Solar surface activity

1. solar storms

A solar storm is an eruption from the surface of the sun, which comes in two components:

1. X-Ray Flare - reaches earth in 8 minutes

2. CME - if too many particles come in they can knock out earths power grids and sometimes push the auroras down to the equator ( low-lattitude aurora )

Solar surface activity

2. coronal mass ejection

solar surface activity

3. solar wind

The solar wind is a continuos stream of charged particles.

- usually deflected by the earths magnetic field

- some are caught in the Van Allen belts, which are hazerdous to satellites

Solar surface activity

4. sunspots

Located in the photosphere.

They're the cooler areas on the sun because of other adjacent parts and are caused by the magnetic fields.

They're the base of the magnetic loops.

Solar surface activity

5. the solar cycle

lasts 11 years

the solar cycle is observed by counting the sunspots visible on the sun

more active period called solar maximum

less active period called solar minimum

Solar surface activity

6. magnetic fields

solar surface activity

7.  Aurorae (Northern Lights)

Solar surface activity

8. convection

hot gas rises and cool gas sinks

example : lava lamp

Solar Structure

1. core

where energy is created by nuclear fusion

(hydrogen is converted to helium here)

the hottest part of the sun made of plasma

Solar structure

2. random walk of photons

the path of photons in the radiative zone as they escape from the sun.

Photons do not travel in a straight line, they are repeatedly absorbed and reimited by atoms, thus making it a very slow process

Solar structure

3. radiative zone

 where energy is transported by photons

they are absorbed and reimited

process takes about 100,000 years

between the core and convection zone.

solar structure

4. convection zone

solar structure

5. hydrostatic equilibrium

balance between the inward force of gravity and the sun's outward force of gas pressure.

 if gravity was greater, star would contract

if pressure was greater, star would expand

both are strongest near the center, and weaker near the surface

solar structure

6. helioseismology

Study of the sun generating soundwaves, causing it to vibrate.

solar structure

7. photosphere

the sun's visible surface

very thin layer where light escapes the sun.

contains : 1. granules, 2. sunspots, 3. solar prominences, and 4. solar flares

solar structure

8. corona

sun's outter layer made of plasma which is hotter than the chromosphere

layer between the sun's chromosphere and the solar wind.

- visible in x-rays and during eclipses

solar energy production ( neutrinos )

1.  fusion

process by which the sun generates energy

process by which 2 or more atomic nuclei join together "fuse" to make a heavier element. and it happens because

the core is hot enough to fuse these 2 nucleis with positive charges.

solar energy production (neutrino)

2. deuterium

A stable isotope of hydrogen with a mass approximately twice that of the usual isotope.

has 1 proton and 1 neutron

solar energy production (neutrino)

3. positrons

anti-matter counterpart of the electron

- has an electric charge +1 (e+)

aka "anti-electron"

solar energy production (neutrino)

4. proton-proton chain

one of several fusion reactions by which stars convert hydrogen to helium.

solar energy production (neutrino)

5. Davis Experiment

Located in Homestake, South Dakota in a gold mine.

Purpose was to detect the solar neutrinos being produced.

- They only found about 1/3 of the expected number of  neutrinos

which caused the solar neutrino problem

solar energy production

6. Kamiokande

Happened in Japan

used a large tank of H20 to detect neutrino interactions with electrons or nuclei of water.

It proved that neutrinos came from the Sun, but again there was "too few" detected.

solar energy production(neutrino)

7. SNO

"Sudbury Neutrino Observatory"

In Ontario, Canada and they used heavy water (D2O)

1. proved the source for the suns energy

2. proved that neutrinos change into 3 types

solar energy production(neutrino)

8. neutrino "oscillations" (metamorphosis)

neutrinos change into 3 types of different neutrinos in route from the sun's core

types:

1. Electrons (original neutrino)

2. Muons

3. Taus

- energy is not "type" it can have any energy, but those from specific reactions have certain energies.

neutrinos are faster than photons over long distances

photons are faster than neutrinos over short distances

properties of light

1. electromagnetic waves

properties of light

2. wavelength

distance between successive ^ crests of waves

blue light has shorter wavelength

red light has longer wavelength

thanks to wavelenghts there is different colors!

properties of light

3. frequency

number of crests that pass through a point

- measured in hertz(hz)

if frequency increases, wavelenght decreases.

wavelenght x frequency = speed of light (c)

properties of light

4. photon energy

depends on the frequency

e= constant (h) x frequency (v)

properties of light

5. electromagnetic spectrum

long <--------------> short (wavelength)

radio - micro - infrared - visible - ultraviolet - xray - gamma

properties of light

6. Doppler-Effect

1. the light will be red-shifted if the source is moving away from us

2. the light will be blue-shifted if the source is moving towards us

this also tells us how fast the source is moving!

types of spectra

1.  thermal "blackbody" emitters

It absorbs all light, not letting it out.

