NGC 3199: Stellar Art by Wolf-Rayet 18

OTA:……………….TAO 150 (f/7.3)

Camera:………….FLI - ML16200 (native resolution 1.13 arcsec/pixel)

Observatory:….Deep Sky West, Chile

EXPOSURES:



EXPOSURES:

…R……..23 x 300 sec.

…B…....22 x 300

…G…….30 x 300

…O…….14 x 1800

…H.….….9 x 1800

…S.…...10 x 1800

Total exposure 22.75 hours

Image Width: 38.5 arcminutes (image A: 1.2 deg)

Processed by Alex Woronow (2020) using PixInsight, Skylum, Topaz, SWT

NGC 3199 owes its bubble shape and complex streamers and arches to a Wolf-Rayet star (WR 18) near its center. Approaching the end of its life, Wolf-Rayet 18 is massive, energetic, flooding its surroundings with thick, intense, hypersonic winds pushing away, heating, and ionizing the pre-existing interstellar cloud of gases and dust before an expanding shock-wave front.

In this original image (at original resolution), if I’ve done the arithmetic correctly, one pixel at the distance of Ngc 3199 (12 ly) spans 620x10^6 km. Therefore the strings of glowing gas, which as small as 3 pixels wide, have a physical width of 1.9 billion kilometers—OMG! Rather remarkable, I’d say. (Image B is a wider view that has other interesting features too.)

Processing: The color assignments for the narrowband images follow their true colors: Ha and SII into red, OIII into equal parts blue and green, with an inferred portion of H-beta going into the blue. But the first step involved subframe selection and weighting using SWT. Then, before being stretched and combined into a color image, The by-filter linear stacks underwent star removal. A synthetic luminosity component came from a mixture of the narrowband, starless images. This synthetic luminosity was denoised and sharpened separately before being combined with the denoised and color-adjusted RGBSHO starless image. Then more processing, and finally, the transference of the stars from a color-calibrated RGB image into the LSHORGB image, from the final presented above…I’ve almost convinced myself the work was worth it. BTW, this rendering has not had any “artistic” touches applied. It’s just as WR 18 sculpted it!