* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Oct 06, 2001
Survey
Document related concepts
Corona Australis wikipedia , lookup
Canis Minor wikipedia , lookup
Auriga (constellation) wikipedia , lookup
Corona Borealis wikipedia , lookup
Cassiopeia (constellation) wikipedia , lookup
Astronomical spectroscopy wikipedia , lookup
Cygnus (constellation) wikipedia , lookup
Dyson sphere wikipedia , lookup
Timeline of astronomy wikipedia , lookup
Aquarius (constellation) wikipedia , lookup
Star of Bethlehem wikipedia , lookup
Perseus (constellation) wikipedia , lookup
Star formation wikipedia , lookup
Transcript
1) A star leaves the main sequence when A) nuclear fuel in its core can supply enough energy to stop its collapse. B) it collapses, and its envelope becomes degenerate. C) it stops fusing hydrogen in its core and starts to expand. D) it forms planets. The HR Diagram at right is provided to assist with answering the following two questions. Spectral Type O5 10,000 B5 A5 K5 M5 Red Giants a d 1,000 Luminosity (solar units) F5 G5 -5 b 100 10 1 0 Main Sequence e 5 .1 .01 f 10 Absolute magnitude 2) Which is hotter, a main sequence star with an absolute magnitude of M= 4 or a white dwarf with a luminosity 100 times smaller than the Sun? A) the main sequence star B) the white dwarf C) They have the same temperature. D) There is insufficient information to determine this. c 3) Which statement is the most correct .001 White Dwarfs about the comparison between a K5 .0001 15 main sequence star and a B5 main sequence star? 20,000 10,000 5,000 A) The K5 star is cooler, less Temperature (K) luminous, smaller, and will not live as long as the B5 main sequence star. B) The K5 star is hotter, less luminous, larger, and will live longer than the B5 main sequence star. C) The K5 star is smaller, hotter, more luminous, and will not live as long as the B5 main sequence star. D) The K5 star is hotter, more luminous, smaller, and will live longer than the B5 main sequence star. E) The K5 star is less luminous, cooler, smaller, and will live longer than the B5 main sequence star. 4) Fragments of Giant Molecular Clouds that proceed on to form stars are called protostars. These protostars heat up even though conditions in their cores are not sufficient to begin nuclear fusion. What causes these protostars to heat up? A) The energy they absorb from nearby hot stars. B) Gravitational energy released from the gas and dust as the fragment collapses. C) Fusion of hydrogen into helium in the envelope of these protostars. D) Energy released from their magnetic fields. 5) Four main sequence stars are described below. Which will have the shortest main sequence lifetime? A) A main sequence star of 50 solar C) A main sequence star that is yellow in masses. color B) A main sequence star that is 0.1 solar D) A main sequence star with a surface radii in size. temperature of 10,000 K 6) When a star like the sun evolves into a red giant, its core A) expands and cools. C) expands and heats. B) contracts and heats. D) contracts and cools. 7) What is a “planetary nebula”? A) It is the disk of gas around a young star. B) It is the cloud from which protostars form C) It is a shell of gas ejected from a star late in its life. D) It is what is left when a white dwarf star explodes as a supernova. 8) What makes a high-mass star's core collapse? A) Energy from its outer layers compresses its core. B) The only thing that can make a star's core collapse is a collision with another star C) Massive stars develop iron cores that cannot fuse anymore, so the core collapses under the force of its own gravity. D) Massive stars' cores don't collapse. They expand and become planetary nebulas. 9) A Main Sequence O star will have a main sequence lifetime of about A) 100 Byrs C) 1 Byrs B) 10 Byrs D) 100 Myrs E) 1 Myrs 10) At the end of a Main Sequence O star’s evolution its core is composed primarily of A) Hydrogen C) Carbon E) Uranium B) Helium D) Iron 11) A 10th magnitude star is ____ than a 5th magnitude star. A) 2 times brighter C) 100 times brighter B) 2 times fainter D) 100 times fainter E) There is insufficient information to answer this question. Use the four HR diagrams shown below to answer the following two questions. Star Pleiades Cluster A Star MCluster B 67 6 8 8 10 10 V 12 V 12 14 14 16 16 18 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 18 2 0 B-V 0.2 Star Cluster C M3 0.4 0.6 0.8 1 B-V 1.2 1.4 1.6 1.8 2 Star Cluster D M35 8 13 14 10 15 16 12 V V 17 14 18 19 16 20 21 18 0 22 0 0.2 0.4 0.6 0.8 1 1.2 1.4 0.2 0.4 0.6 0.8 1 1.2 1.4 B-V B-V 30) Which of the following is the most correct ranking for the age of the star clusters from youngest to oldest? A) A<B<C<D C) C<B<A<D B) D<C<A<B D) D<A<B<C 31) Which of the star clusters has a large number of stars that are producing energy by core Heburning? A) Star Cluster A C) Star Cluster C B) Star Cluster B D) Star Cluster D 32) Proxima Centauri is a main sequence star that appears red when viewed from Earth, as a result which of the following are true: A) It is hotter than an O spectral class main sequence star. B) It is moving toward the Earth. C) It is moving away from the Earth. D) It will live longer than a B spectral class main sequence star. E) It is the same size as a red giant star of the same temperature. Refer to H-R diagram illustrating the evolutionary track of a 1 solar mass star to the right to answer the following 5 questions 33) Which of the objects listed below would be observed along the portion of the track marked (e)? A) White dwarf B) Planetary Nebula C) Red Giant D) Horizontal Branch star E) None of the above e -10 d -5 0 M +5 b c a +10 +15 +20 O 34) Which of the methods of energy production is at active along the portion of the track marked (d)? A) Core H-burning C) Shell H-burning B) Core He-burning D) Shell He-burning B A F G K M E) Proton-proton chain 35) At which of the lettered positions on the H-R diagram (a) through (e) will the star spend the most time? 36) Which of the following processes is responsible for the evolution along the track marked (b)? A) The star’s core has exhausted its energy supply and the star is shrinking and cooling. B) The core is expanding and raising the stars temperature and radius. C) The core has stopped producing energy and shell of energy production around the collapsing core is causing the star to increase in radius. D) The core is now all iron and the star is about to supernova. 37) Along the track marked (e) the core of the star is composed of A) Hydrogen C) Carbon B) Helium D) Iron E) Uranium Please solve the following two numerical problems. Clearly show how you have arrived at your result. The points awarded will be based on how clearly you have demonstrated good problem solving practices. Three points each. 1) The spectrum of the star designated HD 20899 is shown below. Ignore the many absorption lines and use the bold smoothed spectrum to answer the following question. Is this star hotter or cooler than the Sun? Estimate λMax from the spectrum and then use Wien’s law to estimate the temperature of the star. Don’t forget to answer the original question. 375 400 425 Wavelength, nm 450 475 2) A star is known to be half the temperature of the Sun and twice its radius. What is its luminosity? You may answer either in Watts or in units of solar luminosity.