This is a mosaic image, one of the largest ever taken by
NASA's Hubble Space Telescope of the Crab Nebula, a
six-light-year-wide expanding remnant of a star's
supernova explosion. Japanese and Chinese astronomers
recorded this violent event nearly 1,000 years ago in
1054, as did, almost certainly, Native Americans. The
orange filaments are the tattered remains of the star and
consist mostly of hydrogen. The rapidly spinning neutron
star embedded in the center of the nebula is the dynamo
powering the nebula's eerie interior bluish glow. The blue
light comes from electrons
Chandra, Hubble, and Spitzer image NGC 1952
A star's spectacular death in the constellation Taurus was
observed on Earth as the supernova of 1054 A.D. Now,
almost a thousand years later, a super dense object --
called a neutron star-- left behind by the explosion is
seen spewing out a blizzard of high-energy particles into
the expanding debris field known as the Crab Nebula. X-ray
data from Chandra provide significant clues to the
workings of this mighty cosmic "generator," which is
producing energy at the rate of 100,000 suns. This
composite image uses data from three of NASA's Great
Observatories. The Chandra X-ray image is shown in blue,
the Hubble Space Telescope optical image is in red and
yellow, and the Spitzer Space Telescope's infrared image
is in purple.
The X-ray image is smaller than the others because
extremely energetic electrons emitting X-rays radiate away
their energy more quickly than the lower-energy electrons
emitting optical and infrared light. Along with many other
telescopes, Chandra has repeatedly observed the Crab
Nebula over the course of the mission's lifetime. The Crab
Nebula is one of the most studied objects in the sky,
truly making it a cosmic icon.
Solar Nucleosynthesis -- proton-proton chain
pp p + p --> H2 + e+ + v_e 100 q < 0.420 MeV
pep p + e- + p --> H2 + v_e 0.4 q = 1.442 MeV
hep He3 + p --> He4 + v_e 0.00002 q < 18.773 MeV
Be7 Be7 + e- --> Li7 + v_e 15 q = 0.862 MeV 89.7%, q = 0.384 MeV 10.3%
B8 B8 --> Be7 + e+ + v_e 0.02 q < 15 MeV
Relevant papers by John N. Bahcall, Sarbani Basu, M. H. Pinsonneault:
http://xxx.lanl.gov/abs/astro-ph/9805135
http://pdg.lbl.gov/1998/solarnu_s005313.pdf
http://www.slac.stanford.edu/pubs/beamline/24/3/24-3-bahcall.pdf
Wikipedia | Main sequence
https://en.wikipedia.org/wiki/Main_sequence
Wikipedia | Stellar evolution
https://en.wikipedia.org/wiki/Stellar_evolution
There are four (4) fates for the end of stars depending on
their masses and the masses of their cores:
Brown Dwarfs--less than 0.6 Ms (Main Sequence .076-0.8 Ms)
Stars less than about 0.6 solar masses, when nuclear fuel
is used up, gravitational collapse shrinks the star, but
no more than the gas temperature-pressure-volume laws of
classical physics allow. We have not found any white dwarf
less massive than 0.6 solar masses. Part of the answer is
that the universe may not be old enough for lower mass
stars to have evolved off the main sequence.
White Dwarfs--0.08 and 1.44 Ms (Main Sequence 0.8-8 Ms)
Stars with core masses between 0.08 and 1.44 solar masses
are destined to become white dwarfs. White dwarfs are
degenerate matter. Further collapse is halted by electron
degeneracy pressure. See pages 456-459 in your textbook.
The vast majority of stars are in this mass range and are
destined to become white dwarfs
Neutron Stars--1.44 and 2.9 Ms (Main Sequence 8-30 Ms)
Core masses between 1.44 and 2.9 solar masses overcome
electron degeneracy pressure and collapse to form neutron
stars, a star that is essentially one gigantic nucleus.
Further collapse is halted by neutron degeneracy
pressure.
Black Holes--3 or more Ms (Main Sequence > 30 Ms)
But for cores with mass of 3 or more solar masses, neutron
degeneracy pressure does not stop the collapse and the
star becomes a black hole with zero physical size, but
with all the mass. Gravity really wins!
In each case, gravity eventually wins, but, to what extent
is determined by the mass and the relative pressures of
the quantum mechanical forces, electron and neutron
degeneracy pressure.
Hubblecast | The Death of Stars (6 min)
http://www.youtube.com/watch?v=zeGxJT2_A0I
Astronomy Picture of the Day Archive
http://apod.nasa.gov/apod/archivepix.html
sam.wormley@gmail.com