Thor's Helmet
Thor's Helmet
Wolf-Rayet Bubble in Canis Major

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Thor's Helmet: So named for its resemblance to the mythical Norse god's helmet, this is a gas cloud being shaped by the stellar winds from a very massive, very hot and very old star at the center of the "helmet," called a "Wolf-Rayet" star (this is the brightest star inside the helmet, just above the center of the helmet). These stars are about 20 times the mass of our Sun, or more, and they are losing mass at very high rates, possibly as a foreshadowing of going supernova. The color of the nebula is caused by ionization of the gas by the hot Wolf-Rayet star. Thor's Helmet is about 15,000 light years away, and about 30 light years across.


Technical Information:

(HaOIIIL)(HaR)(OIIIG)(OIIIB): Lum Data: 345 minutes; Ha Data: 690 minutes; OIII Data: 420 minutes; RGB: 165:180:225. Luminance layer consists of a blending of the luminance, OIII and Ha data; red channel consists of a blending of the Ha data and the R data; green channel consists of a blending of the OIII data and the G data; and blue channel consists of a blending of the OIII data and the B data. Ha and OIII images were all 30-minutes subexposures; RGB images were all 15-minute subexposures.

Equipment: 14.5" RC Optical Systems Ritchey-Chretien Cassegrain telescope with ion-milled optics; SBIG STL11000M (with Astrodon Generation 2 filters), on a Bisque Paramount ME German Equatorial Mount.

Image Acquisition/Camera Control:MaximDL, working in concert with TheSky v6, all controlled with ACP Observatory Control software.

Processing: All images calibrated (darks and dawn flats), aligned, sigma reject performed, and combined in Pixinsight. Some post-processing performed in Pixinsight; some in Photoshop CS5.

Location: Data acquired remotely from Fair Dinkum Skies, near Moorook, South Australia.

Date: Images taken in January and February of 2015. Image posted May 8, 2015.

CCD Chip temperature: -5C

Copyright 2015 Mark de Regt

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