Question

Question 4: Alpha Centauri is a binary star system (the two individual stars are called Alpha Centauri A and B) that is part of a triple star system (the third star is Proxima Centauri). This is the closest star system to the Sun. Alpha Centauri A and B are so close that if they are viewed with the naked eye they are seen as one star from the Earth. The absolute magnitude of Alpha Centauri A is 4.4, while the absolute magnitude of Alpha Centauri B is 5.7. The distance to Alpha Centauri is 1.35 pc.

a) Calculate the apparent magnitude of both Alpha Centauri A and B.

b) Calculate the apparent magnitude of Alpha Centauri, when seen as one object.

c) If Alpha Centauri A is able to fully eclipse Alpha Centauri B, how much does the radiant flux change when this happen, compared to when both stars are not eclipsing each other?

Answer 1

Apparent magnitutu is thebrightness measured by an observerwith a specificdistance. According to inverse square law of brightness smaller the distance , greater the brightness.

a. Apparent magnitude of A

            m - M = 5 log (d/10)

            m - 4.4 = 5 log ( 1,35/10)

            m - 4.4 = - 4.34

            m = 0.06

Apparent Magnitude of B

          m - M = 5log(d/10)

          m - 5.7 = 5 log (1,35/10)

          m - 5.7 = -4.34

          m = 1.36

           Where M is the absolute magnitute and m is the apparent magnitude.

     Alpha centauri A have more brightness compared to B. Since A have the low apparent magnitude.