Apply the concepts of blackbodies, flux, luminosity, inverse-square law, etc.

the first exoplanet to be discovered around a so-called main-sequence star was a half-­‐jupiter mass planet orbiting very close to the star 51 pegasi (mv = +5.49 mag, d = 15.61 pc).

a. calculate the absolute visual magnitude (mv) of 51 peg.

b. the sun’s absolute magnitude is mv = 4.8. using your answer to (a), calculate the ratio of the luminosity of 51 peg to the sun (lsun).

[hint: review the relationship between luminosity, flux, and distance, as discussed in class.]

c. the spectrum of 51 peg peaks at a wavelength of 520 nm. use wien’s law to calculate the temperature of 51 peg.

d. the sun’s surface temperature is 5780 k. using equation (5.100) in the reading, calculate the ratio of the radius of 51 peg to the sun (rsun).

e. if the planet 51 peg b orbits at a radius of 0.053 au in 4.23 days, how many times larger is the incident flux on the planet’s atmosphere than the solar flux at the earth?