20131029

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

Astronomy 210, fall semester 2013
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.
"The process of self-starting stars or planets from a molecular cloud is a very interesting concept. In a way it shows that the cosmos is forever changing and in billions of years it could look completely different."

"The cheerleaders."

"I loved the pictures of the star clusters and the nebulas, very pretty."

"I think it's interesting that protons repel each other. It's kind of like magnets."

Makes me mad how pink, blue, red, violet are the only 'real' nebulae colors, and that the other colors are 'false.'"

"I find interstellar dust interesting because its made of particles which are about the size of particles found in cigarette smoke."

"The fact that the sun can kill us one day."

"I found the 'house party' example to be very interesting and relatable. I liked how you compared a real life situation to astronomy, it makes it very easy to learn, understand, and remember."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"I don't understand how stars of different masses evolve differently. Why do massive stars move quicker? Does it have to do with the amount of energy they produce? If so, then why does that affect the rate of aging?"

"I've been confused since day one, sorry. The sky just ain't my thing."

"Nuclear fusion was kind of confusing...I think its name makes it seem more intimidating than it really is. I want to hear more about it in class."

Briefly explain why "cold fusion" (producing energy from hydrogen fusion at room temperature) would be implausible.
"Because hydrogen protons naturally repel against each other, so in order for them to fuse together the pressure as well as the temperature need to be extremely high."

"It would be implausible because the protons would be moving too slow and not collide."

Fusion requires high temperatures in order for nuclei to move quickly enough to:
break heavy elements apart.  * [1]
create convection currents.  ** [2]
overcome gravity.  * [1]
overcome repulsion.  ***************** [17]
(Unsure/guessing/lost/help!)  [0]

A __________ main-sequence star has the fastest fusion rate.
low-mass (red dwarf).  * [1]
medium-mass (sunlike).  [0]
massive.  ******************* [19]
(There is a tie.)  [0]
(Unsure/guessing/lost/help!)  * [1]

Match the three different types of nebulae with their colors.
(Only correct responses shown.)
Emission: pink [95%]
Reflection: blue [95%]
Dark: brown/black [95%]

Match the three different types of nebulae with their composition.
(Only correct responses shown.)
Emission: hydrogen [86%]
Reflection: small dust particles [95%]
Dark: large dust particles [81%]

If there was an open invitation to a house party (no specific time given), when would you show up?
Early, or on time.  ** [2]
When the most people should be there.  ****************** [18]
After most everyone has left.  * [1]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"A reflection nebula and a dark nebula are similar in having small or large dust particles, so how do you tell them apart most easily?" (Small dust particles, like in cigarette smoke are bluish in appearance, while larger dust particles from an oil fire appear brown/black.)

"Those videos of space you keep showing us make me feel so tiny and insignificant. :(" (You're welcome.)

"So, pretty sure your presentations help out way better than the book. Fo' real though, P-dawgie."

"The 'house party' analogy really worked! Makes it so much easier to remember."

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