* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Startalk
Chinese astronomy wikipedia , lookup
History of Solar System formation and evolution hypotheses wikipedia , lookup
Aries (constellation) wikipedia , lookup
Dyson sphere wikipedia , lookup
Star of Bethlehem wikipedia , lookup
Corona Borealis wikipedia , lookup
Space Interferometry Mission wikipedia , lookup
Orion (constellation) wikipedia , lookup
Auriga (constellation) wikipedia , lookup
Corona Australis wikipedia , lookup
International Ultraviolet Explorer wikipedia , lookup
Cassiopeia (constellation) wikipedia , lookup
Observational astronomy wikipedia , lookup
Canis Minor wikipedia , lookup
Cosmic distance ladder wikipedia , lookup
Cygnus (constellation) wikipedia , lookup
Star catalogue wikipedia , lookup
Perseus (constellation) wikipedia , lookup
Canis Major wikipedia , lookup
Aquarius (constellation) wikipedia , lookup
Type II supernova wikipedia , lookup
Stellar classification wikipedia , lookup
Future of an expanding universe wikipedia , lookup
H II region wikipedia , lookup
Stellar kinematics wikipedia , lookup
Corvus (constellation) wikipedia , lookup
Stellar evolution wikipedia , lookup
StarTalk Sanjay Yengul May 2016 "To know ourselves, we must know the stars." Twinkle Twinkle … How many stars are there? How big are these stars? Picture of night sky What are they made of ? Why do they shine? Are they all the same? How are they born how do they die? PHOTO COURTESY NASA The constellation Orion as seen from the space shuttle Endeavour (STS-54) Astronomical Units 1 AU = distance between earth and the sun 1 Light Year = 63,000 AU = 10 trillion km Speed of light: 300,000 km/s (186,000 miles/s) The Sun is about 8 light minutes away! Our nearest star: Alpha Centauri – 4 light years away! What is a star? A big glowing ball of gas! Contains mainly H and He They have a core that is dense and super hot! Nuclear fusion is the source of their energy! They vary in size, temperature, brightness & color! How far is that star? For stars < 400 light years away: Parallax or Triangulation For stars farther way: Indirect Method based on brightness measurement Galaxies A collection of stars Trillions of Galaxies in the Universe Our Galaxy is called the The Milky Way Galaxy It contains billions of stars Age: ~10 billion years, Size: 100,000 light years Scale of Galaxies Spectra Spectral Classes Spectral Class Color Ave.Temp. (K) O Blue-violet 30,000 B A F G Blue-white White Yellow-white Yellow 20,000 10,000 8,000 6,000 K Orange 4,000 M Red-orange 3,000 Familiar Examples Mintaka (delta Orionis) Rigel, Spica Vega, Sirius Canopus, procyon Sun, Capella Arcturus, Aldebaran Antares, Betelgeuse Star Classification Classes of Stars by Luminosity Class Description Familiar Examples Ia Bright Supergiants Rigel, Betelgeuse Ib Supergiants Polaris (the North star), Antares II III Bright Giants Giants Mintaka (delta Orionis) Arcturus, Capella IV Sub-giants Altair, Achenrar (a Southern Hemisphere star) V not classified Main sequence White dwarfs Sun, Sirius Sirius B, Procyon B PHOTO COURTESY OF NASA The Hertzsprung-Russell Diagram. The Sun, 12 brightest stars of the Northern Hemisphere and white dwarf companion stars to Sirius and Procyon are shown. Star Classification Classes of Stars by Luminosity Class Description Familiar Examples Ia Bright Supergiants Rigel, Betelgeuse Ib Supergiants Polaris (the North star), Antares II III Bright Giants Giants Mintaka (delta Orionis) Arcturus, Capella IV Sub-giants Altair, Achenrar (a Southern Hemisphere star) V not classified Main sequence White dwarfs Sun, Sirius Sirius B, Procyon B PHOTO COURTESY OF NASA The Hertzsprung-Russell Diagram. The Sun, 12 brightest stars of the Northern Hemisphere and white dwarf companion stars to Sirius and Procyon are shown. Birth of a star A gravity disturbance causes clumps of gas and dust to collapse inward, heat up In ~ million years a small dense core forms – the protostar! When T = 7 million K, fusion starts If the mass is big enough (0.1 solar mass) a new stable star If the mass is not big enough brown dwarf! PHOTO COURTESY OF NASA Death of a star Stars like the Sun Several billion years later, run out of hydrogen fuel – the core contracts under gravity, outer layers expand due to heat Red Giant Burns Helium Planetary Nebula White Dwarf Black Dwarf The Rotten Egg planetary nebula More Massive Stars than the Sun: Burn H, He C Fe Explode into a supernova Neutron Star or a Black Hole Meanwhile the shock from the supernova can initiate star formation in other interstellar clouds Hubble Space Telescope photographs COURTESY OF NASA The rings around Supernova 1987A Scale of the Universe References http://stars.astro.illinois.edu/sow/star_intro.html http://stars.astro.illinois.edu/sow/spectra.html http://www.iflscience.com/space/how-big-our-place-universe http://www.enchantedlearning.com/subjects/astronomy/stars/startypes.sht ml Colors and Temperatures: https://docs.kde.org/trunk5/en/kdeedu/kstars/ai- colorandtemp.html http://science.howstuffworks.com/star5.htm