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.
"I found the S-B law to be interesting because it is used to measure the brightness of a star even though it's light years away."
"I found the 'cheerleader model' to be very interesting and fascinating. It makes sense to understand tiny molecules doing this, but people?"
"Stars have a lot of shell layers and they all have pressure that has to be right so the star can be stable."
"The reason fusion takes place only in the core of the sun is because that is where the pressure is the greatest. The explanation for this was super clear, and that was great because I felt as though it could be really confusing. It was also interesting to connect this concept with the idea of diving in a pool, because I'm sure everyone has experienced swimming too deep and having an earache as a result as some point in time."
"The center of the sun is 100 times as dense as water but at the bottom of its photosphere it is 3,400 times less dense then Earth's atmosphere at sea level."
"I loved the section on fusion. Specifically that when there is little pressure and low temp. there is little to no fusion."
"Fusion makes helium from hydrogen."
"I think it's really interesting how mass size and luminosity all work together and correlate into the H-R diagram, but I also find it interesting that there are stars that don't fit into this correlation."
"Something I found very interesting to me are the kinds of nebulae that are depicted. I find it very compelling and crazy to understand the amount of gas and dust there is to produce a nebula."
"I found the different colors of the nebula to be very interesting, because I've always been curious as to why they are different colors."
"How different nebulae get their distinct colors, and that there are only certain colors available for nebulae. I've seen green and orange colored ones online, but those are all Photoshopped or altered through filters because nebulae can only produce red, pink/purple, blue, brown, or black shades."
"I found that the nebulae were interesting because now I know what the colors really mean when I'm looking at pictures of space. (Ex: I find a picture of mainly blue clusters of stars and can identify that it's a reflection nebulae with small dust particles.)"
"I like the the 'house party' reference to the lifetime of certain mass stars. I was wondering how guests at a house party would tie in to stars but its so very true that there are those three types of people that show up to a party and eventually leave at a certain time."
"The formation of stars and how a collapsing cloud never forms a single star."
Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"I am still a little confused on the classifications of stars using the H-R diagram. I have trouble with the labeling of each letter."
"I found the H-R diagram to be kind of confusing. This might be due to the fact that I was out of class sick last Thursday when we first went over it, but I could use a few clarifications. I also don't completely understand the concept of outliers on the diagram (ie: supergiants, white dwarfs, etc.) and how all of these are classified as not necessarily existing on the diagram even though they are all so different."
"Why don't white dwarfs, giants, and super giants have any correlation between mass and luminosity? is there a scientific explanation for this?"
"How do the nebulae form into stars? I don't think I understand the exact process of how they all come together. Does fusion start before the star and gravity kind of pulls it all together?"
"I did not quite understand how hydrogen atoms fuse to make heavier atoms."
"Fusion was confusing."
"I was a bit confused on how the H-R diagram of stars worked and also on the three different types of nebulas."
"I found the house party model to be confusing of how you apply that to finding out what kind of stars they are according to the diagram."
"Star cluster age was a bit confusing to me."
"How a shock wave triggers star formation."
Rank the luminosities of these main-sequence stars (1 = brightest, 3 = dimmest). (There are no ties.)
(Only correct responses shown.)
Massive: brightest luminosity [100%]
Medium-mass (sunlike): medium luminosity [100%]
Low mass (red dwarf): dimmest luminosity [100%]
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 [87%]
Medium-mass (sunlike): medium fusion rate [100%]
Low mass (red dwarf): slowest fusion rate [87%]
Fusion requires high temperatures in order for nuclei to move quickly enough to:
break heavy elements apart. ***** [5] create convection currents. * [1] overcome gravity. * [1] overcome repulsion. *************** [15] (Unsure/guessing/lost/help!) * [1]
Briefly explain why "cold fusion" (producing energy from hydrogen fusion at room temperature) would be implausible.
"Since hydrogen protons are of the same charge, they naturally repel one another. This means that when they are not being squeezed together by high pressure/heat, they will not join together and fusion will not take place."
"'Cold fusion' from hydrogen would be implausible because a hydrogen nucleus is actually just a proton and since protons are all positively charged they must undergo immense pressure and temperature to combat repulsion. If there is not enough temperature that would make the protons move faster they would in turn not have enough pressure to combat repulsion and could not produce energy."
"Hydrogen would move too slowly under low temperatures, therefore they won't collide with each other very much, or not at all."
"Since the protons are positively charged, they will repulse each other."
"I don't exactly understand this."
Match the three different types of nebulae with their colors.
(Only correct responses shown.)
Emission: pink [91%]
Reflection: blue [91%]
Dark: brown/black [100%]
Match the three different types of nebulae with their composition.
(Only correct responses shown.)
Emission: hydrogen [96%]
Reflection: small dust particles [91%]
Dark: large dust particles [91%]
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 [70%]
Medium-mass (sunlike): medium main-sequence lifetime [96%]
Low mass (red dwarf): longest main-sequence lifetime [74%]
If there was an open invitation to a house party (no specific time given), when would you show up?
Early, or on time. * [1] When the most people should be there. ******************* [19] After most everyone has left. *** [3]
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"I'm having trouble connecting a lot of the book with the questions and presentations. It usually makes more sense looking at the presentations then reading the book. I also have been having trouble with the H-R Diagram because I'm not sure how to find information with the OBAFGKM letters. I think I'm just slow with this information and need a review."
"Could you please go over the H-R diagram again? I'm having trouble understanding how to find stuff like M5. I'm probably just a bit slow, but it'd really help. Thanks!"
"Review of the H-R diagram and why certain stars don't fit in would be helpful."
"If you could please go over emission, reflection and dark nebulae."
"Can you go over the whole turn-off point thing? How is it determined where the turn-off point is located and how do you determine if a star in the cluster is coming or going?"
"Will there be any more extra credit similar to what was offered last week?" (Yes.)
"How does the house party model apply to a star cluster's age?"
"House parties are lame, man."
"When would you show up to the house party?"
"How important is punctuality in astronomy?"
"Do you analyze the weekly reading assignments after everyone has completed it or simply after midnight? Is it therefore annoying when students finish the assignments right before midnight?" (I compile all the student responses to the reading assignment early in the morning before class, but I do peek at some of the more interesting comments before the midnight deadline. It is interesting to see how close to midnight some students get when submitting their responses.)
No comments:
Post a Comment