In: Physics
1). A star with an absolute magnitude of 4.5 is located 50 pc from Earth. Ignoring the dimming effect of the interstellar medium, its apparent magnitude will be...
Question 38 options:
54.5 |
|
8.0 |
|
1.0 |
|
4.5 |
|
-7.5 |
2). The absolute magnitude of a star is 2.6, but its apparent magnitude viewed from Earth is 8.9. How far away from Earth is the star?
Question 37 options:
182 pc |
|
18.2 pc |
|
1995 kpc |
|
1995 pc |
|
19.95 kpc |
3). Two stars have the same radius, but surface temperatures star A is 3,000 K and the surface temperature of star B is 12,000 K. How much more luminous is star B than star A?
16 times more luminous. |
|
256 times more luminous. |
|
4 times more luminous. |
|
9000 times more luminous. |
|
This cannot be determined from the information given. |
4). A star has an absolute magnitude of 2.84. What is its luminosity in solar units?
Question 40 options:
6.3 times more luminous than the Sun |
|
0.16 times as luminous as the Sun |
|
2.5 times more luminous than the Sun |
|
0.40 times as luminous as the Sun |
|
97 times more luminous than the Sun |
Please help. Thanks
1) Apparent magnitude,
Explanation: Conversion formula for absolute and apparent magnitude is as follows,
where = apparent magnitude, = absolute magnitude and =distance between star and earth.
2) Distance, =182 pc
Explanation: as we know that the formula for distance is,
where is the luminocity difference and given by , and is the magnitude difference between apparent and absolute magnitudes.
3) 256 times more luminous
Explanation: Luminicity is directly proportional to and .
4) Luminisity in solar units= 0.16 times as luminous as the sun
Explanation: from the formula
where and are the luminisity of the Star and Sun respectively and and are the absolute masses of the star and sun respectively.