2. The nearest star named Alpha centauri of the solar
system is 4.29 light years away. Express this distance
in terms of parsecs ?
[Ans. 1.31 parsec]
Answers
Answer:
Given:
The distance of the star is,=4.29 ly
We know that one light year is the distance travelled by light in one year.
1 light year = 3×10
8
×365×24×60×60
=94608×10
11
m
Therefore, the distance in 4.29 ly can be written as:
4.29 ly=405868.32×10
11
m
We know that 1 Parsec is also the unit of distance and its value is:
1 parsec=3.08×10
16
m
Now, to express the distance in terms of parsec.
4.29ly=
3.08×10
16
405868.32×10
11
=1.32 parsec
The diameter of the Earth's orbit is,
d=3×10
11
m
The angle made by the star on the Earth's orbit can be given by:
θ=
405868.32×10
11
3×10
11
=7.39×10
−6
rad
But, the angle covered in 1sec=4.85×10
−6
rad
So, the parallax in viwing the star at two different positions of the Eart's orbit:
for, 7.39×10
−6
rad=
4.85×10
−6
7.39×10
−6
=1.52