Fall 2003 Special Topics: Astrophysics (Phys 493)
Dr. I. Fernini
Homework # 4
Due Saturday, November 22 - Late HW won't be accepted anymore.
If a star has an apparent magnitude of –0.4 and a parallax of 0.3”, what is:
a/ the distance modulus
b/ the absolute magnitude
The Sun has an apparent visual magnitude of –26.75.
a/ Calculate its absolute visual magnitude
b/ Calculate its magnitude at the distance of Alpha
Centauri (1.3 pc)?
c/ The Palomar Sky Survey is complete to magnitude as
faint as +19. How far away (in parsecs) would a star
identical to the Sun have to be in order to just barely
be bright enough to be visible on Sky Survey
The V magnitude of two stars are both observed to be 7.5, but their blue magnitudes are B1=7.2 and B2=8.7.
a/ What is the color index of each star?
b/ Which star is the bluer and by what factor is it
brighter at blue wavelengths than the other star?