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| − | ==题目==
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| − | 1. On December 21, 2020, Jupiter was at $$(\alpha,\delta)=(20^{h}10^{m},-20°34′)$$. Which constellation was Saturn in?
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| − | (a) Capricornus
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| − | (b) Aquarius
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| − | (c) Pisces
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| − | (d) Aquila
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| − | 2. What is the spectral type of a star with a luminosity of 5.86 * 10<sup>26</sup> W and radius of 8.51 * 10<sup>8</sup> m?
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| − | (a) A
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| − | (b) F
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| − | (c) G
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| − | (d) K
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| − | (e) M
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| − | 3. The exoplanet HD 209458b has a mass of 0.71 Jupiter masses and orbits HD 209458 with an orbital period of 3.53 days. HD 209458 has a mass of 1.15 Solar masses. Assuming that the orbit of HD 209458b is circular (which is a good approximation here) and that its orbit lies perfectly in our line of sight, what is the radial velocity semi-amplitude of HD 209458 due to the orbital motion of HD 209458b, in m/s?
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| − | (a) 69.6 m/s
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| − | (b) 85.9 m/s
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| − | (c) 94.2 m/s
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| − | (d) 120.8 m/s
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| − | 4. The photon number density of a blackbody depends on temperature as $$nd = a(\frac{k_{B}T}{\hbar_{c}})^{n}$$ where $$k_{B}$$ is the Boltzman constant, $$\hbar$$ is the reduced Planck’s constant, $$c$$ is the speed of light and $$T$$ is the blackbody temperature. Here, $$a$$ is a dimensionless numerical constant. What is the value of $$n$$?
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| − | (a) 1
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| − | (b) 2
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| − | (c) 3
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| − | (d) 4
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| − | 5. HD 209458b has a radius of 1.35 Jupiter radii, while the radius of HD 209458 is 1.20 Solar radii. What is the transit depth of HD 209458b, in percent?
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| − | (a) 0.013%
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| − | (b) 0.13%
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| − | (c) 1.3%
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| − | (d) 13%
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