IAO 2012, Теория, младша възраст — Задача 4. Stars on Mars
XVII International Astronomy Olympiad — Theoretical round — Group α
Бележка
General note. Maybe not all problems have correct questions. Some questions (maybe the main question of the problem, maybe one of the subquestions) may make no real sense. In this case you have to write in your answer (in English or Russian): «impossible situation – ситуация невозможна». Of course, this answer has to be explained numerically or logically.
Data from the tables (Planetary data, stars, constants, etc.) may be used for solving every problem.
The answers «Да-Yes» or «Нет-No» have to be written in English or Russian.
Planetary data
Элементы орбит. Физические характеристики некоторых планет, Луны, Солнца и Эриды
Parameters of orbits. Physical characteristics of some planets, Moon, Sun and Eris
| Небесное тело, планета / Body, planet | Среднее расстояние от центрального тела / Average distance to central body, in astr. units | in km | Сидерический (или аналогичный) период обращения / Sidereal period (or analogous), in tropical years | in days | Наклон орбиты / Orbital inclination, | Эксцентриситет / Eccentricity, | Экваториальн. диаметр / Equat. diameter, km | Масса / Mass, kg | Средняя плотность / Av. density, g/cm³ | Ускор. своб. пад. у пов. / Grav. accelr. at surf., m/s² | Наклон оси / Axial tilt | Макс. блеск, вид. с Земли / Max. magn. From Earth **) | Альбедо / Albedo |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Солнце / Sun | 1392000 | 1989000 | 1,409 | ||||||||||
| Меркурий / Mercury | 0,387 | 57,9 | 0,241 | 87,969 | 0,206 | 4 879 | 0,3302 | 5,43 | 3,70 | 0,06 | |||
| Венера / Venus | 0,723 | 108,2 | 0,615 | 224,7007 | 3,40 | 0,007 | 12 104 | 4,8690 | 5,24 | 8,87 | 177,36 | 0,78 | |
| Земля / Earth | 1,000 | 149,6 | 1,000 | 365,2564 | 0,00 | 0,017 | 12 756 | 5,9742 | 5,515 | 9,81 | 23,44 | 0,36 | |
| Луна / Moon | 0,00257 | 0,38440 | 0,0748 | 27,3217 | 5,15 | 0,055 | 3 475 | 0,0735 | 3,34 | 1,62 | 6,7 | 0,07 | |
| Марс / Mars | 1,524 | 227,9 | 1,880 | 686,98 | 1,85 | 0,093 | 6 794 | 0,6419 | 3,94 | 3,71 | 25,19 | 0,15 | |
| Юпитер / Jupiter | 5,204 | 778,6 | 11,862 | 4 332,59 | 1,30 | 0,048 | 142 984 | 1899,8 | 1,33 | 24,86 | 3,13 | 0,66 | |
| Сатурн / Saturn | 9,584 | 1433,7 | 29,458 | 10 759,20 | 2,48 | 0,054 | 120 536 | 568,50 | 0,70 | 10,41 | 26,73 | 0,68 | |
| Эрида / Eris | 68,05 | 205 029 | 43,82 | 0,435 | 2 326 | 0,0167 | 2,52 | 0,7 | 0,96 |
**) Для Луны – в среднем противостоянии.
**) For Moon – in mean opposition.
Константи
Некоторые константы и формулы / Some constants and formulae
| Скорость света в вакууме, c (м/с) | 299 792 458 | Speed of light in vacuum, c (m/s) |
| Гравитационная постоянная, G (Н·м²/кг²) | Constant of gravitation, G (N·m²/kg²) | |
| Солнечная постоянная, A (Вт/м²) | 1367 | Solar constant, A (W/m²) |
| Параметр Хаббла, (км/с/МПк), среднее значение | 71 | mean value, Hubble parameter, (km/s/Mpc) |
| диапазон значений | 50-100 | diapason of values |
| Постоянная Планка, h (Дж·с) | Plank constant, h (J·s) | |
| Заряд электрона, e (Кл) | Charge of electron, e (C) | |
| Масса электрона, (кг) | Mass of electron, (kg) | |
| Соотношение масс протона и электрона | 1836.15 | Proton-to-electron ratio |
| Постоянная Фарадея, F (Кл/моль) | 96 485 | Faraday constant, F (C/mol) |
| Магнитная постоянная, (Гн/м) | Magnetic constant, (H/m) | |
| Универсальная газовая постоянная, R (Дж/моль/К) | 8.314 | Universal gas constant, R (J/mol/K) |
| Постоянная Больцмана, k (Дж/К) | Boltzmann constant, k (J/K) | |
| Постоянная Стефана-Больцмана, (Вт/м²/К⁴) | Stefan-Boltzmann constant, (W/m²/K⁴) | |
| Константа смещения Вина, b (м·К) | 0.002897 | Wien’s displacement constant, b (m·K) |
| Лабораторная длина волны Hα (Å) | 6562.81 | Laboratory wavelength of Hα (Å) |
| Длина тропического года, T (сут) | 365.242199 | Tropical year length, T (days) |
| Стандартная атмосфера (Па) | 101 325 | Standard atmosphere (Pa) |
| Ослабление видимого света земной атмосферой в зените (минимально) | Visible light extinction by the terrestrial atmosphere in zenith (minimum) | |
