21st Century Astronomy 6E
6th Edition
ISBN: 9780393690675
Author: Laura Kay, Stacy Palen, George Blumenthal
Publisher: W. W. Norton
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Chapter 20, Problem 42QP
To determine
The average orbital speed of the star.
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Students have asked these similar questions
a) Calculate the period of the solar system's orbit around the Milky Way. Assume that we are 8.5
kpc from the galactic center and assume that the mass of the Milky Way interior to our orbit is
~ 10¹¹ solar masses.
Alpha Centauri is a multiple star system only 1.34 parsecs away. The apparent magnitudes of the
two main stars are:
a Cen A: my = +0.01;
a Cen B: my = +1.33.
b) Calculate the ratio of the flux we receive in the V filter from a Cen A to the flux we receive
from a Cen B.
c) Calculate the absolute magnitude My of a Cen B.
Question A1
a)
The Large Magellanic Cloud (LMC) is a galaxy in the vicinity of the Milky Way. It is at a
distance of 50 kpc, and has a size across of 9.86 kpc.
Consider a star similar to Vega (absolute magnitude M = 0.58) which is at the edge of the
LMC as seen on the sky. What is its apparent magnitude? Show your calculation.
b) A second similar star is observed near the centre of the LMC as seen on the sky with an
observed apparent magnitude of m = 20.3. Is this consistent with the star being a member
of the LMC? Explain your reasoning.
c) An observational study has derived a map of the extinction Ay across the LMC, and shown
that its average value is 0.38, with a standard deviation of 0.57.
For the star discussed in part (b), if extinction is taken into account, does your conclusion
about the star's membership of the LMC change? Explain your reasoning. You may assume
that the star may suffer the full (positive) range of extinction found in the study of the LMC.
d) Which other…
The absolute magnitude of a star in the Andromeda galaxy (distance 690 kpc) is M = 5. It explodes as a supernova, becoming onebillion (10 9 ) times brighter. What is its apparent magnitude?
Chapter 20 Solutions
21st Century Astronomy 6E
Ch. 20.1 - Prob. 20.1CYUCh. 20.2 - Prob. 20.2CYUCh. 20.3 - Prob. 20.3CYUCh. 20.4 - Prob. 20.4CYUCh. 20 - Prob. 1QPCh. 20 - Prob. 2QPCh. 20 - Prob. 3QPCh. 20 - Prob. 4QPCh. 20 - Prob. 5QPCh. 20 - Prob. 6QP
Ch. 20 - Prob. 7QPCh. 20 - Prob. 8QPCh. 20 - Prob. 9QPCh. 20 - Prob. 10QPCh. 20 - Prob. 11QPCh. 20 - Prob. 12QPCh. 20 - Prob. 13QPCh. 20 - Prob. 14QPCh. 20 - Prob. 15QPCh. 20 - Prob. 16QPCh. 20 - Prob. 17QPCh. 20 - Prob. 18QPCh. 20 - Prob. 19QPCh. 20 - Prob. 20QPCh. 20 - Prob. 21QPCh. 20 - Prob. 22QPCh. 20 - Prob. 23QPCh. 20 - Prob. 24QPCh. 20 - Prob. 25QPCh. 20 - Prob. 26QPCh. 20 - Prob. 27QPCh. 20 - Prob. 28QPCh. 20 - Prob. 29QPCh. 20 - Prob. 30QPCh. 20 - Prob. 31QPCh. 20 - Prob. 32QPCh. 20 - Prob. 33QPCh. 20 - Prob. 34QPCh. 20 - Prob. 35QPCh. 20 - Prob. 36QPCh. 20 - Prob. 37QPCh. 20 - Prob. 38QPCh. 20 - Prob. 39QPCh. 20 - Prob. 40QPCh. 20 - Prob. 41QPCh. 20 - Prob. 42QPCh. 20 - Prob. 43QPCh. 20 - Prob. 44QPCh. 20 - Prob. 45QP
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- How close, r, to the center of a neutron star would a manned satellite be orbiting if it were at the location where the gravitational force from the star equaled the gravitational force of the Earth's surface? RN = neutron star radius = 1 × 104 kmM N = neutron star mass = 3 × 1030 kgG = universal gravitational constant = 6.67 × 10-11 N m2 / kg2g⊕ = Earth gravitational acceleration = 9.807 m/s²arrow_forwardWhich of the below rotation curves best represents the orbital speeds stars in the Milky Way Galaxy would have if there were no dark matter in the galaxy? A B Distance Distance C D Distance Distance А.А В. В С. С D.D Velocity Velocity Velocity Velocityarrow_forwardA star has an element in its atmosphere that normally emits a line of frequency fs = 7.5 x 10^14 vib/s. If astronomers measure the frequency of this line to be fo = 7.7 x 10^14 vib/s, then how fast are the Earth and this star traveling relative to each other? Remember that the correct equation for the speed v is given by v = [(fo^2 - fs^2) / (fo^2 + fs^2)] c Remember fo^2 means "fo squared."arrow_forward
- A light of wavelength 620 nm is emitted from the following four places. What wavelength is observed for this light by an observer a long distance away? (The objects are not moving with respect to the observer) The surface of a 0.84 solar mass white dwarf that has a radius of 708000 km: ? The surface of a 2.52 solar mass neutron star that has a radius of 14.2 km: 2 Schwarzschild radii from a 20 solar mass black hole: ? 1.048 Schwarzschild radii from a 20 solar mass black hole: ?arrow_forwardImagine a planet orbiting a star. Observations show a Doppler shift in the star's spectrum of 58 m/s over the 3.3 day orbit of the planet. What is the mass of the planet in kg? Assume the star has the same mass as the Sun (2.0 x1030 kg), there are 365.25 days in a year, and 1AU = 1.5 x 1011 m.arrow_forwardIn the parallax method of determining stellar distances, the angle to a star is measured while the earth is on one side of the sun and then again six months later, as in the diagram below. Assume the earth-sun distance is 1 Astronomical Unit. The parallax angle of Alpha Centauri is 0= 2.1 x 10-4 ° . Find the distance from the sun to a Centauri in light years. Assume a circular orbit for the Earth. a Centauri Earth (June) Earth (December) Sunarrow_forward
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