Hola amigos: A VUELO DE UN QUINDE EL BLOG., la Agencia Espacial NASA nos informa sobre el: NASA's Hubble Space Telescope (HST), ha descubierto una galaxia extremadamente distante llamado : The mammoth galaxy cluster Abell 2744.. la información dice..."Mirando a través de una lupa cósmica gigante, el Telescopio Espacial Hubble de la NASA ha detectado una pequeña, débil galaxia - una de las galaxias más lejanas jamás visto. El objeto diminuto se estima en más de 13 millones de años luz de distancia......
Esta galaxia ofrece un vistazo de nuevo a los primeros años de formación del universo y puede ser sólo la punta del iceberg.
"Esta galaxia es un ejemplo de lo que se sospecha que es abundante, la población subyacente de extremadamente pequeñas, objetos débiles que existían unos 500 millones de años después del Big Bang, el comienzo del universo", explicó el líder del estudio Adi Zitrin del Instituto de California de Tecnología en Pasadena, California. "El descubrimiento está diciendo a nosotros galaxias tan débiles como existe éste, y que debe continuar en busca de ellos y los objetos aún más débiles, para que podamos entender cómo las galaxias y el universo han evolucionado con el tiempo."..............
The mammoth galaxy cluster Abell 2744 is so massive
that its powerful gravity bends the light from galaxies far behind it, making
these otherwise unseen background objects appear larger and brighter than they
would normally.
Image Credit:
NASA, J. Lotz, (STScI)
Peering through a giant cosmic magnifying glass, NASA’s Hubble Space
Telescope has spotted a tiny, faint galaxy -- one of the farthest galaxies ever
seen. The diminutive object is estimated to be more than 13 billion light-years
away.
“This galaxy is an example of what is suspected to be an abundant, underlying
population of extremely small, faint objects that existed about 500 million
years after the big bang, the beginning of the universe,” explained study leader
Adi Zitrin of the California Institute of Technology in Pasadena, California.
“The discovery is telling us galaxies as faint as this one exist, and we should
continue looking for them and even fainter objects, so that we can understand
how galaxies and the universe have evolved over time.”
The galaxy was detected by the Frontier Fields program, an ambitious
three-year effort that teams Hubble with NASA’s other great observatories -- the
Spitzer Space Telescope and Chandra X-ray Observatory -- to probe the early
universe by studying large galaxy clusters. These clusters are so massive their
gravity deflects light passing through them, magnifying, brightening, and
distorting background objects in a phenomenon called gravitational lensing.
These powerful lenses allow astronomers to find many dim, distant structures
that otherwise might be too faint to see.
The discovery was made using the lensing power of the mammoth galaxy cluster
Abell 2744, nicknamed Pandora’s Cluster, which produced three magnified images
of the same, faint galaxy. Each magnified image makes the galaxy appear 10 times
larger and brighter than it would look without the zooming qualities of the
cluster.
The galaxy measures merely 850 light-years across -- 500 times smaller than
our Milky Way galaxy-- and is estimated to have a mass of only 40 million suns.
The Milky Way, in comparison, has a stellar mass of a few hundred billion suns.
And the galaxy forms about one star every three years, whereas the Milky Way
galaxy forms roughly one star per year. However, given its small size and low
mass, Zitrin said the tiny galaxy actually is rapidly evolving and efficiently
forming stars.
The astronomers believe galaxies such as this one are probably small clumps
of matter that started to form stars and shine, but do not yet have a defined
structure. It is possible Hubble is only detecting one bright clump magnified
due to the lensing. This would explain why the object is smaller than typical
field galaxies of that time.
Zitrin’s team spotted the galaxy’s gravitationally multiplied images using
near-infrared and visible-light photos of the galaxy cluster taken by Hubble’s
Wide Field Camera 3 and Advanced Camera for Surveys. But they needed to measure
how far away it was from Earth.
Usually, astronomers can determine an object’s distance based on how far its
light has been stretched as the universe slowly expands. Astronomers can
precisely measure this effect through spectroscopy, which characterizes an
object’s light. But the gravitationally-lensed galaxy and other objects found at
this early time period are too far away and too dim for spectroscopy, so
astronomers use an object’s color to estimate its distance. The universe’s
expansion reddens an object’s color in predictable ways, which scientists can
measure.
Zitrin’s team performed the color-analysis technique and took advantage of
the multiple images produced by the gravitational lens to independently confirm
the group’s distance estimate. The astronomers measured the angular separation
between the three magnified images of the galaxy in the Hubble photos. The
greater the angular separation due to lensing, the farther away the object is
from Earth.
To test this concept, the astronomers compared the three magnified images
with the locations of several other closer, multiply-imaged background objects
captured in Hubble images of Pandora’s cluster. The angular distance between the
magnified images of the closer galaxies was smaller.
“These measurements imply that, given the large angular separation between
the three images of our background galaxy, the object must lie very far away,”
Zitrin explained. “It also matches the distance estimate we calculated, based on
the color-analysis technique. So we are about 95 percent confident this object
is at a remote distance, at redshift 10, a measure of the stretching of space
since the big bang. The lensing takes away any doubt that this might be a
heavily reddened, nearby object masquerading as a far more distant object.”
Astronomers have long debated whether such early galaxies could have provided
enough radiation to warm the hydrogen that cooled soon after the big bang. This
process, called reionization, is thought to have occurred 200 million to 1
billion years after the birth of the universe. Reionization made the universe
transparent to light, allowing astronomers to look far back into time without
running into a “fog” of cold hydrogen.
The team’s results appeared in the September online edition of The
Astrophysical Journal Letters.
The Hubble Space Telescope is a project of international cooperation between
NASA and the European Space Agency. NASA's Goddard Space Flight Center in
Greenbelt, Maryland, manages the telescope. The Space Telescope Science
Institute (STScI) in Baltimore conducts Hubble science operations. STScI is
operated for NASA by the Association of Universities for Research in Astronomy,
Inc., in Washington.
For images and more information about Hubble, visit:
NASA
Guillermo Gonzalo Sánchez Achutegui
Inscríbete en el Foro del blog y participa : A Vuelo De Un Quinde - El Foro!
No hay comentarios:
Publicar un comentario