Fall 2003 Special Topics: Astrophysics
(Phys 493)
Dr. I.
Fernini
Homework
# 4
Due Saturday,
November 22 - Late HW won't be accepted anymore.
Problem 1:
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
Problem 2:
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
photographs?
Problem 3:
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?