Awesome+pics.+of+Nubulas+and+Galaxies!!!

CARTWHEEL GALAXYEAGLE NEBULA [|] CATS EYE NEBULA Star Cycle

<>This is a super nova sorry if it isn't a good picture

[[[][|http://store.spaceimages.com/pilofcreat2.html|]http://store.spaceimages.com/cargal.html|]] To see pictures near the end of a stars life go to


 * 1) //Giant Molecular Cloud//--large dense gas cloud (with dust) that is cold! 100,000's to few million solar masses of material that has fragments of 10's to 100's solar masses that start collapsing for some reason (shock waves, cool enough for gravity to take over, etc.).
 * 2) //Protostar//--gas clump collapsing and heating up in center as it collapses. Gravitational energy being converted to heat. Lots of Infrared and Microwave radiation produced. Gets hot enough to glow red (2000-3000 K), but gas/dust cocoon blocks visible light. IR and Microwave can pass through dust.
 * 3) //T-Tauri//--starlike object visible to outside. Strong winds eject lots of material from young star (preferentially along rotational axes). Cocoon gas/dust blown away. Star starts fusion. [|Index]
 * 4) //Main Sequence//--star is stable because of Hydrostatic Equilibrium. Fusing Hydrogen to Helium **in core**. Stars spends about 90% lifetime as main sequence.
 * 5) //Subgiant, Red Giant, Supergiant//--Run out of core fusion fuel. Hydrostatic equilibrium upset. The Core shrinks. Fusion in shell around core stars. This Fusion is very rapid. The Luminosity (energy output) increases so gas envelope surrounding the core puffs out. At the bloated out surface, the energy is spread out over a larger area so each square centimeter will be cooler giving the light a red color. Red giants can eject a lot of mass through ``winds''. Note: A Red Giant may be large in terms of linear size, but it is //less// massive than the main sequence star it came from!
 * 6) Core Fusion--core has shrunk enough to create high enough temperatures to start Helium (or heavier element) fusion. In low mass stars the onset of Helium fusion can be **very** rapid, producing a burst of energy-//helium flash//. Eventually it settles down. Fusion is releasing more energy than main sequence stage, so star is bigger, but stable!
 * 7) Red Giant, Supergiant--core fuel runs out again. If massive enough, repeat stage 5. Number of times to do stages 5 --> 7 cycle depends on mass. [|//Stellar nucleosynthesis//] of heavy elements. Interplay of gravity and nuclear fusion. [|Index]
 * 8) //Planetary Nebula or Supernova//-- outer layers ejected as core shrinks to most compact state. Low mass stars (//0.08 - 5 M[[image:http://www.maa.mhn.de/Symb/sol.xbm align="bottom"]]// during main sequence) will go the planetary nebula route; high mass stars (//5 - 50M//[[image:http://www.maa.mhn.de/Symb/sol.xbm align="bottom"]] during main sequence) will go the explosive supernova route. Supernova explosion happens because the core has formed a very stiff neutron star and the infalling outer layers rebound off it (analogy: drop a basketball with a tennis ball on top of it; see the tennis ball really bounce off the basketball when the basketball hits the floor).
 * 9) //Remnant//--low mass core ( < 1.4 M[[image:http://www.maa.mhn.de/Symb/sol.xbm align="bottom"]]) shrinks to //white dwarf//. Electrons prevent further collapse. Size about that of Earth. Outer layers are planetary nebula. Higher mass core (//1.4 M[[image:http://www.maa.mhn.de/Symb/sol.xbm]] < M[[image:http://www.maa.mhn.de/Symb/core.xbm align="bottom"]] < 3 M[[image:http://www.maa.mhn.de/Symb/sol.xbm]]//) shrinks to neutron star. Supernova happens when //neutron star// is created. Neutrons prevent further collapse. Size about that of a large city. Highest mass core shrinks to a point. On the way to total collapse it may momentarily create a neutron star and the resulting supernova rebound explosion. Gravity finally wins. Nothing holds it up. Space so warped around the object that it effectively leaves our space. //Black hole!// Event horizon radius =//3 * M [[image:http://www.maa.mhn.de/Symb/core.xbm]]// km, where the core mass is relative to the Sun. Details about the remnants are given in the [|Stellar Remnants] section below.=

[|Index]
 * //Stellar Nucleosynthesis//--creating heavier elements from lighter elements in stars. Heavy elements (heavier than Helium) made in cores of stars (up to Iron). Elements heavier than Iron are made in supernova explosion. Lowest mass stars can only synthesize Helium. Stars around the mass of our Sun can synthesize Helium and Carbon. Massive stars with //M[[image:http://www.maa.mhn.de/Symb/asterix.xbm align="bottom"]] > 5 M[[image:http://www.maa.mhn.de/Symb/sol.xbm]]// can synthesize Helium, Carbon, Oxygen, Neon, Magnesium, Silicon, Sulfur, Argon, Calcium, Titanium, Chromium, Iron.


