Rosette: The Shockwave Map [NII - SII]

This is not a typical astrophoto of the Rosette Nebula. I used a pixelmath by subtracting narrowband images taken with two different filters and telescopes to reveal the hidden shockwaves and ionization fronts inside this giant star-forming region.

 

To isolate specific physical processes within the nebula, I captured deep exposures of the Ha (656.3 nm) and [SII] (6716/6731 Å) emission lines using two different optical setups:

 

6nm Astronomik filters with an f/5 Newtonian, and 3nm Antlia filters with an f/3 Newtonian.

 

By subtracting the 3nm narrowband stacks (shifted slightly due to the fast focal ratio) from the broader 6nm stacks, I effectively suppressed the dominant emission cores of hydrogen and sulfur, leaving behind faint residual structures primarily associated with the [NII] (654.8 nm, 658.3 nm) emission lines and possibly the stronger component of the SII doublet (likely 6716 Å).

 

These emission lines are significant because they trace zones of partial ionization, shock fronts, and turbulent interactions within ionized hydrogen regions. [NII] is often enhanced in regions where ionization fronts meet denser neutral material or where energetic stellar winds create compression fronts. [SII] serves as a key diagnostic of shock-excited gas, commonly studied in supernova remnants but also present in star-forming regions.

 

Color mapping:

Red: residual [NII] emission (Ha 6nm – Ha 3nm)

Blue: residual [SII] emission (SII 6nm – SII 3nm

Green: a blend of both, highlighting transitional zones

Stars are from broadband RGB.

 

Full size: www.astrobin.com/lopwd6/

 

The picture was taken from Budapest (Bortle 7) and Tibolddaroc Hungary (Bortle 4), between 2022 Jan - 2024 Jan.

 

Integration:

Ha 6nm: 5h 35min

Ha 3nm: 10h 31min 40sec

S2 6nm: 5h 45min

S2 3nm: 10h 5 min

RGB (Stars): 30min" (3x10*60s)

 

Scope setup:

F3, 3nm filters: 200/800 Newt. & Starizona Nexus 0.75, Antlia 3nm Ha & S2 filter

 

F5, 6nm filters: 150/750 Newt. & Baader MPCC Mark 3; Astronomik 6nm Ha & S2 filter

 

EQ6 belt mod

ZWO LRGB filters

Asi 1600MM Pro

Asi 178MM guiding

 

 

Done