THE UNIVERSE

1- DEFINITION

The universe is The sum of all that exist, this includes the time, the space, the matter and the energy.

2- HISTORY OF OUR VISION OF THE UNIVERSE

2.1 1st Hypothesis. the universe is formed just by “The Milky Way”.

The geocentric model: Aristotle established that the Earth was located in the centre of the universe and everything revolve around the Earth

The heliocentric model: Copernicus said that the sun was located in the centre of the Universe and everything revolve around the sun.

2.2 the discovery the Andromeda Galaxy

Hubble found this Galaxy using the greast Hooker Telescope. Thanks to this discovery was probed that the universe isn’t formed just for our Galaxy.

2.3- The Big Bang theory

In 1929 Hubble discovered that the galaxies move. Thanks to this phenomenon Hubble realized that the universe is in expansion, in the past it was smaller and compacted.

The expansion not only affect to the matter it also affect to the radiation.

After the Big Bang the universe was very hot, it was formed by a plasma of protons and electrons particles. Light interacted with this plasma. Nuclear reactions were produce and atomic nuclei were formed.

As the atomic nuclei were formed light didn’t interacted with them.

Materia oscura

El universo empezó a expandirse tras el Big Bang. La gravedad es la única fuerza que actúa y provoca

que los cuerpos se atraigan. Los astrónomos piensan que a causa de la gravedad

(si es muy fuerte) la expansión frenara, pero si la fuerza de la gravedad es débil el universo seguirá expandiéndose.

La gravedad esta relacionada con la densidad y esta se puede medir de varias formas: medir la cantidad de materia brillante y medir la masa dinámica. sumando la m. brillante y la masa dinámica no se puede frenar la expansión. Aun considerando la materia oscura no se podría parar la expansión.

El universo acelerado

Es posible estudiar el futuro del universo midiendo la variación de velocidad de expansión. Con esto también podemos estudiar la velocidad del pasado.

Gracias a un estudio sabemos que la velocidad de expansión era mas lenta en el pasado.

“El universo esta acelerando” ya que hay una fuerza actuando sobre él que nosotros desconocemos.

3- Big structures of the universe

Galaxies Galaxies are huge groups of stars,

gas and dust. There are different types:

1. Spiral galaxies2. Elliptical galaxies3. Irregular galaxies

Cumulus The galaxies are grouped to form

even large structures, called “Cumulus”.

Our galaxy is part of a cumulus called “ The Local Group”. It is composed of 3 big spiral galaxies (Milky Way, Andromeda and M33) and 30 small galaxies

Nebulae

Are giant clouds of gas and dust with different shapes. They are the result of big explosions that occur at the end of the life of very massive stars.

Quasars and Black Holes Quasars:

Are stellar objects that emit a large amount of energy as radio waves. It could be nuclei of galaxy information

Black Holes:

Are objects in which the light can’t escape because of the enormous gravitational attraction.

STARS

The stars

The stars are huge of spheres of H and He gas. They are formed in a nebulae and thy get old an die. The hottest stars are blue, and the coldest are red.

Energy of a star

The stages of the life of a star depend on the amount of energy that is capable of generating at all times. Inside the stars are produced nuclear reaction that emit energy. The stars are in a continuous state of nuclear fusion.

Vital cycle of a star

Stars are born in a galactic nebulae which are composed mainly of H and He.

1- Protostar: are produced by the contraction of the nebula. Are formed by H.

2- Young star: protostar became a star when H transformed into He trough nuclear fusion. It take places in the core.

3-Red giant star:

is the final stage of the life o a star. They are formed by He.

Nuclear reaction take places outside the core.

Due the increased of density, the core begins to shrink becoming denser and an increase of temperature is also produced. The nuclear reactions accelerated.

the production of energy increased and therefore the thermal pressures and radiation pressures increased. The star becomes bigger, the out layers cool-down and the star gets red.

When the H is consumed the star contract and reduce it sides formed white dwarf star.

4- Red Supergiant Star:

It’s a different final of a star life.

Due the high temperatures He is going to produce elements like carbon an oxygen by nuclear fusion.

Now the star has two areas of energy production: the core where the He is converted into O and C; and the outer layers where H is converted into He.

When the nuclear reactions stop the star becomes a White Dwarfs Star.

BY……………………………………………………………………

Juan Carlos Salinas andAlex Bernal Marín