For a circular velocity profile of the type (r) = ar¹ ar1/9, where a is a constant and r is the radial distance from the centre of a spiral galaxy, find the ratio (r)/(r), where (r) is the epicyclic frequency and 2(r) is the angular velocity. Enter your answer to 2 decimal places.

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The sun orbits the center of the Milky Way galaxy for a period of 2.5x10^8 years. (a) Assuming a circular orbit of radius 2.4x10^20 m, compute the mass of the Milky Way. (b) Estimate the number of stars in the Milky Way, assuming the average star mass equals the mass of the sun—2.0x10^30 kg

Time left 1:45:56 A star has initially a radius of 680000000 m and a period of rotation about its axis of 33 days. Eventually it changes into a neutron star with a radius of only 45000 m and a period of 0.3 s. Assuming that the mass has not changed, find Assume a star has the shape of a sphere. (Suggestion: do it with formula first, then put the numbers in) [Recommended time : 5-8 minutes] (a) the ratio of initial to final angular momentum (Li/Lf) Oa. 2.17E+15 Ob. 24 Oc. 0.0416 Od. 4.61E-16 (b) the ratio of initial to final kinetic energy Oa. 4.85E-23 Ob. 396000 Oc. 2.53E-6 Od. 2.06E+22

In the deep space between galaxies, the number density of atoms is as low as 106 atoms/m3, and the temperature is a frigid 2.7 K. part (a)  What is the pressure, in pascals, in the region between galaxies?  part (b)  What volume, in cubic meters, is occupied by 3.5 mol of gas? Part (c)  If this volume is a cube, what is the length of one of its edges, in kilometers?

On a 1-to-10^19 scale our Milky Way galaxy would just about fit on a soccer field. On this scale, how far is the distance from the sun to alpha centauri (one of the closest stars to the sun, at a distance of 4.4 light years).

For a circular velocity profile of the type (r) = αν ar³/6, where a is a constant and is the radial distance from the centre of a spiral galaxy, find the ratio (r)/(r), where (r) is the epicyclic frequency and 2(r) is the angular velocity. Enter your answer to 2 decimal places.

The visible section of the Universe is a sphere centered on the bridge of your nose, with radius 13.7 billion light-years. (a) Explain why the visible Universe is getting larger, with its radius increasing by one light-year in every year. (b) Find the rate at which the volume of the visible section of the Universe is increasing.

Double stars are stars which are close enough and move slowly enough that they orbit each other.  Each star is located at the focus of the ellipse of its orbit around the other star.  Consider a binary star system which has an average angular separation of 6.1" arc and a period of 87.3 years. The annual parallax of the stars, p, is 0.192"arc.  We call the measure of the angular separation of the two stars, .  [remember that 1 degree is divided into 60 'arc (read this as 60 minutes of arc) and each 1'arc is subdivided into 60"arc (read this as 60 seconds of arc)].  The distance to the binarystar system is calculated from its parallax , p, of 0.192"arc, which has been measured carefully over a period of the last 92 years.  First we must calculate the distance to the binary system:  D  =  1/p   where p is the parallax in seconds of arc giving D in parsecs.  The distance, D =  1/p = ________ pc How many light years does this correspond to?  (remember that 1 pc = 3.26 lt yr)  D (in light…

A volume in space is exactly 1.00 pc3. Conversion from parsec to meters is 1 pc= 3.086 x 1016 m. How many cubic meters are contained in one cubic parsec?