USAAAO 2021, I кръг — Задача 3
USAAAO 2021 - First Round · 30 януари 2021 г.
PHYSICAL AND ASTRONOMICAL CONSTANTS
| c | Speed of light in vacuum | |
| e | Elementary charge | |
| m | Neutron rest mass | |
| m | Proton rest mass | |
| m | Electron rest mass | |
| m | Helium-4 rest mass | |
| h | Planck’s constant | |
| H | Hubble’s constant | 70 (km/s)/Mpc |
| k | Boltzmann’s constant | |
| b | Wien’s constant | |
| G | Gravitational constant | |
| Stefan-Boltzmann constant | ||
| c | First Radiation Constant | |
| c | Second Radiation Constant | |
| N | Avogadro constant | |
| R | Gas constant | |
| a | Bohr radius | |
| Bohr magneton | ||
| M | Solar mass | |
| R | Solar radius | |
| L | Solar luminosity | |
| T | Solar temperature | 5770 K |
| M | Earth mass | |
| R | Mean Earth radius | |
| I | Earth moment of Inertia | |
| R☾ | Mean Moon radius | |
| M♃ | Mean Jupiter mass | |
| R♃ | Mean Jupiter radius | |
| a♃ | Mean orbital radius of Jupiter | 5.2 AU |
| a☾ | Mean semimajor axis Moon orbit | |
| 1 light year | ||
| 1 AU | Astronomical Unit | |
| 1 pc | Parsec | |
| 1 year | ||
| 1 sidereal day | 86164 s | |
| 1 erg | ||
| 1 bar |
ENERGY CONVERSION : 1 joule (J) = electronvolts (eV)
Условие
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?
(a) 69.6 m/s
(b) 85.9 m/s
(c) 94.2 m/s
(d) 120.8 m/s
Отговори
- B
Решение
Using conservation of angular momentum, . Assuming a circular orbit and solving for semi-major axis using Kepler’s 3rd law, . Plugging into the expression above, we find .
Answer: B
Оригинал в Архива: usaaao2021_exam1.pdf · официални решения: usaaao2021_exam1_solutions.pdf