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Monday, July 16, 2012

'Ghost Galaxies' of Early Universe Seen by Hubble Telescope

These images, released on July 10, 2012, reveal the small and faint star-starved dwarf galaxy, Leo IV, a close neighbour of our Milky Way galaxy. Leo IV is one of more than a dozen ultra-faint dwarf galaxies …more The Hubble Space Telescope has captured images of three odd galaxies that may help scientists solve a 13 billion-year cosmic mystery. The galaxies are so old and faint that astronomers nicknamed them "ghost galaxies" in a description. The objects are among the smallest and faintest galaxies near our own Milky Way galaxy, researchers said. "These galaxies are fossils of the early universe: they have barely changed for 13 billion years," scientists explained in a July 10 announcement. "The discovery could help explain the so-called 'missing satellite' problem, where only a handful of satellite galaxies have been found around the Milky Way, against the thousands that are predicted by theories." The three galaxies observed by the Hubble telescope are known as Hercules, Leo IV and Ursa Major. All three objects are small dwarf galaxies that appear to have begun forming about 13 billion years ago and then — for an unknown reason — their growth hit a cosmic wall. Since the universe is estimated to be about 13.7 billion years old, the galaxies were born sometime within the first billion years of the cosmos. [Video: Hubble Telescope Sees Ghost Galaxies] "These galaxies are all ancient and they’re all the same age, so you know something came down like a guillotine and turned off the star formation at the same time in these galaxies," said study leader Tom Brown of the Space Telescope Science Institute in Baltimore, Md. "The most likely explanation is a process called reionization." In the history of the universe, the reionization period marks a time when the cosmos transformed from being filled with cool neutral hydrogen (which carried no charge) into a universe with ionized hydrogen that had been split into its component electrons and protons. That change made the hydrogen fog of the early universe transparent to ultraviolet light. The universe was filled with the neutral hydrogen about 300,000 years after the Big Bang, with the reionization period occurring sometime in the 1 billion years that followed, astronomers have said. Scientists suspect that radiation from the first stars and galaxies caused the reionization. In the new study, Brown and his colleagues found that the same radiation that triggered the reionization of the universe may have also stunted star formation in dwarf galaxies such as those spotted in the new Hubble telescope views. The team is actually studying Hubble observations of six faint dwarf galaxies, but only completed its analysis of the Hercules, Leo IV and Ursa Major objects. The Hubble observations are follow-up looks at data from the Sloan Digital Sky Survey, which identified about a dozen of the ultra-faint galaxies. The three galaxies observed in Brown's study are irregular objects that coalesced about 100 million years before reionization began. They are only 2,000 light-years wide, smaller than the dwarf galaxies seen today near the Milky Way. They are all between 330,000 and 490,000 light-years from Earth. The process of reionization may have stripped the galactic dwarfs of the vital gas required to build more stars and grow into larger galaxies, the researchers said. With little active star formation, such dwarf galaxies could be all but invisible to astronomers trying to understand why so few of the objects have been found, when theories predict that thousands should be visible, they added. There is one more oddity about the faint ancient dwarf galaxies. They appear to have 100 times as much dark matter as normal visible matter, the researchers said. That's substantially more dark matter than the younger, brighter dwarf galaxies seen near the Milky Way, which typically have about 10 times as much dark matter as normal matter, they added. "The small galaxies in our study are made up mostly of dark matter because their hydrogen gas was ionized and the stars got turned off," Brown said. The research is detailed in the July 1 edition of the Astrophysical Journal Letters. Brown and his team used the Advanced Camera for Surveys aboard Hubble to obtain the new dwarf galaxy views. The Hubble Space Telescope has been peering deep into the universe since its launch in 1990. The space observatory's mission overseen by NASA and the European Space Agency.

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Camuflaje OVNI

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En nuestro mundo, una de las facultades que más nos asombra del mundo animal es la llamada mimetismo. Esta es la capacidad de los organismos vivos para pasar inadvertidos para los depredadores. Las variantes son múltiples, desde cambiar el color del pelaje, confundiéndose con su medio, hasta el de adquirir las formas de su entorno, incluso cuando nosotros mismos observamos el comportamiento de animales de nuestro interés, utilizamos el recurso del camuflaje. En la guerra la invisibilidad es una premisa, es por eso que la nación que logre duplicar el camuflaje OVNI obtendrá todas las ventajas sobre su enemigo. Actualmente existen naves invisibles, por lo menos para el radar, como el llamado Stealth Fighter, que por su diseño y pintura especial pasa inadvertido para los radares.

Einstein, en una de sus teorías afirmaba que mediante procesos magnéticos haciendo vibrar un objeto, esté podría desplazar el espectro electromagnético visible que despiden los objetos haciéndolos completamente indistinguibles para el ojo humano. Teoría que se probaría en el tristemente célebre experimento Filadelfia en 1947, con repercusiones bastante lamentables.

Los rayos infrarrojos y ultravioleta están por encima y por debajo, respectivamente, del espectro visible para el ojo humano. Para que una frecuencia infrarroja pueda ser perceptible son necesarios elementos ópticos y tecnológicos de los que carece el ojo humano, sin embargo, un ejemplo claro para poder realizarlo en nuestro hogar, basta colocar un telemando frente a una cámara de video y observarlo en el monitor de televisión.

Esto explicaría cómo aparece y cómo queda registrado en un video un OVNI, cuando al realizar la grabación éste no se observa y ni siquiera es el centro de atención. No obstante, este fenómeno también se produce en negativos fotográficos aun cuando este proceso (óptico químico) es diferente al video. Dando una idea de que si nuestras percepciones físicas no pueden detectar estos avistamientos, sí se cuenta con elementos para poder observarlos.

Otro tipo de camuflaje OVNI (al menos físico y visible), sería el de adoptar las formas del entorno atmosférico, en este caso nubes. Se han registrado avistamientos donde los observadores de estos fenómenos, ven claramente cómo las nubes tienen movimientos caprichosos en el cielo. Estos movimientos por cierto muy semejantes a los observados a través de la historia, donde incluso algunos casos se observan bajar entidades de las mismas.

Por otra parte, la misma maniobrabilidad de algunos OVNI´s hacen que pasen desapercibidos para algunos instrumentos de detección, esto como es de suponerse, sólo es necesario hallarse fuera del campo que cubre un radar, colocándose por encima o por debajo para pasar inadvertido. En medio de estos parámetros explicativos queda otra interrogativa, ¿se pueden ver o fotografiar entidades que se desarrollan en un plano de tres dimensiones? No, no se puede, ya que no obedecen las leyes físicas y ópticas del mismo comportamiento que conocemos, haciendo imposible dejar constancia en una placa o en un video, al menos con la óptica terrestre tal y como la conocemos.

Como se podrá deducir entonces, el hecho de que observemos OVNI´s en el cielo, sólo puede tratarse de un acto consciente de ser observados y enterarnos que allá arriba está sucediendo algo.