21st Century Astronomy
6th Edition
ISBN: 9780393428063
Author: Kay
Publisher: NORTON
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Chapter 15, Problem 39QP
To determine
Years required for a hydrogen atom to reach a newly forming protostar.
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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.
H5.
A star with mass 1.05 M has a luminosity of 4.49 × 1026 W and effective temperature of 5700 K. It dims to 4.42 × 1026 W every 1.39 Earth days due to a transiting exoplanet. The duration of the transit reveals that the exoplanet orbits at a distance of 0.0617 AU. Based on this information, calculate the radius of the planet (expressed in Jupiter radii) and the minimum inclination of its orbit to our line of sight.
Follow up observations of the star in part reveal that a spectral feature with a rest wavelength of 656 nm is redshifted by 1.41×10−3 nm with the same period as the observed transit. Assuming a circular orbit what can be inferred about the planet’s mass (expressed in Jupiter masses)?
(a) If the actual separation between HD 80606 and HD 80607 is 2000 AU, determine the orbital
period of the binary star system.
(b) How many orbits will the planet HD 80806b make around its parent star in the time that the
two stars complete one orbit about their common center of mass? The semimajor axis of the
planet's orbit is 0.44 AU.
(c) What is the ratio of the force of gravity exerted on HD 80606b by its parent star to that
exerted by HD 80607 when it is aligned between the two stars?
Chapter 15 Solutions
21st Century Astronomy
Ch. 15.1 - Prob. 15.1CYUCh. 15.2 - Prob. 15.2CYUCh. 15.3 - Prob. 15.3CYUCh. 15.4 - Prob. 15.4CYUCh. 15 - Prob. 1QPCh. 15 - Prob. 2QPCh. 15 - Prob. 3QPCh. 15 - Prob. 4QPCh. 15 - Prob. 5QPCh. 15 - Prob. 6QP
Ch. 15 - Prob. 7QPCh. 15 - Prob. 8QPCh. 15 - Prob. 9QPCh. 15 - Prob. 10QPCh. 15 - Prob. 11QPCh. 15 - Prob. 12QPCh. 15 - Prob. 13QPCh. 15 - Prob. 14QPCh. 15 - Prob. 15QPCh. 15 - Prob. 16QPCh. 15 - Prob. 17QPCh. 15 - Prob. 18QPCh. 15 - Prob. 19QPCh. 15 - Prob. 20QPCh. 15 - Prob. 21QPCh. 15 - Prob. 22QPCh. 15 - Prob. 23QPCh. 15 - Prob. 24QPCh. 15 - Prob. 25QPCh. 15 - Prob. 26QPCh. 15 - Prob. 27QPCh. 15 - Prob. 28QPCh. 15 - Prob. 29QPCh. 15 - Prob. 30QPCh. 15 - Prob. 31QPCh. 15 - Prob. 32QPCh. 15 - Prob. 33QPCh. 15 - Prob. 35QPCh. 15 - Prob. 36QPCh. 15 - Prob. 37QPCh. 15 - Prob. 38QPCh. 15 - Prob. 39QPCh. 15 - Prob. 40QPCh. 15 - Prob. 41QPCh. 15 - Prob. 42QPCh. 15 - Prob. 43QPCh. 15 - Prob. 44QPCh. 15 - Prob. 45QP
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- White Dwarf Size II. The white dwarf, Sirius B, contains 0.98 solar mass, and its density is about 2 x 106 g/cm?. Find the radius of the white dwarf in km to three significant digits. (Hint: Density = mass/volume, and the volume of a 4 sphere is Tr.) 3 km Compare your answer with the radii of the planets listed in the Table A-10. Which planet is this white dwarf is closely equal to in size? I Table A-10 I Properties of the Planets ORBITAL PROPERTIES Semimajor Axis (a) Orbital Period (P) Average Orbital Velocity (km/s) Orbital Inclination Planet (AU) (106 km) (v) (days) Eccentricity to Ecliptic Mercury 0.387 57.9 0.241 88.0 47.9 0.206 7.0° Venus 0.723 108 0.615 224.7 35.0 0.007 3.4° Earth 1.00 150 1.00 365.3 29.8 0.017 Mars 1.52 228 1.88 687.0 24.1 0.093 1.8° Jupiter 5.20 779 11.9 4332 13.1 0.049 1.30 Saturn 9.58 1433 29.5 10,759 9.7 0.056 2.5° 30,799 60,190 Uranus 19.23 2877 84.3 6.8 0.044 0.8° Neptune * By definition. 30.10 4503 164.8 5.4 0.011 1.8° PHYSICAL PROPERTIES (Earth = e)…arrow_forwardConsider a disk with disk temperature T = T0(r/AU)−1 with T0 = 200K.and surface density given by Σ = Σ0(r/AU)−1, with Σ0 = 104 kg/m2. Assume that the protostar has mass Mstar = M⊙. You may assume the gas is composed of a 5:1 mixture of H2 molecules and helium atoms, and ignore trace amounts of heavier elements. how much less is the orbital speed of the gas at 1 AU than the Keplerian speed?arrow_forwardDetermining the orbit of the two stars of Kepler-34, also called A and B. These two stars together are called a binary. A) Assume that star A has a mass of 1 solar mass and star B also has a mass of 1 solar mass. The semi major axis is 0.23 AU and the eccentricty is 0.53. What is the orbital period of the stellar A-B binary in days? Ignore the (much less massive) planet and focus on the orbit of the binary. B) Now let's consider the orbit of the planet, called "b". Since the planet orbits some distance away from the stars, it is an acceptable approximation to pretend like the stellar binary is like a single star with a mass that is the sum of the masses of stars A and B and that the mass of planet "b" is very small, calculate the semi-major axis in AU of the planet's orbit with a period of 289 days. (note: I think for this problem you are supposed to use Newton's version of Kepler's third law P2= 4π2/G(M1-M2)x a3 but, I'm not sure if that's the right thing to do). 1 solar mass= 2 x…arrow_forward
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