Anonymous
Anonymous asked in 科學及數學其他 - 科學 · 7 years ago

# Physics Astronomy 問題!10點!

1.

SN1987A was a supernova in the Large Magellanic Cloud,which is a nearby galaxy.The exploded star was surrounded by rins of gases.The angular radius of the inner ring was measured to be 0.834".Energetic radiation and particles were seen coming out from the core at the speed of light,lightening the inner ring.

a)

it took about 248 days for radiation to travel from the core to the inner ring. Find the radius of the ring in light years.

b)

Hence find the distance to the supernova in light years.

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Lv 7
7 years ago

(a) Since the radiation and particles coming out from the core are travelling at the speed of light, i.e. 3 x 10^8 m/s, distance travelled in 248 days

= (248 x 24 x 3600) x (3x10^8) m

= 6.418 x 10^15 m

Because 1 light-year = 9.461 x 10^15 m

Hence, radius of the inner ring = 6.418x10^15/9.461x10^15 light year = 0.6784 light year

(b) Given radius of inner ring = 0.834"

tan(0.834") = 0.6784/d

where d is the distance of the supernova

hence, d = 0.6784/tan(0.834") light-years = 1.68 x 10^5 light-years