Astronomy
1st Edition
ISBN: 9781938168284
Author: Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher: OpenStax
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Chapter 21, Problem 6E
Look at the four stages shown in Figure 21.8. In which stage(s) can we see the star in visible light? In infrared
Figure 21.8 Formation of a Star. (a) Dense cores form within a molecular cloud. (b) A protostar with a surrounding disk of material forms at the center of a dense core, accumulating additional material from the molecular cloud through gravitational attraction. (c) A stellar wind breaks out but is confined by the disk to flow out along the two poles of the star. (d) Eventually, this wind sweeps away the cloud material and halts the accumulation of additional material, and a newly formed star, surrounded by a disk, becomes observable. These sketches are not drawn to the same scale. The diameter of a typical envelope that is supplying gas to the newly forming star is about 5000 AU. The typical diameter of the disk is about 100 AU or slightly larger than the diameter of the orbit of Pluto.
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Astronomers studying regions like the Orion Giant Molecular Cloud have observed that a wave of star formation can move through them over many millions of years. What sustains such a wave of star formation in a giant molecular cloud?
A. radio waves from complex molecules move slowly through the cloud, causing stars to form
B. when a group of stars form, they remove so much material from the cloud that only a big empty place is left, into which new matter from other clouds falls, making more stars
C. when giant molecular clouds collide with each other, they do so not just once, but many times
D. the dust in these clouds is so heavy, it is always settling inward toward the cloud's center causing star formation in its wake
For each statement concerning main sequence stars, select T True, F False, G Greater than, L Less than, or E Equal to.
A) The surface temperature of a O type star is .... than a K type star.
B) On the main sequence, the mass of a O type star is .... than a F type star.
C) On the main sequence, a M type star's life is .... than a G type star.
D) The surface temperature of our Sun is .... than the surface temperature of Sirius.
E) When stars start hydrogen burning, thier mass determines where they are on the main sequence.
F) Based on the relative lifes of M and G type stars we expect the number of M stars to be .... than the number of G type stars.
Which of the following statements is wrong?
A. A main-sequence star is cooler and brighter than it was as a protostar.
B. Carbon fusion occurs in high-mass stars but not in low-mass stars because the cores of low-mass stars never contain significant amounts of carbon.
C. when a main-sequence star exhausts its core hydrogen fuel supply, the core shrinks while the rest of the star expands.
D. After a supernova explosion, the remains of the stellar core will be either a neutron star or a black hole.
Chapter 21 Solutions
Astronomy
Ch. 21 - Give several reasons the Orion molecular cloud is...Ch. 21 - Why is star formation more likely to occur in cold...Ch. 21 - Why have we learned a lot about star formation...Ch. 21 - Describe what happens when a star forms. Begin...Ch. 21 - Describe how the T Tauri star stage in the life of...Ch. 21 - Look at the four stages shown in Figure 21.8. In...Ch. 21 - The evolutionary track for a star of 1 solar mass...Ch. 21 - Two protostars, one 10 times the mass of the Sun...Ch. 21 - Compare the scale (size) of a typical dusty disk...Ch. 21 - Why is it so hard to see planets around other...
Ch. 21 - Why did it take astronomers until 1995 to discover...Ch. 21 - Which types of planets are most easily detected by...Ch. 21 - List three ways in which the exoplanets we have...Ch. 21 - List any similarities between discovered...Ch. 21 - What revisions to the theory of planet formation...Ch. 21 - Why are young Jupiters easier to see with direct...Ch. 21 - A friend of yours who did not do well in her...Ch. 21 - Observations suggest that it takes more than 3...Ch. 21 - Suppose you wanted to observe a planet around...Ch. 21 - Why were giant planets close to their stars the...Ch. 21 - Exoplanets in eccentric orbits experience large...Ch. 21 - When astronomers found the first giant planets...Ch. 21 - An exoplanetary system has two known planets....Ch. 21 - Kepler’s third law says that the orbital period...Ch. 21 - Calculate the transit depth for an M dwarf star...Ch. 21 - If a transit depth of 0.00001 can be detected with...Ch. 21 - What fraction of gas giant planets seems to have...
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