UNIVERSE (LOOSELEAF):STARS+GALAXIES
6th Edition
ISBN: 9781319115043
Author: Freedman
Publisher: MAC HIGHER
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Chapter 18, Problem 5Q
To determine
The H-II regions and also determine the kind of stars near which they are found. Also, determine why only these stars give rise to H-II stars.
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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.)
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 O
A 46M Sun
main sequence star loses 1 Msun of mass over 105 years. (Due to the nature of this problem, do not use rounded intermediate values in your calculations including answers submitted in WebAssign.)
How many solar masses did it lose in a year?
By how much will its luminosity decrease if this mass loss continues over 0.8 million years?
Due to the nature of this problem, for all parts, do not use rounded intermediate values in your calculations-including answers submitted in WebAssign.
To determine the number of solar masses lost per year, divide the mass lost by the number of years over which it was lost.
Mlost
tlost-yr
Part 1 of 3
dM =
dM =
MSun/yr
Chapter 18 Solutions
UNIVERSE (LOOSELEAF):STARS+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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- Are supergiant stars also extremely massive? Explain the reasoning behind your answer.arrow_forwardIn the HR diagrams for some young clusters, stars of both very low and very high luminosity are off to the right of the main sequence, whereas those of intermediate luminosity are on the main sequence. Can you offer an explanation for that? Sketch an HR diagram for such a cluster.arrow_forwardHow do stars typically “move” through the main sequence band on an HR diagram? Why?arrow_forward
- Astronomers find that 90% of the stars observed in the sky are on the main sequence of an HR diagram; why does this make sense? Why are there far fewer stars in the giant and supergiant region?arrow_forwardDescribe the evolution of a star with a mass similar to that of the Sun, from the protostar stage to the time it first becomes a red giant. Give the description in words and then sketch the evolution on an HR diagram.arrow_forwardH II regions can exist only if there is a nearby star hot enough to ionize hydrogen. Hydrogen is ionized only by radiation with wavelengths shorter than 91.2 nm. What is the temperature of a star that emits its maximum energy at 91.2 nm? (Use Wien’s law from Radiation and Spectra.) Based on this result, what are the spectral types of those stars likely to provide enough energy to produce H II regions?arrow_forward
- How do the two types of supernovae discussed in this chapter differ? What kind of star gives rise to each type?arrow_forwardIf you were to compare three stars with the same surface temperature, with one star being a giant, another a supergiant, and the third a main-sequence star, how would their radii compare to one another?arrow_forwardIf a 100 solar mass star were to have a luminosity of 107 times the Sun’s luminosity, how would such a star’s density compare when it is on the main sequence as an O-type star, and when it is a cool supergiant (M-type)? Use values of temperature from Figure 18.14 or Figure 18.15 and the relationship between luminosity, radius, and temperature as given in Exercise 18.47. Figure 18.15 Schematic HR Diagram for Many Stars. Ninety percent of all stars on such a diagram fall along a narrow band called the main sequence. A minority of stars are found in the upper right; they are both cool (and hence red) and bright, and must be giants. Some stars fall in the lower left of the diagram; they are both hot and dim, and must be white dwarfs. Figure 18.14 HR Diagram for a Selected Sample of Stars. In such diagrams, luminosity is plotted along the vertical axis. Along the horizontal axis, we can plot either temperature or spectral type (also sometimes called spectral class). Several of the brightest stars are identified by name. Most stars fall on the main sequence.arrow_forward
- Why do nebulae near hot stars look red? Why do dust clouds near stars usually look blue?arrow_forwardLook at the four stages shown in Figure 21.8. In which stage(s) can we see the star in visible light? In infrared radiation? 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.arrow_forward: What does the H-R diagram show? Explain the main sequence of stars.arrow_forward
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