21st Century Astronomy: The Solar System (Sixth Edition)
6th Edition
ISBN: 9780393691283
Author: Laura Kay; Stacy Palen; George Blumenthal
Publisher: W. W. Norton
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Chapter 19, Problem 35QP
To determine
To compare the luminosity of
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A Type la supernova explodes in a galaxy at a
distance of 6.10×107 light-years from Earth. If
astronomers detect the light from the
supernova today, how many years T have
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An astronomical image shows two objects that have the same apparent magnitude, i.e., the same brightness. However, spectroscopic follow up observations indicate that while one is a star that is within our galaxy, at a distance dgal away, and has the same luminosity as the Sun, the other is a quasar and has 100x the luminosity of the entire Milky Way galaxy. What is the distance to the quasar? (You may assume, for this rough calculation, that the Milky Way has 1011 stars and that they all have the luminosity as the Sun.) Give your response in Mpc. Value: dgal = 49 pc
Figure 2 shows the "rotation curve" of
NGC 2742. It plots the “radial velocity
(V)" (how fast material is moving
either toward or away from us) that is
measured for objects at different
distances (R = radius") from the
center of the galaxy. The center of the
galaxy is at 0 kpc (kiloparsecs) with a
speed of 9 km/sec away from us.
(These velocities have been corrected
for the observed tilt of the galaxy and
represent true orbital velocities of the
stars and gas.)
200
100
U4779
-100
As you can see, one side of the galaxy
is moving with a negative velocity
(spinning toward us), while the other
side has a positive velocity (spinning
away from us). Using Newton's
gravity equation, we will be able to
determine the gravitational mass of the
entire galaxy and how the mass varies
versus distance from the galaxy's center.
-200
-8
8
-4
Radius (kpc)
Read the following text carefully and follow the instructions:
Select five radii spaced evenly from 0-10 kpc across the galaxy. Your selections should…
Chapter 19 Solutions
21st Century Astronomy: The Solar System (Sixth Edition)
Ch. 19.1 - Prob. 19.1ACYUCh. 19.1 - Prob. 19.1BCYUCh. 19.2 - Prob. 19.2CYUCh. 19.3 - Prob. 19.3CYUCh. 19.4 - Prob. 19.4CYUCh. 19 - Prob. 1QPCh. 19 - Prob. 2QPCh. 19 - Prob. 3QPCh. 19 - Prob. 4QPCh. 19 - Prob. 5QP
Ch. 19 - Prob. 6QPCh. 19 - Prob. 7QPCh. 19 - Prob. 8QPCh. 19 - Prob. 9QPCh. 19 - Prob. 10QPCh. 19 - Prob. 11QPCh. 19 - Prob. 12QPCh. 19 - Prob. 13QPCh. 19 - Prob. 14QPCh. 19 - Prob. 15QPCh. 19 - Prob. 16QPCh. 19 - Prob. 17QPCh. 19 - Prob. 18QPCh. 19 - Prob. 19QPCh. 19 - Prob. 20QPCh. 19 - Prob. 21QPCh. 19 - Prob. 22QPCh. 19 - Prob. 23QPCh. 19 - Prob. 24QPCh. 19 - Prob. 25QPCh. 19 - Prob. 26QPCh. 19 - Prob. 27QPCh. 19 - Prob. 28QPCh. 19 - Prob. 29QPCh. 19 - Prob. 30QPCh. 19 - Prob. 31QPCh. 19 - Prob. 32QPCh. 19 - Prob. 33QPCh. 19 - Prob. 34QPCh. 19 - Prob. 35QPCh. 19 - Prob. 36QPCh. 19 - Prob. 37QPCh. 19 - Prob. 38QPCh. 19 - Prob. 39QPCh. 19 - Prob. 40QPCh. 19 - Prob. 41QPCh. 19 - Prob. 42QPCh. 19 - Prob. 43QPCh. 19 - Prob. 44QPCh. 19 - Prob. 45QP
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- Consider 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_forwardIf a galaxy contains a supernova that at its brightest has an apparent magnitude of 17, how far away is the galaxy? Assume that the absolute magnitude of the supernova is -19.arrow_forwardA Cepheid variable in the Andromeda galaxy has a period of 22 days and a mean apparent magnitude of19.5.(a) Calculate the distance modulus of the Andromeda galaxy.(b) Given that the Andromeda galaxy is approaching the Milky Way with a velocity of 119 km/s, roughlyestimate how long before these two galaxies collide? Provide your answer in years.arrow_forward
- The gas in the outer region of the Andromeda galaxy is found to be orbiting the galaxy with a velocity of 250 km/s. The gas is at a distance of 35 kpc from the center of the galaxy. The total mass of the galaxy is _______ solar masses.arrow_forwardSuppose that a galaxy has 109 M⊙ of neutral HI gas with a temperature of about 10 K. Estimate the luminosity of the 21 cm wavelength radiation that is expected from the galaxy. Answer in watts.arrow_forwardIf a galaxy contains a supernova that at its brightest has an apparent magnitude of +15, how far away is the galaxy? Assume that the absolute magnitude of the supernova is −17. Use the magnitude-distance formula: d = 10(mV − MV + 5)/5 .arrow_forward
- If a galaxy has a radial velocity of 21,641 km/s, what is its expected distance from the Hubble Law? Assume that the Hubble Constant is 71 km/s/Mpc. Answer in Mpcarrow_forwardQuestion 3: (a) A Type la supernova is seen to occur in the central bulge of a spiral galaxy. At its peak, the total apparent magnitude of the bulge plus the supernova is V= 13.68. Pre-explosion images reveal the bulge alone to have a magnitude V= 14.21. Assuming that all Type Ia supernova have peak absolute visual magnitudes of My = -19.30, calculate the distance to this galaxy, assuming there is no extinction in the direction of the supernova.arrow_forwardQuestion 3: (a) A Type la supernova is seen to occur in the central bulge of a spiral galaxy. At its peak, the total apparent magnitude of the bulge plus the supernova is V= 13.68. Pre-explosion images reveal the bulge alone to have a magnitude V= 14.21. Assuming that all Type Ia supernova have peak absolute visual magnitudes of My = -19.30, calculate the distance to this galaxy, assuming there is no extinction in the direction of the supernova. (b) Estimate the observed wavelength of the Hẞ line (rest-frame wavelength 486.1 nm) in this galaxy. Assume the Hubble constant has the value 67.4 kms ¹Mpc-¹.arrow_forward
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