4. Using the Wein and S-B laws explain the color and brightness changes that occur as T is increased.

10. How many times can light travel around the globe in a second?

11. What does Wein's law give as the maximum emission wavelength of Rigel (Te=12,200K)

12. Procyon peaks at 445[nm]. How hot is it?

13. The 486.133[NM] Hb line in Megrez appears at 486.112[nm]. What is the radial velocity?

14. Rigel's 656.280 Ha line appars at 656.331 [nm]. So?

15. To make the red Ha line green (about 520 nm) how fast would you have to go?

1. a perfect absorber!... Beats me... they dont! (see 3.)

2. The Planck blackbody function maximum, found by setting the derivative of the Planck function equal to zero (the "usual way").

3. The area under the Planck function sT⁴, the power emitted per square metre by a blackbody at temperature T.
...we use it to quantify bodies like stars or planets by quoting an "effective temperature" Te, the temperature of a blackbody that radiates the same power as an astronomical body. It is a useful number.

4.As T rises the Planck curve maximum shifts blueward and the area under the curve increases really fast-- as T⁴.

10. 299,792,458[m/s] / 40,000,000[m] = 7.48[/s] ... seven and a half times per second.

11. max wavelength is 3,000,000[nm K] / 12,200[K] = 246 [nm] (I use 3,000,000 instead of 2,987,000.)

12. T is about 3,000,000[nm K] / 445[nm] = 6740 [K].

13. V=299792.458 [km/s] (486.112-486.133)/486.133 = -13 [km/s] ... 13 km/s towards us.

14. V=299792.458 [km/s] (656.331-656.280)/656.280 = +23 [km/s} ... 23 km/s away from us.

15. V=299792.458 [km/s] (520-656.28)/656.28 = - 0.21c = -62,150 km/s -- 21% the speed o lite!