Foundations of Astronomy, Enhanced
13th Edition
ISBN: 9781305980686
Author: Michael A. Seeds; Dana Backman
Publisher: Cengage Learning US
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Chapter 11, Problem 6RQ
To determine
What prevents a giant molecular cloud fragment from collapsing to zero radius and what happens to the density, pressure, and temperature to slow the continued collapse. What happens to the given temperature outside of the core as the core of the fragment slows its insider-out collapse.
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Students have asked these similar questions
1) a) Calculate the Jeans length for the dense core of a giant molecular cloud with T=10 K, n =
1010/m³, and µ=2.
b) Estimate the adiabatic sound speed for this core, using y=5/3.
c) Use this speed to find the amount of time required for a sound wave to cross the cloud
t3=2Rj/vs.
d) Compare your answer with the free-fall scale and comment your results.
1. A planetary nebula has an angular diameter of 76 arc seconds and a distance of 5100 ly. What is its linear diameter (in ly)?
Hint:
Use the small-angle formula:
angular diameter (in arc seconds)
2.06 ✕ 105
=
linear diameter
distance
2. Suppose a planetary nebula is 3.2 pc in diameter, and Doppler shifts in its spectrum show that the planetary nebula is expanding at 31 km/s. How old is the planetary nebula in yr? (Note: 1 pc = 3.1 ✕ 1013 km and 1 yr = 3.2 ✕ 107 s.)
A planetary nebula expanded in radius 0.3 arc seconds in 30 years. Doppler measurements show the nebula is expanding at a rate of 35 km/s. How far away is the nebula in parsecs?
First, determine what distance the nebular expanded in parsecs during the time mentioned. Δd = vpc/sTs
So we first need to convert the rate into pc/s and the time into seconds:
vpc/s = vkm/s (1 pc / 3.09 x 1013km)
vpc/s = ?
Ts = (Tyr)(365 days/yr)(24 hrs/day)(3600 s/hr)
Ts = ? s
Δd= vpc/sTs
Therefore, Δd = ? pc
Chapter 11 Solutions
Foundations of Astronomy, Enhanced
Ch. 11 - Prob. 1RQCh. 11 - Prob. 2RQCh. 11 - Prob. 3RQCh. 11 - Prob. 4RQCh. 11 - Prob. 5RQCh. 11 - Prob. 6RQCh. 11 - Prob. 7RQCh. 11 - Prob. 8RQCh. 11 - Prob. 9RQCh. 11 - Prob. 10RQ
Ch. 11 - Prob. 11RQCh. 11 - Prob. 12RQCh. 11 - Prob. 13RQCh. 11 - Prob. 14RQCh. 11 - Describe the three ways thermal energy can be...Ch. 11 - Prob. 16RQCh. 11 - Prob. 17RQCh. 11 - How does the CNO cycle differ from the...Ch. 11 - Prob. 19RQCh. 11 - Prob. 20RQCh. 11 - Prob. 21RQCh. 11 - Prob. 22RQCh. 11 - Prob. 23RQCh. 11 - Prob. 24RQCh. 11 - Prob. 25RQCh. 11 - Prob. 1DQCh. 11 - Prob. 2DQCh. 11 - Prob. 3DQCh. 11 - Prob. 4DQCh. 11 - Prob. 5DQCh. 11 - Prob. 6DQCh. 11 - Prob. 1PCh. 11 - Prob. 2PCh. 11 - Prob. 3PCh. 11 - Prob. 4PCh. 11 - If a protostellar disk is 200 AU in radius and the...Ch. 11 - Prob. 6PCh. 11 - Prob. 7PCh. 11 - Prob. 8PCh. 11 - Prob. 9PCh. 11 - Prob. 10PCh. 11 - Prob. 11PCh. 11 - Prob. 12PCh. 11 - If the Orion Nebula is 8 pc in diameter and has a...Ch. 11 - Prob. 14PCh. 11 - Prob. 1LTLCh. 11 - Prob. 2LTLCh. 11 - Prob. 3LTLCh. 11 - Prob. 4LTLCh. 11 - Prob. 5LTLCh. 11 - Prob. 6LTL
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- Why do nebulae near hot stars look red? Why do dust clouds near stars usually look blue?arrow_forwardWhat is a planetary nebula? Will we have one around the Sun?arrow_forwardIf a giant molecular cloud is 38 pc in diameter and a shock wave can sweep through it in 6 million years, how fast is the shock wave going in kilometers per second? (Notes: 1 pc = 3.1 1013 km; 1 yr = 3.2 107 s.) answer in km/sarrow_forward
- Which of the following statements is/are true regarding a nebula? Which of the following statements is/are true regarding a nebula? It is believed that each planet in our solar system began as its own nebula. Over time, a nebula becomes cooler and grows in size. The density of a nebula is greatest at the edges and least in the center. There are no nebulas left in our galaxy because they have all formed stars and planets. Over time, a star will form at the center of a nebula.arrow_forwardExplain what makes the planetary nebula glow and what makes the supernova remnant glow. Which of these two kinds of gas clouds continues to glow for a longer time and why?arrow_forward. 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.arrow_forward
- Place the following events in the formation of stars in the proper chronological sequence, with the oldest first and the youngest last. w. the gas and dust in the nebula flatten to a disk shape due to gravity and a steadily increasing rate of angular rotation x. a star emerges when the mass is great enough and the temperature is high enough to trigger thermonuclear fusion in the core y. the rotation of the nebular cloud increases as gas and dust concentrates by gravity within the growing protostar in the center z. some force, perhaps from a nearby supernova, imparts a rotation to a nebular cloud y, then z, then w, then x z, then y, then w, then x w, then y, then z, then x z, then x, then w, then y x, then z, then y, then w MacBook Air on .H. O O O Oarrow_forwardIf a giant molecular cloud is 73 pc in diameter and a shock wave can sweep through it at 9 million years, how fast is the shock wave going in km per second? 1 pc = 3.1× 10^13 km; 1 yr = 3.2 × 10^ 7 s.arrow_forwardIf a giant molecular cloud has a diameter of 56 pc and drifts relative to nearby objects at 19 km/s, how long (in yr) does it take to travel a distance equal to its own diameter?arrow_forward
- For a main sequence star with luminosity L, how many kilograms of hydrogen is being converted into helium per second? Use the formula that you derive to estimate the mass of hydrogen atoms that are converted into helium in the interior of the sun (LSun = 3.9 x 1026 W). (Note: the mass of a hydrogen atom is 1 mproton and the mass of a helium atom is 3.97 mproton. You need four hydrogen nuclei to form one helium nucleus.)arrow_forwardAssuming that at the end of the He burning phase of the stellar core (r < R_core) has no H or He or other metals and is composed completely of Carbon, X=Y=0, X_c = 1 ; The envelope above the core has a normal stellar composition ( r > R_core). Calculate the length of time in years that a 1M_sol and 10M_sol star will live on the horizontal branch or the time between the start and end of the He burning phase. Assume that the normal relationship between mass and luminosity holds for horizontal branch stars. Please be as detailed as possiblearrow_forward
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