NGC 602 and Beyond Credit: NASA, ESA, and the Hubble Heritage Team (STScI / AURA) - ESA/Hubble Collab.
-Stars are born in giant molecular clouds, which have cold, dense cores. - Stars are not born alone! They are born in structures
For Einstein it begins with the equivalence principle. According to Newton and Galileo Gravitational accelerations are the same for all pointlike particles, regardless of composition, charge, thermodynamic state, etc. This is different
How far? The Distance Ladder.
(see http:/www.astro.ucla.edu/~wright/distance.htm for more details.)
Determining distances is one of the more difficult tasks in astronomy. No single method works in all cases, rather different methods work in different rang
Line Broadening Processes
Spectral lines are not delta functions (I.e., not infinitely narrow functions) of frequency and wavelength. Several processes conspire to broaden lines. 1. Natural (QM) Broadening Result of the Heisenberg Uncertainty Principle.
Basic Characteristics of Electromagnetic Radiation.
Brief review of EM waves, with a view towards astronomical application. I. Traveling wave characteristics E&M radiation consists of transverse waves with alternating electric and magnetic fields, and amp
The Interstellar Medium of the Galaxy
the multiphase cloudy gas between the stars. Clouds are not as bright as stars! We must use a variety of observing techniques to see them, including: reddening, optical & UV absorption lines, 21 cm emission & absorpti
- At higher densities and pressures than a WD can support, we get the reaction:
p + e- > n + ,
And the neutrons become degenerate > neutron star.
Like one giant atomic nucleus.
- M 1 Msun, R 10-20 km!
density 1014 g/cm-3.
A few teaspoons of
The simplicity and universality of thermal radiation result from the requirement of equilibrium between the radiation and matter. Only one variable, T, determines the Planck spectrum. Many radiation processes in astrophysics produce a
Thermal Radiation (Blackbody, Cavity Radiation).
The theory of the interaction of electromagnetic waves with solids, liquids and gases began at about the same time as the in vacuo EM theory. In 1859 G. Kirchhoff summarized the work to date in 3 empirical
* Can outshine an entire galaxy (L 1010 Lsun for weeks. * Produce copious neutrinos, and heavy elements.
Material ejected by SN explosions. Distribution of heavy elements into space. Trigger for later star formation. All mat
Stellar Populations in the Galaxy
Stars are fish in the sea of the galaxy, and like fish they often travel in schools. Star clusters are relatively small groupings, the true schools are stellar populations. Populations often correlate with specific compon
Active Galactic Nuclei and Quasars
A little history. 1960 Discovery of radio stars. Weird optical spectra, emission lines at unusual wavelengths. Quasi-Stellar Radio Source, Quasar or QSO. 1963 Maarten Schmidt suggests that the strange lines = H emission
The Hubble (Sandage) tuning fork diagram is the most basic and fundamental system. The periodic table of galaxies.
Spiral classification criteria:
- Bulge size - Openness of the arms (pitch angle). - Resolu