APOD: The Iris Nebula in a Field of Dust (2018 Aug 01)

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APOD Robot
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APOD: The Iris Nebula in a Field of Dust (2018 Aug 01)

Post by APOD Robot » Wed Aug 01, 2018 4:07 am

Image The Iris Nebula in a Field of Dust

Explanation: What blue flower grows in this field of dark interstellar dust? The Iris Nebula. The striking blue color of the Iris Nebula is created by light from the bright star SAO 19158 reflecting off of a dense patch of normally dark dust. Not only is the star itself mostly blue, but blue light from the star is preferentially reflected by the dust -- the same affect that makes Earth's sky blue. The brown tint of the pervasive dust comes partly from photoluminescence -- dust converting ultraviolet radiation to red light. Cataloged as NGC 7023, the Iris Nebula is studied frequently because of the unusual prevalence there of Polycyclic Aromatic Hydrocarbons (PAHs), complex molecules that are also released on Earth during the incomplete combustion of wood fires. The bright blue portion of the Iris Nebula spans about six light years. The Iris Nebula, pictured here, lies about 1300 light years distant and can be found with a small telescope toward the constellation of Cepheus.

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Re: APOD: The Iris Nebula in a Field of Dust (2018 Aug 01)

Post by Boomer12k » Wed Aug 01, 2018 7:02 am

Nice wide field...

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Torpedobait

Re: APOD: The Iris Nebula in a Field of Dust (2018 Aug 01)

Post by Torpedobait » Wed Aug 01, 2018 11:40 am

I hate to quibble about grammar, but your editing missed the instance where the writer said: "Not only is the star itself mostly blue, but blue light from the star is preferentially reflected by the dust -- the same affect that makes Earth's sky blue." The correct word is "effect". I expect better from rocket scientists! :lol2:

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Re: APOD: The Iris Nebula in a Field of Dust (2018 Aug 01)

Post by neufer » Wed Aug 01, 2018 12:17 pm

Click to play embedded YouTube video.
Torpedobait wrote:
Wed Aug 01, 2018 11:40 am

I hate to quibble about grammar, but your editing missed the instance where the writer said: "Not only is the star itself mostly blue, but blue light from the star is preferentially reflected by the dust -- the same affect that makes Earth's sky blue." The correct word is "effect".
https://www.etymonline.com/word/affect wrote:
<<affect (n.) late 14c., "mental state," from Latin affectus "disposition, mood, state of mind or body produced by some external influence.">>
Art Neuendorffer

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Re: APOD: The Iris Nebula in a Field of Dust (2018 Aug 01)

Post by Chris Peterson » Wed Aug 01, 2018 2:11 pm

Torpedobait wrote:
Wed Aug 01, 2018 11:40 am
I hate to quibble about grammar, but your editing missed the instance where the writer said: "Not only is the star itself mostly blue, but blue light from the star is preferentially reflected by the dust -- the same affect that makes Earth's sky blue." The correct word is "effect". I expect better from rocket scientists! :lol2:
Well, we're rocket scientists, not brain surgeons!
Chris

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neufer
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Re: APOD: The Iris Nebula in a Field of Dust (2018 Aug 01)

Post by neufer » Wed Aug 01, 2018 2:52 pm

Chris Peterson wrote:
Wed Aug 01, 2018 2:11 pm
Torpedobait wrote:
Wed Aug 01, 2018 11:40 am

I hate to quibble about grammar, but your editing missed the instance where the writer said: "Not only is the star itself mostly blue, but blue light from the star is preferentially reflected by the dust -- the same affect that makes Earth's sky blue." The correct word is "effect". I expect better from rocket scientists! :lol2:
Well, we're rocket scientists, not brain surgeons!
https://www.phrases.org.uk/meanings/its-not-rocket-science.html wrote:
<<Most of the early citations of 'not rocket science' relate to football; for example, this piece from a sports report in the Pennsylvania newspaper The Daily Intelligencer, December 1985:

"Coaching football is not rocket science and it's not brain surgery. It's a game, nothing more."

