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Parsamyan 21 A Reflection Nebula

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#1 Rick J

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Posted 24 May 2013 - 02:44 PM

Parsamyan 21/Parsamian 21 is a reflection nebula caused by the outflow from the young FU Orionis star HBC 687. Coming from its south end is the Herbig Haro object HH221 which may be the little jet seen below the bright cloud that hides the star. This nebula is located in Aquila. I was unable to find a distance estimate for it. Some papers likened this nebula to the far more famous Hubble's Variable Nebula. Though about the only similarity I see is the faint southern jet. It certainly doesn't have the ringlike shape of Parsamyan 21. See also Jim Shuder's fine image of this object at: http://www.pbase.com...137713564/large .

The illuminating and creating star is listed as a variable but photometric data in one paper found only a very tiny fluctuation in its brightness over the years so while it varies it is barely noticeable. The star itself is hidden by the dust and gas around it though it can be seen in IR light according to one paper which had a picture showing just the star and no hint of nebulosity. If you look very closely at my image it appears there is a bit of faint nebulosity to the northeast and north northwest. It would take a lot of hours to bring that out at my image scale. Except for that it appears there may be dark dust not illuminated by the star around the nebula as it sits in a slightly dark hole in the stars. Some of the lack of stars matches where the faint nebulosity is in my image. WISE shows a red circular blob that is centered on the star not the nebula or the dark cloud that I see. http://irsa.ipac.cal..._wise_1&proj... Enter Parsamian 21 in the search box and hit search. Click on the Multi-color tab above the IRAS image. The circle in all images is centered on the illuminating star according to their position cursor. The longer the wavelength the larger the blob and the cooler the dust it is seeing.

I imaged this one at 0.5" per pixel some of the same nights as NGC 206 accepting some additional loss of resolution and transparency . The full image is well over 2 megabytes in size so I cropped it to smaller sizes. Seeing had deteriorated a bit, partly because this object is lower in the sky than NGC 206. The professional images I found on the net show it bluer than either Jim or I saw it. I can't explain the difference.


14" LX200R @ f/10, L=6x10'x1 RGB=2x10'x2, STL-11000XM, Paramount ME

Cropped to 3500x2500 pixels at 0.5" per pixel
http://www.spacebant...ntid=4617&stc=1

Cropped to one quarter frame, 2004x1336 pixels at 0.5" per pixel
http://www.spacebant...18&d=1369373201

Attached cropped to 800x800 and reduced a bit in compression to meet the 200K size limit.

Rick

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#2 Lionel M

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Posted 24 May 2013 - 03:38 PM

Hi Rick,

I didn't know this object.
Beautiful image, interesting explanations, thanks for sharing knowledge :)


lionel

#3 Mike7Mak

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Posted 24 May 2013 - 04:01 PM

Interesting object. Pretty low at +9 dec but worth a try in a month or two. Transits at 3 am now.

Excellent image, nice depth, color, and the dark nebula is quite obvious.

#4 Dan Crowson

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Posted 24 May 2013 - 06:25 PM

Really neat object and write-up. Thanks for sharing Rick.

Dan

#5 LazyLightning

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Posted 25 May 2013 - 02:34 AM

Really like this one Rick.

#6 Rick J

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Posted 26 May 2013 - 01:52 AM

Thanks all.

Due to my typical seeing and this objects small size it is a difficult one for me to do. I'd liked to have used longer subs but seeing didn't support that. I'd get one frame one night and several nights later be able to grab another. Not the way I like to work so don't expect this often. Those blessed with good seeing and dark skies (not good for NB) should give it a try. It will be around for a while. Think I got the last frame in September and first about this time of the year. Most were in August as that was my best imaging month for the year.

Rick






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