North American Nebula Details in Ha (David McClain)

North American Nebula Details in Ha

Raw Ha frames courtesy of Deep Sky West Remote Observatory in New Mexico, USA. (deepskywest.com) Data obtained with FSQ 106EDXiii / QSI683wsg / Lodestar / Paramount MyT.

9 hrs total integration (18x1800) Ha.

Processing in PixInsight. Images were stacked, aligned, drizzle integrated, and cropped for this presentation.

Features along the "Central American" spur, which had previously appeared to be jutting columns, now appear to be regions of erosion in a layer of some substantial thickness. Interesting!

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Oops! Revision has some TGV noise removal that was forgotten in the original submission.

Zoom in a bit and notice how "depth" appears, much like viewing cells under a microscope. It almost appears that the background is defocused in relation to the foreground. Of course this is only an illusion from a monocular view. We can't truly ascertain any depth except by inference.

Calculations of the ionization of HII show that it is extremely efficient, and an optical depth of unity occurs over a column depth of around 100 pc. The smallest features shown here are on the order of 1 arcsec. With a presumed distance of 700 pc, those features would correspond to about 3-4 light-days in extent, or about 700 AU.

... now this is very odd... Rotate the image by 90 deg and it begins to look like jutting features again, not erosion. I had never viewed this nebula on its side before. I know our brains are wired such that we have difficulty recognizing faces when viewed upside down. Perhaps this is a similar illusion?

Original
Final
B

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Status	Basic failed
Started	...
Astrometry.net job	1127701
PixInsight job	n/a
PixInsight queue size	n/a
PixInsight stage	n/a

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