By besas jemarie d espuerta ma frechilyn joy c september 3 2012
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By : Besas , Jemarie D . Espuerta . Ma.Frechilyn Joy C. September 3, 2012 . STARS. WHAT IS A STAR?. A huge ball of ionized gas

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By besas jemarie d espuerta ma frechilyn joy c september 3 2012

By: Besas, Jemarie D.

Espuerta. Ma.Frechilyn Joy C.

September 3, 2012

STARS


What is a star
WHAT IS A STAR?


Stars

  • A huge ball of ionized gas

  • A body that at some time in its life generates its lights and heat by nuclear reactions, specifically by the fusion of hydrogen into helium under conditions of enormous temperature and density.


What are constellations
WHAT ARE CONSTELLATIONS?

  • names for groups of stars that appear to form shapes in the sky. They were given their names many hundreds of years ago to help us remember which stars are which. We used constellations to divide up the sky: finding one can help us find another because constellations



Stellar properties
STELLAR PROPERTIES found in about the same place.

A. TEMPERATURE

Wien’s Law : “The hotter the star is, the shorter the wavelengths it emits.”

Thus, HOT STARS will appear BLUE and WHITE while COOL STARS will be RED.


Stars

B. LUMINOSITY found in about the same place.

- the amount of energy a body radiates each second.

Inverse Square Law for Luminosity:

“ As light spreads out from a source, it spreads over progressively larger areas as the distance from the source increases.”


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  • Absolute Magnitude found in about the same place.is the star’s actual brightness.

  • Apparent Magnitude is how bright stars appears on Earth.

  • The higher the number, the dimmer is the star.


Stars

C. RADIUS found in about the same place.

Stefan Boltzmann Law: “ The luminosity of an object depends on its temperature.”

Thus, an increasing temperature or radius of a star makes it more luminous.


Stars

D. COMPOSITION found in about the same place.

“ The spectrum of a star is the amount of energy it emits at each wavelength. As light moves from its core to its surface layers, atoms absorb the radiation at some wavelength, creating dark absorption line that tells the composition of the stars.”


Stars

E. SPECTRAL CLASS found in about the same place.

O, B, A, F, G, K, M,

where O is the hottest and Mis the coolest


Evolution of stars
EVOLUTION OF STARS found in about the same place.

  • Stars come from interstellar gases drawn together by gravity which compresses and heats the gas forming a protostar.

  • Further heating of the protostar’s core will lead to the fusion of hydrogen into helium accompanied by a tremendous


Stars

release of energy. This release of energy keeps the stars hot.

  • It creates pressure that balances and stops the gravitational pull, changing protostar into a Main Sequence Star.

  • The amount of interstellar gas determines the size of the star, larger


Stars

amount of interstellar gas, the larger is the star. Yet, the bigger the star, the shorter is its life span.

  • As soon as the hydrogen in the core of a massive stars is exhausted, the core shrinks and heats up, turning the star into a giant.


Stars


Stars

dense star, a but eventually compresses the helium in the core to start another nuclear fusion, turning it into a white dwarf.

  • Giant stars have more dramatic end. Because of the tremendous heating from gravitational compression of their cores, they can ignite fuels in their core easily, forming other elements such as


Stars

carbon, neon, silicon and eventually iron. Since the iron core cannot burn and will collapse, it triggers a supernova explosion. shrinks again, turning it into a red giant once more. The outer layer is then driven off a planetary nebula shell. The core


Stars

The core produces a core cannot burn and will collapse, it triggers a supernova explosion. shrinks again, turning it into a neutronstar, or in the case of a super giant which continues to collapse, a BLACK HOLE


Black holes
BLACK HOLES core cannot burn and will collapse, it triggers a supernova explosion. shrinks again, turning it into a

  • The intense gravitational field left when a giant star collapses.

  • It is called a black hole because not even light can escape.


Stars

THANK YOU core cannot burn and will collapse, it triggers a supernova explosion. shrinks again, turning it into a 