A1 21 Galaxies

download A1 21 Galaxies

of 33

  • date post

    29-Aug-2014
  • Category

    Education

  • view

    1.755
  • download

    0

Embed Size (px)

description

Miller's Astronomy 1 lecture notes on Galaxies

Transcript of A1 21 Galaxies

  • Galaxies LACC: 25.2, 3, 5 Types of Galaxies: Ellipticals, Spirals, Irregular; The Hubble Tuning Fork Diagram; what kinds of stars make up galaxies (mass to light ratio) Galaxy Clusters; Galaxy Superclusters Measuring the Distances to Galaxies An attempt to answer the big questions: where are we? what is the universe made of? Monday, November 30, 2009 1
  • Galaxies like colorful pieces of candy ll the Hubble Deep Field - humanity's most distant yet optical view of the Universe. The dimmest, some as faint as 30th magnitude (about four billion times fainter than stars visible to the unaided eye), are the most distant galaxies and represent what the Universe looked like in the extreme past, perhaps less than one billion years after the Big Bang. To make the Deep Field image, astronomers selected an uncluttered area of the sky [about 2.5 arcmin across] in the constellation Ursa Major (the Big Bear) and pointed the Hubble Space Telescope at a single spot for 10 days accumulating and combining many separate exposures. With each additional exposure, fainter objects were revealed. The nal result can be used to explore the mysteries of galaxy evolution and the infant Universe. http://apod.nasa.gov/apod/ap980607.html Monday, November 30, 2009 2
  • Hubble Tuning-Fork Diagram http://ifa.hawaii.edu/~barnes/ast110_06/trotn.html Monday, November 30, 2009 3
  • Types of Galaxies All bright galaxies fall into one of three broad classes according to their shape: Spiral Galaxies (~75%) Elliptical Galaxies (20%) Irregular Galaxies (5%) http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit4/types.html Monday, November 30, 2009 4
  • Types of Galaxies Despite the fact that the Hubble Sequence is based only on the appearance of galaxies (morphology of galaxies), several physical properties of galaxies vary smoothly along the sequence. We have, little gas and dust lots of gas and dust mainly Pop II stars Pop I & II stars Reddish Bluish little ongoing star formation star formation large bulge small bulge tight,smooth arms open, loose arms Mass: 108-1013 MSun (Ellipticals) 1012-109 MSun (Spirals) http://zebu.uoregon.edu/~imamura/123/lecture-3/lecture-3.html Monday, November 30, 2009 5
  • Types of Galaxies Spiral Galaxies Elliptical Galaxies Irregular Galaxies Properties: Properties: Properties: Mass: 109 - 1012 Msun Mass: 105 - 1013 Msun Mass: 106 - 1011 Msun Diameter: 5 - 50 kpc Diameter: 1 - 200 kpc Diameter: 1 - 10 kpc Luminosity: 108 - 1011 Luminosity: 106 - 1012 Luminosity: 106 - few Lsun Lsun x 109 Lsun Structure & Dynamics: Structure & Dynamics: Structure & Dynamics: Disk + Spheroid Spheroid of old stars Chaotic structure, lots Supported by with little gas or dust of young blue stars relatively rapid rotation, Supported by random Moderate rotation in but spheroid is puffed motions of stars with Irregulars, but very up by random motions. some very slow rotation chaotic motions as well. http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit4/types.html Monday, November 30, 2009 6
  • Spiral Galaxies Classication Description Sa Bright core, tightly wound spiral arms Core dimmer than Sa, spiral arms more Sb loose Core dimmer than Sb, open spiral Sc structure, more dust and gas Dim core, loosely wrapped spiral structure, Sd lots of dust and gas and new star growth http://astronomyonline.org/Astrophotography/GalaxyMorphology.asp Monday, November 30, 2009 7
  • Barred Spiral Galaxies Classication Description SBa Bright core, tightly wound spiral arms Core dimmer than SBa, spiral arms more SBb loose Core dimmer than SBb, open spiral SBc structure, more dust and gas Dim core, loosely wrapped spiral structure, SBd lots of dust and gas and new star growth http://astronomyonline.org/Astrophotography/GalaxyMorphology.asp Monday, November 30, 2009 8
  • Spiral Galaxies Some other important properties of spiral galaxies include (Sparke and Gallagher, page 172 214): Spiral galaxies produce most of the luminous light in the Universe due to new star birth in the spiral arms Majority of galaxies in the Universe are spiral galaxies Half of all spiral galaxies are in the bared spiral class Spiral galaxies obey the Tully-Fisher relation brighter galaxies rotate faster Spiral galaxy rotation curves are dominated by Dark Matter Rotation of stars in the spiral arms are organized while the rotation of stars in the bulge are not (random rotation orbits about the nucleus) http://astronomyonline.org/Astrophotography/GalaxyMorphology.asp Monday, November 30, 2009 9
  • Spiral Galaxies: Supermassive Black Holes The results ... show a close relationship between the black hole mass and the stars that comprise an elliptical galaxy or the central bulge stars of a spiral galaxy. http://spaceightnow.com/news/n0006/05hstblackholes/ Monday, November 30, 2009 10
  • Elliptical Galaxies Type E: Ellipticals Show little internal structure: Elliptical in shape No disks, spiral arms, or dust lanes Brightest stars are red Classied by the degree of apparent atness: E0 is circular E7 is attest (~3:1 aspect ratio) http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit4/types.html Monday, November 30, 2009 11
  • Elliptical Galaxies: Supermassive Black Hole Though much more analysis remains, an initial look at Hubble evidence favors the idea that titanic black holes did not precede a galaxy's birth but instead co-evolved with the galaxy by trapping a surprisingly exact percentage of the mass of the bulbous hub of stars and gas in a galaxy. http://spaceightnow.com/news/n0006/05hstblackholes/ Monday, November 30, 2009 12
  • Irregular