7. Let's characterize a typical neutron star. (a) Compute its luminosity in units of the solar luminosity. Consider that the neutron star has a surface effective temperature of 106 K and a radius of 7 km. (b) In which wavelength does the neutron star radiate most energy (in nm)? (c) In which region of the spectrum it will be easier to detect / observe such an object (look at Figure 2)? mmmmmm 0.0001 nm 0.01 nm Gamma rays 400 nm Increasing energy X-rays Increasing wavelength 10 nm 1000 nm 0.01 cm Ultra- violet Infrared Visible light 500 nm 600 nm Figure 2: Electromagnetic spectrum 1 cm 1m Radio waves Radar TV FM 700 nm 100 m AM

7. Let's characterize a typical neutron star. (a) Compute its luminosity in units of the solar luminosity. Consider that the neutron star has a surface effective temperature of 106 K and a radius of 7 km. (b) In which wavelength does the neutron star radiate most energy (in nm)? (c) In which region of the spectrum it will be easier to detect / observe such an object (look at Figure 2)? mmmmmm 0.0001 nm 0.01 nm Gamma rays 400 nm Increasing energy X-rays Increasing wavelength 10 nm 1000 nm 0.01 cm Ultra- violet Infrared Visible light 500 nm 600 nm Figure 2: Electromagnetic spectrum 1 cm 1m Radio waves Radar TV FM 700 nm 100 m AM

College Physics

11th Edition

ISBN:9781305952300

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter1: Units, Trigonometry. And Vectors

Section: Chapter Questions

Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...

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Based on what you know about main-sequence stars, select all of the correct statements from the following list. 1. Since the interiors of stars cannot be observed, there are no theories about their structure. 2. More massive stars are hotter and brighter. 3. The weight of a star must be balanced by internal pressure. 4. More massive stars live longer; they take longer to use up all their energy. 5. Stars change position on the main sequence throughout their lives. 6. Outward energy flow in a star is by conduction only.
Match each characteristic below to the appropriate stellar end state. (Select W-White dwarf, N-Neutron star, B-Black hole. If the first is W and the rest N, enter WNNNNNNN). A) Size defined by its Schwarzschild radius. B) Typically about the size of Earth. C) Usually has a very strong magnetic field. D) In a binary system it can explode as a supernova. E) Supported by electron degeneracy pressure. F) Sometimes appears as a pulsar. G) Viewed from afar, time stops at its event horizon. H) Has a mass no greater than 1.4 solar-masses.
A solar type star evolves into a red giant with a luminosity 1000 L⊙ and radius of 1 AU. Determine the surface temperature that the red giant will have. State the wavelength of peak emission for the red giant star and which part of the EM spectrum this corresponds to.
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3. Consider the following stellar spectra from the sun and from a supercluster of galaxies. ABSORPTION LINES FROM THE SUN ABSORPTION LINES FROMA SUPERCLUSTER OF GALAXIES BAS11 v = 0.07c, d 1 billion light years (a) Describe the movement of the stars in the supercluster relative to the sun. (b) Suppose the absorption lines on the bottom spectrum had varying thickness. What would this indicate about the stars in the supercluster?
Indicate whether the following statements are true or false (Select T-True, F-False. If the first is T and the rest are F, enter TFFFF) A) A planetary nebula forms when a star violently explodes. B) White dwarfs are composed mostly of hydrogen. C) A white dwarf is the remnant of the star's core visible after the outer layers have been ejected. D) A planetary nebula is the remnant of the outer envelope of a star. E) White dwarfs are small dense objects about the size of the Earth.
Describe the plysical environment and processes to obtain the emission line spectra and absorption line spectra from the stars. Describe the physical environment and processes to obtain the emission line spectra and absorption line spectra from the stars. haha maintained a high
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.
A main sequence star of mass 25 M⊙has a luminosity of approximately 80,000 L⊙. a. At what rate DOES MASS VANISH as H is fused to He in the star’s core? Note: When we say “mass vanish '' what we really mean is “gets converted into energy and leaves the star as light”. Note: approximate answer: 3.55 E14 kg/s b. At what rate is H converted into He? To do this you need to take into account that for every kg of hydrogen burned, only 0.7% gets converted into energy while the rest turns into helium. Approximate answer = 5E16 kg/s c. Assuming that only the 10% of the star’s mass in the central regions will get hot enough for fusion, calculate the main sequence lifetime of the star. Put your answer in years, and compare it to the lifetime of the Sun. It should be much, much shorter. Approximate answer: 30 million years.
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We will take a moment to compare how brightly a white dwarf star shines compared to a red giant star. For the sake of this problem, let's assume a white dwarf has a temperature around 10,000 K and a red giant has a temperature around 5,000 K. As for their stellar radiatin, the white dwarf has a radius about 1/100th that of the Sun, and a red giant has a radius around 100 times larger than the Sun. With this in mind, how does the luminosity of a red giant star compare to that of a white dwarf (Hint: do not try to enter all of these numbers into the luminosity equation {it won't go well}; instead, remember that you are only interested in the ratio between the two, so all common units and components can be divided out)? Please enter your answer in terms of the luminosity of the red giant divided by the luminosity of the white dwarf and round to two significant figures. Also, please avoid using commas in your answer.
A)The star 58 Eridani is a feint but naked-eye star similar to the Sun. Suppose that you are observing this star in the night sky without a telescope. Ignoring any interstellar extinction or atmospheric absorption, approximately how many photons per second arrive at your retina? Show all steps in calculation . B) The Mid-infared Instrument (MIRI , camera and spectrograph ) on the James Webb Space Telescope operates in the band 5-28 µm . For 58 Eridani , approximatley how many photons per second can be used by this instrument ? Assume that MIRI takes all the photons from the full JWST mirror . Show all steps in calcultation . Describe breifly two or three other factors which play a role in determining the sensetivitu of an instrument such as MIRI ?