21st Century Astronomy
6th Edition
ISBN: 9780393428063
Author: Kay
Publisher: NORTON
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Question
Chapter 15.2, Problem 15.2CYU
To determine
The reason for the molecular cloud fragment collapse.
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Based on what you know about observations of the interstellar medium at wavelengths other than for visible light, select all of the correct statements from the following list.
-The 21-cm radio observations are of neutral hydrogen.
-Much interstellar dust between stars is not visible.
-The source of hot gas observed at X-ray wavelengths is not known.
-All interstellar material is cool.
-Interstellar dust is observed at ultraviolet wavelengths.
-Giant molecular clouds consist mostly of CO molecules.
-Material observed at wavelengths longer than that of visible light is usually cool.
At the low temperature found in some interstellar molecular clouds (around 100 K), molecular oxygen emission is strongest at a wavelength of 0.2521 cm. Determine the speed (in km/s) of a low temperature molecular cloud containing molecular oxygen if its strongest emission is at a wavelength of 0.1885 cm. Note that this cloud is moving towards us, so the answer should be negative.
. The radius of the nebula is about 0.401 light-years. The gas is expanding away from the star at a rate of about 37
kilometers/second
. Considering that distance = velocity x time, calculate how long ago the gas left the star if its speed has been constant the whole time. Make sure you use consistent units for time, speed, and distance. Answer in years.
Chapter 15 Solutions
21st Century Astronomy
Ch. 15.1 - Prob. 15.1CYUCh. 15.2 - Prob. 15.2CYUCh. 15.3 - Prob. 15.3CYUCh. 15.4 - Prob. 15.4CYUCh. 15 - Prob. 1QPCh. 15 - Prob. 2QPCh. 15 - Prob. 3QPCh. 15 - Prob. 4QPCh. 15 - Prob. 5QPCh. 15 - Prob. 6QP
Ch. 15 - Prob. 7QPCh. 15 - Prob. 8QPCh. 15 - Prob. 9QPCh. 15 - Prob. 10QPCh. 15 - Prob. 11QPCh. 15 - Prob. 12QPCh. 15 - Prob. 13QPCh. 15 - Prob. 14QPCh. 15 - Prob. 15QPCh. 15 - Prob. 16QPCh. 15 - Prob. 17QPCh. 15 - Prob. 18QPCh. 15 - Prob. 19QPCh. 15 - Prob. 20QPCh. 15 - Prob. 21QPCh. 15 - Prob. 22QPCh. 15 - Prob. 23QPCh. 15 - Prob. 24QPCh. 15 - Prob. 25QPCh. 15 - Prob. 26QPCh. 15 - Prob. 27QPCh. 15 - Prob. 28QPCh. 15 - Prob. 29QPCh. 15 - Prob. 30QPCh. 15 - Prob. 31QPCh. 15 - Prob. 32QPCh. 15 - Prob. 33QPCh. 15 - Prob. 35QPCh. 15 - Prob. 36QPCh. 15 - Prob. 37QPCh. 15 - Prob. 38QPCh. 15 - Prob. 39QPCh. 15 - Prob. 40QPCh. 15 - Prob. 41QPCh. 15 - Prob. 42QPCh. 15 - Prob. 43QPCh. 15 - Prob. 44QPCh. 15 - Prob. 45QP
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Similar questions
- A molecular cloud is about 1000 times denser than the average of the interstellar medium. Let’s compare this difference in densities to something more familiar. Air has a density of about 1 kg/m3, so something 1000 times denser than air would have a density of about 1000 kg/m3. How does this compare to the typical density of water? Of granite? (You can find figures for these densities on the internet.) Is the density difference between a molecular cloud and the interstellar medium larger or smaller than the density difference between air and water or granite?arrow_forwardDescribe the characteristics of the various kinds of interstellar gas (HII regions, neutral hydrogen clouds, ultra-hot gas clouds, and molecular clouds).arrow_forwardWhy evidence can you cite that the interstellar medium contains both gas and dust?arrow_forward
- Describe how the 21-cm line of hydrogen is formed. Why is this line such an important tool for understanding the interstellar medium?arrow_forwardWhere does interstellar dust come from? How does it form?arrow_forwardPrepare a table listing the different ways in which dust and gas can be detected in interstellar space.arrow_forward
- How would the density inside a cold cloud (T=10K) compare with the density of the ultra-hot interstellar gas (T=106K) if they were in pressure equilibrium? (It takes a large cloud to be able to shield its interior from heating so that it can be at such a low temperature.) (Hint: In pressure equilibrium, the two regions must have nT equal, where n is the number of particles per unit volume and T is the temperature.) Which region do you think is more suitable for the creation of new stars? Why?arrow_forwardConsider a grain of sand that contains 1 mg of oxygen (a typical amount for a medium-sized sand grain, since sand is mostly SiO2). How many oxygen atoms does the grain contain? What is the radius of the sphere you would have to spread them out over if you wanted them to have the same density as the interstellar medium, about 1 atom per cm3? You can look up the mass of an oxygen atom.arrow_forwardGive several reasons the Orion molecular cloud is such a useful “laboratory” for studying the stages of star formation.arrow_forward
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