Presentation on theme: "Types of Stars Life Cycle of Stars Galaxies"— Presentation transcript:
1 Types of Stars Life Cycle of Stars Galaxies AstronomyTypes of StarsLife Cycle of StarsGalaxies
2 Characteristics of Stars ColorGas CompositionTemperatureMagnitude
3 Color/ TemperatureA star’s surface temperature can be determined by their colorBlue stars have a temperature above 30,000 KRed stars are much coolerYellow stars have temperatures between 5000 and 6000 K (such as our Sun)
4 Binary Stars Binary Stars Pair of stars that orbit around each other Stars are kept together by gravityMore than half of all stars are binary or clusters
6 Taken from Hubble Space Telescope Star ClusterTaken from Hubble Space Telescope
7 Star Distance Measurement A light-year is the best unit to express stellar distance.It is the distance light travels in one year.Example: A star that is 4.3 light-years away means that it takes 4.3 years for light from that star to reach our Sun.
8 Magnitude This is how bright the star is (or appears to be) It can appear brighter if…The star is really close to EarthActual brightness usually depends on size
9 Hertzsprung–Russell Diagram Makes no sense without caption in book
10 Hertzsprung-Russell Diagram Shows relationship between a star’s magnitude and temperatureMain-Sequence line–as magnitude increases, so does temperatureNotice how stars are colored blue, red, and yellow!!!
11 Hertzsprung–Russell Diagram Makes no sense without caption in book
12 H-R Diagram Almost 90% of all stars belong on the main-sequence The brighter stars are the hottest (blue)50 times more massive than Sun
13 H-R Diagram ContinuedIn the upper right corner of diagram are the red giantsLarge red giants are called supergiants (Betelgeuse in constellation Orion)In the lower-central part of diagram are the white dwarfs
14 Hertzsprung–Russell Diagram Makes no sense without caption in book
19 Gravity is important!!Gravity squeezes particles into the center of the cloud of dust and gasWithout gravity, stars would not develop!!
20 Balanced ForcesMakes no sense without caption in book
21 Nuclear Fusion A star is born once nuclear fusion has begun Nuclear fusion is the process of combining atoms to create tremendous amounts of energy.The first atoms to combine are hydrogen. They combine to create helium.
22 Main-Sequence StageStars age at different rates while in the main-sequenceHot, massive blue stars burn their hydrogen really fastYellow stars (our sun) are in this stage for 10 billion yearsRemember: Our sun is only 5 billion years old…. So it still has 5 billion years left just in this stage!!
24 Red-Giant Stage Star expands 100’s to 1000’s size of main-sequence starConvert helium to carbon to produce fuel and delay deathEventually all usable elements will be burnedYellow stars (sun) usually spend less than a billion years as a red giant
25 Burnout and Death A star’s life cycle depends on the star’s mass. Medium Mass Stars and Massive Stars will evolve and die differently
26 Medium-Mass Stellar Death Medium-Mass Stars (our sun)Become red giantsDuring collapse as red giant, create a round cloud of gas known as a “planetary nebula”End as white dwarfsThe leftover centers of the star
27 Taken from Hubble Space Telescope Planetary NebulaMakes no sense without caption in bookTaken from Hubble Space Telescope
28 Taken from Hubble Space Telescope Planetary NebulaTaken from Hubble Space Telescope
29 High-Mass Stellar Death High-Mass StarRed Giant implodes and creates a supernovaThe gravity becomes too strong for the star to withstandExtremely rareThe last supernova to be seen with the naked eye was in 1987.The explosion actually began before civilization began here on Earth, but it took 169,000 years for the light from the explosion to reach Earth.
30 Crab Nebula in the Constellation Taurus Makes no sense without caption in bookTaken from Hubble Space Telescope
31 Taken from Hubble Space Telescope SupernovaTaken from Hubble Space Telescope
32 Taken from Hubble Space Telescope Supernova RemnantTaken from Hubble Space Telescope
33 Star Remnants Black Holes Remnants of supernova event These remnants are so massive that they collapseGravity is so strong that light can not escapeBlack holes do not “swallow up” other starsHowever, some of the gas and dust from the star may spiral into the black hole.Black holes were first “seen” by x-ray waves.
35 Black HoleMakes no sense without caption in book
36 Review Medium-Mass Stars Massive Stars Cloud of gas and dust Main-SequenceRed GiantPlanetary NebulaWhite DwarfMassive StarsCloud of gas and dustMain-SequenceSupergiantSupernovaBlackhole
37 GalaxiesA galaxy is a group of stars, dust, and gases held together by gravityThe smallest galaxies still contain a few million stars.Galaxies were first classified by Edwin Hubble in the 1920’sThree types of galaxiesSpiralEllipticalIrregular
38 Types of Galaxies Spiral Disk-shaped with arms extending from center 30% of galaxies are spiralOur galaxy, the Milky Way GalaxyThe outer edges of the spiral are blue because most of the blue stars in this galaxy are located on the spiral’s “arms”The yellow and red stars are located in the middle
49 The Big Bang Theory Theory about the origin of the universe At one time, the entire universe was confined to a dense, hot, supermassive ball. (To the size of a tennis ball!)Then, about 13.7 billion years ago, a violent explosion occurred, hurling energy in all directionsSome of the expanding energy turned into matterMatter made nebulas, which then made stars. Stars eventually made galaxies.
50 The BigBangTheoryMakes no sense without caption in book
51 Supporting EvidenceIn 1964, Robert Wilson and Arno Penzias, using a giant radio wave antenna, found radiation that was coming to Earth from all directions in spaceCalled “Cosmic Background Radiation”This radiation was actually created from the Big Bang.
52 Future for the Universe? Two possible futures:The Universe will expand forever (most popular)The outward expansion will stop and inward contraction will beginThese are just theories--- no one is certain how the Universe began and if it will end.