A planet was discovered orbiting around the star HD68988. Its orbital distance was measured to be 10.5 million kilometers from the center of the star, and its orbital period was estimated at 6.3 days. What is the mass of HD68988?Express your answer in kg and in terms of our sun's mass.
2007-03-15 15:55:24 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Physics
star -- Fs=G Ms m /r^2 = m r w^2 where w=2 pi/T
mass of star Ms = 4 pi^2 r^3 / G Ts^2 ----(1)
Ms = 4 (3.14)^2 (10.5*10^9)^3 / 6.67*10^-11 (544320)^2
= 2.31 {10^30} kg
Sun -earth Msun = 4 pi^2 R^3 / G Te^2 ----(2)
where R is radius of earth and Te = 1day around
Ms / Msun = r^3 Te^2 / R^3 Ts^2
Ms / Msun = (10.5*10^9/6400*10^3)^3 [1/6.3]^2
= (10.5*10^4/64)^3 [1/6.3]^2
=1.1126 *10^8
Ms = 1.1126 *10^8 Msun
2007-03-15 16:49:58 · answer #1 · answered by anil bakshi 7 · 2⤊ 3⤋
665811237 kg
2007-03-15 16:03:04 · answer #2 · answered by Anonymous · 0⤊ 2⤋