Use the following formula (fitted to data) L Mo/year gR M = -4x10-13n for the mass loss of asymptotic giant branch stars to: a) explain why L, g (gravity on surface), and R enter the equation the way they do (nominator or denominator). b) show that the expression for M is equivalent to LR M = -4x10-137 Mo/year - M c) estimate the mass loss rate of a star with M = 1 Mo, L = 7000 Lo,T = 3000 K. Assume n = 1 and use the Stefan-Boltzmann equation to calculate R (in Ro). %3D

Use the following formula (fitted to data) L Mo/year gR M = -4x10-13n for the mass loss of asymptotic giant branch stars to: a) explain why L, g (gravity on surface), and R enter the equation the way they do (nominator or denominator). b) show that the expression for M is equivalent to LR M = -4x10-137 Mo/year - M c) estimate the mass loss rate of a star with M = 1 Mo, L = 7000 Lo,T = 3000 K. Assume n = 1 and use the Stefan-Boltzmann equation to calculate R (in Ro). %3D

Stars and Galaxies (MindTap Course List)

10th Edition

ISBN:9781337399944

Author:Michael A. Seeds

Publisher:Michael A. Seeds

Chapter12: Stellar Evolution

Section: Chapter Questions

Problem 7P

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You can estimate the age of the planetary nebula in image (c) in Figure 22.18. The diameter of the nebula is 600 times the diameter of our own solar system, or about 0.8 light-year. The gas is expanding away from the star at a rate of about 25 mi/s. Considering that distance=velocitytime , 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. Figure 22.18 Gallery of Planetary Nebulae. This series of beautiful images depicting some intriguing planetary nebulae highlights the capabilities of the Hubble Space Telescope. (a) Perhaps the best known planetary nebula is the Ring Nebula (M57), located about 2000 lightyears away in the constellation of Lyra. The ring is about 1 light-year in diameter, and the central star has a temperature of about 120,000 °C. Careful study of this image has shown scientists that, instead of looking at a spherical shell around this dying star, we may be looking down the barrel of a tube or cone. The blue region shows emission from very hot helium, which is located very close to the star; the red region isolates emission from ionized nitrogen, which is radiated by the coolest gas farthest from the star; and the green region represents oxygen emission, which is produced at intermediate temperatures and is at an intermediate distance from the star. (b) This planetary nebula, M2-9, is an example of a butterfly nebula. The central star (which is part of a binary system) has ejected mass preferentially in two opposite directions. In other images, a disk, perpendicular to the two long streams of gas, can be seen around the two stars in the middle. The stellar outburst that resulted in the expulsion of matter occurred about 1200 years ago. Neutral oxygen is shown in red, once-ionized nitrogen in green, and twice-ionized oxygen in blue. The planetary nebula is about 2100 light-years away in the constellation of Ophiuchus. (c) In this image of the planetary nebula NGC 6751, the blue regions mark the hottest gas, which forms a ring around the central star. The orange and red regions show the locations of cooler gas. The origin of these cool streamers is not known, but their shapes indicate that they are affected by radiation and stellar winds from the hot star at the center. The temperature of the star is about 140,000 °C. The diameter of the nebula is about 600 times larger than the diameter of our solar system. The nebula is about 6500 light-years away in the constellation of Aquila. (d) This image of the planetary nebula NGC 7027 shows several stages of mass loss. The faint blue concentric shells surrounding the central region identify the mass that was shed slowly from the surface of the star when it became a red giant. Somewhat later, the remaining outer layers were ejected but not in a spherically symmetric way. The dense clouds formed by this late ejection produce the bright inner regions. The hot central star can be seen faintly near the center of the nebulosity. NGC 7027 is about 3000 light-years away in the direction of the constellation of Cygnus. (credit a: modification of work by NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration; credit b: modification of work by Bruce Balick (University of Washington), Vincent Icke (Leiden University, The Netherlands), Garrelt Mellema (Stockholm University), and NASA; credit c: modification of work by NASA, The Hubble Heritage Team (STScI/AURA); credit d: modification of work by H. Bond (STScI) and NASA)
Topic: Life Cycle of Stars Q. Describe what would our Sun look like from Earth if it was a massive star? Pls answer in 2-3 sentences. Thank You!
Match each characteristic below of a one-solar-mass star to its appropriate phase. Answer M for Main-sequence Star, or P for Protostar. If the first is M and the rest P, enterMPPPPPP). A) energy generated by nuclear fusion B) pressure and gravity are NOT precisely balanced. C) surface radiates energy at same rate that core generates energy D) radius much larger than the Sun E) energy generated by gravitational contraction F) lasts about 10 billion years G) luminosity much greater than the Sun
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. ]
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 is the escape velocity (in km/s) from the surface of a 1.1 M. neutron star? From a 3.0 M, neutron star? (Hint: Use the formula for escape velocity, V̟ = 2GM -; make sure to express quantities in units of meters, kilograms, and seconds. Assume a neutron star has a radius of 11 km and assume the mass of the Sun is 1.99 × 1030 kg.) 1.1 M neutron star km/s 3.0 M. neutron star km/s If a neutron star has a radius of 12 km and a temperature of 8.0 x 10° K, how luminous is it? Express your answer in watts and also in solar luminosity units. (Hint: Use the relation . Use 5,800 K for the surface temperature of the Sun. The luminosity of the Sun is 3.83 x 1026 W.) luminosity in watts luminosity in solar luminosity units Lo
The evolutionary track for a star of 1 solar mass remains nearly vertical in the HR diagram for a while (see Figure 21.12). How is its luminosity changing during this time? Its temperature? Its radius? Figure 21.12 Evolutionary Tracks for Contracting Protostars. Tracks are plotted on the HR diagram to show how stars of different masses change during the early parts of their lives. The number next to each dark point on a track is the rough number of years it takes an embryo star to reach that stage (the numbers are the result of computer models and are therefore not well known). Note that the surface temperature (K) on the horizontal axis increases toward the left. You can see that the more mass a star has, the shorter time it takes to go through each stage. Stars above the dashed line are typically still surrounded by infalling material and are hidden by it.
If 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.
Observations suggest that it takes more than 3 million years for the dust to begin clearing out of the inner regions of the disks surrounding protostars. Suppose this is the minimum time required to form a planet. Would you expect to find a planet around a 10-MSunstar? (Refer to Figure 21.12.) Figure 21.12 Evolutionary Tracks for Contracting Protostars. Tracks are plotted on the HR diagram to show how stars of different masses change during the early parts of their lives. The number next to each dark point on a track is the rough number of years it takes an embryo star to reach that stage (the numbers are the result of computer models and are therefore not well known). Note that the surface temperature (K) on the horizontal axis increases toward the left. You can see that the more mass a star has, the shorter time it takes to go through each stage. Stars above the dashed line are typically still surrounded by infalling material and are hidden by it.
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?
Stars that have masses approximately 0.8 times the mass of the Sun take about 18 billion years to turn into red giants. How does this compare to the current age of the universe? Would you expect to find a globular cluster with a main-sequence turnoff for stars of 0.8 solar mass or less? Why or why not?
Why 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?