NGC 2359, also known as Thor’s Helmet, is an emission nebula in the constellation Canis Majoris. The bubble-shaped nebula consists of a mixture of material lost by the central Wolf-Rayet star at an earlier ejection and the surrounding interstellar medium, which is swirled, compressed and ionized by interaction with its strong stellar wind. NGC 2359 has an apparent brightness of +11.45 mag and an angular extension of 10′ × 5′. It is about 15,000 light years away from the solar system and has a diameter of about 20 light years. It still expands at 26 kilometers per second. The mass of the bubble is estimated at 70 to 140 solar masses [Wikipedia].
The photo is a bicolor image from 27. Feb. 2019 with exposure times of 10 x 10min in the light of the “forbidden” lines of the double ionized oxygen and 8 x 10min in the light of the hydrogen alpha line.
Equipment: 115/800mm APO refractor on EQ6 pro synscan, Baader narrow band filter, ATIK383L+ at -20°C sensor temperature, finder guiding. Location: Near Marienstatt Abbey in the northern Westerwald,
Author: Peter Stinner, member of the STScI.
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