Stars, Galaxies and the Universe

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A. Observing the Stars

               1) Sun (Sol)

                         (a) only star in our solar system

               2) other stars are great distances

                         (a) Alpha Centauri

                                   (1) next nearest star

                                   (2) 40 trillion km away from Earth

                                            (i) 4 ˝ light years

               3) most spectacular solar flare ever recorded

                         (a) November 3rd, 2003

                         (b) propelled by magnetic forces

                         (c) spans more than 365,000 miles of the solar surface

               4) light year

                         (a) the distance light travels in one (1) year

                                   (1) 10 trillion km (6 million million miles)

               5) constellations

                         (a) pictures in the sky

                                   (1) a pattern or picture outlined by stars

                                   (2) Greek, Roman Gods/Goddesses

                                   (3) Mayan, Incan Symbols

               6) star brightness

                         (a) magnitude

                                   (1) apparent (observed)

                                            (i) temperature

                                            (ii) size

                                            (iii) distance

                                   (2) absolute

                                            (i) brightness you would see if all stars were placed

                                                 at equal distance from Earth

                                                      1. 10 parsecs – 32.6 light years

               7) color and temperature

                         (a) spectroscope

                                   (1) breaks light into the colors of the spectrum

                                   (2) band seen is called the stars spectrum

                                   (3) provide chemical makeup

                                            (i) dark lines indicate elements present

                         (b) red stars – coolest

                         (c) orange stars

                         (d) yellow stars

                         (e) white stars

                         (f) blue stars – hottest

               8) variable stars

                         (a) change in stars brightness over days or hours

                                   (1) Cepheid

                                            (i) undergoes one complete brightness cycle

                                   (2) Nova

                                            (i) sudden bright change due to explosion

               9) life cycle of a star

                         (a) H-R Diagram

                                   (1) Ejnar Hestsprung and Henry Russell

                                   (2) compares temperature and absolute magnitudes of stars

                                   (3) Main Sequence

                                            (i) majority of stars

                                   (4) White Dwarfs

                                            (i) small dense stars size of Earth       

                                   (5) Giants and Super Giants

                                            (i) stars with great diameters

               10) formation of stars

                         (a) Nebula

                                   (1) huge cloud of gas and dust

                                   (2) gravity forces gas to contract, forms proto-star

                                            (i) young, not hot enough for nuclear fusion

                                            (ii) temperature rises as matter contracts

                                   (3) main sequence

                                            (i) nuclear fusion begins

                                                      (a) hydrogen combines to form helium

                                            (ii) hydrogen depletes

                                   (4) giant/super giant

                                            (i) core becomes hotter

                                            (ii) nuclear fusion begins changing helium to carbon

                                   (5) final stage (affected by star’s mass)

                                            (i) white dwarf

                                                      (a) Sun

                                            (ii) supernova

                                                      (a) exploding star of intense brightness

                                                               (i) neutron star

                                                                         (a) extremely dense packed neutrons

                                                                         (b) pulsar – radiates (lighthouse)

                                                               (ii) black hole

                                                                         (a) region around which no  light/mass can escape

                                                               (iii) white hole(?)

                                                                         (a) opposite of black hole

                                                                         (b) worm hole

               11) groups of stars

                         (a) binary star systems

                                   (1) system of two (2) stars orbiting each other

                         (b) multiple star systems

                                   (2) groups of three (3) or more stars

                         (c) star clusters

                                   (1) open cluster

                                            (i) irregularly shaped group of stars

                                   (2) globular cluster

                                            (i) spherically-shaped group of stars

      B. Galaxies

               1) elliptical

                         (a) pumpkin-shaped; evenly bright

                         (b) few dark nebula

               2) spiral

                         (a) milky way

                                   (1) bright center

                                   (2) radiating arms of stars and nebula

               3) irregular

                         (a) having neither a spiral or elliptical shape

      C. The Universe

               1) motion

                         (a) spectra

                                   (i) spectroscope

                                   (ii) the greater the shift in spectra, the faster the star is moving

                         (b) Doppler effect

                                   (a) apparent change of wavelength occurring when an object is moving

                                            (1) blueshift

                                                      (i) shorter wavelength

                                                      (ii) star approaching

                                            (2) redshift

                                                      (i) longer wavelength

                                                      (ii) star receding

               2) Hubble’s law

                         (a) the further a galaxy is from Earth, the faster the star is moving

               3) Big Bang Theory

                         (a) comparison of redshifts in galaxy spectra

                         (b) 15 million years ago

                                   (i) mix of radiation and particles

                                   (ii) temperature rose to produce nuclear fusion

                                   (iii) matter exploded sending radiation and particles into space

                                   (iv) matter cooled and gravity collected matter into nebulae

                                   (v) galaxies formed

                                            (1) nebula hypothesis

                                                      (i) sun and planets formed together

                                                      (ii) large collection of gas and dust

                                                      (iii) main mass pulled to center and formed sun

                                                      (iv) smaller clumps of material collided and clumped together,

                                                            settling into one plane

                                                      (v) sun began nuclear fusion causing remaining gas and dust to

                                                           be carried away with solar wind

                                                      (vi) end of crater formation

The Sun



H-R Diagram

Eagle Nebula

Ring Nebula

Draco Nebula

Binary Star System

Globular Cluster

Double Cluster

Open Cluster

Elliptical Galaxy

Spiral Galaxy

Irregular Galaxy


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