V-861 Scorpi

V-861 Scorpi

Descubierto por el satélite corpernico en 1978, el V-861 Scorpi es junto al “cygnus X1” los mayores candidatos a ser agujeros negros de nuestro universo.

Un agujero negro es como un sistema espiral de succiòn, que desaparece todo aquello que entra en su orbita, la razón de esto es que han sido en un pasado estrellas que hacia su fase final de vida y muerte, han sobrepasado las etapas de Enana Blanca (aquella estrella que se queda sin su energía) y Estrella de Neutrones (o “supernova” en donde la concentración de a energía al momento de su muerte sobrepasa el punto de contracción de la enana blanca y por lo tanto una vez en su núcleo estalla dejando toda una nebulosa de gas y dejando residuos de neutrones que colapsan en su interior formando la luz que conocemos), sin embargo si vamos aún más allá en la fuerza y potencia con la cuál la energía de una estrella se concentra antes de su desaparición, vemos el proceso de formación de un agujero negro, en los cuales la concentración de los átomos que daban lugar a la luz y energía de dicha estrella, se compactan tanto en un núcleo que tiende a tener una densidad y crear una gravedad infinita aún no entendida por la física, es este el caso donde la ex-estrella forma un punto que parece invisible o es totalmente oscuro y que si algún cometa pasase por su campo de orbita se vería atraída por esta gravedad a su interior, o en si en un espiral hacia entrar dentro de este estado de invisibilidad, he ahí lo por lo que se cree que estos agujeros negros constituyen portales a otros universos paralelos, o bien a otros puntos en el espacio y/o tiempo de nuestro universo. Nada de esto es muy distinto a esos sistemas de emociones o energías que nos consumen como seres humanos, esas sensaciones de depresión extrema, donde el circuito se cierra constantemente y estamos como dentro de nuestras propias ideas redundantes, con los horizontes cerrados, y en fin esos espirales en descenso, donde la desvalorización, y el ser se ven corrompidos y reducidos a su menos expresión…. Zzzzuuuuuuuuip. En el agujeroªªª

¿to be continued”Z

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History

Pierre-Simon Laplace, one of the originators of the nebular hypothesisMain article: History of Solar System formation and evolution hypotheses
Ideas concerning the origin and fate of the world date from the earliest known writings; however, for almost all of that time, there was no attempt to link such theories to the existence of a "Solar System", simply because it was not generally known that the Solar System, in the sense we now understand it, existed. The first step towards a theory of Solar System formation and evolution was the general acceptance of heliocentrism, the model which placed the Sun at the centre of the system and the Earth in orbit around it. This conception had been gestating for millennia but was only widely accepted by the end of the 17th century. The first recorded use of the term "Solar System" dates from 1704.[1]

The current standard theory for Solar System formation, the nebular hypothesis, has fallen into and out of favour since its formulation by Emanuel Swedenborg, Immanuel Kant, and Pierre-Simon Laplace in the 18th century. The most significant criticism of the hypothesis was its apparent inability to explain the Sun's relative lack of angular momentum when compared to the planets.[2] However, studies since the early 1980s of young stars have shown them to be surrounded by cool discs of dust and gas, exactly as the nebular hypothesis predicts, which has led to its re-acceptance.[3]

Understanding of how the Sun will evolve required an understanding of the source of its power. Arthur Stanley Eddington's confirmation of Albert Einstein's theory of relativity led to his realisation that the Sun's energy comes from nuclear fusion reactions in its core.[4] In 1935, Eddington went further and suggested that other elements might also form within stars.[5] Fred Hoyle elaborated on this premise by arguing that evolved stars called red giants created many elements heavier than hydrogen and helium in their cores. When a red giant finally casts off its outer layers, these elements would then be recycled to form other star systems.[5]


[edit] Formation
See also: Nebular hypothesis

[edit] Pre-solar nebula

Hubble image of protoplanetary discs in the Orion nebula, a light-years-wide "stellar nursery" likely very similar to the primordial nebula from which our Sun formedThe nebular hypothesis maintains that the Solar System formed from the gravitational collapse of a fragment of a giant molecular cloud which was likely several light-years across.[6] Until the early 2000s, the conventional view was that the Sun formed in relative isolation, but studies of ancient meteorites reveal traces of short-lived isotopes like iron-60 which only form in exploding, short-lived stars. This indicates that a number of supernovae occurred near the Sun while it was forming. A shock wave from one of these supernovae may have triggered the formation of the Sun by creating regions of over-density within the cloud, causing these regions to collapse. Because only massive, short-lived stars produce supernovae, the Sun must have formed in a large star-forming region which produced massive stars, possibly similar to the Orion nebula.[7][8]

One of these regions of collapsing gas (known as the pre-solar nebula)[9] would form what became the Solar System. This region had a diameter of between 7000 and 20,000 astronomical units (AU)[6][10][11] and a mass just over that of the Sun. Its composition was about the same as that of the Sun today. Hydrogen and helium, which were produced by Big Bang nucleosynthesis, formed about 98% of the mass. The remaining 2% of the mass consisted of heavier elements that were created by nucleosynthesis in earlier generations of stars.[12] Late in the life of these stars, they ejected heavier elements into the interstellar medium.[13]

