Fri. Jan 17th, 2020

6 × 1? # 15: Phenomena of the Universe

Before starting we recommend that you be more related to what comes next visit the post The life of a star, how they are born, evolve and die.

• What is a Supernova?

The supernova is "A stellar explosion that occurs as a conclusion of the final stage of a star's life", explains to Hypertext Jonay González Hernández, investigator Ramón y Cajal of the Institute of Astrophysics of the Canary Islands. These bursts throw in all directions the matter that contained the star.

Why does it happen when the stars are dying? A star explodes because the “Fuel that generates energy in the star's core ends and, therefore, the radiation pressure that prevents the collapse of the star ends, the star yields to gravity, giving rise to stellar residues that are not stable against gravity that does not stop ”Gonzalez points out. In the end everything is a matter of fuel, without it the star cannot continue to shine.

But to get to the explosion before you have to know that there are two types of supernovae: "Those that produce the most massive stars, approximately 10 masses of the Sun, and those that produce stars below this mass"says Gonzalez. In the case of the first, the massive stars without companion and isolated, end up producing after the explosion "A stellar residue" that it would be about "A neutron star or a black hole".


• What is a black hole?

Black holes are the cold remains of ancient stars, so dense that no material particle, not even light, is capable of escaping its powerful gravitational force.

While many stars end up becoming white dwarfs or neutron stars, black holes represent the last phase in the evolution of huge stars that were at least 10 to 15 times larger than our sun.

When the giant stars reach the final stage of their lives they explode in cataclysms known as supernovae. Such an explosion disperses most of the star in space vacuum, but a large number of "cold" remains remain where fusion does not occur.

In young stars, nuclear fusion creates energy and a constant external pressure that is in balance with the force of inner gravity produced by the star's own mass. However, in the inert remains of a supernova there is no force that resists gravity, so the star begins to fall back on itself.

Without a force that slows gravity, the emerging black hole shrinks to a volume zero, at which point it becomes infinitely dense. Even the light of this star is unable to escape its immense gravitational force, which is trapped in orbit, so the dark star is known as black hole.

Black holes attract matter, and even energy, to themselves, but not to a greater extent than other stars or cosmic objects of similar mass. This means that a black hole with the same mass as that of our sun would not "aspirate" more objects towards itself than our sun with its own gravitational force.

The planets, light and other matter must pass near a black hole to be attracted within its range. When they reach a point of no return, it is said that they have entered the event horizon, a point from which it is impossible to escape because it requires moving at a speed greater than that of light.

Since they are so small, distant and dark, black holes cannot be observed directly. Despite this, scientists have confirmed the long-held suspicions of its existence. This is usually done by measuring the mass of a region of space and looking for areas with a large dark mass.

There may be supermassive black holes in the center of some galaxies, including our Milky Way.


• What are quasars?

Quasars are phenomena that arise when a huge black hole, located in the nucleus of a galaxy, begins to absorb all the matter it finds in its vicinity. When this occurs, due to the enormous rotation speed of the accretion disk formed, a gigantic amount of energy is produced, released in the form of radio waves, light, infrared, ultraviolet and x-rays, which makes quasars the brightest objects in the known universe.

The word Quasar is an acronym for quasi stellar radio source (almost stellar radio sources).

It is believed that quasars are fed by the accretion of supermassive black holes in the nucleus of distant galaxies, making them very bright versions of a general class of objects known as active galaxies. The mechanism that seems to explain the emission of the large amount of energy and its rapid variability is unknown. The knowledge of quasars has progressed very rapidly, although there is no clear consensus on its origins.

Quasars have been discovered to 12.000 millions of light years from Earth. This is approximately the age of the Universe. Despite the enormous distances, the energy that arrives in some cases is very large. As an example, the s50014 + 81 it's some 60.000 times brighter than the entire Milky Way.

