The Death of a Star

The Death of a Star
The White Dwarf
Origin: Most white dwarfs
are the former cores of AGB
stars.
The amount of mass blown
off by the solar wind is the
determining factor in
whether or not the core will
become a white dwarf.
This is called the
Chandrasekhar limit. A core
must have a mass of less
than 1.4 solar masses to
become a white dwarf.
The white dwarf is a star
that has run out of
nuclear fuel. It is mostly
made up of carbon with
a small percentage of
oxygen.
They are about the size
of the Earth
The white dwarf will
spend the rest of its days
radiating the last of its
heat into space until it is
undetectable.
Unless ………………….
Type I Supernova
This is the only hope for the
white dwarf’s continued
existence.
If it was born into a binary star
system, the white dwarf can
take mass from it’s neighbor
until its core exceeds the
Chandrasekhar limit.
Animation
In Leo
This explosion happens very quickly….
The amount of energy released in 1 second is the same as the total
amount of energy released during the main sequence phase of the
star’s life.
They are bright enough to outshine the galaxies they are apart of.
Supernova 1987A
•
The closest supernova in the last four
centuries was seen in 1987
Type II Supernova
Type II Supernovas
result from stars whose
dying cores were
bigger than 1.4 solar
masses.
What happens in the Core
Its all about the nuclear
reactions
Hydrogen—tens of
billions of years
Helium—one million
years
Carbon—a few centuries
Oxygen—months
Silicon into iron—days
Neutronization of Iron
Crab Supernova
Supernova
Neutron Star
The new iron core of the star is
under so much pressure at this time
that fusion is no longer possible.
This incredible amount of pressure
is enough to force the electrons to
react with the protons turning
them all into neutrons.
Without the outward resistance of
the electrons the core collapses to
about 50 km in radius.
The amount of energy released is
equal to the Sun’s luminosity for
ten’s of billions of years.
The remaining outer layers are
blown away by the explosion.
The leftover is a neutron star.
Discovery of the
Neutron Star
Pulsar at center of
Crab Nebula
pulses 30 times
per second
Search for radio
waves
Black Holes
Black Holes are created by a collapsing core that is too massive to
become a neutron star. (3+ solar masses – Neutron limit)
The force of gravity in a black hole is so strong that not even light
can escape its gravitational field.
The only way we can detect them are their gravitational influences
on objects around them
Inside the Black Hole
Click me
If our sun were to be
replaced by a black hole
of equal mass, nothing
would change for us
except for problem of
having no light or heat.
•The disk surrounding a black
hole is called the event
horizon.
•Think of it like a drain, once
inside the drain there is no
escape.
•Time moves slower the
closer you are to inner edge
of the event horizon (click me)
Our Own Little Black Hole
We believe that the center of our galaxy is a
super massive black hole
The Core of the Milky Way
Orbits of stars at
center of the Milky
Way indicate a black
hole with mass of 4
million MSun
Black Hole
References
http://cc.ysu.edu/physics-astro/crab.jpg
http://space.newscientist.com/data/images/ns/cms/dn8460/dn8460-1_600.jpg
http://apod.nasa.gov/apod/image/0009/whitedwarf_hst.jpg
http://www.galaxyphoto.com/high_res/hst_panetary.jpg
http://www.sciencedaily.com/images/2007/10/071023164005.jpg
http://img.qj.net/uploads/articles_module/63904/supernova.jpg
http://constellationx.nasa.gov/images/resources/brochures/may04/life_cycles/pic4_grand_canyon_lg.jpg
http://www.esa.int/images/400_black_hole.jpg
http://www.scienceclarified.com/images/uesc_09_img0541.jpg
http://upload.wikimedia.org/wikipedia/commons/thumb/5/50/HST_SN_1987A_20th_anniversary.jpg/320pxHST_SN_1987A_20th_anniversary.jpg
http://www.astro.ku.dk/dark/pr/images/supernova.jpg
http://www.jyi.org/articleimages/960/originals/img0.jpg
http://space.newscientist.com/data/images/ns/cms/dn8368/dn8368-1_579.jpg
rst.gsfc.nasa.gov/Sect20/A6.html
http://chandra.harvard.edu/photo/2006/n49/n49_opt.jpg
http://a52.g.akamaitech.net/f/52/827/1d/www.space.com/images/070820_neutron_star_02.jpg
http://www.cartoonstock.com/newscartoons/cartoonists/rbr/lowres/rbrn4l.jpg
http://www.roe.ac.uk/~pnb/images/Black-hole.jpg