Astro 1Web Test-3 Sample Qs PDF

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Answers to practice exam for Unit 3...

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Astronomy 1 - Section 5 Choose the SINGLE answer which is BEST.

3 FORM S

1. An ”onion skin” shell burning structure develops in a) a neutron star. b) a star like the Sun. d) a star much less massive than the Sun. e) a white dwarf. 2. What is a T-Tauri star? a) a star that will become a planetary nebula b) a star in an open star cluster d) one of the most massive stars on the main sequence e) a star in a globular star cluster 3. A large luminosity star a) is always at a larger distance than a small luminosity star c) is always redder than a star with a small luminosity d) is at a lower temperature than a small luminosity star e) is always at a smaller distance than a small luminosity star 4. The stars in the halo of our galaxy are a) not affected by reddening and extinction. b) in a very flat distribution. c) older and bluer than those in the disk. d) never in globular clusters.

If a red giant appears the same brightness as a red main sequence star, which one is further away? b) we can’t tell c) it depends on the phase of the Moon d) the main sequence star e) they are at the same distance

2 6. If you could convert the Earth (mass 6 × 1027g) into pure energy, how much energy would be produced (in ergs) compared to what the Sun produces over its whole life (1.2 × 1051 ergs)? The speed of light c = 3 × 1010 cm/s. a) more than 10 times more b) three times less c) roughly the same amount d) three times more

7. Which star is the furthest away if all have the same apparent brightness? a) type G main sequence star b) type F main sequence star c) type M main sequence star e) white dwarf 8. The heaviest nuclei of all are formed a) during helium burning b) during carbon burning c) during a nova explosion e) during all stages of stellar evolution of massive stars 9. In the Eagle nebula a shock wave crashes into colder, dark gas. What does this cause? a) formation of large amounts of dust made of carbon and silicon b) causes no stars to form in the region for about 500,000 years c) causes a reflection nebula e) destruction of all Bok globules 10. Fill in the blank in the following chemical reaction that occurs in the Sun: Deuterium + proton =??+ energy: a) deuterium-2 b) hydrogen-1 d) carbon-12

3 11. In nuclear fusion, energy is produced because: a) Hydrogen is not stable. c) of the energetic impact of collisions. d) gravity leads to collapse. e) positrons are produced. 12. What method of extrasolar planet relies on the star getting brighter than usual and then fainter again? a) astrometry b) radial velocity c) direct imaging e) transits 13. Which of the following has the smallest radius? a) type A main sequence star b) main sequence star with surface temperature 8000K c) type K main sequence star d) white dwarf

14. The Milky Way galaxy has a rotation curve that a) decreases rapidly with increasing radius in the disk, indicating no dark matter is present. b) stays constant out to large radii in the disk, indicating that no dark matter is present. c) increases drastically with increasing radius. d) decreases rapidly with increasing radius in the disk, indicating the presence of dark matter.

15. Which of the following is the coldest at its surface? a) main sequence star with radius ten times the Sun’s radius c) d) blue main sequence star e) 3 solar luminosity main sequence star

4 16. Why would a person be torn apart as he fell feet first into a black hole? a) because of the force of friction b) because he would be travelling at the speed of light c) time is distorted so that by the time the light from his feet reached his eyes, years would have elapsed e) because of the rotation of the black hole 17. Which of the following is FALSE? a) Scientists have teleported the quantum state of individual atoms from one location to another. b) Organisms have been found living in water as hot as 235 degrees F. c) Planets have been discovered in binary star systems. d) Some microorganisms can survive years of radiation exposure in space.

18. Why does the main sequence part of a star’s life end? a) The Helium in the core is exhausted. b) The gravitational force is not longer large enough to balance the pressure. c) d) The temperature drops so that nuclear reactions are no longer possible. e) Much of the mass of the star has evaporated. 19. When using different points in the Earth’s orbit as a baseline for a parallax experiment it is best to do the observations: a) 1 day apart. b) 2 years apart. c) 1 month apart. d) 1 year apart.

20. What is the FIRST thing that happens when a main-sequence star runs out of fuel in the core? a) The star turns into a white dwarf c) The star explodes as a supernova d) Helium starts burning into Carbon in the core e)

5 21. Which of the following will have the shortest lifetime on the main sequence? a) b) main sequence star with surface temperature 3000K c) main sequence star with luminosity one tenth that of the Sun d) the Sun e) main sequence star with mass 2 times the Sun 22. The event horizon of a black hole is a) The distance at which a star is torn apart by tidal forces b) The distance from which we can see inside the black hole c) The point of infinite density d) The distance at which a human body is torn apart by tidal forces e) 23. The brightest 100 stars viewed from Earth are mostly not on the main sequence (even though most stars are) because: a) only high mass stars formed near to us in the Galaxy. b) c) our region of the Galaxy is very young. d) the main sequence is the shortest part of a star’s life so stars don’t spend much time there. e) our region of the Galaxy is very old. 24. A 2 solar mass main sequence star is at the same distance as a 0.2 solar mass main sequence star. Which star appears brighter? a) depends on the phase of the Moon c) stars are approximately the same brightness d) the 0.2 solar mass main sequence star e) cannot tell with the information given 25. The temperature of the photosphere of the Sun is closest to a) 107 K b) 106 K c) 100K d) 600000K...