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MW 9 - Integrated Flux Nebula in the constellation Bird of Paradise (Apus) and the galaxies IC 4633 and IC 4535

Short description:

In the constellation Apus (the Bird of Paradise) there are large molecular clouds (Integrated Flux Nebula (IFN), they lie far above the disk plane of our galaxy near the southern celestial pole. Integrated Flux Nebulae are relatively newly defined astronomical objects, the term IFN was coined by the American amateur American amateur astronomer Steve Mandel. They are extremely weak luminous, cold molecular cooling clouds of the interstellar medium and are consist mainly of the elements hydrogen, carbon, carbon monoxide carbon monoxide and other elements. They are conspicuously concentrated in the towards the northern and southern celestial poles.

Compared to the typical and well-known gas nebulae within the plane of our Milky Way (reflection nebulae, H-II regions), IFNs lie outside the disc centre of the Galaxy. And unlike most nebulae in the Galactic plane, they do not reflect, scatter or ionise due to the radiation of individual stars or star clusters, but due to the energy of the integrated energy flow of ALL stars in the Milky Way. IFNs have been little studied because they are extremely faint and do not stand out against the noise of the sky background in a less than perfect dark sky.

The Bird of Paradise is one of the constellations introduced at the end of the 16th century by the Dutch sailors Pieter Dirkszoon Keyser and Frederick de Houtman. It is not known whether the sailors "created" the constellation or took it over from the inhabitants of the South Seas. It is an inconspicuous constellation near the southern celestial pole, only two stars are brighter than 4th magnitude. Johann Bayer included the constellation under the name "Avis Indica" (Indian Bird) in his celestial atlas Uranometria published in 1603.

Our image shows a large part of MW 9 (Mandel/Wilson) in the constellation of the Bird of Paradise. The north-eastern part (top left of the image) is reminiscent of an approaching, large bird of prey. At the bottom right of the image are two brighter galaxies, IC 4633 and IC 4635, both at a distance of about 110 million light years from the solar system, IC 4633 (3 x 4 arcminutes) is classified as type Sc and IC 4633 (3 x 0.7 arcminutes) as Hubble SBb type. Furthermore, our image shows some faint galaxies from the Leda and PGC catalogue. A distance of MW 9 to the solar system is not known.

Further Informationen:
A nice description (german language only) of the constellation Pavo can be found here. For the project of photographing IFNs by Steve Mandel a pdf-file in download here.

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