b) Which of the two proposals described below would you choose to fund?Project Beta:An X-ray wavelength telescope, located near the North Pole, which will be used toexamine the Sun.Project Alpha:An infrared wavelength telescope, placed on a satellite in orbit around Earth, which willbe used to view supernovae.Exploin VOur rooooning

Project Beta: An X-ray wavelength telescope will be used to study the Sun and will be positioned…

Answered: b) Which of the two proposals described…

Horizons: Exploring the Universe (MindTap Course List)

14th Edition

ISBN:9781305960961

Author:Michael A. Seeds, Dana Backman

Publisher:Michael A. Seeds, Dana Backman

Chapter12: The Milky Way Galaxy

Section: Chapter Questions

Problem 15RQ

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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 ?
Suppose a spectral line from an object in space was shifted from 5007.0 to 5100.0 Angstroms. What can we tell about this object? A) It is a star. B) It is very cold. C) It is blueshifted, hence coming towards us. D) Its radial velocity is positive, meaning it is moving away from us. E) It is a planet in a distant galaxy. F) It is an exoplanet.
level an ther will such radars disturb such radio astronomy measurements 4. If the intensity of the Sun peaks in the optical range, at a frequency of about 3:4 x 10 Hz, what is the temperature of the Sun? Use the Wien displacement law (1.25). If all of the power is emitted only between 3 and 4 x 10 Hz, how many photons per cm² arrive at the earth when the Sun is directly overhead? What is the power received on earth per cm³? A value for the solar power is 135mW per cm². How does this compare to your calculation?
Background: Design and completely analyze an optical system to measure how fast the Sun is spinning,based on the Doppler shift between the west side of the sun (always turning toward us atvelocity v1) and the east side (turning away from us, also at velocity v1). It turns out the Sun hasvery sharp emission lines at a wavelength of λ = 630.0 nm. You may ignore Earth’s rotation andatmosphere.You’ll need at least 2 parts in your optical system. First, you’ll need to gather (maybe focus,maybe magnify?) the light from only the outer edge of the sun—no more than 5% of itsdiameter as seen from Earth. Be sure your system blocks out the rest of the sun when taking ameasurement of one side or the other. Second, you’ll need to very precisely and accuratelyseparate the sun’s spectrum into different wavelengths so you can measure the difference inwavelength caused by the Doppler shifts. You can use any combination of any optical elementswe have discussed in class: lenses, mirrors, pinholes,…
1. The Orion Nebula is a gas-rich region in which stars are being born. The nebula is at a distance ofVariable Stars about 1344 lyr from Earth. Suppose you observe a star in the Orion Nebula to have an apparent magnitude of 6.75 mag. Calculate the absolute magnitude of the star. Also calculate the luminosity of theThe breakthrough in measuring distances to remote parts of our Galaxy, and to other galaxies as well, came star in units of the solar luminosity (knowing that the absolute magnitude of the Sun is 4.8 mag). Jfrom the study of variable stars. Most stars are constant in their luminosity, at least to within a percent or two. Like the Sun, they generate a steady flow of energy from their interiors. However, some stars are seen to vary in
Remote Spectroscopy. Spectrometers mounted on aircraft and satellites have been used to obtain spectralinformation about the earth. How do these systems work? Cite specific uses of these remote spectroscopytechniques.
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 your calculation. Look up any required information about the star using Wikipedia. Use sensible approximations so your calculation is straightforward. For example you could consider only the region of the spectrum where the photon flux peaks. b) The Mid-Infrared Instrument (MIRI, camera and spectrograph) on the James Webb Space Telescope operates in the band 5 – 28 µm. For 58 Eridani, approximately 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 your calculation. Describe briefly two or three other factors which play a role in determining the sensitivity of an instrument such as MIRI?
B2. A spherical star is detected by an astronaut in a spacecraft at a distance z of 1.5×10¹2 kilometers. The star can be regarded as a blackbody with a temperature of 11,300 K. The radius r of the star is 3.5×106 kilometers. (a) Calculate the radiant exitance and the radiant intensity of the star. (b) Calculate the irradiance that can be detected by the astronaut. (c) The photodetector used by the astronaut in the spacecraft has a responsivity of 120 kV/W and an photosensitive area of 0.5 mm². Calculate the output voltage of the detector in the detection of the star. CAMINS +II+ Figure B2
The Stefan-Boltzmann equation can be used to estimate the size of asteroids. "Sigma," the Stefan-Boltzmann constant, is 5.67 x 10 Watts/m²K. If you want to abbreviate Plus 1.1415 You measure the infrared emission from an asteroid and conclude that it has a temperature of 249 K. Using rader you find the distance, and are then able to use your infrared brightness to determine a luminosity of 7.21E+12 Watts. If you assume the asteroid is roughly spherical, what is its radius in meters? CHECK ANSWER
Why don’t we see hydrogen Balmer lines in the spectra of stars with temperatures of 3,200 K? a. There is no hydrogen in stars this cool. b. The stars are hot enough that most of the hydrogen is ionized and the atoms cannot absorb energy. c. These stars are so cool that nearly all of the hydrogen atoms are in the ground state. d. Stars of this temperature are too cool to produce an absorption spectrum. e. Stars of this temperature are too hot to produce an absorption spectrum.
Why was the Hipparcos satellite able to make more accurate parallax measurements than ground-based telescopes?
5. The two images below show a portion of the Trifid Nebula. The image on the left was made with visible light, while the image on the right (shown to the same scale) is an infrared image from the Spitzer Space Telescope. Explain why the dark streaks in the visible-light image appear bright in the infrared image. (a) Reflection nebula, Dust lanes Emission nebula. R I 10 pc www V U X G (b) wwwwww R V U X G

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