Astar is transited by a planet. from the measured period t and the transit duration tdur alone, show that one can obtain an upper bound on the density of the transited star: p.,max 3r/(gr2) hint: combine kepler's law and eq. 6.7 to eliminate the separation a, and then extract the density of the spherical star. the upper bound is obtained by assuming an impact parameter b 0. a. b. suppose that from the transit light curve one can measure the total transit duration, tt, between the "first contact" and the "last contact" of the planet and the star, and also the duration of the "flat" part of the transit, t, during which the planet is fully superimposed on the star's disk. show that in this case, utilizing also the transit depth (eq. 6.6), b can be determined, and hence the star's density (and not just upper bound) can be found.