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

Astronomy 210, fall 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.
"The H-R diagram is great once you know how to read it."

"It was interesting to find out the luminosity, size and temperature for the stars using the H-R diagram."

"Big stars don't last as long as small ones, it makes sense but it just feel more right that because they're big it's a longer time for them to burn out."

"One thing I found interesting about main sequence stars is that the more massive they are, the more luminous they are."

"I had heard of nuclear fusion, but I didn't realize that was what fueled a star. It puts our efforts to replicate it here on Earth into perspective."

"Did not know that there were dust clouds in space that block out stars to where it looks like there is a black blotch."

"That there are different nebula as I was very vaguely informed on what one even was."

"Something that I found very interesting from this presentation was the notion of nebulas. Nebulas look like clouds in space but they serve a much larger purpose."

"How the reflection, emission, and dark nebula get their colors."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"Something that I found personally confusing was the part where it talked about fusion, I was confused because the presentation doesn't really go into depth as to how it works. If you could explain it that would be great."

"Cold fusion, I just can't wrap my mind around it. Hydrogen and its isotopes at room temperature dissolve into a specific solid at such a high concentration a strong nuclear force occurs and boom, cold fusion?"

"Lifetime of stars?"

"Interstellar medium. I think I have the base idea about it but I would how we were able to find the interstellar dust in the vacuum of space."

"Is this a trick question? Everything’s confusing before you understand it 🤷‍♂️."

"I personally found all the reading to be a bit of an information overload and hope to have a lot of things clarified by next class."

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 [71%]
Medium-mass (sunlike): medium fusion rate [100%]
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.  ***** [5]
create convection currents.  **** [4]
overcome gravity.  ** [2]
overcome repulsion.  *** [3]
(Unsure/guessing/lost/help!)  [0]

Briefly explain why "cold fusion" (producing energy from hydrogen fusion at room temperature) would be implausible.
"Under low pressures and temperatures, hydrogen does not get squeezed very much, and moves too slowly, they won't collide with each other."

"Because nuclear fusion requires high temperatures to overcome the natural forces that normally prevent that kind of thing."

"Due to the fact that nuclei which are positively charge would not collided with each other but would repulse each other so the atoms could not create energy."

"Fusion can't happen in cold temperatures because protons are positively charged and repel each other."

"Have no clue."

"I'm not sure."

Match the three different types of nebulae with their colors.
(Only correct responses shown.)
Emission: pink [86%]
Reflection: blue [86%]
Dark: brown/black [93%]

Match the three different types of nebulae with their composition.
(Only correct responses shown.)
Emission: hydrogen [86%]
Reflection: small dust particles [71%]
Dark: large dust particles [71%]

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 [64%]
Medium-mass (sunlike): medium main-sequence lifetime [93%]
Low mass (red dwarf): longest main-sequence lifetime [57%]

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.  ***** [5]
After most everyone has left.  * [1]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Does interstellar matter dust turn into a planet or a star? Both?" (Yes, either is possible.)

"I found this survey a bit difficult and could really use extra help."

"The picture of the nebulae are cool and I think we show see more of them."

"Nebulae have amazing colors."

"I love learning about stars! They're one of the most fascinating subjects in astronomy for me, given that our star is the only reason we're even alive."

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