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. It makes sense that it's necessary, but I had no idea that the weight and pressure of star layers must be equal to prevent the star from collapsing in on itself. The thought of a star compromised of many layers that must maintain equilibrium is intriguing."
"That pressure and temperature are the key factors in determining if hydrogen fuses or not."
"I find pictures of nebulae beautiful, so understanding that it's either the hydrogen atoms, or different density dust clouds are what makes that happen is amazing."
"How particles in space can completely change the color of the space around you. It's just really interesting to me because I love pretty colors."
"Learning how stars are born is very interesting. Knowing their origin is something I didn't understand."
"I think it's pretty cool how when some stars explode, it causes more stars to form because of the gas and dust smashing together. That star really went out with a 'bang.'"
"To learn that small stars will go on to live longer than the current age of the universe."
"I thought your house party explanation was interesting because it is a much easier way to remember the different mass stars age."
"The house party model was interesting when comparing it to stars. The massive stars come early and leave early. The medium mass stars come a little later but don't stay too late. While the low mass stars come way later and leave way later also."
"I found that you can connect so many things to real life, like the cheerleaders and the house party."
"I haven't gotten to the reading yet."
Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"Some of the reading in this chapter was a little dry and confusing at first, but when paired with the presentations was understandable."
"The H-R diagrams were confusing because I did not understand what they were trying to represent."
"The section on hydrogen fusion was a lot to take in. I could use some confirmation that I'm headed in the right direction."
"I think the fusion portion was very confusing for me. It's confusing for me because I don't quite understand what it is."
"The star formation and nebulae was a bit confusing just because I don't get how the star becomes a star from it."
"I found interstellar reddening to be confusing. How can dust scatter blue light out of star light?"
"I skimmed through the whole house party analogy and I didn't get the story at all so I want to hear it so it will help me."
"The house party model."
"The turn-off point for star clusters."
"Didn't really find anything to be all that confusing."
Rank the luminosities of these main-sequence stars (1 = brightest, 3 = dimmest). (There are no ties.)
(Only correct responses shown.)
Massive: brightest luminosity [94%]
Medium-mass (sunlike): medium luminosity [91%]
Low mass (red dwarf): dimmest luminosity [94%]
Rank the fusion rates of these main-sequence stars (1 = fastest, 3 = slowest). (There are no ties.)
(Only correct responses shown.)
Massive: fastest fusion rate [76%]
Medium-mass (sunlike): medium fusion rate [94%]
Low mass (red dwarf): slowest fusion rate [79%]
Fusion requires high temperatures in order for nuclei to move quickly enough to:
break heavy elements apart. ******* [7] create convection currents. *** [3] overcome gravity. ** [2] overcome repulsion. **************** [16] (Unsure/guessing/lost/help!) ***** [5]
Briefly explain why "cold fusion" (producing energy from hydrogen fusion at room temperature) would be implausible.
"Fusion requires very hot temperature in order for photons to overcome repulsion."
"Because a hydrogen nucleus is positively charged and will repel other hydrogen (due to the same charge), and so at room temperature there will not be enough factors to get them to collide."
"Fusion occurs when protons undergo high pressures and temperatures so cold fusion would be implausible."
Match the three different types of nebulae with their colors.
(Only correct responses shown.)
Emission: pink [82%]
Reflection: blue [79%]
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 [94%]
Dark: large dust particles [94%]
Rank the lifetimes of these main-sequence stars (1 = shortest, 3 = longest). (There are no ties.)
(Only correct responses shown.)
Massive: shortest main-sequence lifetime [73%]
Medium-mass (sunlike): medium main-sequence lifetime [88%]
Low mass (red dwarf): longest main-sequence lifetime [76%]
If there was an open invitation to a house party (no specific time given), when would you show up?
Early, or on time. **** [4] When the most people should be there. ******************** [29] After most everyone has left. [0]
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"I think going over this information with you in class would greatly help me to understand it a little bit better."
"Can you go over why stars with more mass would have shorter lifetimes?"
"'After it has depleted all the hydrogen in its core, it begins to die, moving from left-to-right, cooling down (and increasing in size), becoming a supergiant. All of these processes for a massive star take an extremely short amount of time.' What, approximately, is that short amount of time?" (A few million years, or even less time than that.)
"Could we please go over the fusion stuff?"
"I tried to look at the stars when the other night, but found that in order to look at the starwheel I needed light. this caused my eyes to have to readjust to the dark. by the time my eyes adjusted again I forgot what was on the starwheel. Any suggestions on how to use a starwheel and avoid the time it takes for my eyes to adjust to the dark?" (Wrap red cellophane or a red piece of cloth over your flashlight (or smartphone light); as red light least affects your night vision.)
"Are you a party go-er, or a party thrower?" (I'm more of a "party go-er," while Mrs. P-dog is more of a "party thrower.")
"When would you show up to the house party?" (Fashionably late. Or early. Depends on how much we like the hosts.)
"Sounds like you've had some house parties with 'low-mass stars' before?" (No comment.)
"How come you don't post the answers to the worksheet packets?" (There is no published answer key for the worksheet packets, but you can e-mail me your responses to specific questions, and I can "grade" them for you by indicating which are correct or incorrect, or also come to office hours to go over them.)
"Will the lecture before Thanksgiving be any shorter?" (That night is just a review session for the next midterm and an extra-credit movie. If you can come, come; if you can't, then make sure you review for the midterm on your own.)
"Favorite genre of music? (I'm one of the DJs for Monday swing dancing at the Madonna Inn.)
"What did you do for Halloween?" (We celebrated Madonnaween at the Madonna Inn the Monday before Halloween. I didn't dress up as a DJ, but did tag-team DJ that night with Mrs. P-dog!)
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