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.
"How others stars compare to the sun. I found it interesting that the sun is not that bright, it's just close."
"Learning about interstellar medium was interesting because I did think space was some what empty before I read this section."
"That space is dirty and full of dust with extra hydrogen floating around."
"The concept of how stars are powered by fusion alone is interesting. There are few things like it in the universe."
"How the colors of clouds in space were from different types of interactions with dust particles or hydrogen atoms."
"That different nebulae produces different colors. Anything pink in the universe automatically catches my attention, and I think it’s so cool that that color occurs naturally in space."
"I found the nebulas to be quite interesting, probably because they are so visually appealing. Also I find the composition of them insane."
"The sequence in the proton-proton chain basically fuels the nuclear reaction in main sequence stars. The conversion of hydrogen protons to helium produces energy in the form of gamma rays and positrons and neutrinos."
"It is unexpected that four hydrogen atoms would be needed to make one helium atom."
"I found how different stars go through different rates of fusion interesting because I previously figured that all stars experienced the same levels of fusion."
"How stars are born and how long they live. Puts our little lives in a little more perspective."
"I really like the 'house party' analogy, put a smile on my face while try to do this homework."
Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"The cheerleader model."
"I'm a bit confused about the 'cold fusion' question because I don't know how it would be implausible."
"How does the hydrogen become squished and turn into helium in the the proton-photon chain?"
"Fusion energy? How is energy created from two things smashing into each other?"
"Why certain types of stars have the lifespans that they do."
"Star cluster ages."
"This lesson isn’t really confusing at all for me. Further review about what colors go to what nebulae and what sizes of stars have to do with fusion and luminosity, etc. for memorization help would be appreciated though."
"I found nothing too confusing for this chapter."
Rank the luminosities of these main-sequence stars (1 = brightest, 3 = dimmest). (There are no ties.)
(Only correct responses shown.)
Massive: brightest luminosity [91%]
Medium-mass (sunlike): medium luminosity [97%]
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 [88%]
Medium-mass (sunlike): medium fusion rate [100%]
Low mass (red dwarf): slowest fusion rate [88%]
Fusion requires high temperatures in order for nuclei to move quickly enough to:
break heavy elements apart. ** [2] create convection currents. ** [2] overcome gravity. ** [2] overcome repulsion. ************************ [24] (Unsure/guessing/lost/help!) **** [4]
Briefly explain why "cold fusion" (producing energy from hydrogen fusion at room temperature) would be implausible.
"Cold fusion is implausible due to it missing one of the two major ingredients. Without the proper high temperature, protons cannot get over their repulsion from each other and can not form a chain to create the necessary hydrogen. With a cool temperature, they will continue to bounce away from each other."
"The temperature isn't high enough for the protons in hydrogen to collide and fuse, so instead, the protons may not collide very much or at all. This means little to no energy is produced."
"Cold fusion is implausible because it is not producing enough energy for the hydrogen protons which already repel each other to collide because they are moving too slow and aren't being squeezed together enough."
"Cold fusion would be implausible because heat is needed to move atoms faster and to overcome repulsion so that they can hit each other more and cause a fusion reaction."
"I don't understand fusion. If we could go into it in more detail in class that would be really helpful."
Match the three different types of nebulae with their colors.
(Only correct responses shown.)
Emission: pink [85%]
Reflection: blue [82%]
Dark: brown/black [88%]
Match the three different types of nebulae with their composition.
(Only correct responses shown.)
Emission: hydrogen [88%]
Reflection: small dust particles [82%]
Dark: large dust particles [88%]
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 [85%]
Medium-mass (sunlike): medium main-sequence lifetime [91%]
Low mass (red dwarf): longest main-sequence lifetime [82%]
If there was an open invitation to a house party (no specific time given), when would you show up?
Early, or on time. ******** [8] When the most people should be there. ************************** [26] After most everyone has left. [0]
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"When would you show up for the house party?" (Whenever I feel like it. #alwayslatebutworththewait)
"Dr. P-dog, Since you have the label 'Doctor' in front for your name this most mean you had to be in college forever. Did you go to a lot of house parties? If so what was the craziness one you ever went to?"
"What's the weirdest model you've ever heard used to describe/explain a topic within astronomy?" (The house party model. Either that, or the turkey/cornish hen model.)
"Do we get to see all massive, medium mass, and low mass stars from Earth?" (Only with a telescope. Typically the low mass and the medium mass stars are too dim to see, compared to the much, much brighter massive stars.)
"In order to prove there are stars behind a dark nebula you would need to use an infrared telescope?" (Yes, or maybe even a radio telescope (which have even longer wavelengths than radio waves).)
"When astronomers notice interstellar reddening, they notice that the stars appear redder than they should for their respective spectral types. How do they know what the spectral types are supposed to be?" (From the specific set of absorption lines.)
"The fusion of hydrogen into heavier elements all the way to iron is the limit of nucular fusion. How are heavier elements forged all the way up to uranium?" (When a massive star explodes as a type II supernova, elements heavier than iron are produced from that excess energy.)
"Will there be more extra-credit points available." (Yes, later this semester.)
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