Week 1 Galactic Structure and Overview Flashcards
what is the problem with baryonic matter in galaxies
it supplies inadequate mass to explain the dynamics of galaxies
what are 3 main things that the composition of an individual galaxy depends on
morphological type
mass
evolutionary age
define Population 1 stars
young ( < ~ 10^9 yr)
high luminosity and hot so appear blue
high level of enriched nucleosynthesised elements
typically found in disc and spiral galaxies
define Population 2 stars
old and massive
luminous but cold so appear red
metal poor
typically found in elliptical galaxies
how are stars classified
by a letter denoting temp and a roman numeral denoting luminosity
example: Sun is GV
define luminosity and its units
the intrinsic power output of the object, measured in W
define flux and its units
power received per unit area of detector measured in Wm^-2
define flux density and its units
flux per unit frequency range measured in units of Wm^-2Hz^-1
what does a higher magnitude basically tell us
higher positive magnitude means that the star is fainter
what is the apparent magnitude equation
m1 - m2 = -2.5 log [F1/F2]
what is the absolute magnitude equation
m - M = -5 + 5 log[d]
