20190416

Online reading assignment: medium-mass stars, massive stars, neutron stars and black holes (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 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 found the fact that low-mass stars take billions of years to die and spend so much time as a main sequence star. To think something like that has lived for so long is pretty cool to think about."

"How the Hummer H2 and SmartCar comparison was used to describe main-sequence lifetimes of stars, it made the material very memorable."

"The comparison between stars and cars."

"How giants cool as they expand. I tried the trick of blowing air on my hand the two different ways and it helped me understand what was being said more."

"The discovery of how stars will undergo 'star-vation' was interesting to me; seeing how stars can almost recycle the atoms they created until they are no longer usable."

"How massive stars undergo type II supernovae explosions."

"That black holes are massive. This is interesting to me because they seem like they would be empty thus have lower mass."

"That tidal forces would make traveling through black holes really hard to do, even if it worked because it would stretch the body, and you would probably die."

"That you can't see a black hole."

"No idea."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"How astronomers know how much mass objects have. This is confusing because it is not like we can ever visit these things, they just know."

"Life spans of different stars."

"The different star deaths kind of confused me, not too much, though. I just got them confused at times."

"I was a little confused on how medium mass stars die. I think I understand the process, but would greatly benefit from reviewing it."

"Death of medium mass stars."

"The picto-quiz part of the medium mass stars and how to tell which stage is which."

"The different categories of (super)nova explosions. I'm not sure how they differ and it would be nice to get some more clarification on them."

"Pulsars."

"I thought understanding the concept of black holes to be confusing. The gravitational field that surrounds black holes, the horizons, tidal forces, and gravitational redshift. I guess it wasn't really confusing because the book was pretty straightforward, but I'm just having a hard time wrapping my head around the idea of it all."

"That you can't see a black hole."

"How the Event Horizon Telescope was able to see the black hole. When will they be able to see a black hole starting to form and how will they be able to catch it the right time?"

"Nothing particularly confusing, pretty easy to follow."

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 SmartCar is more fuel efficient it uses less gas and because the Hummer H2 isn't as fuel efficient, it has a bigger gas tank to make up for its lack of efficiency."

"Because although the SmartCar has a smaller fuel tank, it also requires less fuel to run. On the other end, the Hummer requires more gas, and has a larger fuel tank to compensate for it."

"The SmartCar engine holds a smaller amount of gasoline but does a better job of efficiently using it whereas the big H2 burns up gasoline much quicker."

Match the end-of-life stage with the corresponding main-sequence star.
(Only correct responses shown.)
Black hole: massive main sequence star [88%]
Neutron star: massive main sequence star [38%]
White dwarf: medium-mass main-sequence star [50%]
(No stellar remnant observed yet: low-mass main-sequence star [46%]

Match the type of explosion (if possible) with the corresponding main-sequence star.
(Only correct responses shown.)
Type II supernova: massive main sequence star: [88%]
Type Ia supernova: medium-mass main-sequence star [73%]
Nova: medium-mass main-sequence star [38%]
Low-mass main-sequence star: (no explosion possible) [66%]

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.  * [1]
hours.  [0]
days.  * [1]
a year.  * [1]
many years.  ** [2]
forever.  ****************** [18]
(Unsure/guessing/lost/help!)  *** [3]

The first rule of astronomy class is...
"Ask questions?"

"To call you P-dog?"

"Be engaged? Don't be disrespectful? Don't eat the nebulas even though they look like cotton candy?"

"Listen to P-dog if you want to be a successful human and know more about astronomy related topics and stuff?"

"I feel like I am missing something because I do not know how to answer this at all."

"Always look up?"

"Study?"

"Buy your own starwheel?"

"Go to class?"

"Do the online reading assignments? "

"To never procrastinate?"

"I honestly have no idea. Did I miss this in class?"

"You do not talk about astronomy class."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"It's funny to talk about Hummers and SmartCars because in high school I drove a SmartCar--it was embarrassing."

"Is there an actual first rule to astronomy class, or was I absent the day we went over it? "

"What is the first rule of astronomy class?"

"Will we discuss the first picture taken of the black hole?"

"What would happen after two black holes collide?" (There would be an even bigger black hole.)

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