| Показатель преломления воды при 20°C, n | 1.334 | Refractive index of water for 20°C, n |
| Момент инерции шара | Moment of inertia of a solid ball | |
| Площадь сферы | Area of sphere | |
| π | 3.14159265 | π |
| e | 2.71828183 | e |
| Золотое сечение, φ | 1.61803399 | Golden ratio, φ |
Data of some stars
Данные о некоторых звёздах / Data of some stars
| RA | DEC | S C | масса / mass | |||||
|---|---|---|---|---|---|---|---|---|
| Солнце | Sun | G2 | ||||||
| Альдебаран | Aldebaran | α Tau | K5 | |||||
| Альтаир | Altair | α Aql | A7 | |||||
| Антарес | Antares | α Sco | M1+B4 | |||||
| Арктур | Arcturus | α Boo | K1 | |||||
| Ахернар | Achernar | α Eri | B3 | |||||
| зв.Барнарда | Barnard’s star | Oph | M4 | |||||
| Бетельгейзе | Betelgeuse | α Ori | M1 | |||||
| Вега | Vega | α Lyr | A0 | |||||
| Денеб | Deneb | α Cyg | A2 | |||||
| Канопус | Canopus | α Car | F0 | |||||
| Капелла | Capella | α Aur | G5+G0 | |||||
| Полярная | Polaris | α UMi | F7 | |||||
| Процион | Procyon | α CMi | F5 | |||||
| Ригель | Rigel | β Ori | B8 | |||||
| Сириус | Sirius | α CMa | A1 | |||||
| Спика | Spica | α Vir | B1 | |||||
| Альфа Центавра | Alpha Centauri | α Cen | ; | G2 ; K1 | ||||
| Бета Центавра | Beta Centauri | β Cen | B1 | |||||
| Эпсилон Эридана | Epsilon Eridani | ε Eri | K2 |
Note for jury and team leaders
The proposed sketches are not full; the team leaders have to give more detailed explanations to students. But the correct solutions in the students’ papers (enough for 8 pts) may be shorter.
Basic criteria for examiners — Note
The given sketches are not full; the team leaders have to give more detailed explanations to students. But the correct solutions in the students’ papers (enough for 8 pts) may be shorter.
Условие
As you know, last year the Polar Bear (whom you have already met in the texts of many International Astronomy Olympiads) arrived to Mars for astronomical observations. Nowadays his friend Penguin also made a fascinating journey to Mars. At the same instant of time, the Bear and the Penguin observe stars in zenith and see Canopus and Sirius respectively. Estimate roughly, what is the distance (measured on the Martian surface) between the animals? At what height above the horizon does the Bear observe Sirius? The solution has to include a picture with an image of the Bear and the Penguin on Mars. Necessary sizes or angular sizes should be in the picture. Recollect for yourself the necessary information about the Polar Bear and Penguin.
Решение
As we may see from the “Data of some stars”, Canopus and Sirius have almost the same RA (Earth based coordinates) while the difference in DEC is significant. It means that the distance between these stars in the Earth sky is approximately equal to the difference in DEC,
After moving the observer to Mars, this angle will not change, although the coordinates in the Martian sky will be different. It means, the distance measured, by along Martian surface, between the points where Canopus and Sirius are in zenith is:
where km is the radius of Mars.
If the Bear sees Canopus in zenith, the zenith angle of Sirius will be , and its height above horizon
Answers: ~2300 km, .
Basic criteria for examiners.
Angular distance at Earth sky — 2 pt.
Understanding angular distance at Earth sky = angular distance at Martian sky — 1 pt.
Understanding angular distance at = angular distance at planet’s surface — 1 pt.
Calculation of the distance between Bear and Penguin — 2 pt.
Calculation of the height of Sirius if Canopus in zenith — 1 pt.
Necessary picture with Bear and Penguin (artistic style) — 1 pt.
Теми и трудност
Трудност: неоценена.
Небесна сфера и сферична астрономия · Небесни координати
Предпоставки: Разширена олимпиадна подготовка
Оригинал в Архива: alphatheo.pdf · официални решения: theosol1.png · допълнителни данни: theosol2.png · допълнителни данни: theosol3.png · допълнителни данни: theosol4.png · допълнителни данни: theo_cr_1.png · допълнителни данни: theo_cr_2.png