20131020

Online reading assignment: stellar parameters (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 parallax, distance, apparent magnitude, absolute magnitude, Wien's law and the Stefan-Boltzmann law.

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'm so surprised that the super giants is 1,000 times larger than the sun's diameter and the giants stars could be 10 to 100 times larger than the sun. I had no idea that it was possible for the stars to be larger than the sun. It seems impossible to me."

"The color scheme of the stars' temperature. It seems opposite, as red should originally seem like a hot color and blue seems like a cool (cold) color."

"That some stars are white and some are other colors, because I always assumed they are all white."

"How bright and how big all the stars are. God created such an expansive universe and everytime I read about it, I become more and more inspired."

"The colors of the stars. I went on a hike right after reading the blog and I took the time to look up and see the difference in the stars colors. I noticed some were white, some yellow, and some very bright. I never noticed this so I found it to be very interesting!"

"That we can find a star's true brightness via finding out its size and temperature."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"When the stars are hotter it is blue and which stars are cooler it is red. I totally thought it was opposite...hotter stars should be red and cooler star should be blue. So I'm assuming that when the stars is hotter it is blue and when it is cooler it is red? I'm confusing myself. And I am so so on the luminosity part there is some parts I understand and some parts I don't. I hope you can explain this to class clearly then I will understandf."

"How to tell which star is hotter & which star has more luminosity using the Stefan-Boltzmann law."

"Was the math with 'no math' actually 'no math,' or did I miss a presentation--hah!"

I am finding the math calculations a little confusing. Going through them in class and using a new example would be very helpful. I just need some clarification of the steps."

"I need some more clarification on the difference between absolute visual magnitude and apparent visual magnitude. I found it confusing because absolute visual magnitude is a hypothetical change in apparent mag.? What is the interaction between the two?"

Which star is hottest?
Blue supergiant.  ********************************** [34]
Yellow supergiant.  * [1]
White dwarf.  **** [4]
Red dwarf.   **** [4]
(Unsure/guessing/lost/help!)  * [1]

Which star is the smallest in size?
Blue supergiant.  [0]
Yellow supergiant.  * [1]
White dwarf.  **************** [16]
Red dwarf.   ************************* [25]
(Unsure/guessing/lost/help!)  [2]

Suppose the sun was moved to a distance of 10 parsecs away. As a result, its __________ magnitude would become dimmer.
absolute.  ************ [12]
apparent.  ********************** [22]
(Both of the above choices.)  ***** [5]
(Neither of the above choices.)  [0]
(Unsure/guessing/lost/help!)  ***** [5]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"I did bad on my last quizzes and my midterm.....I'm going to kick butts from now on! I'm going to study study study study my butt off. Lesson learned!"

"Star sizes were confusing."

"Is there a way to find out my course grade to date?" (Yes. On the "Summary" grade tab.)

"If we get an 'A' by the end of the semester do we still have to take the final?" (No. If you have enough points for a certain grade, those points cannot be taken away from you.)

"I know this has nothing to do with the reading or presentation slides, but I'm sort of confused by the apparent absence of online reading assignment 6 and 8. Were these ever assigned at one time or another?" (Because there are so many Monday holidays this semester, we're skipping those reading assignments, as well as several chapters and a a quiz.)

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