28 October 2016 | NGC 772

NGC 772

Credit: Karel Teuwen | Click image to enlarge and here for full-size (13MB)

Image Data
  • Location: Verclause (France)
  • Date taken: 26, 27, 29, 30/08 and 01, 02, 03, 04/09/2016
  • Camera: FLI ML16803 + CFW-5-7
  • Optics: 40cm corrected [email protected]
  • Filters: Astrodon Gen2 Tru-Balance E-series LRGB
  • Exposure: Lum : 500 min (1x1bin) and RGB 280:280:280 min (1x1bin)

NGC 772 is located in the constellation of Aries at approximately 130 million light years in distance. It’s classified as an unbarred spiral galaxy and is believed to be twice the size of our own galaxy at 200,000 light years across. It also has a designation of Arp 78. This additional classification by Halton Arp in 1966 was due to the galaxy being an irregular shape and having a peculiar structure that at that time was not understood.

There are several other satellite galaxies close-by. Directly above NGC772 there’s a line of three galaxies, right to left NGC770, 2MASX J01590581+1857308 and on the left PGC 7493. The gravitational tidal force of the dwarf elliptical galaxy NGC770 is thought likely to have caused the single elongated outer spiral arm.

There’s a noticeable Integrated Flux Nebula (IFN) or its other name Galactic Cirrus around the whole frame. IFN are huge and soft nebulous filament systems belonging to the high galactic latitudes of the Milky Way. The largest of these systems extends along the northernmost constellations of the Northern hemisphere. The clouds themselves are made up of infinitesimally small interstellar dust particles hydrogen and carbon monoxide and other elements, but because of our position in the Milky Way we are always looking outwards and so our views include these huge dust systems.

Galactic Cirrus was first recorded on an optical plate at the Palomar Observatory in 1965 and then catalogued by B.T. Lynds. The IFN can be seen because the interstellar dust within the cloud reflects blue light and also glows red as it is illuminated by the very glow of our own Milky Way. For some time it was mistakenly identified as evidence of galactic interactions in some specific area, or by many imagers it was actually considered to be an artifact and so was processed out. Only now are we fully appreciating the expanse and depth of this faint and tantalising interstellar dust.

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