Transcript The Universe: Galaxies, Stars, and Nebulae

The Universe: Galaxies,
Stars, and Nebulae
March 3, 2011
The Universe
 All
physical matter and energy that
exist in space:
 Planets
 Stars
 Galaxies
 All the contents of intergalatic
space
A Planet
 Most
scientist agree that a planet:
a star – such as the Sun
 Is round - due to the strength of its
own gravitational pull
 Orbits
Galaxies
single stars – includes:
Stars, Gas, and Dust
Variety of shapes, sizes, and
colors
Clustered in Groups
Gravitationally attracted/held
together
 NOT
Galaxies
Milky
Way = part of Local
Group
5 million light years across
In 1999 HST
est. 125 billion galaxies;
HST found 3,000 visible
galaxies in space
(Hubble Space Telescope)
Galaxies
Spiral = Milky Way
 Stars
form “arms”,
curve out from
center, disk or
pancake shaped
 Holds old & young
stars, gas, & dust
http://www.hdwallpapers.com/photo/Space_pictures/Spiral_Galaxy_M81
Galaxies
Elliptical
 Stars
form
shape like a
football
http://www.astronet.ru/db/xware/msg/1226180
Galaxies
Irregular
 No special
shape = blobs
w/threads
 Holds large
amount of
gas and dust
http://apod.nasa.gov/apod/ap081229.html
Stars
Large ball of gas that
creates & emits its
own radiation

Variety of shapes,
sizes, and colors
 Nebula, Main
Sequence, Red &
Super Giants,
White Dwarf,
Brown Dwarf, &
Supernova

UM = Magnitude =
degree of brightness
Lifecycle – NO
star lives forever
 Born,
Matures,
Grows old, &
Dies
Nebula – dense region
inside begins to
shrink, warm up,
becomes a protostar
http://www.calvin.edu/academic/phys/observatory/images/Astr110.Fall2006/deLa
nge.html
A Star is born

Protostar – critical
temperature is
reached – hydrogen
begins fusing into
helium
http://photojournal.jpl.nasa.gov/
Once a star is born it becomes a

Main Sequence Star
– shines as nuclear
reactions inside
produce light and
heat
http://www.for68.com/new/2005/12/su86402129331912150024200-0.htm

But if it doesn’t have
enough mass to
produce radiant heat
it becomes a Brown
Dwarf
http://dsc.discovery.com/news/2009/04/20/brown-dwarf-cool.html
At this point Stars can become a Super
Giant or Red Giant
Super Giant

Star of greater mass
Expands, cools, &
turns red
http://apod.nasa.gov/apod/ap001222.html
Super Giant EXPLODES
blasting away outer
layers becoming a
Super Nova
http://news.discovery.com/space/beautiful-supernova-violence.html
Supernova can become either:
Neutron Star –
core collapses &
becomes very dense
http://www.science.psu.edu/news-and-events/2007-news/Fox8-2007.htm
Black Hole – core
collapses
completely &
vanishes
http://www.nasa.gov/mission_pages/chandra/multimedia/photo09-078.html
If a Star becomes a Red Giant, then
Red Giant – star
of less mass
expands, glows red
as it cools, then
http://smithsonianscience.org/2010/03/archaeological-%E2%80%9Cdig%E2%80%9D-in-outerspace-uncovers-an-ancient-star/
Planetary Nebula
– outer layer of gas
puff off; hot core will
be white dwarf
http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-astro-nebula.html
Red Giant =Planetary Nebula = White
Dwarf = White Dwarf Cooling
White Dwarf –
very dense, almost
transparent
http://www.jpl.nasa.gov/news/features.cfm?feature=576
White Dwarf
Cooling – takes
billions of years to
cool then fades to
black
http://imagine.gsfc.nasa.gov/docs/science/know_l1/dwarfs.html
Cooling White Dwarf = Black Dwarf
Black Dwarf - A
non-radiating ball
of gas; star stops
glowing
http://news.discovery.com/space/intermediate-black-hole-implicated-in-stars-death.html