Prior to the 1980s, 'brain surgery' had been the occupation that simple tasks were said not to be. 'It's not brain surgery' dates from the 1960s. Before that, straightforward tasks were simply said to be 'as easy as pie' or 'as easy as falling off a log'.>>
Art Neuendorffer

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Re: APOD: The Iris Nebula in a Field of Dust (2018 Aug 01)

Post by Chris Peterson » Wed Aug 01, 2018 2:58 pm

neufer wrote:
Wed Aug 01, 2018 2:52 pm
Chris Peterson wrote:
Wed Aug 01, 2018 2:11 pm

Well, we're rocket scientists, not brain surgeons!
Nor is there one at the end of a space flight with all the landing parameters programmed in advance!
Chris

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DL MARTIN

Re: APOD: The Iris Nebula in a Field of Dust (2018 Aug 01)

Post by DL MARTIN » Wed Aug 01, 2018 3:00 pm

I wonder who came up with "There is no eraser on the end of a scalpel."?

Yiminy

Re: APOD: The Iris Nebula in a Field of Dust (2018 Aug 01)

Post by Yiminy » Wed Aug 01, 2018 4:21 pm

DL MARTIN wrote:
Wed Aug 01, 2018 3:00 pm
I wonder who came up with "There is no eraser on the end of a scalpel."?
The internet gives credit to "Douglas Leonard Martin in a letter to FDA in 1975"

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Re: APOD: The Iris Nebula in a Field of Dust (2018 Aug 01)

Post by MarkBour » Wed Aug 01, 2018 5:22 pm

APOD Robot wrote:
Wed Aug 01, 2018 4:07 am
the same affect that makes Earth's sky blue
© 2013 The Gilder Lehrman Institute of American History
www.gilderlehrman.org
Arthur Chapman, “Out Where the West Begins” (1917)

Out where the handclasp’'s a little stronger,
Out where the smile dwells a little longer,
That’s where the West begins;

Out where the sun is a little brighter,
Where the snows that fall are a trifle whiter,
Where the bonds of home are a wee bit tighter,
That’s where the West begins.

Out where the skies are a trifle bluer,
Out where the friendship’s a little truer,
That’s where the West begins;

Out where a fresher breeze is blowing,
Where there’s laughter in every streamlet flowing,
Where there’s more of reaping and less of sowing,
That’s where the West begins.

Out where the world is in the making,
Where fewer hearts in despair are aching,
That’s where the West begins.

Where there’s more of singing and less of sighing,
Where there’s more of giving and less of buying,
And a man makes a friend without half trying—
That’s where the West begins.
Mark Goldfain

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Re: APOD: The Iris Nebula in a Field of Dust (2018 Aug 01)

Post by neufer » Wed Aug 01, 2018 7:15 pm

Chris Peterson wrote:
Wed Aug 01, 2018 2:58 pm
Nor is there one at the end of a space flight with all the landing parameters programmed in advance!
  • Not that it wouldn't fit:
https://www.esa.int/spaceinimages/Images/2018/07/Fenix wrote:
Fenix : ESA 25/07/2018 4:22 pm

<<Sometimes the key to innovation is staying simple. Italian tech company D-Orbit applied this principle to their winning product submitted to last year’s Space Exploration Masters competition. In the case of D-Orbit’s Fenix propulsion system, the idea was both simple and small. The pen-sized booster prototype, is just 10 cm long and 2 cm wide – allowing small satellites to work smarter and explore farther.

The 10 x 10 x 10 cm CubeSats are deployed directly into orbit from space. They currently have no propulsion system to change orbit or deorbit at the end of their missions. With the FENIX, CubeSats could be employed for longer missions farther out in space.

