This week's questions are about the binary RW Mon that we will be working with in the salmon Astrophysics 2006 booklet (page 16) and about binary stars in general.
The binary star reading is Chapter 19(9-11)
this one is harder than average if you don't do the following:
cut out two star shapes {= circles! of different sizes} with scissors and paper and try it!! and I almost guarantee if you *refuse* to do this, you will get this question wrong and be really embarrassed! and even worse!: not get any credit!
1. This one is a review: a) Which star has the bigger orbit, star A or star B? How do you know?
b) Which star is eclipsed (i.e., which star is behind the other) at time = 0? star A or star B? The answer is contained entirely in the radial velocity graphs of RW Mon at the top of page 18! Explain how you knew (of course!).
2. a) The eclipses of RW Mon (one of which is a total eclipse and the other of which is an annular eclipse) both have flat bottoms (see the light curve -- the plot of apparent magnitude of time in the Astro salmon book page 18). Some eclipsing binaries, however, have light curves that have pointy bottoms (like the letter V or like an upside down teepee) give TWO situations (I think there are 3! go for 3 if you can) that would produce a light curve with pointy bottoms as opposed to flat bottoms.
b) Suppose that you have a binary like RW Mon, where both stars' spectral lines are visible in a single superimposed spectrum (the stars are so close together that we can't see the star separately or therefore get separate spectra for the two star). And clearly both sets of spectral lines are seen, otherwise we wouldn't have the wavelength shifts of each star and thus wouldn't have the radial velocities of each star as a function of time. So how do astronomers (in general) know which star (the bigger or the smaller) is in front at each of the two eclipses (e.g., at phase = 0.0 and phase = 0.5 for RW Mon) that occur during one orbit period? make sure that you use the cutouts!!
3. Now look at the flux curve (middle graph, page 18): the plot of apparent magnitude vs time for the system.
a) The real question here is a fill in the blank (with reason): The deeper eclipse in an eclipsing binary system's light curve is always the eclipse of the ________________ star. (Fill in the blank !) and explain of course! BUT WAIT!
b) to make the answer to the above almost obvious, answer this question first: In which eclipse (the deeper or the shallower) is more star area covered? (have you checked the cutouts?)
now go back and answer the question in (a)
I did my own work on this JIT.
Click on the button to send the results to Kolena or click to start over.
[return to the astro home page]