20131103

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

Astronomy 210, fall semester 2013
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, and on 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.
"A black hole cannot be seen."

"A SmartCar and a Hummer have the same range on a full fuel tank."

"Because some stars are convective and others aren't, it completely determines the lifespan of that star, because convective stars are given more access to hydrogen fuel to stay alive."

"Once a medium-mass star has reached the end of its main-sequence lifetime, it begins to stave off 'starvation,' becoming a giant. I think it is interesting that the medium mass star becomes a giant."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"Black holes and spacetime--how they begin, and effects on spacetime."

"I don't understand the purpose of a black hole and what goes in there, also are there many in our galaxy?"

"The different types of stars and their explosions and remnants."

"How two stars can be born at the same time, but due to their different masses, evolve at different rates. How much quicker/slower will a smaller mass star evolve than a larger mass star?"

"Pulsars--I still do not exactly understand what it is and its importance in science."

"I find it confusing that no low mass stars have died yet."

"Black holes again. I don't understand how something can have infinite density and how if you're falling into a black hole it looks like you're falling forever from an outside observer. This is wrinkling my brain!"

"There was nothing confusing--it was just quite a bit of information to remember."

"It seems that a white dwarf is needed to form both a type Ia supernova and a nova. Both phenomena seem similar to each other but can't possibly be related."

A Hummer H2 and a SmartCar ForTwo can travel the same distance with a full tank of gas. Briefly explain how this is possible.
"Even though the Hummer H2 gets lower mileage than the SmartCar, it has a bigger fuel tank."

"The Hummer has a much larger tank. It might not burn the fuel as efficiently but it has a lot more fuel to begin with."

"This is possible because they are traveling the same distances."

These main-sequence stars will become which type of stellar remnant?
(Only correct responses shown.)
Massive main sequence star: (neutron star or black hole) [84%]
Medium-mass main-sequence star: white dwarf [61%]
Low-mass main-sequence star: (no stellar remnant observed yet) [49%]

These main-sequence stars could undergo which type of explosion?
(Only correct responses shown.)
Massive main sequence star: type II supernova [63%]
Medium-mass main-sequence star: (nova or type Ia supernova) [86%]
Low-mass main-sequence star: (no explosion possible) [26%]

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.  ***** [5]
hours.  * [1]
days.  ** [2]
a year.  ** [2]
many years.  * [1]
forever.  *************************** [27]
(Unsure/guessing/lost/help!)  ***** [5]

The first rule of astronomy class is...
"...refer to your instructor as P-dog."

"...come to class?"

"...to have fun?"

"...to meet the Math 123, Math 123SI, or the equivalent prerequisite?"

"...don't stare directly at the sun."

...get a good grade."

"...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.
"What's the second rule of astronomy class?"

"I am still a little confused on the three categories of stars and their explosions and remnants." (I will go over some of these in class...just so long as you remember the first rule of astronomy class.)

"Does a black hole lead to other dimensions?" (Maybe. Let me know when you find out.)

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