A black hole is an object with mass, but no spatial extent. It truly is a particle. A black hole may form from a dead star. Such a black hole has a mass several times the mass of the Sun. Imagine a black hole whose mass is ten times the mass of the Sun. a. Would you expect the period of an object orbiting the black hole with a semimajor axis of 1 AU to have a period greater than, less than, or equal to 1 yr? Explain your reasoning. b. Use Equation 7.6 to calculate this period.

Astronomers believe there are something like 100 million neutron stars in the Galaxy, yet we have only found about 2000 pulsars in the Milky Way. Give several reasons these numbers are so different. Explain each reason.

Once again in this chapter, we see the use of Kepler’s third law to estimate the mass of supermassive black holes. In the case of NGC 4261, this chapter supplied the result of the calculation of the mass of the black hole in NGC 4261. In order to get this answer, astronomers had to measure the velocity of particles in the ring of dust and gas that surrounds the black hole. How high were these velocities? Turn Kepler’s third law around and use the information given in this chapter about the galaxy NGC 4261-the mass of the black hole at its center and the diameter of the surrounding ring of dust and gas-to calculate how long it would take a dust particle in the ring to complete a single orbit around the black hole. Assume that the only force acting on the dust particle is the gravitational force exerted by the black hole. Calculate the velocity of the dust particle in km/s.

What is the orbital period (in s) of a bit of matter in an accretion disk that is located 6 ✕ 105 km from a 99 M black hole?    Hint:  Use the circular orbit velocity formula,  Vc =    GM r .    s

Use the Schwarzchild formula, Rs = 2GM/c2 , where Rs = Radius of the star, in meters, that would cause it to become a black hole M = Mass of the star, in kilograms, G = A constant, called the gravitational constant = 6.7 * 10-11m3/kg .s2, c = Speed of light = 3 * 108 meters per second. to determine to what length the radius of the Sun must be reduced for it to become a black hole. The Sun’s mass is approximately 2 * 1030 kilograms ?

Use the Schwarzchild formulaRs =2GM / c2whereRs = Radius of the star, in meters, that would cause it to become a black holeM = Mass of the star, in kilogramsG = A constant, called the gravitational constant= 6.7 x 10-11 m3 / kg . s2c = Speed of light= 3x108 meters per secondto determine to what length the radius of the Sun must be reduced for it to become a black hole. The Sun’s mass is approximately 2 x 1030 kilograms.

(Astronomy) Schwarzschild Radius.  Part A: Find the Schwarzschild radius for the least massive black hole. Part B: Is your calculated value greater than, the same as, or smaller than the diameter of a typical neutron star and the diameter of Manhattan, New York, which is around 10.9 km?

F2 Which of the following can a black hole not "eat" or consume? #3 E another black hole a planet black holes can eat anything O a cloud of gas and dust O a star F3 $ 4 R F4 Q Search DII % 5 F5 T L ☀ < F6 6 Y ☀ F7 & 7 PrtScn U F8

(Astronomy) PSR1913+16 Problem II. Using only the Figure, what are the maximum radial velocities as found from the redshift and blueshift, respectively? Note: redshifts have positive radial velocities values in the figure, whereas blueshifts have negative radial velocity values.  (Answer in km/s)