17 December 2016 | The Iris Nebula

The Iris Nebula

Image credit: Patrick Winkler | Click image to enlarge

Image Data

  • Location: Siegenfeld, Austria
  • Date: 3 nights in September 2016
  • Camera: FLI ML 16200
  • Optics: TeleVue NP 127fli
  • Mount: ASA DDM60 Pro
  • Exposure: LRGB 180 60 60 60 (5 min subs)

On Earth, we tend to find dust nothing more than a nuisance that blankets our furniture and causes us to sneeze. Cosmic dust can also be a hindrance to astronomers because cameras using visible light cannot see through it. However, studying cosmic dust in detail helps astronomers to pin down the ingredients of the raw mixture that eventually gives birth to stars.

The Iris Nebula, or NGC 7023, seems to be clogged with cosmic dust. With bright light from the nearby star HD 200775 [1] illuminating it from above, the dust resembles thick mounds of billowing cotton. It is actually made up of tiny particles of solid matter, with sizes from ten to a hundred times smaller than those of the dust grains we find at home [2]. Both background and foreground stars are dotted throughout the image.

NGC 7023 is a reflection nebula, which means it scatters light from a massive nearby star, in this case, HD 200775. Reflection nebulae are different from emission nebulae, which are clouds of gas that are hot enough to emit light themselves. Reflection nebulae tend to appear blue because of the way light scatters.

NGC 7023 was discovered by Sir William Herschel in 1794; the nebula is in the constellation of Cepheus, the King, in the northern sky. NGC 7023 is approximately 1400 light-years from Earth and about six light-years across.

[1] HD 200775 is about ten times the mass of the Sun.

[2] The typical sizes of cosmic dust grains range between a few hundredths of a micron and several microns.

Source

EAPOD Archive

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