Astronomy 2022 November 14-16

cores left behind after stars less than 10M lose their envelopes as planetary nebulae. As they cool, supported against gravitational collapse by electron degeneracy pressure. Can’t exceed 1.44 M

stars between .5-8 M produce these, our sun will become one with a mass of .55 M

stars between 8-10 M produce these, Sirius B is the first of these discovered with radius 5.8k Km, 1 M

hydrogen shell, helium shell, carbon/oxygen core. Residual heat 200-300 million K. No fusion, KH heating. Will fade as they cool

can’t exceed mass of 1.44 M. If a white dwarf exceeds this, electron degeneracy pressure can’t prevent core collapse.

no spectral hydrogen or helium lines, strong silicon lines. Created when white dwarf exceeds chandrasekhar’s limit and the core collapses, carbon oxygen fusion kicks in, leads to more fusion and greater heat and carbon detonation

high mass= upper main sequence. 10.25 M= Fe core/supernova/neutron star. 25+ M= Fe core/supernova/stellar black hole

inert Fe core, mass 1.2-1.4 M, size of Earth. Onion skin fusion shells. Envelope extends 5 AUs

violent explosion of a high mass star. Without energy source, Fe core starts to collapse. Reaches a temperature of 10 billion K and density of 10^10 gm/cm^3. Triggers energy consuming processes. Core is becoming a neutron star

energy consuming process. Heavy elements (Fe, Ni) disintegrate back into HE nuclei, protons combine with electrons forming neutrons

energy consuming process, massive amounts of neutrinos are created and carry energy away

core collapses from diameter of earth to diameter 10 miles, core is now a neutron star, continues to collapse until reaching density of 2.4 x 10^14 g/cm^3. Strong nuclear force takes over and stops collapse, along with neutron degeneracy pressure. Triggers core bounce, releases neutrinos

envelope starts falling in at .25c, collides with shockwave from core at .5c. Area where they meet accelerated by heat and neutrinos at .1c. Within a few hours reaches surface, rips envelope apart

elements all the way up through Fe and Ni created in cores of high mass stars. Results made as shockwaves move through expanding supernova. Elements released into galaxies as ISM, forms GMCs, form protostars

remnant cores of massive stars 10-25 M. No fusion or gravitational contraction, shines by residual heat. 1.5-2 M, 10 mile radius, escape velocity .07 C. Density 100 million grams/cm^3

outer core ions and electrons. Inner crust electrons, neutrons, nuclei. Outer core neutron proton fermi liquid and gas. Inner core quark gluon plasma

rapidly spinning magnetized neutron stars, discovered 1967 by Jocelyn Bell. Discovered pulsating radio source and named it LGM 1

spinning magnetic field generates electric field. Accelerates electrons with emit polar jets along magnetic poles

young neutron stars fast spinning and found in supernova remnants, pulsar rates slow. Old neutron stars cold and hard to find

Stars between .5-10 M become white dwarfs, collapse of their cores stopped by electron degeneracy pressure
Stars between 10-25 M become neutron stars, collapse stopped by neutron degeneracy pressure
Stars greater than 25 M become black holes, nothing can stop collapse of core

black hole formed by the gravitational collapse of an individual star

black hole thousand to tens of thousands mass

black hole with the mass of millions or billions, mostly found in center of galaxies. Biggest galaxies have the biggest, smallest have smallest. Tied to galaxy formation, formed as IMBH merge

so strong the escape velocity exceeds the speed of light, in-falling matter is vertically stretched and squeezed to infinite density (spaghettification)

ntire mass of a black hole is concentrated in an infinite density, zero volume singularity
Radius of the event horizon Schwarzschild radius
Accretion disc composed of matter falling into the gravity well of the BH and radiating energy as x-rays
Singularity is surrounded by event horizon where he escape velocity equals the speed of light

objects with infinite density and zero volume. A place in which the fiery marriage of Einstein’s relativistic laws with the quantum laws is consummated. The fruit of that marriage, the laws of quantum gravity, come into full blossom in singularities

Einstein’s gravity. Matter tells spacetime how to curve/changes the shape, and spacetime tells matter how to move and gives a path for light and time. Time slows as gravity gets stronger, so clocks approaching singularity of a black hole will run more slowly. At event horizon all time stops

states at an altitude of 20k km, where we position GPS satellites, atomic clock runs 45 milliseconds faster each day than they do on earth, gravity affects time

states at a speed of 14k km/h, speed of our GPS satellites, atomic clocks run 7 microseconds slower each day than Earth. Speed affects time

newton’s formulation of Kepler’s 3rd law M1+M2=a^3/p^2

estimated 1 billion stellar mass black holes in our galaxy (first Cygnus, closest Unicorn). Look for x ray sources, superheated gases pulled into black hole. Also look for stars orbiting a massive unseen object (bigger than 3 M), and affect of gravity on surroundings

x rays binaries, bright x ray sources identified by x ray observatory satellites

galaxy’s gravity acts as a lens and bends and brightens light from quasar behind it

Far away from a black hole: if your distance is more than 3 R, gravity is the same as that of a star of the same mass
Close to a black hole: if your distance is less than 3 R, no stable orbits, all matter eventually gets pulled in

time appears to slow and eventually stop as you approach the event horizon (as seen by distant observer). Time flows as always for in-falling. Light emerging from black hole gravitationally shifted to longer wavelengths

black holes are not totally black, evaporate slowly by emitting subatomic particles and photons. 3 M black hole requires 10^63 years to completel evaporate

geometric shortcut/Einstein-Rosen bridge. Bridge to white hole. Crossable in both directions, stable, size, time required, strength of gravitational field

intermediate mass black holes thought to form when multiple stellar mass black holes go through a series of mergers

about 1% of all active galaxies have these, powered by supermassive black holes (10^6-10^10). Appear as bright point source 20 AU, sometimes brighter than entire galaxy. Spectrum of hydrogen for 3C273, massive red shift, moving incredibly fast and incredibly far

type of active galaxy, stellar radio source. Highest levels of x-ray emissions. Brightest objects in universe. Polar jet radio source, accretion disk x ray source, polar jet radio source (anatomy). 3C 273 example

type of active galaxy, high levels of UV emissions

type of active galaxy, high levels of radio emissions.