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MM Astro Final
Review questions from quizzes
| Question | Answer |
|---|---|
| Which of the following statements is true about the Sun's photosphere? | All choices are correct (opaque to transparent, 5780 K, and granular appearance from hot rising material) |
| Why does the proton-proton chain require high temperatures? | Because at high temperatures the protons have enough speed to overcome the electrical repulsion |
| The maximum number of sunspots occur ____ years. | every 11 |
| Where on the Sun are spicules located? | Chromosphere |
| Near the Sun's core, energy is mainly transported by | Photons |
| IN the outer part of the Sun, just below the photosphere, the energy is transported mainly by | Convection |
| What is the energy source of the Sun? | Fusion of hydrogen to helium |
| What prevents the Sun from further collapsing under its own gravity? | The gas pressure generated at high temperature at the Sun's interior |
| What kind of information can astronomers obtain from the spectrum of a star? | All choices are correct (Temp, Luminosity, Composition, Radial velocity) |
| What types of spectra are used in the OBAFGKM classification scheme? | Line absorption spectra |
| Which star is hotter than K but cooler than an F star? | G star |
| The Balmer lines correspond to wavelengths in the ____ part of the spectrum of a ____ atom. | visible; hydrogen |
| The HR Diagram is a diagram plotted the stars according to their | Luminosity and temperature |
| The star Aldebaran is cooler and much more luminous than the Sun. Where do you expect to find Aldebaran in the HR diagram? | top right |
| The luminosity of a star is determined by the star's ____ and _____ | diameter; surface temperature |
| Where are the Sun's granules located? | Photosphere |
| Where on the Sun are sunspots located? | Photosphere |
| A parsec is a unit of measure used to describe a | distance of stars |
| The star Procyon has apparent magnitude of 0.4, while Rigel has 0.1. Which of the two stars appear brighter to an observer on Earth? | Rigel |
| Which method is used to determine a star's temperature? | Wien's law |
| Which of the following statements about the mass-luminosity relation is correct? | It relates the luminosity to the mass for main sequence stars ONLY |
| Where on an HR diagram would a hot star of low luminosity be located? | Bottom left |
| Which method is used to determine a star's mass? | Kepler's 3rd law in binary system |
| The spectrum of a star shows the 656 nm absorption line shifted to 658 nm. Which of the following can we conclude about this star? | The star is receding from us. |
| Binary star systems are very important because they allow | measurement of star masses |
| What is the source of energy as a star evolves from an interstellar cloud to the protostar stage? | Gravity |
| A protostar becomes a main sequence star when it | starts fusing hydrogen to helium |
| Hydrostatic equilibrium is the balance between ____ of a star and ____ | the internal pressure; gravity |
| Which main sequence star has the largest mass? | O type star |
| The main source of energy in main sequence stars is ____ | fusion of hydrogen to helium |
| Why do high mass stars, like the O and B type stars have a short life on the main sequence? | Because high mass stars burn their hydrogen very fast |
| Why is it necessary for the cores of high mass stars to have higher temperature than interiors of low mass stars? | High mass stars need the higher temperature to raise the internal pressure and balance gravity's pull |
| Which of the following processes will occur once a star depletes the hydrogen in its core? Which of the following processes will occur once a star depletes the hydrogen in its core? | The core will shrink and heat up while the outer layers will expand and cool down |
| If the Sun's core stopped producing energy, then: | The core would shrink because of gravity and heat up |
| The high-mass stars become ____ variables when they cross the instability strip, while the low-mass stars become ____ variables | Cepheid; RR Lyrae |
| Which star is a remnant of a low mass star? | Planetary nebula |
| How do most of the heavier elements up to iron form in the Universe? | By nucleosynthesis in the cores of massive stars |
| ____ is the most significant force that determines the evolution of stars | Gravity |
| Which of the following statements about white dwarfs is correct? | Their core is composed mainly of carbon and oxygen |
| Which of the following objects do you expect to find at the center of a planetary nebula? | White dwarf |
| What is the approximate size of a white dwarf? | About the size of the Earth |