 * Cluster color-magnitude diagrams change with age. //Main Sequence Turnoff//-mass at that point tells you age of cluster. Assume that all stars in cluster form at about the same time. Stars slightly heavier than turnoff have already evolved away from main sequence.

[|Index] First I'll give a definition of ``degenerate matter'' as used in astronomy. Then I'll discuss the different types of core remnants. What I'll call ``remnants'' in this section is the compressed core. The spewed out gases in supernova explosions and planetary nebula are also sometimes referred to as ``supernova remnant or ``planetary remnant, but I'll be focussing on the remaining core left after the spectacular mass loss has occurred. It is important to remember that what happens to the core depends on the mass of the **core**, rather than the original mass of the main sequence star from which it came, because the only thing left for gravity to really compress is the core.


 * //Degenerate matter//--very dense matter in a state where the pressure no longer depends on temperature due to quantum mechanical effects. Rules: a) Certain permitted energies in a given space; b) Only 2 electrons (for white dwarfs) or 2 neutrons (for neutron stars) can share the same energy level in a given volume at one time; c) Closest spacing depends inversely on mass of particle (electrons further apart than neutrons and protons). Features:
 * 1)  Electrons or neutrons locked into place because all the lower energy shells are filled up and the only way they can move is to absorb enough energy to get to upper energy shells (**hard** to do!). To compress a degenerate gas means to change the degenerate particle motions. But that requires A LOT of energy. Degenerate particles have no ``elbow room'' and their jostling against each other strongly resists compression. Gas like hardened steel!
 * 2)  To change speed of degenerate particles requires A LOT of energy. Adding heat only causes the non-degenerate particles to move faster, but the degenerate ones supplying the pressure are unaffected.======[|Index]
 * //White Dwarfs//--if core mass < 1.4 solar masses. Electrons are degenerate. Mass of Sun compressed to size of Earth. Higher mass compressed to smaller radius! Neutrons and protons have room to move around freely. The density is about 1,000,000 g/cm[[image:http://www.maa.mhn.de/Symb/3.gif align="top"]] (one sugarcube > 1 car!). White dwarf cools off from initial formation temperature of about 100,000 K. Form as outer layers of red giant star puff out to make planetary nebula. ======
 * //Neutron Stars//--1.4 < core mass < 3 solar masses. Compression so great that protons fuse with electrons to form neutrons. Neutrons are degenerate. About 30 km across! Density [[image:http://www.maa.mhn.de/Symb/p2x10t14.gif align="bottom"]] g/cm[[image:http://www.maa.mhn.de/Symb/3.gif align="top"]] (one sugarcube =mass of humanity!). Formed in supernova explosion.======[|Index]
 * //Pulsars//--rapidly rotating neutron stars with STRONG magnetic fields ([[image:http://www.maa.mhn.de/Symb/10t9-10t12.gif align="bottom"]] times Sun's). Light flashes with period of milliseconds at start and lengthening to periods of about 4 minutes over time. Why would neutron stars be fast rotators? Conservation of angular momentum (remember spinning ice skater)! Slowly rotating Red Giant star has same angular momentum as tiny, fast rotating neutron star. Rotating neutron star only thing that could create that frequency of pulses. //Lighthouse model//-strong magnetic field creates electric field making charged particles (mostly electrons) flow out of the magnetic poles. As the charged particles spiral around the magnetic field lines, they produce a **non**-thermal radiation (synchrotron) beam at the magnetic poles. If the beam sweeps past Earth, we see a flash of light.
 * 1) Radiation production robs energy from pulsar so pulsar rotation slows down (angular momentum does **slowly** decrease).
 * 2) Every now and then, neutron star suddenly shrinks by about 1 mm. Spin rate suddenly increases to conserve angular momentum. See glitch in pulse rate.======[|Index]
 * //Black Holes//--core mass > 3 solar masses. Gravity finally wins, compressing core to mathematical point at center. Formed in supernova explosion. Surface gravity so strong that nothing can escape (not even light!) within a certain distance from mass point. Boundary is called the //event horizon// (or //Schwarzchild radius//)-no messages of events happening within radius (= 3 * core mass [in solar masses] km) make it to the outside. Use Einstein's General Relativity to describe gravitational effects. Gravitational Redshift & Time Dilation. Signatures of a black hole:
 * 1) For binary, look at how the black hole moves visible companion around. Use Kepler's 3rd law to find sum of masses. Guess mass of visible companion then find unseen companion's (black hole's) mass.
 * 2) For binary, look for X-rays produced in hot //accretion disk//--material pulled off visible companion spirals onto black hole. Disk formed. Friction increases inward causing increasing temperature as approach the event horizon-produce wide spectrum of radiation. To make rapidly varying X-rays, unseen companion must be **small!**