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 26Q
To determine
The reasons for disks to form around contracting protostar.The connection between disks and bipolar outflows.
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Suppose two protostars form at the same time, one with a mass of 0.5MSunSun
[Select ALL answers that are true in alphabetical order]A) The 10MSun protostar will have a smaller change in surface temperature during this phase than the 0.5MSun protostar.B) The 10MSun protostar will reach the main sequence cooler and fainter than the 0.5MSun protostar.C) The 10MSun star will end its main-sequence life before the 0.5MSun star even completes its protostar stage.D) The 10MSun protostar will have a smaller change in luminosity during the sequence shown than the 0.5MSun protostar.E) The 10MSun protostar will be much more luminous than the 0.5MSun protostar.
What critical event must occur in order for a protostar to be-
come a star?
When a region of a molecular cloud collapses, a protostar is formed. How do the temperature and density change as a protostar gets smaller and smaller?
Group of answer choices
The temperature decreases and the density decreases.
The temperature decreases and the density increases.
The temperature increases and the density decreases.
The temperature increases and the density increases.
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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- Look 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_forwardWhat is a planetary nebula? Will we have one around the Sun?arrow_forwardAre supergiant stars also extremely massive? Explain the reasoning behind your answer.arrow_forward
- Two protostars, one 10 times the mass of the Sun and one half the mass of the Sun are born at the same time in a molecular cloud. Which one will be first to reach the main sequence stage, where it is stable and getting energy from fusion?arrow_forwardOn which edge of the main sequence band on an HR diagram would the zero-age main sequence be?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
- If our Sun were surrounded by a cloud of gas, would this cloud be an emission nebula? Why or why not?arrow_forwardPlace 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_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
- Suppose a protostar has a luminosity of 157,341 Lo and a surface temperature of 4,540 K (Kelvins). What is the radius of this protostar? [Enter your answer as a multiple of the Sun's radius. I.e., if you find R = 20 Ro enter 20. This problem is easier if you start with the relevant equation and create a ratio using the Sun's values. Recall that the Sun has a surface temperature of 5778 K. ]arrow_forwardWhat 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?arrow_forwardThe place on the H–R diagram where contracting protostars first become visible is a. the horizontal branch. b. the instability strip. c. the birth line. d. the zero-age main sequence. e. none of the above.arrow_forward
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