1. one form of continuos spectrum ( no gaps )

2. nearly all objects emit thermal radiation (stars,planets, even us humans )

3. depends on only 1 property : temperature

- hotter objects emit more light per unit surface area at all frequencies of light. the total power increases in proportion to its temperature to the 4th power.

wavelength max = max brightness

wavelength peak = hottest

types of spectra

2. Wien's Law

hotter objects emit more intensely at shorter wavelenghts (blue)

cooler objects emit longer wavelenghts (red)

types of spectra

3. Stefan-Boltzmann Law

types of spectra

4. Kirchhoffs Law

1. a hot dense glowing object "blackbody" emits a continuos thermal spectrum

2. a hot low density gas emits light at only certain wavelengths "emission line spectrum"

3. light with a continuos spectrum passing through a cool gas produces dark "absorption lines"

types of spectra

5. continuos line

types of spectra

6. emission lines

types of spectra

7. absorption line

types of spectra

7. electron energy levels

electrons must gain energy in order to jump from a lower orbit to a higher energy orbit.

- when electrons fall from a higher to a lower orbit/energy level, they lose energy releasing a photon

- the lowest energy level for an atom is called the groundstate, all levels above it are excited levels

forces

1. electromagnetic force

- charged matter only

- stronger than gravity

- infinite range

- self cancels ( attracts or repels ) ex. neutron star

- responsible for all phenomena one encounters in daily life

forces

2. strong force

- short range

- holds nuclei together against electric force

forces

3. weak force

- short range

- converts particles and transmutes elements  (proton->neutron)

forces

4. gravity

- works on any mass

- infinite range

- weak

- cumulative ( attracting matter together )

- controls large bodies

forces

5. gravity as an inverse-square law

forces

6. center of mass for orbits of 2 bodies

energy

1. gravitational potential

energy

2. kinetic

energy

3. thermal

energy

4. electromagnetic (radiation)

energy

5. mass-energy

most compact form of energy

e=mc ^2

energy

6.conservation laws of energy

energy

7. angular momentum

causes objects to rotate faster as they shrink in size.

rotational momentum of a spinning/orbiting object.

example: pulsar (spinning neutron star)

properties related to total light output

1. luminosity

properties related to total light output

2.apparent brightness

the intensity of the stars light that reaches us

- depends on its luminosity & distance

properties related to total light output

3. inverse square law of light

brightness varies inversely as distance squared

divide a fixed luminosity evenly over a larger surface area, and there will be less energy per unit surface area.

properties related to total light output

4. apparent and absolute magnitudes

1. apparent magnitude : brightness of a star as it appears from earth

2. absolute magnitude : measure of a stars intrinsic brightness, an alternate scale for luminosity

or apparent magnitude a star would have if it were 10 parsecs away (32.6 light years)

these are two other ways to make an HR diagram*

properties related to total light output

5. distance

dependant (relative) property of a star

the distance to celestial objects?

properties related to total light output

6. parallax

difference in appartent position of a star viewed upon 2 different lines of sight

- measured by the angle of inclination between those 2 lines.

properties related to surface temperature

1. continuos spectrum

properties related to surface temperature

2. wavelenght of peak intensity

the higher the temperature of a blackbody, the shorter the wavelenght of maximum emission

- hottest state a star can be

properties related to surface temperature

3. color

properties related to surface temperature

4. spectral type O-M

OBAFGKM

( oh be a fine girl, kiss me )

O is the hottest

M is the coolest

defined by which absorption lines are seen in a stars spectrum and the relative strengths of these lines.

radius

1. from luminosity and temperature

 luminosity formula has radius, temp. and luminosity in it.

If you know L and T, you can find radius

- a luminous star of low temp must be a large one

- a high temp star can only have a low luminosity if it is very small

radius

2. mass from the law of gravity applied to binary stars

Radius

3. types of binary stars

1. visual - follow the positional changes of one or both stars over the orbit. You see the stars move back and forth.

2. spectroscopic - where you see 2 spectral lines shifting back and forth in wavelength due to the doppler shift. You see evidence in their orbit. double or single lined binaries.

3. eclipsing - combined brightness shows. When one star moves infront of the other causing "dips" in the light curve

mapping star properties

1. hertzsprung-russell (HR) diagram

the main sequence

1. significance of the main sequence

the main sequence

2. mass-luminosity relation

mass is related to luminosity (only in main sequence stars) if mass increases +2, and luminosity increases by a factor of 8

1. larger masses exert greater weight (force) at center

2. requires higher central pressure to maintain balance

3. faster rate of nuclear fusion reactions

4. luminosity increases strongly with mass

main sequence

3. mass-lifetime relation

lifetime means : how long a star can be on the main sequence

- amount of fuel is proportional to mass

- high mass stars burn fuel like a bus

- low mass stars burn fuel like a hybrid

- the initial mass of a star will determine its spectral type, luminosity, and lifetime on the main sequence

high lum/mass stars live less, and low lum/mass live longer.

ages of star clusters from their HR diagrams

1. star clusters

ages of star clusters from their HR diagram

2. main sequence "turn off" point

most massive stars die off first

as time passes, lower mass stars begin to move off the main sequence

the clusters age is equal to the main sequence stars, for older clusters, more of the main sequence has peeled off.