Astronomy D8

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    Its cold outside, so lets warmIts cold outside, so lets warm--up!!up!!

    What is the difference between the

    apparentmagnitude and theabsolute magnitude of a star??

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    How stars SHINE!!!!!How stars SHINE!!!!!

    Please put your warm-up away

    and get out your note sheet!

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    How starsHow stars FORMFORM

    Nebula-

    A large cloud in space

    containing dust,

    hydrogen gas, helium

    gas and plasma.

    *Stars are formed in

    nebulae

    The space between

    stars is called

    interstellar space andit contains mostly gas

    and dust. Its density is

    extremely low-

    approximately 1 atom

    per cc.

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    Components of NebulaeComponents of Nebulae The dust in a Nebula is not

    like house dust, its made

    up of much smallerparticles that typically

    includes carbon and

    silicate molecules

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    These beautiful regions of nebula, the

    formation of gas, dust and other materials

    clump together to form larger masses

    which attract more matter and eventuallyget big enough to form a star.

    Here are some examples

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    This picture wasThis picture was

    taken from thetaken from theHubble Telescope,Hubble Telescope,

    its called NGCits called NGC--

    604 and is located604 and is located

    in a neighbor spiralin a neighbor spiral

    galaxy of ours, 2.7galaxy of ours, 2.7million light yearsmillion light years

    away from us.away from us.

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    These are the starThese are the star

    forming Pillars offorming Pillars ofCreation spottedCreation spotted

    by theHubbleby theHubble

    Telescope.Telescope.

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    Many Nebula form from the gravitationalcollapse of gas in the interstellar medium

    (ISM).

    As the material collapses under its own

    weight, stars may form in the center.

    Here are some examples

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    This is the RosettaThis is the Rosetta

    Nebula in theNebula in the

    Monoceros regionMonoceros regionof our galaxyof our galaxy-- thethe

    Milky way!Milky way!

    It is 5,200 light yearsIt is 5,200 light years

    from Earth.from Earth.

    It is roughly 130 ly inIt is roughly 130 ly in

    diameter.diameter.

    Its mass = 10,000Its mass = 10,000solar masses!solar masses!

    Wow!Wow!

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    This is the FlameThis is the Flame

    Nebula located inNebula located in

    the constellation ofthe constellation ofOrion.Orion.

    The heart of theThe heart of the

    nebula is usuallynebula is usually

    hidden by the dusthidden by the dustbut this image wasbut this image was

    taken in IR light andtaken in IR light and

    its beauty wasits beauty was

    exposed!exposed!

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    Some nebula are the result of supernovaexplosions (the death of short lived

    massive stars.)

    Example

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    This is theCrab Nebula in theConstellation of Taurus. ThisThis is theCrab Nebula in theConstellation of Taurus. This

    Nebula is actually visible with the naked eye on a clear night.Nebula is actually visible with the naked eye on a clear night.

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    Some Nebula are called Dark Nebula

    and seem to be the creepers of the bunch

    (if you ask me), they tend to look a little

    more scary.

    Such as..

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    This is a dark nebula called HorseHeadThis is a dark nebula called HorseHead

    Its so dense that it obscures light from behind it.Its so dense that it obscures light from behind it.

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    And our last beauty for the day: Planetary Nebula- These are the gaseous

    shells that are ejected as giant stars

    transform into white dwarfs.

    Example

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    This is called the Helix Nebula (Planetary Nebula)

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    This is the Eskimo Nebula (planetary Nebula)

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    Cat EyeCat Eye

    NebulaNebula

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    The Life of a StarThe Life of a Star

    1. Protostar- born in a

    nebula, gases come

    together and begin

    nuclear fusion.2. Star- the phase where

    the star burns fuel. The

    more massive the star,

    the shorter its lifespan!

    3. Red giant/supergiant-

    when stars run out of

    fuel, the outside

    expands and the insidecontracts.

    4. White Dwarf-One

    possible outcome. The

    remainder of a star,

    after the outer layerexpands away.

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    5. Super Nova- If a star

    doesnt become a white

    dwarf, it will supernova

    (aka- explode!)6. Neutron Star- Whats

    left after a supernova

    (suuuuper dense core)

    7. Black Hole- The most

    massive pre-supernova

    stars may become

    black holes after theysupernova. The density

    reaches extreme highs

    and pulls everything

    inward to the point

    where light cannoteven escape!

    The Life of a StarThe Life of a Star

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    How do stars produce light??How do stars produce light??

    Stars emit TONS of energy!!

    We can see some of it in the form of visiblelight.

    When the temperature of a protostar (star

    beginning to form) gets hot enough NuclearFUSIONoccurs.

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    How do stars produce light??How do stars produce light??

    Stars produce light by Nuclear FUSION.

    This is when two atomic nuclei combine to

    form a larger nucleus with a higher mass.

    (ex: hydrogen becomes helium)

    These guys can explain it better than me

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    What about Nuclear Fusion as anWhat about Nuclear Fusion as an

    alternative source of power?alternative source of power?

    Lets see what these guys have to say

    about it