Lecture 11 Flashcards
(21 cards)
define luminosity
amount of E the star radiates per second
equivalent to power
apparent brightness decreases with _____
what law is this?
distance
inverse square law
unit of luminosity?
J/s or W
unit of temp used for stellar properties?
K
unit of radius?
m or Rsun
unit of mass?
Kg or Msun
the intrinsic luminosity of a star is determined by __ and ____
based on what law?
temp and radius
stefan boltzmann law
according to wien’s law, which is cooler?
a) red stars
b) blue stars
red
according to stefan boltzmann law, which is dimmer?
a) red stars
b) blue stars
red
what is the balmer series?
electron transitions to 2nd excited state
what energy levels show red?
n=3 to n=2
what energy levels show blue?
n=4 to n=2
what energy levels show violet?
n=5 to n=2
what causes the pattern of lines in spectra?
b/c electron transitions depend on temperature
what is the hottest class of star?
O
what is the coolest class of star?
M
list the sequence of classes of stars
O B A F G K M
within A stars, what is the hottest and coolest stars?
hottest: A0
coolest: A9
which has a bigger temp difference?
a) B9 and A0
b) A0 an A9
b)
according to the stefan boltzmann law, how is luminosity related w/ temp?
luminosity doesn’t always scale w/ temp
in the main sequence, compare the quantity of cool vs hot stars
many more cool stars
BUT cool stars are harder to observe
