20131027

Online reading assignment: fusion, nebulae, star cluster ages (SLO 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.
"That all protons are positively charged and hate each other and repel."

"That you were able to relate cheerleading with fusion."

"Star formation--because it's freaking awesome."

"That a lot of what we see in pictures from outer space have false colors or are an artistic interpretation. This is intriguing because I didn't realize that photographer have so much liberty in editing space photos."

"How you were able to compare the star cluster age to a house party. Clever!"

"The process of star formation is interesting to me. I'm just fascinated by stars in general and learning how they form, how they live, and how they die is all pretty interesting to me."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"Fusion. All the pressure and stuff like that was really confusing."

"I need a bit more clarification on the application of the house party model. I understood the model, but I'm not sure that I'm applying it correctly."

"It was mentioned that main-sequence stars follow a pattern but there are other stars that follow no pattern, and it wasn't explained why."

"I feel like I have the same confusing comment each week. The vocabulary and formulas constantly throw me off. I feel like I am always look back to remind myself what a word is in reference to."

"How you know the age of a star. I know you need to look at the H-R diagram but where do you go from there?"

"I'm kind of confused about what a protostar is. I know that it is in a cloud and it's destined to become a star."

Briefly explain why "cold fusion" (producing energy from hydrogen fusion at room temperature) would be implausible.
"Cold fusion is implausible because protons would be moving too slow and would hardly collide, if they even collide at all."

"Because there is not enough heat and pressure to force the hydrogen atoms to fuse into helium atoms."

Fusion requires high temperatures in order for nuclei to move quickly enough to:
break heavy elements apart.  ****** [6]
create convection currents.  ***** [5]
overcome gravity.  ** [2]
overcome repulsion.  ************************* [25]
(Unsure/guessing/lost/help!)  *** [3]

A __________ main-sequence star has the fastest fusion rate.
low-mass (red dwarf).  ****** [7]
medium-mass (sunlike).  **** [4]
massive.  ************************* [25]
(There is a tie.)  ***** [5]
(Unsure/guessing/lost/help!)  * [1]

Match the three different types of nebulae with their colors.
(Only correct responses shown.)
Emission: pink [83%]
Reflection: blue [85%]
Dark: brown/black [98%]

Match the three different types of nebulae with their composition.
(Only correct responses shown.)
Emission: hydrogen [85%]
Reflection: small dust particles [83%]
Dark: large dust particles [76%]

If there was an open invitation to a house party (no specific time given), when would you show up?
Early, or on time.  *********** [11]
When the most people should be there.  **************************** [28]
After most everyone has left.  ** [2]

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.)

"So is it possible for there to be multiple parts to a nebulae? It seems that way from some of the pictures but I wasn't sure if there could be different type all clumped together." (Yes.)

"Why does fusion produce helium atoms? Just, why helium?" (It's the next largest stable element. Helium can be fused to produce larger elements, etc., but this is more difficult to do (with more protons in each nuclei that would repel each other), and would release less energy in the end, so heavier fusion requires higher temperatures, and is typically done near the end of a star's viable lifetime.)

"The 'house party model' may seem silly, but it is things like that that help me remember different things. For example, I remember that a lunar eclipse happens during a full moon by thinking of the band LMFAO. I can then remember that the 'LMF' part stands for 'Lunar Moon Full.'"

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