what is the angular diameter in arc seconds of a star like the sun (diameter= 1,400,000 km) located 8 light years (7.57 x 10^13 km) fom earth?

a. 0.038

b. 8

c. 0.0038

d.200,00

e. 1,400,000

Respuesta :

Answer:

[tex]\theta = 0.0038\ arc\ sec[/tex]

option c

Explanation:

given data:

Diameter of a star = 1,400,000 km

star distance from sun [tex]= 7.57\times 10^{13} km[/tex]

we know that

Angle is given as

[tex]\theta = \frac{d}{r} = \frac{14\times 10^5}{7.57\times 10^{13}}[/tex]

[tex]\theta = 1.849\times 10^{-8} rad[/tex]

we know that

[tex]1\ arc\ second  = 4.84\times 10^{-6} rad[/tex]

[tex]1 rad = \frac{1\ arc\ sec}{4.84\times 10^{-6}}[/tex]

SO, [tex]\theta = \frac{1.849\times10^{-8}}{4.84\times10^{-6}}[/tex]

[tex]\theta = 3.82\time 10^{-3} arc sec[/tex]

[tex]\theta = 0.0038\ arc\ sec[/tex]

option c

Answer:

Option (C)

Explanation:

Here, Diameter= 1,400,000 km = 1.4 x 10^6 km

         Distance= 7.57 x 10^13 km

According to the formula, angular diameter= Diameter/Distance

[tex]\alpha = \frac{Diameter}{Distance}[/tex]

[tex]=\frac{1.4\times 10^6}{7.57}\times 10^{-13}[/tex]

[tex]=0.18\times 10^{-7}\text{ radian}[/tex]

Since 1 radian=206265 arc second,

Therefore,

[tex]206265\times 0.18\times 10^{-7}[/tex]

[tex]=\frac{37127.7}{10^7}[/tex]

= .00371 arc second

Hence, the approximate answer is option (C) i.e. 0.0038 arc second.