Your traditional view of astronomy is optical. Think of the center as being red center with old stars, but in infrared the view is flipped around. It’s a way to reorient your wavelength orientation.

Introduction to Dust

What is dust? Is it just very small asteroids/meteorites.

There’s some periodicity to when major extinctions occur.

We get 40 tons a day of interstellar stuff landing on earth. 1 dust grain/m²/10 hours Most of it is vaporizing.

Is it that sneeze inducing stuff?

Is it conscious dark matter is especially attracted to adults?

Is it the stuff of which we are made?

The Milky Way is patchy¹

Herschel 1800 hypothesized there must be patchy obscuration

Trumpler 1930 smaller star clusters fainter than expected, because in part obscured by dust.

Jargon

• Extinction - extinguishing light
• Reddening
• Polarization
• reflection nebulae

In regular interstellar space dust is about 150m apart. The entire Galaxy is filled with dust.

Zodiacal dust is in the plane of the solar system.

Interstellar dust: silicate, carbon

Circumstellar: CO, silicon carbide, amorphous silicate, PAHS,² water ice, polyformaldehyde

Cometary: silicates, PAHs, water ice

Asteroidal: carbonaceous chondrites

His concept of this interplanetary dust is that it’s sort of an accretion process. The dust is tinier than human hair. Dust is constantly being created from stars and other sources.

Some of the dust is really tiny.

Mid-infared features are attributed to vibrational modes of PAHs, aromatic ring skeletons with H atom appendages. Triggered by optical or UV photons.

Mid-infrared emissions are ubiquitous

Small dust grains form in the atmospheres of stars especially Red Giants. Because theory suggests dust grains will only survive for about a billion years.

We watched a short film about NASA’s Stardust mission, which was designed to bring back samples of stardust.³

See the Stardust module re-enter. Very, very cool.

Expectations:

Comets formed in the cold, outermost reaches of the early solar system, where the material was similar to general interstellar space. Ices formed 30 degrees above absolute zero. Solid matter mostly aggregates of tiny grains, minerals, and carbon. Ancient remains of interstellar dust. A small portion would be silicate crystals, created by mild warming by the Sun.

BUT the results

The deep carrot-like tracks in the aerogel required relatively large storng particles. Particles a million times more massive than interstellar dust. Interstellar dust composed only a small portion Wild 2. Silicate crystals are prevalent in Wild 2, unlike in interstellar dust. Moreover they are larger and have compositions more complex than expected. Extreme heating required.

SOFIA Stratospheric Observatory for Infrared Astronomy

Watched short film “More than the eye can see” about infrared

I will frankly admit that I’m almost totally lost right now. I think what he’s talking about is what you can extrapolate about the universe based on dust and how to do it. There are a lot of numbers which I’m not holding onto. Other people are asking intelligent questions.

Ooo! Posters of the galaxies he found with the Spitzer.

1. We are seeing very pretty pictures that I wish I could show you. [↩]
2. Polycyclic Aromatic Hydrocarbon [↩]
3. Not the Neil Gaiman film [↩]

Tags: Journal, LaunchPad Astronomy Workshop

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