Stars ppt

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Stars:

Stars NATIONAL CAPITAL REGION INDIVIDUAL TEACHERS OUTPUT Project 6 Elementary School

What is a star? :

What is a star? A star is a sphere of gas held together by its own gravity .

What are Stars? :

What are Stars? Stars are hot bodies of glowing gas that start their life in Nebulae. They vary in size, mass and temperature, diameters ranging from 450x smaller to over 1000x larger than that of the Sun. Masses range from a twentieth to over 50 solar masses and surface temperature can range from 3,000 degrees Celsius to over 50,000 degrees Celsius.

The Sun as seen in X-rays(from the Yohkoh satellite) :

The Sun as seen in X-rays(from the Yohkoh satellite)

The color of a star is determined by its temperature, the hottest stars are blue and the coolest stars are red. :

The color of a star is determined by its temperature, the hottest stars are blue and the coolest stars are red.

The Sun has a surface temperature of 5,500 degrees Celsius, its color appears yellow.:

The Sun has a surface temperature of 5,500 degrees Celsius, its color appears yellow.

The Sun's Outer Layers:

The Sun's Outer Layers Only the Sun's outer layers, collectively referred to as the solar 'atmosphere', can be observed directly. The distinct regions to the solar atmosphere are as follows: the photosphere, the chromosphere , and the corona . The three regions have substantially different properties from each other, with regions of gradual transition between them.

Slide 8:

There is not really a "surface" to the Sun. The Sun is a bunch of gas which gets denser and denser as you move from space toward the solar core. The photosphere would then represent the depth at which we can see no deeper toward the core. Think of what a thick cloud looks like when you look down on it from an airplane - it looks solid, but it isn't.

Life Cycle of a Star:

Life Cycle of a Star Small Stars- The Life of a Star of about one Solar Mass. Small stars have a mass up to one and a half times that of the Sun. Stage 1- Stars are born in a region of high density Nebula, and condenses into a huge globule of gas and dust and contracts under its own gravity.

Stage 2 -:

Stage 2 - A region of condensing matter will begin to heat up and start to glow forming Protostars . If a protostar contains enough matter the central temperature reaches 15 million degrees centigrade.

Stage 3 -:

Stage 3 - At this temperature, nuclear reactions in which hydrogen fuses to form helium can start.

Stage 4 -:

Stage 4 - The star begins to release energy, stopping it from contracting even more and causes it to shine.

Stage 5 -:

Stage 5 - A star of one solar mass remains in main sequence for about 10 billion years, until all of the hydrogen has fused to form helium.

Stage 6 -:

Stage 6 - The helium core now starts to contract further and reactions begin to occur in a shell around the core.

Stage 7 -:

Stage 7 - The core is hot enough for the helium to fuse to form carbon. The outer layers begin to expand, cool and shine less brightly. The expanding star is now called a Red Giant.

Stage 8 -:

Stage 8 - The helium core runs out, and the outer layers drift of away from the core as a gaseous shell, this gas that surrounds the core is called a Planetary Nebula.

Stage 9 -:

Stage 9 - The remaining core ( thats 80% of the original star) is now in its final stages. The core becomes a White Dwarf the star eventually cools and dims. When it stops shining, the now dead star is called a Black Dwarf.

The set of images below shows the star going into a stage called Supernova and contracting to become a neutron star:

The set of images below shows the star going into a stage called Supernova and contracting to become a neutron star

Vocabulary:

Vocabulary Protostar An early stage in the evolution of a star, after the beginning of the collapse of the gas cloud from which it is formed, but before sufficient contraction has occurred to permit initiation of nuclear reactions at its core. Context : The material in the center of the nebula forms a clump, called a protostar .

White dwarf :

White dwarf A star, approximately the size of the earth, that has undergone gravitational collapse and is in the final stage of evolution for low-mass stars, beginning hot and white and ending cold and dark Context: Similar to the neutron star, the medium-sized star will dim and shrink, becoming a white dwarf.

The core becomes a White Dwarf the star eventually cools and dims. When it stops shining, the now dead star is called a Black Dwarf. :

The core becomes a White Dwarf the star eventually cools and dims. When it stops shining, the now dead star is called a Black Dwarf.

Nebula :

Nebula A cloud of interstellar gas and dust . Context: A star forms from a cloud of dust and gas known as a nebula.

neutron star:

neutron star Extremely dense, compact star composed primarily of neutrons, formed from the collapsed core of a supernova. Context: Neutron stars may be only 20 km in diameter, but they have a mass equal to about one-and-a-half times the mass of the sun.

Red giant STAR:

Red giant STAR A n intermediate stage of a star's evolution during which the hydrogen fuel supply begins to run out the star's core contracts; the outer shell begins to expand and, because it is also cooling, glows red Context: The sun will become a red giant in about five billion years.

Supernova:

Supernova The final explosion of a large star, caused by the gravitational collapse of the core, during which the star's luminosity increases by as much as 20 magnitudes and most of the star's mass is blown away at very high velocity, sometimes leaving behind an extremely dense core Context: Supernovas burn so brightly they can be seen up to 10 billion light years away.

THANK YOU!!!:

THANK YOU!!!

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