20151027

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

Astronomy 210, fall semester 2015
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 seems that stars are delicate beings, as they are simply held together by pressure. Would seem that anything could come and destroy that balance."

"Some colors in photos of nebulae could be fake if they're not blue, pink, or brown/black. It's just something I hadn't known and now I'll always think about it when I see pictures or videos of stars."

"The house party model."

"I really enjoyed relating fusion to cheerleading. This was extremely helpful and interesting for me because I have been a cheerleader for 13 years so this definitely helped me pay attention and understand the material!"

"That an emission nebula is a cloud of hydrogen atoms illuminated by a nearby star. As the electron falls back down to lower orbitals, it may give off a violet photon, or a blue photon, or a red photon. These violet, blue, and red photons are perceived by the observer's naked eye as a pinkish lavender color."

"The sun takes 4 million tons of mass and converts it into energy every second."

"Why different types of nebulae have different colors from another."

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 why cold fusion would be implausible at room temperatures."

"I do not understand cold fusion really."

"Hydrogen fusion. Just got lost in reading it. I can not wrap my head around it."

"This was a pretty straightforward lesson."

"The nebulae types. I think I need a bit more clarification regarding reflection, emission and dark nebulae."

"I remember learning about protons and hydrogen atoms in high school and enjoying it but for some reason I find them super-confusing here."

"Hydrostatic equilibrium is still confusing, I'm having trouble comprehending weight versus pressure."

Rank the luminosities of these main-sequence stars (1 = brightest, 3 = dimmest). (There are no ties.)
(Only correct responses shown.)
Massive: brightest luminosity [88%]
Medium-mass (sunlike): medium luminosity [92%]
Low mass (red dwarf): dimmest luminosity [96%]

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 [75%]
Medium-mass (sunlike): medium fusion rate [92%]
Low mass (red dwarf): slowest fusion rate [71%]

Fusion requires high temperatures in order for nuclei to move quickly enough to:
break heavy elements apart.  *** [3]
create convection currents.  ** [2]
overcome gravity.  ***** [5]
overcome repulsion.  ******** [8]
(Unsure/guessing/lost/help!)  ****** [6]

Briefly explain why "cold fusion" (producing energy from hydrogen fusion at room temperature) would be implausible.
"Heat is needed to move atoms faster, to overcome repulsion, so they will collide. If the atoms are cold, they will not move quickly, thus will not be able to overcome repulsion."

"Cold fusion would be implausible because fusion stems from heat which causes movement, cold would lessen the movement making no fusion possible. I may be totally lost but that is my guess."

"The hydrogen photons won't be moving fast enough at room temperature, (because it's too 'cold') and because of this, they'll be just hitting each other slowly and weaker, and this won't allow fusion to take place."

"The physics of it is impossible. It just wouldn't happen."

Match the three different types of nebulae with their colors.
(Only correct responses shown.)
Emission: pink [92%]
Reflection: blue [83%]
Dark: brown/black [96%]

Match the three different types of nebulae with their composition.
(Only correct responses shown.)
Emission: hydrogen [83%]
Reflection: small dust particles [88%]
Dark: large dust particles [79%]

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 [63%]
Medium-mass (sunlike): medium main-sequence lifetime [79%]
Low mass (red dwarf): longest main-sequence lifetime [54%]

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.  ************ [12]
After most everyone has left.  * [1]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Do you watch The Walking Dead? Because I just watched the most recent episode before filling this out so I was HIGHLY distraught while taking this survey." (#teamdaryl or #teamcarol?)

"I would like it if you lecture more then normal in class about these chapters. I am feeling lost."

"I like how you used cheerleaders for the model of stellar fusion."

"Can you please explain cold fusion a little in the next class?"

"Whats your favorite backpacking spot?" (Big Pine Creek, North Fork Trail.)

"Are you really having a house party?"

"I'm not a huge fan when it comes to parties, so I'd either go early, leave early, or go when most people arrive and then sneak out earlier than most."

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