The most spectacular of the quasars is not their remoteness, but that they may be visible. A quasar should be as bright as 1.000 galaxies together so that it can appear as a weak star, if it is several billion light years away. But even more surprising is the fact that this enormous energy comes from a region whose size does not exceed a light year (less than one hundred thousandth of the size of a normal galaxy). The brightness of the quasars oscillates with periods of a few months, therefore, their size must be smaller than the distance that the light travels in that time.

At first, astronomers did not see any relationship between quasars and galaxies, but the gap between these two types of cosmic objects has gradually filled up when galaxies were discovered whose nucleus resembles a quasar. Today, quasars are thought to be the nuclei of very young galaxies, and that the activity in the nucleus of a galaxy decreases over time, although it does not disappear altogether.

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• What is a wormhole?

A wormhole is a tunnel that connects two points of space-time, or two parallel universes.

One has never been seen and it is not proven that they exist, although mathematically they are possible.

They are called that because they resemble a worm that crosses an apple inside to reach the other end, instead of running it outside. Thus, wormholes are shortcuts in the fabric of the space time. They allow to join two very distant points and arrive more quickly than if the Universe were crossed at the speed of light.

According to Einstein's theory of general relativity, wormholes may exist. They have an entrance and an exit at different points of space or time. The tunnel that connects them is in the hyperspace, which is a dimension produced by a distortion of time and gravity.

The scientists Einstein and Rosen They raised this theory by studying what was happening inside a black hole. That's why they are also called Einstein-Rosen Bridge.

There are two kinds of wormholes:

Intrauniverse: connect two points away from the Cosmos.

Interuniverse o Schwarzschild holes: connect two different Universes.

Can you travel through time?

Scientists believe that a wormhole has a very short life. It opens and closes again quickly. Matter would be trapped in it or, even if it managed to exit through the other end (a white hole), it could not return. Obviously, we could not choose where it would lead.

According to general relativity, it is possible to travel to the future, but not to the past. If you could travel to the past, we could alter history, for example, causing us to never be born. It would be something impossible.


• What is a white hole?

According to the general theory of relativity, a white hole is a hypothetical region of the universe that cannot be accessed and from which light and matter escape. If we remember we will have a black hole is just the opposite.

In this sense, we can define white holes from their opposites, that is, they would be pure black anti-holes. White holes share with their brothers properties such as mass, load and angular momentum, only that the equations that govern their operations are identical but posed in reverse.

Scientists suggest that the material absorbed by black holes in the past is returned in the future by the event horizon of white holes. Even theoretical models of these objects indicate that there are no obvious differences between them. Even so, it seems that white holes would not be as stable as black holes and that they would collapse immediately under the weight of their own gravitational effect.

Are there white holes?

White holes belong to the world of theory, so they have always been considered a mathematical oddity and are not as taken into account by scientists as their dark brothers, since there seems to be no natural processes that lead to their formation.


• How were constellations formed?

The constellations are human interpretations of the random arrangement of the stars in the sky, that is to say they are the product of imagination and completely arbitrary.

Therefore, to say that they were formed is technically incorrect. It would be better to say that they arose in the collective imagination of a people or a civilization.

The stars of a given constellation are not necessarily associated and can be found hundreds of light years from each other, but in the eyes of an observer on Earth they can take a certain form, as if it were a classic children's game of joining the dots, only that they join visually and imaginary.

If you are interested in this topic, we recommend our previous post How to observe the constellations and planets.

Since, since prehistory, ancient civilizations created their own constellations, generally imagining forms and figures of gods, creatures or mythological beings linked to their beliefs and experiences, the constellations have had very significant changes throughout history.

Some were very popular and then forgotten. Others managed to stay and be known and used by different cultures.


All themes have been suggested by: DENNIS PALAVECINO, Ulises Tolosa, Carlos Andres Miranda, Fran Cisco, John Stalin, Toni Esteve, Tatiana Zamora, Sebastian MA, Warren Gianfranco Becerra Peralta, Milagros Freire, Kevin Stiven Cossio, Luis Burbano, Carlosdavila 2000 2000, Hulio Sanchez Batista and Laura Calzadilla

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