It can be shown that if an object orbiting a star of mass M in a circular orbit of radius R has speed v, then M G Suppose a star orbits the center of the galaxy it is contained in with an orbit that is nearly circular with radius R = 2.5 x 1018 and velocity v = 230 km/s. Use the result above to estimate the mass of the portion of the galaxy inside the star's orbit (place all of this mass at the center of the orbit). Mass =

A star is 1.0 x 104 ly (light-years) from the center of its galaxy and is moving in a circle around that center at a speed of 110 km/s. (a) How long does it take the star to make one revolution about the galactic center? (b) How many revolutions has the star completed since it was formed about 5.6 x 109 years ago?

An astronomer observed the motions of some galaxies. Based on his observations, he made the following statements. Which one of them is most likely to be false? Take Hubble's constant to be 67 km/s/Mpc. A. A galaxy observed to be moving away from us at a speed of 70 km/s is at a distance of about 1 Mpc from us. B. A galaxy observed to be moving away from us at a speed of 700 km/s is at a distance of about 10 Mpc from us. C. A galaxy observed to be moving away from us at a speed of 7000 km/s is at a distance of about 100 Mpc from us. D. A galaxy observed to be moving away from us at a speed of 70000 km/s is at a distance of about 1 Gpc from us. Is the answer D? Thank you!

1. Consider our Sun - it is in orbit around the center of our Milky Way Galaxy. The velocity of the Sun in its orbit is about 250 km/s. The distance to the center of the galaxy is about 9.1 kpc (kiloparsecs). We can use Kepler's third law to calculate the mass of the galaxy interior to the Sun's orbit. We assume that the orbit is circular so that the semimajor axis is just the radius of the circular orbit = 9.1 kpc. First we need to calculate the number of AU's in 9.1 kpc. (Note that 1 Крс - 1000 рс - 3260 1t yrs and 1 pc - 206,265 AU.) %3D a =r =9.1kpc = (9.1kpc) 1000 pc 206,265AU] 1kpc AU Sun 1pc

You observe a star orbiting in the outer parts of a galaxy. The distance to this galaxy is known, and you are able to take a spectra of this star and determine its velocity. The star is 22 kpc from the galaxy center and moving in a circular orbit with speed 304 km/s. Compute the total mass of the galaxy internal to the star's orbit. You will get a large number; express it in scientific notation and in units of solar masses [e.g., 4.2e10]. [Hint: there is a Box in Chapter 22 of your textbook that will be of help. See also the course formula sheet.]

According to the tiny world experiment, there are only 5.2 intermediates between any two people on Earth (thus 6-degree of separation). This is a remark that has been made for well over half a century. The Internet may be useful in this regard. Let's pretend that everyone on Earth doubles their friend count on Facebook, Twitter, and every other social network they participate in (2x). Calculate the relative distance between us now. What do you think it is?

Galaxy B moves away from galaxy A at 0.501 times the speed of light. Galaxy C moves away from galaxy B in the same direction at 0.729 times the speed of light. How fast does galaxy C recede from galaxy A? Express your answer as a fraction of the speed of light. Galaxy C recedes from Galaxy A at C

Asap, Typed format

You observe a star orbiting in the outer parts of a galaxy. The distance to this galaxy is known, and you are able to take a spectra of this star and determine its velocity. The star is 19 kpc from the galaxy center and moving in a circular orbit with speed 382 km/s. Compute the total mass of the galaxy internal to the star's orbit. You will get a large number; express it in scientific notation and in units of solar masses [e.g., 4.2e10]. [Hint: there is a Box in Chapter 22 of your textbook that will be of help. See also the course formula sheet.]

Explain Variable Gravitational Acceleration ?