Assume that a planet just like Earth orbits the bright star named Sirius.If this Earth-like planet orbits with a semimajor axis of 1 AU and an orbital period of 7 months, what is the mass of Sirius? A) 3 M_Sun B) 12 M_Sun C) 8 M_Sun D) 5 M_Sun E) 17 M_Sun

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Quizplus · Accepted Answer

Using Kepler's third law, the mass of Sirius can be calculated. The formula is P^2 = a^3 / M, where P is the period in years, a is the semimajor axis in AU, and M is the mass of the star in solar masses. For P = 7/12 years and a = 1 AU, solving gives M ≈ 3 M_Sun.

Assume That a Planet Just Like Earth Orbits the Bright