IC 410 In Ha(Astrodon 5nm)
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The Rosette Nebula (also known as Caldwell 49) is an H II region located near one end of a giant molecular cloud in the Monoceros region of the Milky Way Galaxy. The open cluster NGC 2244 (Caldwell 50) is closely associated with the nebulosity, the stars of the cluster having been formed from the nebula's matter.
The cluster and nebula lie at a distance of 5,000 light-years from Earth) and measure roughly 130 light years in diameter. The radiation from the young stars excites the atoms in the nebula, causing them to emit radiation themselves producing the emission nebula we see. The mass of the nebula is estimated to be around 10,000 solar masses.
The Iris Nebula (also known as NGC 7023 and Caldwell 4) is a bright reflection nebula in the constellation Cepheus. The designation NGC 7023 refers to the open cluster within the larger reflection nebula designated LBN 487.
The nebula, which shines at magnitude +6.8, is illuminated by a magnitude +7.4 star designated SAO 19158. It is located near the Mira-type variable star T Cephei, and near the bright magnitude +3.23 variable star Beta Cephei (Alfirk). It lies 1,300 light-years away and is six light-years across.
The Tarantula Nebula was observed by Nicolas-Louis de Lacaille during an expedition to the Cape of Good Hope between 1751 and 1753. He catalogued it as the second of the "Nebulae of the First Class", "Nebulosities not accompanied by any star visible in the telescope of two feet". It was described as a diffuse nebula 20' across.Johann Bode included the Tarantula in his 1801 Uranographia star atlas and listed it in the accompanying Allgemeine Beschreibung und Nachweisung der Gestirne catalogue as number 30 in the constellation "Xiphias or Dorado". Instead of being given a stellar magnitude, it was noted to be nebulous.The name Tarantula Nebula arose the mid 20th century from the appearance in deep photographic exposures.30 Doradus has often been treated as the designation of a star, or of the central star cluster NGC 2070, but is now generally treated as referring to the whole nebula area of the Tarantula Nebula.
