Classroom Aid - Density Wave Theory
Channel: David Butler
Date: 2020-08-16

Text - http://howfarawayisit.com/wp-content/uploads/2020/08/The-Local-Galaxy-Volume-2020-edition.pdf
Wiki page
https://howfarawayisit.fandom.com/wiki/Encyclopedia_Howfarawayica
In this segment of our “How far away is it” video book, we cover the local galaxy volume compiled by the Spitzer Local Volume Legacy Survey team.

The survey covered 258 galaxies within 36 million light years. We take a look at just a few of them including: NGC 4214, Centaurus A, NGC 5128 Jets, NGC 1569, majestic M81, Holmberg IX, M82, NGC 2976,the unusual Circinus, M83, NGC 2787, the Pinwheel Galaxy M101, NGC 6503, the Fireworks Galaxy and its disappearing star, M106, NGC 3344, NGC 4485, the Sombrero Galaxy M104 including Spitzer’s infrared view, NGC 1512, the Whirlpool Galaxy M51, M74, M66, and M96. In addition, we cover the Density Wave theory that attempts to explain how spiral arms in spiral galaxies exist as they do.

We end with a look at the tuning fork diagram created by Edwin Hubble with its description of spiral, elliptical, lenticular and irregular galaxies.