soal latihan astronomi III

1. If the Earth rotated in the opposite sense (clockwise rather than counterclockwise), how long would the solar day be?
2. Suppose that the Earth’s pole was perpendicular to its orbit. How would the azimuth of sunrise vary throughout the year? How would the length of day and night vary throughout the year at the equator? at the North and South Poles? where you live?
3. You are an astronaut on the moon. You look up, and see the Earth in its full phase and on the meridian. What lunar phase do people on Earth observe? What if you saw a first quarter Earth? new Earth? third quarter Earth? Draw a picture showing the geometry.
4. If a planet always keeps the same side towards the Sun, how many sidereal days are in a year on that planet?
5. If on a given day, the night is 24 hours long at the North Pole, how long is the night at the South Pole?
6. On what day of the year are the nights longest at the equator?
7. From the fact that the Moon takes 29.5 days to complete a full cycle of phases, show that it rises an average of 48 minutes later each night.
8. What is the ratio of the flux hitting the Moon during the first quarter phase to the flux hitting the Moon near the full phase?
9. Titan and the Moon have similar escape velocities. Why does Titan have an atmosphere, but the Moon does not?
10. Having observed the sunrise every day in the same location, the astronomer noticed that the azimuth of the sunrise point changes in the range of 90° during the year. Please find the latitude of the observation place. The refraction and solar disk size can be neglected.
11. Two stars have the same physical parameters. They are observed close to each other in the sky, but their distances are different. Both stars and the observer are situated inside the uniform cloud of interstellar dust. The photometric measurements of these stars in B band gave the results 11m and 17m, in V band the results were 10m and 15m. What is the ratio of distances to these stars? Assume that the extinction property of interstellar dust is proportional to the wavelength in the degree of (–1.3).
12. The magnitude of total umbral lunar eclipse is equal to 1.865. Please find the duration of totality. The expansion of the umbra caused by atmosphere can be disregarded
13. The radius of the Galaxy is equal to 15 kpc, the thickness of its disk being many times less. The mass of the galaxy is equal to 1011 solar masses and it is distributed uniformly in the volume of the galaxy. Two stars are rotating around the center of the galaxy in the same direction by the circular orbits with radii equal to 5 kpc and 10 kpc. Please find the synodic period of the first star while observing from the vicinity of the second star.
14. The white dwarf with radius 6000 km, surface temperature 10000 K and mass equal to solar one moves through the interstellar cluster of comet cores, each one has radius 1 km and density 1 g/cm3. How many comets must fall on the white dwarf every day to increase its luminosity in two times?
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16. Bintang A tampak mempunyai kecerlangan yang sama pada filter merah dan biru. Bintang B tampak lebih terang pada filter merah daripada filter biru. Bintang C tampak lebih terang pada filter biru daripada di filter merah. Urutkan bintang-bintang itu berdasarkan pertambahan temperaturnya.
17. The binary star Capella has a total magnitude of 0.21^m and the two components differ in magnitude by 0.5^m. The parallax of Capella is 0.063”. Calculate the absolute magnitudes of the two components.
18. There are about 250 millions of the stars in the elliptical galaxy M32. The visual magnitude of this galaxy is 9. If the luminosities of all are equal, what is the visual magnitude of one star in this galaxy?
19. Two stars have the same apparent magnitude and are of the same spectral type. One is twice as far away as the other. What is the relative size of the two stars?
20. Sebuah galaksi diamati memiliki magnitudo visual m_V = 21. Magnitudo ini berasosiasi dengan energi dari 10¹¹ bintang yang ada di dalamnya (terdiri dari 3 jenis). Perkirakan/hitung jarak galaksi tersebut. Untuk itu gunakan asumsi sebagai berikut

Jenis bintang	MV	Jumlah (%)
a	1	20
b	4	50
c	6	30