I was able to do a better pseudo Hubble Palette with L-Ultimate in this shot of the Cave Nebula. Better than the previous shot of the Bubble Nebula.
Sh2-155 (also designated
Caldwell 9,
Sharpless 155 or
S155) is a
diffuse nebula in the constellation
Cepheus, within a larger nebula complex containing emission, reflection, and dark nebulosity. It is widely known as the
Cave Nebula, though that name was applied earlier to Ced 201, a different nebula in Cepheus. Sh2-155 is an ionized
H II region with ongoing
star formation activity,
[1] at an estimated distance of 725 parsecs (2400 light-years) from Earth.
[2][3]Sh2-155
[4] was first noted as a galactic emission nebula in 1959 in the extended second edition of the
Sharpless catalogue,
[5] being a part of the much larger Cep OB3
Association.
[5] Although Sh2-155 is relatively faint for amateur observation, some of its structure may be seen visually through a moderately sized telescope under dark skies.
[6][7]Sh2-155 lies at the edge of the Cepheus B cloud (part of the Cepheus
molecular cloud), and is
ionized by young stars from the Cep OB3 association.
[8] It has been suggested that radiation from the hot
O-type star HD 217086 is compressing the region, triggering the formation of a new generation of stars.
[9] A study of the region's
young stellar objects by the
Chandra X-ray Observatory and
Spitzer Space Telescope shows a progression of stellar ages in front of the cloud, supporting the hypothesis of
triggered star-formation.
[10][11]
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