Eta Carinae, Keyhole, and the Tiny Homunculus NebulaeOTA: CDK24
Camera: Moravian 61000 Pro
Observatory: Heaven's Mirror, Chile
Date of Capture: Mar '23
Date of Processing: Jun '23 – Jan '24
Exposures:
R: 6 x 180 sec
G: 9 x "
B: 10 x "
H: 7 x 900 sec
O: 7 x "
S: 9 x "
Total Exposure time: 6.9 hours
Image Width: 30 arc-minutes
Processing Tools:
1. Commercial: PixInsight, Topaz, Photo Director 365, Aurora HDR, Luminar Neo
2. Pixinsight Addons: NoiseXTerminator, BlurXTerminator, StarXTerminator, Normalize Scale Gradient
3. My Scripts: NB_Assistant, AC_Restar, Subframe Weighting Tool (Excel w/ J. Hunt), ColorTweaker, StarTweaker
Target Description:
The primary image centers on the Keyhole Nebula, a region within the vastly larger Eta Carina Nebula. Eta Carina is the bright star near the center of the images. Very common in amateur descriptions of this region, the Keyhole Nebula is mistaken for the famous Homunculus Nebula. The Homunculus Nebula is tightly around the star Eta Carina, which at the scale of these data does little more than make Eta Carinae appear elongated (Image B).
The fine dark lines, more prevalent in the bright nebula that abuts the large dark channels, could be shockwave generated and, perhaps, echoes of those shockwaves. The same effect can be seen in my image of M 45 (
https://astrob.in/xuuavb/0/), and something similar occurs in this ESO image of the Keyhole nebula:
In this case, the structures are attributed to magnetic lines (and imaged in polarized light). Perhaps magnetic lines of force are responsible for the lines in my pictures as well…the lines look structurally similar but most of those lines in this image host crossing lines. That appears to rule out a magnetic origin for many of t he structures—back to shockwave fragmenting the cloud hypothesis, for those structures, at least.
(1)
https://iopscience.iop.org/article/10.3847/1538-4357/ac0c80Statistics:
Distance:9K ly
Apparent Magnitude: 1
Pixel Span at Target: 16K km
Alex Woronow 
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