The Iris Nebula


Oct. 9, 2020

Caldwell Catalog C4

This beautiful, blushing nebula is unique amongst its counterparts. While many of the nebulae visible in the night sky are emission nebulae — clouds of dust and gas that are hot enough to emit their own radiation and light — Caldwell 4, otherwise known as the Iris Nebula or NGC 7023, is a reflection nebula. This means that its color comes from the scattered light of its central star, which lies nestled in the abundant star fields of the constellation Cepheus. Located some 1,400 light-years away from Earth, the Iris Nebula’s glowing gaseous petals stretch roughly 6 light-years across.

This nebula is of particular interest to scientists because of its colors. Reflection nebulae glow because they are made up of extremely tiny particles of solid matter, up to 10 or even 100 times smaller than dust particles on Earth. These particles diffuse the light around them, giving the nebula a second-hand glow that’s typically bluish (like our sky). While the Iris Nebula appears predominantly blue, it includes large filaments of deep red, indicating the presence of an unknown chemical compound likely based on hydrocarbons. Studying nebulae like this one helps astronomers learn more about the ingredients that combine to make stars.

This close-up image, showing one rosy-colored region within Caldwell 4, is a composite of four exposures captured by Hubble’s Advanced Camera for Surveys in visible and near-infrared filters. Astronomers also studied the nebula with Hubble’s Near Infrared Camera and Multi-Object Spectrometer to determine which chemical elements are present in Caldwell 4.

Image Credit: NASA/ESALast Updated: Oct. 9, 2020Editor: Yvette Smith

9 thoughts on “The Iris Nebula

  1. Nobel winner
    Sir Roger Penrose: ‘The Big Bang was not the beginning. There was something before, and that something is what we will have in our future.
    He said he had found six ‘warm’ points in the sky (dubbed ‘Hawking Points’) which are around eight times the diameter of the Moon, that ‘leak’ radiation and eventually evaporate away entirely. The timescale for the complete evaporation of a black hole is huge, possibly longer than the age of our current universe, making them impossible to detect. However, Sir Roger believes that ‘dead’ black holes are from earlier universes or ‘aeons’ and observable now.

  2. hmmmm…. I don’t know, it looks kind of like Baby Dumbo holding up a book and trying to read it, or soemthing.

    Nice photo, though. When I see something like that, I wonder how many of those stars have planetary systems around them. I like this.

  3. Can’t contain myself:

    Shakespeare Quick Quotes. There are more things in heaven and earth, Horatio, Than are dreamt of in your philosophy. – Hamlet (1.5.167-8), Hamlet to Horatio.
    Sounds about right… scarily right.

  4. I read a novel a long time ago, whose name I can’t recall, but it was set in a future Ice Age on Earth. The cause of the Ice Age was known without doubt: the Solar System had passed through a vast interstellar dust cloud (or vice versa). It wouldn’t take much scattering to substantially reduce the insolation at the top of the atmosphere. But that’s a first-order item. Such things as shifting the spectrum due to preferential scattering, magnetohydrodynamic effects of solar wind/dust interactions and their effect on the Earth’s magnetosphere, and dust in the Earth’s atmosphere…well, we could go on and on with the topics, and have no answers yet.

    But every discussion I’ve seen on the topic dismisses it out of hand. Why is that?

    • I’m wondering about how red those stars are. Guessing they might be somewhat obscured by (or embedded in) the dust to be that reddened. The Hubble has the ability to see into a small portion of the near infrared. James Webb telescope will see into much of the infrared band.

  5. The Hubble Telescope is like the Energizer Bunny, it just keeps going and going and going.

    The Hubble Telescope is an amazing, on-going story. It is worth every penny we spent on it.

    I think planetary formation is a natural consequence of star formation. If you see stars, there will be smaller bodies orbiting them, except possibly in some unusual cases.

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