Concept explainers
The Speed of Supernova Debris. The kinetic energy
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The Cosmic Perspective (9th Edition)
- The Large Magellanic Cloud has about one-tenth the number of stars found in our own Galaxy. Suppose the mix of high- and low-mass stars is exactly the same in both galaxies. Approximately how often does a supernova occur in the Large Magellanic Cloud?arrow_forwardLook elsewhere in this book for necessary data, and indicate what the final stage of evolution-white dwarf, neutron star, or black hole-will be for each of these kinds of stars. A. Spectral type-O main-sequence star B. Spectral type-B main-sequence star C. Spectral type-A main-sequence star D. Spectral type-G main-sequence star E. Spectral type-M main-sequence stararrow_forwardConsider the following five kinds of objects: open cluster, giant molecular cloud, globular cluster, group of O and B stars, and planetary nebulae. A. Which occur only in spiral arms? B. Which occur only in the parts of the Galaxy other than the spiral arms? C. Which are thought to be very young? D. Which are thought to be very old? E. Which have the hottest stars?arrow_forward
- A stellar black hole may form when a massive star dies. The mass of the star collapses down to a single point. Imagine an astronaut orbiting a black hole having eight times the mass of the Sun. Assume the orbit is circular. a. Find the speed of the astronaut if his orbital radius is r = 1 AU. b. Find his speed if his orbital radius is r = 11.8 km. c. CHECK and THINK: Compare your answers to the speed of light in a vacuum. What would the astronauts orbital speed be if his orbital radius were smaller than 11.8 km?arrow_forwardMost stars close to the Sun are red dwarfs. What does this tell us about the average star formation event in our Galaxy?arrow_forwardWhat is an event horizon? Does our Sun have an event horizon around it?arrow_forward
- Where in the Galaxy would you expect to find Type II supernovae, which are the explosions of massive stars that go through their lives very quickly? Where would you expect to find Type I supernovae, which involve the explosions of white dwarfs?arrow_forwardAstronomers believe there are something like 100 million neutron stars in the Galaxy, yet we have only found about 2000 pulsars in the Milky Way. Give several reasons these numbers are so different. Explain each reason.arrow_forwardHuman civilization is about 10,000 years old as measured by the development of agriculture. If your telescope collects starlight tonight that has been traveling for 10,000 years, is that star inside or outside our Milky Way Galaxy? Is it likely that the star has changed much during that time?arrow_forward
- Why are so many astronomical objects in the universe flat today? (Like the solar system, Saturn's ring, black hole accretion discs) Let's focus on our galaxy. Originally, the galaxy was a huge spherical cloud of gas and dust, much larger than it is today, and rotating much more slowly. Explain using gravity and the conservation of angular momentum, why the galaxy today is a flat disc that rotates faster.arrow_forwardLet’s say you’re looking for extrasolar planets. You observe a star that has a spectral shift in the line that is supposed to be at at 656.28011 nm – this star shows this line at 656.28005 nm. What is the radial velocity of star (in m/s) and in what direction in relation to you? a) 27.4 m/s, towards b) 27.4 km/s, away c) -27.4 m/s, toward d) -27.4 km/s, awayarrow_forwardAround 2.5 centuries ago, several physicists of the time came up with the notion of a dark star. This was a star so dense, with so much gravity, that not even light could escape. The calculations used Newtonian mechanics. In class, we calculated the escape speed from the surface of the earth or the distance from the sun, and the mass of the planet or star. Here, the process is partially reversed. Calculate the dark star radius from the mass of the star and the escape speed. Answer in kilometers. c = 3*108 m/s M = 2.4*1030 kg G = 2/3 * 10-10 N*m2/kg2arrow_forward
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