20171108

Online reading assignment: medium-mass stars, massive stars, neutron stars and black holes (SLO campus)

Astronomy 210, fall semester 2017
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 the evolution of medium-mass stars, massive stars, neutron stars and black holes.

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 enjoyed the metaphor comparing cars to stars in regards to life span and mileage. I think that it's interesting that those two vehicles have the same range of fuel, because it's not something you would expect from their appearance."

"A Hummer H2 and a SmartCar ForTwo can travel the same distance with a full tank of gas. I never took into account the different sizes of the fuel tank only the vast differences of gas mileage."

"It's pretty interesting that no low-mass stars have died yet."

"I found the lifespan of the different kinds of stars pretty interesting because the low mass stars never die."

"Even though the universe has been around for many years I find it fascinating that low mass stars are still out there even though in my mind they should extinct."

"I found interesting was discovering that bigger stars have a shorter time span. You would think that larger stars would live longer since they are so big."

"Something I found interesting,is that the sun will eventually burn through its resources and kill off Earth which I never knew."

"I thought it was interesting that helium can only fuse into heavier elements at a temperature of 100,000,000 K. But no core of any main sequence star can even get that hot, so the helium hangs out in the center of the star."

"It's crazy to think the white dwarf kind of sucks the life out of its companion star, enough to where it kills them both *explodes into the abyss*"

"How the dropping of a basketball and tennis ball at the right time can mimic the explosion of a supernova."

"A lot of the imagery used in the presentations to illustrate a black hole was interesting, engaging, and helpful."

"The end of life cycle for a star makes sense now. I didn't fully understand how it ended."

"The death of the sun--obviously it's a bit depressing to think about but the process itself, including eventually vaporizing the earth is fascinating. It's probably more fascinating knowing that it won't happen during my lifetime, otherwise it would be horrifying. The death of stars in general is interesting and the fact that our sun shares that fate is just a powerful thing to think about."

"It's interesting that when a star can no longer use it's energy and support the crushing gravity it freaks out and its outer layers spaz out and blow up off the imploding core."

"I thought it was interesting that a black hole can actually go on forever and the fact that they can actually warp space. Truly mind-blowing."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"Also how low-mass stars have not died yet, it's interesting and confusing. How long have they been there? Are they all from the same star cluster, or did they start out on their own? Can anything be learned about the universe from them? So many questions!"

"How do we know that no low mass stars haven't expired yet? Maybe they have and just didn't leave a trace of their existence."

"I'm confused about the low mass stars. What happens when they die? Do they even die?"

"The end of life stages were hard to grasp because it didn't feel like the masses of the stars were explicitly mentioned and so it was just overall confusing to me."

"During helium fusion of a star, does the star actually grow in size? If not, how does it expand."

"Right now, pretty much everything is a little confusing. It was a lot of information to take in."

"I still don't get why a neutron star creates pulsars and the more I read about all the actions of dying stars the more I get confused. the book makes things pretty complex."

"Something that was a bit confusing were the different types of supernova explosions and what exactly makes them different. As well as what differentiates a regular nova from a supernova."

"In general, supernovas are a bit hard to wrap my head around."

"Black holes are still a little confusing for me."

"I don't understand how black holes bend space time. I think this is so confusing because don't quite understand what spacetime is."

"Time dilation has me very confused."

A Hummer H2 and a SmartCar ForTwo can travel the same distance with a full tank of gas. Briefly explain how this is possible.
"The smart car is small and has a small tank of gas. The H2 is big and has a large tank of gas. Their fuel capacity/mileage ratios are reverse of one another. They go the same distance."

"Even if the SmartCar has better mileage it has a smaller tank, the Hummer has less mileage but it has a bigger tank."

"The Hummer H2 has a larger gas tank but has less mpg than the SmartCar ForTwo. However, the Smartcar has a smaller gas tank, but has greater mpg than the Hummer, so in turn they will travel the same distance with a full tank of gas."

Match the end-of-life stage with the corresponding main-sequence star.
(Only correct responses shown.)
Black hole: massive main sequence star [86%]
Neutron star: massive main sequence star [51%]
White dwarf: medium-mass main-sequence star [59%]
(No stellar remnant observed yet: low-mass main-sequence star [59%]

Match the type of explosion (if possible) with the corresponding main-sequence star.
(Only correct responses shown.)
Type II supernova: massive main sequence star: [84%]
Type Ia supernova: medium-mass main-sequence star [73%]
Nova: medium-mass main-sequence star [49%]
Low-mass main-sequence star: (no explosion possible) [62%]

If you were to leap into a black hole, your friends would typically watch you falling in for __________ before you entered the event horizon.
seconds.  ** [2]
hours.  [0]
days.  [0]
a year.  [0]
many years.  ***** [5]
forever.  ************************* [25]
(Unsure/guessing/lost/help!)  ***** [5]

The first rule of astronomy class is...
"Study."

"Go to class."

"Create a study group."

"Pay attention. Show up? Look up? Is this a trick?"

"Look to the stars to find the answers you seek...about stars."

"To make intelligent hypothetical theories and to use the scientific method to study the physics of stars and outer space, from moons to black holes; an educated scientific hypothesis is very important, and some say it's necessary to getting a good grade"

"Eat a meal before you come to class."

"Come to class fully caffeinated and ready to learn."

"Wait, I thought this was astrology..."

"Don't look at the sun through a telescope."

"Talk with everyone about astronomy class."

"Do not talk about astronomy class."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"What made you decide on doing a three hour class? In both lab and lecture?" (All science labs at Cuesta College are three hours long. The three hour lecture is because it's hard enough to get students to come to campus one night a week.)

"Could you please explain white dwarfs in the next class, I was confused with white dwarfs, thank you."

"A little confused by this weeks presentations so I'm looking forward to hearing you go over them."

"Please go over the different types of explosions. Thanks!"

"Can you 'dumb' this section down?" (Eh, I'm going to smart you up.)

"Are we ever going to see a picture of Mrs. P-dog?" (Didn't I show you a picture of us in the first week of class? Eh, here's another pic.)

"Is Fight Club one of your favorite movies?" (Sir, is this a test?)

"What's the first rule of astronomy class?"

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