20190417

Online reading assignment: medium-mass stars, massive stars, neutron stars and black holes (SLO 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 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 think that everything in this presentation is interesting. Especially the pictures and GIF animations provided of what the life stages look like. It's not something a student outside of the astronomy class would see and understand."

"Comparing low-mass and medium-mass stars to a SmartCar and a Hummer. It made the analogy easier to remember."

"I found the H2 versus Smartcar example a great way to put this section into perspective. Not having great mileage but having the capacity to compensate for it."

"That a lower mass star can survive substantially longer than a larger mass star."

"I like the refrigerator analogy and 'star-vation.' It helped me understand the stages in which order a star will use certain fuels."

"I liked your refrigerator analogy about stars having to eat helium after all the hydrogen is gone because a star's got to eat, right?!"

"Stars from about the size of the sun could turn into giant stars and massive stars could potentially become supergiants. Red dwarfs are fully convective meaning that their life expectancies are extended."

"How if you open mouth breathe on your hand it will be warm, but if you purse your lips it will be cool. I found that it made the information easier to understand."

"That a medium-mass star becomes a giant."

"How different mass stars die differently."

"I found it interesting that the more massive the star the longer it keeps fusing. So after hydrogen it fuses helium into carbon, and if its massive it keeps going. I didn't know stars fused beyond hydrogen."

"That the energy generated in the core of a star is what opposes gravity and supports the star."

"I thought the information about how stars die was interesting because I didn't know the many ways they could go."

"That an entire star's life revolves around this single force that is gravity. The star is using gravity to create more energy for itself from its core to continue living, and at the very end, it has a life or death battle with gravity where it can either lose and become consumed in darkness, (black hole) or continue in peace in ultimate stability (neutron star)."

"I found it interesting that there are different types of supernovas: type Ia and type II."

"Massive star death. Probably one of the coolest things about the universe. Who doesn't like explosions?"

"Black holes and the effect it has on spacetime and what is around it. The fact that you can't see it but you can feel it is crazy."

"Black holes are very interesting because we do not know what they do and they are scary."

"Black holes, because what is even their purpose?"

"To see how there is a 'black hole' in Lake Berryessa. I don't know how to swim and just looking at the image makes me scared."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"I didn't understand the Hummer H2 and SmartCar question."

"There wasn't anything that was too confusing. At first I was a little lost with the car example."

"The medium-mass star stages. I'm a bit fuzzy on how a star that is losing its fuel source is increasing in size. Normally in most situations its the other way around. So I am curious to see how this works."

"The different types of (super)novae."

"Binary system explosions."

"Black holes, because they seem so complicated, how could we ever really comprehend what they actually are and do."

"How black holes work and what happens when something gets sucked into it."

"The event horizon of a black hole. I am unsure what the event horizon is even after reading the definition in the textbook I am still confused."

"Black holes were confusing. Everything about that section just went over my head."

"I can't really wrap my head around a black hole's time dilation. How do we know this exists?"

"I have a lot of questions. I'm sure as I listen to you explain it that will help though. I learn by listening."

"A little bit of everything was confusing. I got the main parts but some of it was slightly confusing."

"I did not find anything particularly confusing."

"Almost everything."

A Hummer H2 and a SmartCar ForTwo can travel the same distance with a full tank of gas. Briefly explain how this is possible.
"Because the Hummer H2 has such low gas mileage it requires a bigger gas tank to get farther. The SmartCar has better gas mileage so it can get away with a smaller tank. One variable is increased while the other is decreased making the total distance even."

"The Hummer and the SmartCar have the same range but two different variables. The Hummer has a lower mpg and a larger gas tank. The SmartCar on the other hand has a high mpg with a small gas tank. Because the SmartCar has a higher mpg, it allows it to use fuel more efficiently. While the Hummer is not fuel efficient, it has to compensate by having a large fuel tank. But ultimately, both vehicles have the same range."

"They can travel the same distance because whilst the H2 having bad gas mileage, it makes up for it by having a large fuel tank to compensate."

"The Hummer has more gas in the car but it burns through it faster where the SmartCar can hold less gas but uses it more efficiently."

"I really don't understand this question."

Match the end-of-life stage with the corresponding main-sequence star.
(Only correct responses shown.)
Black hole: massive main sequence star [64%]
Neutron star: massive main sequence star [58%]
White dwarf: medium-mass main-sequence star [48%]
(No stellar remnant observed yet): low-mass main-sequence star [42%]

Match the type of explosion (if possible) with the corresponding main-sequence star.
(Only correct responses shown.)
Type II supernova: massive main sequence star: [76%]
Type Ia supernova: medium-mass main-sequence star [70%]
Nova: medium-mass main-sequence star [42%]
Low-mass main-sequence star: (no explosion possible) [55%]

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.  *** [3]
hours.  * [1]
days.  * [1]
a year.  * [1]
many years.  *** [3]
forever.  ***************** [17]
(Unsure/guessing/lost/help!)  ******* [7]

The first rule of astronomy class is...
"I don't know."

"Study?"

"Keep looking up?"

"Be intrigued by space?"

"Read the textbook materials and show up to class?"

"Pay attention?"

"You cannot see black holes by themselves?"

"To ask questions?"

"Prepare?"

"To have fun while learning?"

"To know the difference between astronomy and astrology?"

"Pay attention and do your reading because it's difficult?"

"Always bring a towel?"

"We have a rule?"

"There is no astronomy class?"

"Don't talk about astronomy class."

"Tell all your friends about astronomy class?"

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"I shared with my sister the house party model. She laughed!"

"I found the reading to be very confusing this week! The presentation slides somewhat helped."

"I am confused at the death of stars and their end-of-life stages. Would it be possible to go over those in class?"

"I would like to learn more about how gold is formed from a supernovae."

"What would be a dumbed-down version of explaining a black hole?"

"Could we go over the black holes section in more detail?"

"I'm good but thank you! Is there going to be another study session before the next midterm? (Yes.)

"Can we review what is going to be on the next quiz and exam in our next classes? (We will.)

"How much will we review as a class for the final?!?!?!?!?!" (The study guide for the final exam will be posted soon. But first get through the next quiz and the second midterm.)

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