Lecture 13
Interstellar medium, formation of stars
Wednesday July 23, 2008
Finished HR diagram from last time, did in-class activity, then lecture
on the ISM/star formation (on Angel).
We discovered that large clouds of gas/dust can fragment and collapse to form stars.
Two relevant youtube videos you might find interesting: Spitzer
looks at star forming regions, and a volume visualization of the Orion nebula.
Tomorrow we will do an in-class activity utilizing DS9, so
if you plan to bring your laptop please install that program.
Concepts:
- Reddening: Dust cloud scatters blue light, lets red light through
- Nebula: "Fuzzy" region composed of diffuse gas and dust
- Reflection nebula: Bluish color, scattered light redirected to line of sight
- Emission nebula: Reddish color (H-alpha), powered by hot young stars
- Dark dust clouds/molecular clouds: cold gas and dust; can be clumped as molecules. See in radio
Vocabulary:
- Protostar: Stage at which collapsing cloud has defined surface but core not hot enough for H->He fusion yet
- T-Tauri phase: Protostars can have strong winds, jets
- Brown dwarf: Failed star (less than 0.08 solar masses) that doesn't fuse H->He in core; still much larger than a planet
Activity:
Used the HR diagram, our intuition, and a little math to evaluate the prospects for intelligent life around Sirius.
Random link:
Excerpt from Chicago Tribune article titled "Heavenly bodies converge for NASA"
NASA has used human cadavers to test the new Orion space capsule that is supposed to take astronauts back to the moon sometime around 2020.
Three cadavers were used in experiments at Ohio State University last year to test the safety of new spacesuits and seats, allowing engineers to measure the extreme forces to which astronauts will be subjected when the capsule returns to earth by parachute after each mission.
Updated July 23, 2008