1) Suppose instead that the extrasolar planet (shown in Figures 1 and 2) became
ID: 1770739 • Letter: 1
Question
1) Suppose instead that the extrasolar planet (shown in Figures 1 and 2) became much more massive, but continued orbiting at the same distance. How would your observations from Earth be different (circle one)?
the star’s light would be shifted even more
the star’s light would be shifted less than before
no change in the light would be observed
2) Suppose instead that the extrasolar planet (shown in Figures 1 and 2) moved farther away from the star, but continued to have the same mass. How would your observations from Earth be different (circle one)?
the star’s light would be shifted even more
the star’s light would be shifted less than before
no change in the light would be observed
3) Under what condition would you not observe a star’s light to ever undergo Doppler shift even when there is an extrasolar planet orbiting the star? Explain your reasoning
Center of Mass Center of Mass Star Extrasolar Planet …… Extrasolar Planet Star Fig 2. Extrasolar Planet and Star As Seen Edge-On Or From The Side Note that the extrasolar planet is moving toward you (not to scale) Fig 1. Extrasolar Planet and Star As Seen From Above (not to scale)Explanation / Answer
(a) Though the mass of the planet is increased, but it continues to move the same distance. And by increasing the mass, distance of the center of mass from the planet's surface has not changed, and not even the acceleration has changed, so the center of mass will be fixed at the same place.
Hence, there will be no shift in the star's light.
(b) Now, since the distance of center of mass has changed, the distance travelled by the planet has changed, and in now increased. So, the center of mass is now having acceleration, an thus there will be a shift in the star's light.
Hence, the star's light would be shifted even more.
(c) Doppler's effect occurs due to the difference in the velocity of a particular wave. So, it can be neglected if the light coming from stars have the same wavelength, means they cover equal distance between the peaks of the waveform.
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