20151028

Online reading assignment: fusion, nebulae, star cluster ages (SLO 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.
"I liked learning about how stars were created because I realized a few classes ago that I had never even given it thought before, and so I had just been wondering how something so powerful comes into existence."

"I found out that the more massive the star, the more luminosity it will have. I did not expect it to be so simple/obvious."

"What nebulae are, it's something I've always wondered about."

"I found the section on the birth of stars interesting as I never previously considered the complex process involved."

"I thought the formation of stars was the most interesting idea. It is fascinating how cold gas of an interstellar cloud can heat up to form a star. This is one of the coolest things in my opinion."

"I thought your explanation of fusion was perfect . The cheerleader analogy was great."

"Finding out why the center of a star has so much pressure."

"I really like the whole house party analogy and it makes a lot of sense."

"I found the part about the different kinds of nebulae especially interesting. I always thought they were extremely beautiful and fascinating but never knew much about them so I really enjoyed learning about why they look the way they do."

"The life span of red dwarfs, I had no idea they lasted for so long. I just think that's really cool (no pun intended?)"

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"I found the H-R diagram a little confusing as it is harder to understand upon first glance."

"I think the most confusing concept was the Coulomb barrier because they need rare conditions to exist and is a confusing idea. I am not sure how they can overcome this force but I guess in the right conditions it can."

"The process of hydrogen fusion was especially confusing. Not only were there a lot of terms involved, but I'm not that great with keeping track of complex steps."

"Hydrostatic equilibrium seems somewhat confusing. It is a lot of information to take in."

"Not necessarily confusing, but the formation of stars. Especially the part regarding how many colors you see simulated of outer space are 'fake' and/or are enhanced."

"Differentiating the types of nebulae. I totally understand the differences, but many are multi-colored. Does this just mean they are a combination of the different types?"

"The process of fusion."

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 [97%]
Low mass (red dwarf): dimmest luminosity [97%]

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 [85%]
Medium-mass (sunlike): medium fusion rate [91%]
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.  **** [4]
create convection currents.  ***** [5]
overcome gravity.  *** [3]
overcome repulsion.  ******************* [19]
(Unsure/guessing/lost/help!)  *** [3]

Briefly explain why "cold fusion" (producing energy from hydrogen fusion at room temperature) would be implausible.
"Cold temperatures do not allow enough collisions between nuclei due to low density."

"The particles wouldn't be moving fast enough"

"Because in order for the hydrogen atoms to overcome repulsion, there has to be a really high amount of pressure and heat."

"This chapter confused me."

"I honestly don't really know."

Match the three different types of nebulae with their colors.
(Only correct responses shown.)
Emission: pink [79%]
Reflection: blue [82%]
Dark: brown/black [85%]

Match the three different types of nebulae with their composition.
(Only correct responses shown.)
Emission: hydrogen [85%]
Reflection: small dust particles [79%]
Dark: large dust particles [85%]

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 [76%]
Medium-mass (sunlike): medium main-sequence lifetime [100%]
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.  ****** [6]
When the most people should be there.  *************************** [27]
After most everyone has left.  * [1]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Is there any way on quiz dates that whoever chose to could meet 30 minutes before class for a quick quiz review/practice problems with you to refresh our minds before the actual quiz?" (Wednesday afternoons I have scheduled office hours from 1:00-2:30 PM; and/or you can make an appointment later that afternoon up to 5:00 PM.)

"How many quiz scores do you drop at the end of the semester?" (Three, out of the eight total this semester.)

"Are you going to throw a house party?" (If you have to ask, you aren't invited.)

"I enjoy learning about stars because well, astronomy, but are we going to ever go outside and look at the stars?" (We'll look at the moon tonight at the Bowen Observatory, because, moon. NO, NEVERMIND. BECAUSE, CLOUDS. THANKS, CLOUDS. THOUDS.)

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