Each of the four boosters is packed with solid propellant that provides thrust which is triggered by a simple electrical ignition system. The boosters can be configured at each corner of the CubeSat or doubled up on either side. Thanks to their lightweight and compact size, they do not take up much instrument space.

D-Orbit won a four-month ticket to test their prototype on the newly-installed ICE Cubes facility in the Columbus module of the International Space Station. The team will test the booster’s safe ignition mechanism inside an ICE cube experiment unit, without firing the actual propulsion system, to ensure that it works and is safe under space conditions.>>
Art Neuendorffer

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Re: APOD: The Iris Nebula in a Field of Dust (2018 Aug 01)

Post by RJN » Wed Aug 01, 2018 7:44 pm

Torpedobait wrote:
Wed Aug 01, 2018 11:40 am
... the same affect that makes Earth's sky blue." The correct word is "effect".
Sorry. I just fixed it on the main NASA APOD site. Thanks!
- RJN

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Re: APOD: The Iris Nebula in a Field of Dust (2018 Aug 01)

Post by Ann » Thu Aug 02, 2018 11:56 am

I know I'm late to the party, but...
APOD Robot wrote:

The brown tint of the pervasive dust comes partly from photoluminescence -- dust converting ultraviolet radiation to red light.
Is that another way of saying that these dust clouds glow a dull red because of low-level Hα emission, presumably caused by stray ultraviolet photons emitted by rare and distant hot stars and even rarer and hotter cataclysmic events?

Or to put it differently: The brown dust clouds are in reality very faint emission nebulas?

Ann
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Re: APOD: The Iris Nebula in a Field of Dust (2018 Aug 01)

Post by neufer » Thu Aug 02, 2018 1:05 pm

Ann wrote:
Thu Aug 02, 2018 11:56 am
APOD Robot wrote:

The brown tint of the pervasive dust comes partly from photoluminescence -- dust converting ultraviolet radiation to red light.
Is that another way of saying that these dust clouds glow a dull red because of low-level Hα emission, presumably caused by stray ultraviolet photons emitted by rare and distant hot stars and even rarer and hotter cataclysmic events?

Or to put it differently: The brown dust clouds are in reality very faint emission nebulas?
https://www.researchgate.net/publication/241545568_Luminescence_of_cosmic_dust_A_result_of_the_interaction_of_radiation_with_solid_matter wrote:
Astrophysics, Vol. 50, No. 4, 2007
0571-7256/07/5004-0548 : 2007 Springer Science+Business Media, Inc.

LUMINESCENCE OF COSMIC DUST -- A RESULT OF THE INTERACTION OF RADIATION WITH SOLID MATTER
  • by I. A. Simonia
-------------------------------------------------------------------------
<<The major forms of luminescence in cosmic dust particles include:

(1) photoluminescence of the particles excited by the UV radiation from stars, and
(2) cathodoluminescence of cosmic dust excited by fast electron and proton fluxes that form part of a stellar wind.

Other possible processes should not be excluded, in particular, thermoluminescence and ion-luminescence of cosmic dust.

UV photons (from the illuminating star) excite photoluminescence in circumstellar dust with variable dispersion. Here the atoms in the dust material go from the ground state to an excited state on absorbing the energy of incident photons and then return to the ground state while emitting optical photons of lower energies. The absorbed energy can reach the luminescence centers in the body of a dust particle in various ways, depending on the state of the particle (crystalline or amorphous). Each dust particle in a nebula will luminesce in a characteristic band that depends on a number of factors, including its chemical and mineralogical composition. If we assume a high level of chemical and mineralogical variety in the dust in a given nebula, then we may expect superposition of the individual spectral components leading to the appearance of broad bands in the spectrum of the nebula. Here the picture might be thus: each reflecting or other nebula would have broad emission in different spectral bands that is characteristic of only of that nebula. Nevertheless, current observational data indicate otherwise. The spectra of reflecting nebulae are found to consist either of extended red emission or of isolated, fairly narrow emissions of luminescence origin.>>
Art Neuendorffer