just hasn't had time to leave a protuberance/dust cloud.


AE Aurigae. Credit and copyright: Martin Pugh.
New stars are not typically leaving their birthplaces trailing a dust cloud. A new star may be kicked out of its birthplace by its young stellar siblings, but to my knowledge it won't be trailing a dust cloud when it leaves. The picture shows AE Aurigae which was kicked out of its birthplace near the Orion Nebula. It is zipping through space at a high speed and has entered another cloud of gas and dust by chance.



Illustration credit: ESO/L. Calçada

Baby stars which accrete matter from protostellar disks may well emit jets, however. Here is an illustration showing what this may look like. These jets may be very long and obvious. The proplyd (protoplanetary disk) in today's APOD doesn't show a jet, however.



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