Astronomy 1F03 Problem Set 3Friday Nov 12th, 2010Please write your answers on a separate sheet and show your working.1. a)The solar wind carries mass away from the Sun at a rate of about 2×109kg/s. Determine how long itwould take the Sun to lose all its mass at this rate.b)For comparison, calculate the rate at which the Sun is losing mass due to nuclear fusion. Fusion directlypowers the luminosity of the Sun so you can use Einstein’s relation,E=mc2, to convert the luminosity intoa mass loss rate.2.Stars spend most of their lives on the main sequence and burn an appreciable fraction of their total hydrogento helium in this period. In the following assume that stars spend their whole lives on the main sequence burningat a fixed luminosity and that all stars burn a fixed fraction of their total mass doing so. The Sun’s lifetime isabout 10 billion years. Use this to estimate the lifetime of:a)A 0.25 solar mass, 0.01 solar luminosity red dwarf star.
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main sequence, Solar luminosity, luminosity blue giant, luminosity red dwarf