Universe: Stars And Galaxies
6th Edition
ISBN: 9781319115098
Author: Roger Freedman, Robert Geller, William J. Kaufmann
Publisher: W. H. Freeman
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Chapter 18, Problem 48Q
To determine
To explain:
The effect on the internal structure of main sequence stars if electrons in hydrogen atoms were not as strongly attracted to the nuclei of those atoms and so, the atoms were easier to ionize.
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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.)
A star with spectral type A0 has a surface temperature of 9600 K and a radius of 2.2 RSun. How many times more luminous is this star than the Sun? (if it is less luminous enter a number less than one)
This star has a mass of 3.3 MSun. Using the simple approximation that we made in class, what is the main sequence lifetime of this star? You may assume that the lifetime of the sun is 1010 yr.
Compare this to the lifetime of a A0 star listed in Table 22.1 (computed using a more sophisticated approach). Is the value you calculated in the previous problem longer or shorter than what is reported in the table? (L for longer, S for shorter) (You only get one try at this problem.)
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
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Chapter 18 Solutions
Universe: Stars And Galaxies
Ch. 18 - Prob. 1QCh. 18 - Prob. 2QCh. 18 - Prob. 3QCh. 18 - Prob. 4QCh. 18 - Prob. 5QCh. 18 - Prob. 6QCh. 18 - Prob. 7QCh. 18 - Prob. 8QCh. 18 - Prob. 9QCh. 18 - Prob. 10Q
Ch. 18 - Prob. 11QCh. 18 - Prob. 12QCh. 18 - Prob. 13QCh. 18 - Prob. 14QCh. 18 - Prob. 15QCh. 18 - Prob. 16QCh. 18 - Prob. 17QCh. 18 - Prob. 18QCh. 18 - Prob. 19QCh. 18 - Prob. 20QCh. 18 - Prob. 21QCh. 18 - Prob. 22QCh. 18 - Prob. 23QCh. 18 - Prob. 24QCh. 18 - Prob. 25QCh. 18 - Prob. 26QCh. 18 - Prob. 27QCh. 18 - Prob. 28QCh. 18 - Prob. 29QCh. 18 - Prob. 30QCh. 18 - Prob. 31QCh. 18 - Prob. 32QCh. 18 - Prob. 33QCh. 18 - Prob. 34QCh. 18 - Prob. 35QCh. 18 - Prob. 36QCh. 18 - Prob. 37QCh. 18 - Prob. 38QCh. 18 - Prob. 39QCh. 18 - Prob. 40QCh. 18 - Prob. 41QCh. 18 - Prob. 42QCh. 18 - Prob. 43QCh. 18 - Prob. 44QCh. 18 - Prob. 45QCh. 18 - Prob. 46QCh. 18 - Prob. 47QCh. 18 - Prob. 48QCh. 18 - Prob. 49Q
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- Give ALL correct answers referring to the properties of known stars, i.e., B, AC, BCD... A) On the main sequence, more massive stars are colder. B) High mass stars are the most numerous type of stars observed in the galaxy. C) Giants are colder than main sequence stars at the same luminosity. D) Giants are brighter than dwarfs at the same temperature. E) On the main sequence, more massive stars are dimmer. F) White dwarf stars are much denser than main sequence stars. Hint: White dwarf stars have about the mass of our sun, but are only the size of the Earth. Therefore, they have a very high density.arrow_forwardWhat are the three possible outcomes of stellar evolution? Describe each possibility, differentiating their means of formation and their subsequent properties. Which stars on the Main Sequence are thought to end up in each of these forms?arrow_forwardThe figure above shows a track on the H-R diagram corresponding to the evolution of a star like the one you’ve just considered. Six stages are numbered. Six stages of stellar evolution are listed below – for each stage, write the number corresponding to its position on the diagram (four of these stages are the same stages you considered in the first part of this tutorial). Horizontal branch: Asymptotic giant branch: White dwarf: Main sequence: Planetary nebula: Red giant branch: What is the approximate mass of this star, in solar masses? Explain how you can tell.arrow_forward
- How are giant molecular clouds (GMCs), the loci of most star formation, themselves formed out of diffuse interstellar gas? What processes determine the distribution of physical conditions within star-forming regions, and why does star formation occur in only a small fraction of the available gas? How is the rate at which stars form determined by the properties of the natal GMC or, on a larger scale, of the interstellar medium (ISM) in a galaxy? What determines the mass distribution of forming stars, the initial mass function (IMF)? Most stars form in clusters (Lada & Lada 2003); how do stars form in such a dense environment and in the presence of enormous radiative and mechanical feedback from other YSOs?arrow_forwardFor 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.arrow_forwardQuestion 41 .Suppose you are looking at H-R diagrams of two similar star clusters. The most luminous main sequence stars in the Porcini cluster are much more luminous than the most luminous main sequence stars in the Morel cluster. What can you conclude? O the Porcini cluster is younger than the Morel cluster O the Porcini cluster is farther away than the Morel cluster O the Porcini cluster is lower in metallicity than the Morel cluster O the Porcini cluster is larger in diameter than the Morel clusterarrow_forward
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