Don McCarthy's Questions of the Week

Problem #1: Follow up from last week.

The following equation characterizes “main sequence” stars: (L/L_⊙) = (M/M_⊙)^α

The letters “L, M” refer to a star’s luminosity and mass, respectively. The symbol “⊙” refers to the Sun. The symbol “α” is a number greater than zero.

After being sure you understand the terms, reflect on what this equation is saying and write a sentence describing a trend you notice. Do not use Google, etc.; just look at the equation and think about it.

Does the equation work for the star Sirius (2 M_⊙ and 25 L_⊙) in the Club’s scale model downstairs?

Problem #2: In case you already know about problem #1. Do this problem without a calculator.

Jack drives a gas-guzzling SUV 15,000 miles a year. It averages 10 mpg. His wife Jill drives an economy car the same distance. It gets 30 mpg.

The couple wants to use less gasoline. They can afford to trade Jack’s clunker for an SUV that gets 13 mpg or trade Jill’s sensible car for a hybrid that gets 60 mpg.

Which trade would save the most gasoline?

T-shirt Design

If you have not done so already, please email Kevin (kevinkhu @ email . arizona . edu) if you would like a t-shirt and/or sweatshirt along with the size by Monday, March 29th.

Don McCarthy's Question of the Week

What patterns and surprises do you notice in this "H-R Diagram"? Every dot represents a measured star.

Meeting minutes

Meeting 3/10

-Dr Shirely presents an awesome new image

-Don McCarthy goes over question of the week 

-march 27th observing run, if interested email Kevin 

-email Kevin if interested in radio observing spring break week. 

-12-4 Fridays Carmen or katie's office hour for local group project

-tshirt designs voted, email Kevin sizes and if you want a sweatshirt possibly 

 

Radio Observing Project

Don McCarthy's Question of the Week

Before attempting the following problem, be sure you understand the meaning of the words "luminosity" and "apparent brightness." Pretend that one of your two favorite stars is 100 times more luminous than the other but appears 100 times fainter. The brighter star has a parallax indicating its distance is 100 light-years. How far away is the fainter star in light-years?

Meeting Minutes 3/3

• The 12 meter observing has been pushed back a week due to scheduling conflicts.
• Don McCarthy went over the question of the week => 1/2 is the solution
• Local group project meeting 12-3 at Katie and Carmen's office hour
• Who is interested in Astroclub shirts, voting on designs next week.
• Binocular Telescope project, read Iraf info on website if interested and this week is the perfect time to start showing up as it will get harder.
• Pictures from Kitt Peak trip were shown

Don McCarthy's Question of the Week

There are 100 airplane passengers, all with assigned seats. They board one at a time. If their assigned seat is open, they must take it. If that seat is occupied, they can take any other seat. The first person randomly chooses a seat. What is the probability that the last person gets her assigned seat?