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Gamma Cassiopeiae Nebula

Sh2-185, IC 59, IC 63

The Gamma Cassiopeiae Nebula is a curtain of nebulous material associated with star Gamma Cassiopeiae (also called Cih or Navi, and representing the central point in the 'W' shape of Cassiopeia). The nebula is formed from two distinct lobes, each illuminated by the light of the star: the fainter of these lobes to the north of the star is designated IC 59, and the brighter to the northeast is IC 63. The combined nebula is also collectively catalogued with the Sharpless number Sh2-185.

The two wedge-shaped objects in this image are the two lobes that make up the Gamma Cassiopeiae Nebula, with IC 63 being the brighter eastern element, and IC 59 the fainter element to the north. Both parts of the nebula are illuminated by the blue star Cih or Gamma Cassiopeiae, partially visible to the southwest here. Imagery provided by Aladin sky atlas

The entire nebula structure is some ten light years across, and extends out from a distance of three light years from the star Cih, which itself is estimated fall some 613 light years from the Solar System. Cih is a highly energetic star, emitting thousands of times as much energy as the Sun, and this radiation interacts with the Gamma Cassiopeiae Nebula to illuminate the hydrogen that makes up it clouds.

Of the two elements that make up the nebula, IC 63, the northeastern lobe, is both a reflection and an emission nebula, shining in reddish light as its atoms are ionised by the radiation from the powerful neighouring star. IC 59 to the north is a little more distant, and shows less direct interaction with Cih's radiation. This northern part of the nebula is primarily a reflection nebula, made visible by the intense starlight emitted by the star.


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