Celestial hemisphere:  Northern  ·  Constellation: Aquila (Aql)
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Parsamian 21, 



    
        

            Gary Imm
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Parsamian 21

Getting plate-solving status, please wait...
Parsamian 21, 



    
        

            Gary Imm
Powered byPixInsight

Parsamian 21

Acquisition details

Dates:
May 18, 2020 ·  May 30, 2020
Frames:
Astrodon Gen2 I-Series Tru-Balance Blue: 30×120(1h) (gain: 139.00) -20°C bin 1×1
Astrodon Gen2 I-Series Tru-Balance Green: 30×120(1h) (gain: 139.00) -20°C bin 1×1
Astrodon Gen2 I-Series Tru-Balance Lum: 60×120(2h) (gain: 139.00) -20°C bin 1×1
Astrodon Gen2 I-Series Tru-Balance Red: 30×120(1h) (gain: 139.00) -20°C bin 1×1
Integration:
5h
Avg. Moon age:
16.72 days
Avg. Moon phase:
35.06%

RA center: 19h29m00s.351

DEC center: +09°3906.40

Pixel scale: 0.282 arcsec/pixel

Orientation: -14.498 degrees

Field radius: 0.110 degrees

More info:Open 

Resolution: 2144x1826

File size: 1.6 MB

Locations: Backyard (Mag 20.8 - Bortle 4.5), Onalaska, Texas, United States

Data source: Backyard

Description

This object is a tiny reflection nebula located 1300 light years away in the constellation of Aquila at a declination of -10 degrees. This nebula spans 1 arc-minute in our apparent view, which corresponds to an width of 0.5 light years.

This nebula was originally cataloged by Dr. Elma Parsamian, the famous Armenian woman astronomer, who I believe is still alive today at the age of 90. The object is described in the 2007 paper, “High-resolution polarimetry of Parsamian 21: revealing the structure of an edge-on FU Ori disc”.

This nebula is similar to the much more famous NGC 2261 in a number of ways. Both are white reflection nebula that surround variable stars. Both are asymmetrically shaped, with a "fan" extending only to one side. Both of these fan shapes have bright edges on either side with a darker void area in the center. Both are comprised of a bright comet-like core which illuminates the cloud of gas and dust.

This is a beautiful object but I have many questions. Here is a quote from my description of NGC 2261 – “I find it very curious that this nebula is so asymmetric. Scientists speculate that a symmetrical counterpart of this fan-shaped nebula exists, but that we cannot see it because it is heavily obscured from our view by dust. It doesn't appear that way to me and I can't really make sense of this unique shape.” Scientist also believe that Parsamian 21 is the result of a bi-polar outflow from a young star, but I just don’t see much happening below the star, just as in NGC 2261.

Also, the interesting lateral star stream higher up in the outflow of Parsamian 21 is puzzling to me. I am also surprised by the apparent dust region above and left of the object, which is blocking out some of the background stars.

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