Let us assume that our galaxy consists of 2.5×1011 stars each of one solar mass. How long will a star at a distance of 50,000 ly from the galactic centre take to complete one revolution ? Take the diameter of the Milky Way to be 105 ly.

Question

Let us assume that our galaxy consists of 2.5×1011 stars each of one solar mass. How long will a star at a distance of 50,000 ly from the galactic centre take to complete one revolution ? Take the diameter of the Milky Way to be 105 ly.

Filo · Accepted Answer

Mass of our galaxy Milky Way,M=2.5×1011 solar mass1 Solar mass = Mass of Sun=2×1030 kgMass of our galaxy,M=2.5×1011×2×1030=5×1041 kgDiameter of Milky Way,d=105 lyRadius of Milky Way,r=5×104 ly1 ly=9.46×1015 m∴r=5×104×9.46×1015       =4.73×1020Since a star revolves around the galactic centre of the Milky Way, its time period is given by the relation:T=(4π2r3/GM)1/2      =6.67×10−11×5×10414×3.142×4.733×1060​​       =1.12×1016 s     =365×24×60×601.12×1016​ years    =3.55×108 years

Question Text	Let us assume that our galaxy consists of $2.5 \times 1 0^{11}$ stars each of one solar mass. How long will a star at a distance of 50,000 ly from the galactic centre take to complete one revolution ? Take the diameter of the Milky Way to be $1 0^{5}$ ly.
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Let us assume that our galaxy consists of $2.5 \times 1 0^{11}$ stars each of one solar mass. How long will a star at a distance of 50,000 ly from the galactic centre take to complete one revolution ? Take the diameter of the Milky Way to be $1 0^{5}$ ly.

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