Question

HD209458b was discovered in 1999, becoming the first exoplanet to be discovered using the transit method: this planet’s orbit is oriented just right, so that it regularly passes in front of its star, as seen from Earth. When this happens, it blocks out a portion of the star’s light. If astronomers notice the star’s brightness dipping for a short time over and over with a consistent period, it suggests a planet is responsible. Further observations of the star’s Doppler shift can reveal the mass of the planet.

HD209458 was one of the stars regularly observed by the HIPPARCOS satellite, so planetary scientists were able to time the planet’s orbital period very precisely: 3.524745 days, give or take about 20 milliseconds. For this lab, let’s just treat it as 3.5 days.

Using Kepler’s Third Law, and assuming the star is the same mass as the Sun, calculate the planet’s orbital semimajor axis. (Hint: don’t forget to convert the period into years first!) (2 points)

Is this planet in the star’s habitable zone? Explain your answer. (1 point)

If this planet were placed in our Solar System at that distance from the Sun, where would it be in relation to the other planets? (For example, “between Earth and Mars” or “beyond Neptune’s orbit.”) (1 point)

Answer 1

As per kepler's law

T² = a³

where T is period and a is semi major axis

3.5 days = 0.0096 years

so,

a³ = 0.00958904²

a = 0.045 AU

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No, this is not in habitable zone, it is too close to its star. This means any liquid will evaporate and surface will be too hot

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Not sure about this one but I think it should be between mars and earth.