equatorial radius of star vega : 1.961 million km or 2.818 R 3 [1.5 p.] What are
ID: 3279962 • Letter: E
Question
equatorial radius of star vega : 1.961 million km or 2.818 R
3 [1.5 p.] What are the consequences of Vega's rotation? Read wikipedia article on Vega and briefly but as quantitatively as you can, describe how would Vega look to us if we weren't looking at it from the direction near its rotational axis, as we do in reality, but near to its equatorial plane. Whould we see a larger or a smaller luminosity? Assuming a rotational velocity at equator rot-236 km/s (from spectroscopic speading of absorption lines) and equatorial radius derived above and mass 2.135 solar masses, what is the ratio of centrifugal to gravitational forces at equator? Do you expect a very non-spherical shape of the star from such a calculation?Explanation / Answer
radius of vega at equator, R = 1.961*10^9 m
rotational velocity at equator, v = 236,000 m/s
go ratio of centrifugal to gravitational force at equator would be
Fc/Fg = v^2*R^2/R*GM = Rv^2/GM
M = mass of the star = 2.135*1.989*10^30 kg
G = 6.67*10^-11
puttin g values
we get
Fc/Fg = 0.3856
so as the ratio is less than one, the gravitational force still dominates the centrifugal force, but we do expect a bulge in the equator due to centrifugal force coming close to gravitational force asnd hance creating less acceleration due to gravity for the material present on the equator at te outer parts
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