UNIVERSE (LOOSELEAF):STARS+GALAXIES
6th Edition
ISBN: 9781319115043
Author: Freedman
Publisher: MAC HIGHER
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Chapter 19, Problem 29Q
To determine
The reason the scientists suspect that population III stars existed in the past even though they never could observe them.
The reason not to observe Population III stars today.
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why are Cepheid variable stars good distance indicators? What about
supernovae?
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
If the hottest star in the Carina Nebula has a surface temperature of 51,000 K, at what wavelength (in nm) does it radiate the most energy?
Hint: Use Wien's law:
?max =
2.90 ✕ 106 nm · K
T
How does that compare with 91.2 nm, the wavelength of photons with just enough energy to ionize hydrogen?
-The wavelength calculated above is shorter than 91.2 nm. Photons at this calculated wavelength will have more than enough energy to ionize hydrogen.
-The wavelength calculated above is longer than 91.2 nm. Photons at this calculated wavelength will have more than enough energy to ionize hydrogen.
-The wavelength calculated above is shorter than 91.2 nm. Photons at this calculated wavelength will not have enough energy to ionize hydrogen.
-The wavelength calculated above is longer than 91.2 nm. Photons at this calculated wavelength will not have enough energy to ionize hydrogen.
Chapter 19 Solutions
UNIVERSE (LOOSELEAF):STARS+GALAXIES
Ch. 19 - Prob. 1QCh. 19 - Prob. 2QCh. 19 - Prob. 3QCh. 19 - Prob. 4QCh. 19 - Prob. 5QCh. 19 - Prob. 6QCh. 19 - Prob. 7QCh. 19 - Prob. 8QCh. 19 - Prob. 9QCh. 19 - Prob. 10Q
Ch. 19 - Prob. 11QCh. 19 - Prob. 12QCh. 19 - Prob. 13QCh. 19 - Prob. 14QCh. 19 - Prob. 15QCh. 19 - Prob. 16QCh. 19 - Prob. 17QCh. 19 - Prob. 18QCh. 19 - Prob. 19QCh. 19 - Prob. 20QCh. 19 - Prob. 21QCh. 19 - Prob. 22QCh. 19 - Prob. 23QCh. 19 - Prob. 24QCh. 19 - Prob. 25QCh. 19 - Prob. 26QCh. 19 - Prob. 27QCh. 19 - Prob. 28QCh. 19 - Prob. 29QCh. 19 - Prob. 30QCh. 19 - Prob. 31QCh. 19 - Prob. 32QCh. 19 - Prob. 33QCh. 19 - Prob. 34QCh. 19 - Prob. 35QCh. 19 - Prob. 36QCh. 19 - Prob. 37QCh. 19 - Prob. 38QCh. 19 - Prob. 39QCh. 19 - Prob. 40QCh. 19 - Prob. 41QCh. 19 - Prob. 42QCh. 19 - Prob. 43QCh. 19 - Prob. 44QCh. 19 - Prob. 45QCh. 19 - Prob. 46QCh. 19 - Prob. 47QCh. 19 - Prob. 48QCh. 19 - Prob. 49QCh. 19 - Prob. 50QCh. 19 - Prob. 51QCh. 19 - Prob. 52QCh. 19 - Prob. 53Q
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- H 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_forwardDescribe several characteristics that distinguish population I stars from population II stars.arrow_forwardAccording to the text, a star must be hotter than about 25,000 K to produce an H II region. Both the hottest white dwarfs and main-sequence O stars have temperatures hotter than 25,000 K. Which type of star can ionize more hydrogen? Why?arrow_forward
- In 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_forwardConsider the following five kinds of objects: open cluster, giant molecular cloud, globular cluster, group of O and B stars, and planetary nebulae. A. Which occur only in spiral arms? B. Which occur only in the parts of the Galaxy other than the spiral arms? C. Which are thought to be very young? D. Which are thought to be very old? E. Which have the hottest stars?arrow_forwardAre supergiant stars also extremely massive? Explain the reasoning behind your answer.arrow_forward
- The best parallaxes obtained with Hipparcos have an accuracy of 0.001 arcsec. If you want to measure the distance to a star with an accuracy of 10%, its parallax must be 10 times larger than the typical error. How far away can you obtain a distance that is accurate to 10% with Hipparcos data? The disk of our Galaxy is 100,000 light-years in diameter. What fraction of the diameter of the Galaxy’s disk is the distance for which we can measure accurate parallaxes?arrow_forwardWhy is star formation more likely to occur in cold molecular clouds than in regions where the temperature of the interstellar medium is several hundred thousand degrees?arrow_forwardIf the Sun were a member of the cluster NGC 2264, would it be on the main sequence yet? Why or why not?arrow_forward
- You have discovered two star clusters. The first cluster contains mainly main-sequence stars, along with some red giant stars and a few white dwarfs. The second cluster also contains mainly main-sequence stars, along with some red giant stars, and a few neutron stars-but no white dwarf stars. What are the relative ages of the clusters? How did you determine your answer?arrow_forwardWhere in the Galaxy would you expect to find Type II supernovae, which are the explosions of massive stars that go through their lives very quickly? Where would you expect to find Type I supernovae, which involve the explosions of white dwarfs?arrow_forwardYou can use the equation in Exercise 22.34 to estimate the approximate ages of the clusters in Figure 22.10, Figure 22.12, and Figure 22.13. Use the information in the figures to determine the luminosity of the most massive star still on the main sequence. Now use the data in Table 18.3 to estimate the mass of this star. Then calculate the age of the cluster. This method is similar to the procedure used by astronomers to obtain the ages of clusters, except that they use actual data and model calculations rather than simply making estimates from a drawing. How do your ages compare with the ages in the text? Figure 22.10 NGC 2264 HR Diagram. Compare this HR diagram to that in Figure 22.8; although the points scatter a bit more here, the theoretical and observational diagrams are remarkably, and satisfyingly, similar. Figure 22.12 Cluster M41. (a) Cluster M41 is older than NGC 2264 (see Figure 22.10) and contains several red giants. Some of its more massive stars are no longer close to the zero-age main sequence (red line). (b) This ground-based photograph shows the open cluster M41. Note that it contains several orange-color stars. These are stars that have exhausted hydrogen in their centers, and have swelled up to become red giants. (credit b: modification of work by NOAO/AURA/NSF) Figure 22.13 HR Diagram for an Older Cluster. We see the HR diagram for a hypothetical older cluster at an age of 4.24 billion years. Note that most of the stars on the upper part of the main sequence have turned off toward the red-giant region. And the most massive stars in the cluster have already died and are no longer on the diagram. Characteristics of Main-Sequence Starsarrow_forward
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