In astronomy, the absolute magnitude, M, of a star is related to its luminosity, L, by the formula M = Msun 1.0857 ln( L / Lsun ) , where Msun = 4.75 and Lsun = 3.839 10^26 watts are constants. By convention, stars with lower absolute magnitude have higher luminosity. Report answers using scientific notation, rounding to 3-decimal places.

A) Find the luminosity when the magnitude is 4.2. Include proper units

B) If the absolute magnitude of a variable star is decreasing at a rate of 0.07 per week, how fast is the luminosity of the star changing when the magnitude is 4.2? Include proper units.

C) Is the luminosity increasing or decreasing at this moment? Why?