Conservation of angular momentum meant that the collapsing nebula spun faster. As the material within the nebula condensed, the atoms within it began to collide with increasing frequency, converting their kinetic energy into heat. The centre, where most of the mass collected, became increasingly hotter than the surrounding disc.[6] Over about 100,000 years,[14] the competing forces of gravity, gas pressure, magnetic fields, and rotation caused the contracting nebula to flatten into a spinning protoplanetary disc with a diameter of ~200 AU[6] and form a hot, dense protostar (a star in which hydrogen fusion has not yet begun) at the centre.[15]

At this point, the Sun is believed to have been a T Tauri star. Studies of T Tauri stars show that they are often accompanied by discs of pre-planetary matter with masses of 0.001–0.1 solar masses.[16] These discs extend to several hundred AU—the Hubble Space Telescope has observed protoplanetary discs of up to 1000 AU in diameter in star-forming regions such as the Orion Nebula[17]—and are rather cool, reaching only a thousand Kelvin at their hottest.[18] Within 50 million years, the temperature and pressure at the core of the Sun became so great that its hydrogen began to fuse, creating an internal source of energy which countered the force of gravitational contraction until hydrostatic equilibrium was achieved.[19] This marked the Sun's entry into the prime phase of its life, known as the main sequence. Main sequence stars are those which derive their energy from the fusion of hydrogen into helium in their cores. The Sun remains a main sequence star today.[20]


[edit] Formation of planets

Artist's conception of the solar nebulaSee also: Protoplanetary disc
The various planets are thought to have formed from the solar nebula, the disc-shaped cloud of gas and dust left over from the Sun's formation.[21] The currently accepted method by which the planets formed is known as accretion, in which the planets began as dust grains in orbit around the central protostar. Through direct contact, these grains formed into clumps between one and ten kilometres (km) in diameter, which in turn collided to form larger bodies (planetesimals) of ~5 km in size. These gradually increased through further collisions, growing at the rate of centimetres per year over the course of the next few million years.[22]

The inner Solar System, the region of the Solar System inside 4 AU, was too warm for volatile molecules like water and methane to condense, so the planetesimals which formed there could only form from compounds with high melting points, such as metals (like iron, nickel, and aluminium) and rocky silicates. These rocky bodies would become the terrestrial planets (Mercury, Venus, Earth, and Mars). These compounds are quite rare in the universe, comprising only 0.6% of the mass of the nebula, so the terrestrial planets could not grow very large.[6] The terrestrial embryos grew to about 0.1 Earth masses and ceased accumulating matter about 100,000 years after the formation of the Sun; subsequent collisions and mergers between these planet-sized bodies allowed terrestrial planets to grow to their present sizes (see Terrestrial planets below).[23]

The Jovian planets (Jupiter, Saturn, Uranus, and Neptune) formed further out, beyond the frost line, the point between the orbits of Mars and Jupiter where the Sun's rays are weak enough for volatile icy compounds to remain solid. The ices which formed the Jovian planets were more abundant than the metals and silicates which formed the terrestrial planets, allowing the Jovian planets to grow massive enough to capture hydrogen and helium, the lightest and most abundant elements.[6] Planetesimals beyond the frost line accumulated up to four Earth masses within about 3 million years.[23] Today, the four gas giants comprise just under 99% of all the mass orbiting the Sun.[24] Theorists believe it is no accident that Jupiter lies just beyond the frost line. Because the frost line accumulated large amounts of water via evaporation from infalling icy material, it created a region of lower pressure that increased the speed of orbiting dust particles and halted their motion toward the Sun. In effect, the frost line acted as a barrier that caused material to accumulate rapidly at ~5 AU from the Sun. This excess material coalesced into a large embryo of about 10 Earth masses, which then began to grow rapidly by swallowing hydrogen from the surrounding disc, reaching 150 Earth masses in only another 1000 years and finally topping out at 318 Earth masses. Saturn may owe its substantially lower mass simply to having formed a few million years after Jupiter, when there was less gas available to consume.[23]

T Tauri stars like the young Sun have far stronger stellar winds than more stable, older stars. Uranus and Neptune are believed to have formed after Jupiter and Saturn did, when the strong solar wind had blown away much of the disc material. As a result, the planets accumulated little hydrogen and helium—not more than 1 Earth mass each. Uranus and Neptune are sometimes referred to as failed cores.[25] The main problem with formation theories for these planets is the timescale of their formation. At the current locations it would have taken a hundred million years for their cores to accrete. This means that Uranus and Neptune probably formed closer to the Sun—near or even between Jupiter and Saturn—and later migrated outward (see Planetary migration below).[26][25] Motion in the planetesimal era was not all inward toward the Sun; the Stardust sample return from Comet Wild 2 has suggested that materials from the early formation of the Solar System migrated from the warmer inner Solar System to the region of the Kuiper belt.[27]

After between three and ten million years,[23] the young Sun's solar wind would have cleared away all the gas and dust in the protoplanetary disc, blowing it into interstellar space, thus ending the growth of the planets.[28][29]