| Which of the following statements describes the evolution of white dwarfs? | White dwarfs become cooler and dimmer as they age |
| The Chandrasekhar limit is the largest ______ a white dwarf can have | mass |
| _______ are remnants of low mass stars | White dwarfs |
| Which of the following properties is not characteristic of young neutron stars? | High luminosity |
| Which of the following statements describes the most likely evolution of a neutron star? | Neutron stars spin slower as they age |
| What is the Schwarzschild radius of a black hole of 10 solar masses? | 30 km |
| Suppose that the Sun was replaced by a black hole of equal mass. How would that affect the planets | The orbits of the planets would not be affected |
| Approximately how far is the Sun from the center of our Galaxy? | 8 kpc |
| What type of object has been proposed to explain the tremendous activity detected at the center of our Galaxy? | A supermassive black hole |
| Harlow Shapley first located the center of our Galaxy in 1917 by | observing the distribution of globular clusters in the galactic halo |
| In which constellation in our sky is the center of our Milky Way Galaxy located? | Sagittarius |
| The Sun's position in the Galaxy is | in the disk of the Galaxy, inside a spiral arm or segment of a spiral arm |
| The dimensions of the disk of our Milky Way Galaxy are | diameter 100,000 light-years; thickness 2000 light-years |
| Cepheid variable stars are useful to astronomers as indicators of | distance, particularly to nearby galaxies |
| Which of the following components of the Galaxy best outline the spiral arms of the Galaxy? | Young O and B stars, dust, and gas |
| The time for the Sun to orbit the galactic center once in its motion in the Galaxy is | 230 million years |
| What force holds the stars in orbit in spiral galaxies? | Gravity |
| Which type of galaxy typically contains the least relative amount of gas and dust? | The elliptical |
| The majority of galaxies in our immediate vicinity (i.e., in the local group) are | Irregular and small elliptical galaxies |
| _____ galaxies contain mostly Population II stars; while _____ galaxies contain both Population I and Population II stars | elliptical; spiral |
| Which type of galaxy has a disk with no spiral arms? | S0 |
| _______ galaxies may contain a few million to few trillion solar masses. | ?? |
| The _____ that is affecting the motion of the Local Group is believed to be a yet unseen _____. | Great Attractor; cluster of superclusters |
| What is the rotation curve of a galaxy? | It is a graph of the orbital velocities at various distances from the center of the galaxy |
| What is the evidence for dark matter? | The fact that the rotation curves of most galaxies become flat at large distances from the center |
| Astronomers believe that the X-ray radiation from the nuclei of active galaxies comes from _____. | from the accretion disk around a massive black hole |
| Which particular property of the Cepheid variables makes them suitable as standard candles? | Their pulsation period is related to their luminosity |
| Which of the following is not true of Hubble’s law? | It can be used to estimate the distance of our neighboring M31 galaxy in Andromeda |
| What value is closer to the presently accepted value of the Hubble constant? | 70 kilometers per second per megaparsec |
| How do astronomers obtain information about the past of the Universe? | By looking at very distant galaxies |
| Which of the following models of the Universe are consistent with Hubble's law? | Redshift of galaxies (Slipher), Expansion of the Universe |
| Which of the following provides the strongest evidence in support of the Big Bang model? | The existence of the cosmic microwave background radiation |
| Recent measurements indicate that some of the most distant galaxies may have recession velocities lower than predicted by Hubble's law. What are the implications of such a discovery? | The expansion of the Universe is speeding up |
| Which of the following findings are in agreement with the predictions of the Big Bang model? | All of the choices are correct |
| Which of the following lists the forms of matter in the order they came to existence in the early Universe? | Quarks, protons, electrons, atoms |
| The inverse of Hubble's constant (1/H) gives the approximate _____. | age of the Universe |
| Recent measurement of the variations of the cosmic background radiation suggest that the curvature of the Universe is ______. | flat (i.e., no curvature) |
| According to the Big Bang model, most of the _____ in the Universe were formed ____. | hydrogen and helium; during the first 3 minutes |
| Presently, the accepted value for the Age of the Universe is ________. | About 14 billion years |
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