what is light?

how is it measured?

light is radiant energy

speed of light in vacuum

c=3x10^8 m/s

=3x10^5 km/s

=186,000 miles/seconds

both as partical and wave

wave of light?

wave lenght?

 wave is a vibration that travels

a light waves are occillating electric and magnetic feilds that travel

from one hump to one hump is wave lenght

400 nanometers is what color on chart?

700 nanometers is ?

which side is each one on?

400 is violet and on left

700 is red and on the right

light as a particle is a ?

what is it?

which color  has more energy?

Photon is light as a particle

photon is proporttional to 1/wavelenght

one violet photon has more energy than a red photon

Electromagnetic Spectrum

name 7 bands and 2 windows?

short end to long end (wave length)

Violet to red

gamma ray, x ray, ultra violet,(v) visible (r) Inforred, Microwave, and radio

two windows

visible and parts of radio

wien's law

wave lenghts and color to temperature?

wavelength is propotional to 1/ temp.

cool stars are red and hot stars are blue

Stefan- baltzmann Law

L is propotional to R^2 T^4

L= light out put

R= radious

T= surface temp.

history of spectrum

Who? What?

Newton- prisim- sun light pass through slit and a prisim and get a rainbow of color sorted out by wavelenght

Fraunhofer- Pass light through 2 diffraction gratings and finds that hundrens of dark lines in sun spectrum

labled AB-HK

Bunsen&Gustar&kirchhaff-finds out about chemical elemits also give off bright lines and compare Elements bright lines to suns bright lines finds Sodium

Bohn-finds out that birght and drak lines are due to change in energy from electron in atoms

Electron can't ?

bigger the jump the shorter the what?

Bright lines means?

Dark Line means?

sit inbetween a level must be on a level

bigger jump shorter the wavelenght =more energy

bright lines= emitting light

dark lines= absorbing light

Doppler Effect

direction of shift?

as source of light comes toward you the wave lenght is shorter as the source pass you the wave lenght becomes longer

-toward is blue shift

-away is red shift

Amount of shift- Speed toward or away

Telescopes

(Visible light teletescope)

Refacting telescope

lens that collects light

problem- Choromatic Abrerration

- color fringing

solution- using multiple collector lens

Reflecting telescope

has a mirror as light collector

no Choromatic Aberration

LGP- light gathering power-make dim objects look bright

lager Diamter is better LGP to diameter^2

RP-Resolving power- abilty to show fine detail

smaller RP is better but Larger Diameter

Earths Atmospher limits RP ability solution is put telescope at higher elevation or in space - Adative optic-

MP- Magnifying power -Ability for things to looker closer and larger

MP= focal length of colector/ focal lenght of eyepiece

-Longer focal lenght collector better MP

the apparent change in an object due to the change in location of the observer

distance is proportional to 1/ parallax angel

shorter the distance the bigger the change

stellar parallax measurements

largest measured?

unit measured in?

compared to light years?

smallest?

Proxima Centauri (can't be seen by naked eye)

size was 0.77 arc. seconds

which is 4.2 light years

smallest is 0.002 arc. seconds

brightness of stars

m M and L

naked eye limit?

m is how bright star appears to be

-# are bright stars, +# are dim stars

M is light out put of a star

M and m are equal when distance is equal to 10 pc

L is for Luminosity which is measurment of light out put of a star ( same as M) 

Sun Luminosity is 3.84 x 10^26 watts

1 solar Luminosity is 1Lsun 

spectra stars

facts?

type?

squences?

sun?

facts- most have dark(absortion) lines

tell surface temp. by darkness of line

doppler shift

types- O B A F G K M

O hotest and M is coldest

10 groups per letter

Sun is G2

Hertzsprung- Russel Diagram

who?

what does it show?

types of stars?

founded by EnJar Hertzsprung and Henry Norris Russel

pots Absoult mag vs. Spectral type

white drawfs  hot and dim

main squence hot bight and cold and dim

giants  cold and brightish dim

super giants bright and hotish cold

Stellar size

method

range

trends

method use the Stefan-bottzman law

L is proportional to R^2 T^4

Luminosity proportional to Radius^2 Surface Temp. ^4

range?

trend- smallest white drawf to lagest super giant

Stellar Density

range

trends

method- 1-Binary star orbit

* sirius A and sirius B

2- center of mass relationships

-mass A over mass B= distance B/ Distance A

- Shorter distance over longer distance

range- 0.08 solar mass to 100 solar mass

trend is main sequence top is high mass bottom in low mass

Stellar density

range and trend

mass over volume

volume is 4/3 wavelength Radious ^3

range- 10^-6 grams / cm^3 to 10^7 grams / cm^3

on graph it is highest density at white drawfs and lowest at super giants

≈ 3/4 hydrogen

1/4 helium

2% heavier elements

stellar life

hydrostatic equilibrum

start at ZAM line cross main sequence

move up and to right (brighter and cooler)

increase in size

hydrostatic equilibrum- gravity pulling on star and engry the star is releasing is the same (fusion)

proton chain

or CNO cycle

 both 4 hydrogen to  1 helium + Energy

short life span top of main sequence

long life span is a bottom of main sequence