20190409

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

Astronomy 210, spring semester 2019
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 think it's crazy that we know what goes on inside of a star on such a small scale."

"I found fusion in general to be interesting because I never really bothered to try to really look into it. It was cool to find it had to do with overcoming repulsion rather than just simply coming together at random moments.

"I liked learning about the different layers of the sun."

"How different colors can be seen in space. Why this is interesting to me is because in middle school we learned that all those colors were photoshopped because no waves (sound and light) could travel through space."

"The pictures of the interstellar medium because they were so pretty and captivating."

"Interstellar reddening"

"For main-sequence stars the mass is correlated the luminosity but other stars do not follow this pattern because there is no correlation between their mass and their luminosity."

"he cheerleader model of the pressure between massive and low-mass stars. It helped me understand how stars get their energy and heat."

"I enjoyed reading about nebula colors."

"It was cool learning the differences of colors in nebulae and why they are different."

"No offense but I couldn't really find any interest with these chapters? It was basic information, but I couldn't really get any enjoyment from this particular section, sorry...?"

"Learning about the types of nebulas."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"Is fusion caused by pressure, or heat? Is it a mix of both or could it happen with just one of those elements?"

"Turn-off points confused me when referring to the house party model. How do you determine which ones are 'coming' and which ones are 'leaving?'"

"What I found slightly confusing was the self-starting and kick-started star formation."

"Fusion confused me somewhat just because there was a lot to it and I didn't understand all of it fully."

"I still think that protons and fusions are still confusing to me, I'm not sure why I've just always had a problem with this kind of stuff."

"The fusion process."

"The H-R diagram. Im not sure how to interpret the information and I would love to have some more elaboration on the topic."

"Fusion rates."

"The H-R diagram was something that took me a few times to understand, but once I understood what it was, it cleared up a lot of the chapter for me."

"Lining up the type of stars with temperature, size, and luminosities."

Rank the luminosities of these main-sequence stars (1 = brightest, 3 = dimmest). (There are no ties.)
(Only correct responses shown.)
Massive: brightest luminosity [95%]
Medium-mass (sunlike): medium luminosity [100%]
Low mass (red dwarf): dimmest luminosity [95%]

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 [100%]
Low mass (red dwarf): slowest fusion rate [75%]

Fusion requires high temperatures in order for nuclei to move quickly enough to:
break heavy elements apart.  ** [2]
create convection currents.  *** [3]
overcome gravity.  *** [3]
overcome repulsion.  ********** [10]
(Unsure/guessing/lost/help!)  ** [2]

Briefly explain why "cold fusion" (producing energy from hydrogen fusion at room temperature) would be implausible.
"You need high temperatures in order to allow the hydrogen to get squeezed and move very quickly which means they collide a lot and are able to fuse."

"The hydrogen would not be moving fast enough to hit hard enough to fuse."

Match the three different types of nebulae with their colors.
(Only correct responses shown.)
Emission: pink [70%]
Reflection: blue [70%]
Dark: brown/black [95%]

Match the three different types of nebulae with their composition.
(Only correct responses shown.)
Emission: hydrogen [60%]
Reflection: small dust particles [80%]
Dark: large dust particles [55%]

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 [60%]
Medium-mass (sunlike): medium main-sequence lifetime [95%]
Low mass (red dwarf): longest main-sequence lifetime [60%]

If there was an open invitation to a house party (no specific time given), when would you show up?
Early, or on time.  ****** [6]
When the most people should be there.  ************** [14]
After most everyone has left.  [0]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"So in the question about the house party...does that mean everyone that goes is a star? Such a nice compliment."

"What kind of star (in the house party model) would resemble someone who comes early AND leaves late?"

"Why do you ask irrelevant questions at the end of the homework? Totally cool, just wondering." (Those questions aren't really irrelevant.)

"Do you have a guess on why some people think Earth is flat and not round?" (Never underestimate the power of first principles.)

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