Online reading assignment: fusion, nebulae, star cluster ages (SLO campus)

Astronomy 210, fall semester 2014
Cuesta College, San Luis Obispo, CA

Students have a weekly online reading assignment (hosted by SurveyMonkey.com), where they answer questions based on reading their textbook, material covered in previous lectures, opinion questions, and/or asking (anonymous) questions or making (anonymous) comments. Full credit is given for completing the online reading assignment before next week's lecture, regardless if whether their answers are correct/incorrect. Selected results/questions/comments are addressed by the instructor at the start of the following lecture.

The following questions were asked on reading textbook chapters and previewing presentations on fusion, nebulae, and star cluster ages.

Selected/edited responses are given below.

Describe something you found interesting from the assigned textbook reading or presentation preview, and explain why this was personally interesting for you.
"Hydrostatic equilibrium--I like the cheerleading analogy because it helped me understand the main concept."

"The 'House Party' model was a pretty clever way to describe stars and their turnoff points."

"There are only three colors emitted by nebulas."

"Fusion was interesting to me because I drive a Ford Fusion."

"Smaller stars will live longer...what? I would have thought that bigger stars would live longer."

"How much the pressure can differ from a large star to a small star. also found it interesting how much pressure and heat have to do with fusion."

"How stars can take hydrogen and change it into helium and energy! Just blows my mind, plus how these elements are made, making planets and life. Never thought of it this way."

"The process of nuclear fusion is interesting because it's where all elements in the universe originate. We're all stardust, man."

"The way an emission nebula works is the same way a neon light works...wow, mind blown!"

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"Turn-off points confused me very much. I had trouble comparing the 'house party' model to it."

"Hydrogen fusion deeply confuses me. Everything about it. The words are hard to understand and the concepts just don't click with me."

"The mass-luminosity relation because I don't understand it."

"As stars leave the main sequence category, does that mean they die? Since all of their hydrogen in their cores leave when leaving the main sequence then what happens? Just made me ponder while reading the section."

"Telling which nebula is which is confusing because I mix up colors a lot."

"What created the interstellar medium and how is it possible for it to form into a star?"

Fusion requires high temperatures in order for nuclei to move quickly enough to:
break heavy elements apart.  ** [2]
create convection currents.  * [1]
overcome gravity.  *** [3]
overcome repulsion.  ************************** [26]
(Unsure/guessing/lost/help!)  *** [3]

Briefly explain why "cold fusion" (producing energy from hydrogen fusion at room temperature) would be implausible.
"Under low pressures and temperatures, hydrogen does not get squeezed very much, and moves slowly, they won't collide with each other very much, or not at all. Not much squeezed, not much energy produced."

"In order for hydrogen fusion to work the protons need a lot of energy so that they move so fast they crash into each other and create energy. A room temperature atmosphere would not produce the need amount of energy."

"I don't understand the fusion section. please help."

"Because it needs heat, not cold."

Rank the fusion rates of these main-sequence stars (1 = fastest, 3 = slowest). (There are no ties.)
(Only correct responses shown.)
Low mass (red dwarf): slowest fusion rate [91%]
Medium-mass (sunlike): medium fusion rate [97%]
Massive: fastest fusion rate [89%]

Match the three different types of nebulae with their colors.
(Only correct responses shown.)
Emission: pink [80%]
Reflection: blue [83%]
Dark: brown/black [91%]

Match the three different types of nebulae with their composition.
(Only correct responses shown.)
Emission: hydrogen [91%]
Reflection: small dust particles [89%]
Dark: large dust particles [94%]

If there was an open invitation to a house party (no specific time given), when would you show up?
Early, or on time.  ****** [6]
When the most people should be there.  ****************************[28]
After most everyone has left.  * [1]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"So what time is the house party? When would you show up to the party? Or does the party not start until P-dog arrives?"

When are we going to look through the telescope at the Bowen Observatory again?" (Next week, after the end of class. Weather permitting.)

"What are you doing for Halloween?" (Already done.)

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