Chapter 15. A Universe of Galaxies. The Hubble Deep Field 10 day exposure –field located in the Big Dipper. Edwin Hubble. Edwin Hubble. Hubble’s Galaxy Classification . Spiral Galaxies.
A Universe of Galaxies
M87 - E1
Large Magellanic Cloud – a small irregular galaxy that orbits the MMilky Way
Comparison of the apparent brightness of stars in the Hyades Cluster with those of the Pleiades Cluster
The Pleiades Cluster is 2.75 times farther away because
(2.75)2 = 7.5 times dimmer
The same luminosities are assumed for all main sequence stars of the same color.
Cepheids of a particular period have very nearly the same luminosity.
00 : 42.7 (h:m)
+41 : 16 (deg:m)
178x63 (arc min)
Andromeda Nebula M3, is actually another spiral galaxy
V = H D
recessional velocity = Hubble’s Constant Distance
Raisin Cake Model
Like raisins in rising raisin cake, galaxies move away from each other in our expanding universe.
A very rough estimate for the age of the universe
All of space and time were created in the Big Bang, which then expands. Analogous to the surface of a balloon.
As the universe expands, photons of radiation are stretched in wavelength, giving rise to the cosmological redshift.
NGC 4038/4039 are a pair of colliding spiral galaxies
The larger number of distorted galaxies in the past suggests that collisions between galaxies were common during the first few billion years.
While the Milky Way forms a new star about once per year, starburst galaxies can form over 100 new stars per year
Jet of particles shooting outward from the nucleus at nearly the speed of light
~ 400,000 light-years
Radio Jet in the Quasar 3C 345, shows a blob of plasma moving away from the core at nearly the speed of light
Doppler Shift of the emission lines in the nucleus of the elliptical galaxy M 87 indicates a 2-3 billion solar mass black hole
Artist’s conception of an accretion disk surrounding a super-massive black hole.