An exoplanet orbits its star on a circular orbit with a radius of 2 AU.If the planet is in the star's habitable zone,the star has a luminosity of:

Question

Quizplus · Accepted Answer

The habitable zone's distance from a star depends on the star's luminosity. The luminosity required for a planet to be in the habitable zone at a distance of 2 AU (twice the distance from Earth to the Sun) can be determined using the inverse square law for luminosity. Since the habitable zone for Earth (1 AU from a star with 1 solar luminosity) requires the star to have 1 solar luminosity, a planet at 2 AU would need the star to have luminosity increased by the square of the distance ratio. (2^2 = 4), thus 4 solar luminosities are needed for a planet at 2 AU to be in the habitable zone.

An Exoplanet Orbits Its Star on a Circular Orbit with a Radius