Cosmology : structure and evolution of the universe Questions and issues: size of universe - innite or nite age - limited or forever (in future and in past) structure - hierarchies : large scale struct. / galaxies / stars evolution - relative amounts of m
Cosmic evolution of galaxies, clusters & AGN : rst galaxies form when ? verify hierarchical gal. formation ? relative formation of AGN & galaxies dark matter
looking to greater distances => looking back in time => critical to estimate distances need a st
Galaxy Collisions very important process
Antennae galaxies - NGC 4038, 4039 visible light infrared
starbursts triggered where gas collides
Collision of 2 Galaxies : 1) prob. of stellar collisions is nil. 2) interstellar gas lls much more of the volume, =>
Galaxies : 3 basic types : spiral - thin disk w/ dust, gas and stars + older spherical star system elliptical - older spheroidal star system (no interstellar gas/dust, no young stars) irregular - irreg. shape , usually lots of gas
Last time : Planets properties primarily due to distance from sun 1) in early formation, ices condensed at large r where it was cool aglomeration to > 15 Mearth enabled accretion of gases H, He 2) hot inner planets cant retain light gases 3) atmosphere im
Interstellar gas & dust / star formation & formation of planetary systems
NGC 891 - a similar galaxy viewed Edge-on
Two major galaxy components : in Milky Way, stars (~90%mass) interstellar matter (10% of mass)
Interstellar matter important
GRBs - the most powerful explosions! SgrA* the black hole at the center of our Galaxy!
Visible wavelength image toward center of Milky Way! Infrared image of! galactic center!
GRBs - gamma ray bursters (100 kev !)! Vela satellite (1965 arms control verica
High Mass Star death :! Supernovae =>! neutron stars => pulsars! stellar mass black holes => Gamma Ray Bursters! added attraction - Galactic center black hole!
Crab Nebula - SN 1054AD, 30 ms pulsar and pulsar wind! X-ray! Visible light!
Evolution of the e
Ring nebula! Late stellar Evolution & ! Death !
How do we get to the planetaries and ! what happens after ?!
Evolution after the main sequence :! H in core converted to He => main sequence phase ends ! 1)! H burns in shell arou
Stellar Structure - Main Sequence Stars! X-ray! UV!
H-R (Hertzsprung-Russell) diagram !
following is meant as an appreciation of deductive powers of physics ! i.e. dont get hung up on learning the equations ,! but appreciate the resul
E-M radiation! ! Black-body (Planck) radiation - continuous at all !" emission depends only on T ! 1) hotter surface emits more ! at all ! ! 2) peak at shorter ! as T rises "
Quantum transitions :! energy levels w/i atoms & molecules quantized! => only di
Star Formation and Physics of Stars!
Star cluster formation !
M13 ! Globular ! cluster! Orion Nebula - M42! 450 pc distance! Gravitational collapse of interstellar ! gas & dust cloud => star formation!
How to understand the workings of
Large, Modern Telescopes !
Why large ?! 2 reasons:! !Light gathering power increases as area (!r2)!
- Palomar 200 tel. can observe ! (200/14)2~200 times faster than the Robinson 14in tel.!
!Angular resolution varies as 1.2 "/D!
diffraction limit of tel. :
Stars ?! Stellar structure ! Mass and Length scales ! Our local viewpoint ! appearance of sky and nding *s, planets, galaxies! changing sky & seasons! phases, eclipses & tides! SUN Visible light! What is the structure! nature of material! How does it shin
Early Universe hotter, more energetic and denser high energy radiation ( rays) dominated matter nuclei destroyed, would not exist pair creation from high-E rays unication of forces Today - follow this evolution as the universe expands cools and lowers its