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Transcript of Stars
Hot = Blue (30,000K+)
Medium = Yellow(5,000-6,000K)
Cool = Red(3,000 K)
Brightness standardized for distance
Brightness as if all stars were viewed from 32.6 light years away.
Brightness as it appears from earth
Affected by distance, size, and temperature of stars.
Car headlights on a highway look small, like a VW bug.
(This is apparent magnitude.)
As they get closer they look bigger, until you realize
it is really a semi-truck.(This is absolute magnitude.)
Organizes stars by
Temperature (Color) & Absolute Magnitude
Temperature & Color
Hurtzprung Russel Diagram (HR)
cloud of dust & gases
large with lots of mass
Very spread out, may contain lots of matter/mass!
Remember, Mass = Gravity
If there is enough gravity, then matter will contract and the star story begins.
L-R = Eagle nebula, Carina nebula, Hubble image, lagoon nebula
Mass in the nebula condenses
Gravitational energy is converted into heat energy.
Lasts about a million years
Gravity generates heat(10 million K)
Hydrogen + Hydrogen = Helium(over simplified!)
gravitational pressure inward and
outward pressure due to nuclear reaction
stage that a star will spend most of its time
Hotter/Brighter = shorter life
Cooler/dimmer = longer life
our sun = goldilocks
Balance between pressure and gravity is off.
Gravity is winning.
Outer layer expands while core contracts.
Easy fuel is gone. Star begins using much larger atoms for fusion.
Called "falling off" of the main sequence.
Medium Mass(sun sized)
Massive stars(3X sun)
Medium Mass stars (sun sized) become Red Giants
Massive Stars become Red Super Giants (3X mass of sun)
Primary fuel for nuclear fusion is Helium to Carbon(Red giants), and Carbon to Iron(Red super giants)
Core contracts and outer layers cool(RED COLOR).
Artist rendition of red super giant light echos.
Outer layers drift away from core.
Nuclear fusion continues to slow
Nuclear fusion stops
Only energy given off is heat
Like a stove that has just been turned off. It's still HOT!
Core is now the size of the Earth. (used to be 1 million times the volume of Earth!)
How does a white dwarf compare to our sun?
All leftover heat is gone
Carbon + pressure = Diamonds?
Stove is cold
core contracts violently
creates an implosion
this is quickly followed by an explosion getting rid of the outer layers.
smaller & more massive than White dwarves
so much gravity that electrons combine with protons to make neutrons.
Sample size of a pea = 100 million tons
strong magnetic fields + rapid rotation = Pulsars
Smaller and more massive than Neutron Stars
Therefore, have much more GRAVITY
Centered on a point, so much that nothing can escape.
Thought to give off energy (X-rays) as matter is “eaten”.
Above =artist rendition
Right = Crab nebula,
left over supernova with
Hubble image of ancient Milky Way white dwarves.
(Ans: Our sun is
larger and cooler.)
Massive (3X mass of
Primary distance = light year
9.5 X 10E12 km (9.5 trillion km)
Definition = the distance light travels in one year.
Fun fact: Position of close stars is determined by parallax. Geometry! Want to be an astronomer? Study MATH!
Fun fact: Mass determined by using binary stars.
First one found? http://news.nationalgeographic.com/news/2011/08/110825-new-planet-diamond-pulsar-dwarf-star-space-science/#.TlhqI2gASil.email
Red Giant(4a) or Red Super Giant
FUSION DEF: small nuclei combine to form larger nucleii.