Mostrando entradas con la etiqueta NASA's Swift spacecraft. Mostrar todas las entradas
Mostrando entradas con la etiqueta NASA's Swift spacecraft. Mostrar todas las entradas

domingo, 12 de febrero de 2017

NASA : Agujero Negro XJ1500+0154.- Un Agujero Negro "Caníbal" Marca un Nuevo Récord


Publicado el 6 feb. 2017
Every so often, an object will pass too close to a black hole and be ripped apart by its intense gravitational forces. As the object, such as a star, approaches the danger zone of the black hole, its stellar debris is flung outward at high speeds, while the star's material falls towards the black hole. This in-falling material becomes hotter and hotter until it generates a signature outburst of X-rays. Astronomers call these "tidal disruption events," or TDEs, and they can be used to better understand how black holes grow and affect their environments.

While astronomers have seen multiple examples of TDEs in recent years, a new discovery stands out among the rest. Using data from three X-ray telescopes: Chandra, Swift, and XMM-Newton, researchers have found a TDE that has lasted about ten years, much longer than other events. What could cause this decade-long meal by the black hole? There are a couple of possibilities. The first is that this black hole, located in a galaxy about 1.8 billion light years from Earth, completely shredded the largest star astronomers have known to be destroyed in a TDE. The other, also intriguing, possibility is that in previous TDEs the star wasn't completely ripped apart, but in this event it was. While astronomers continue to study this source and look for others like it, we are reminded just how amazing black holes can be.

Un Agujero Negro "Caníbal" Marca un Nuevo Récord

 
07.02.17.- Un agujero negro gigante destruyó una estrella y luego se atiborró de sus restos durante aproximadamente una década, según los astrónomos. Esto es 10 veces más tiempo que cualquier episodio observado de la muerte de una estrella por un agujero negro.
Los investigadores hicieron este descubrimiento utilizando datos del Observatorio de Rayos X Chandra y el satélite Swift de la NASA, así como el XMM-Newton de la ESA.
El trío de telescopios en órbita encontró evidencias de un "evento de interrupción de mareas" (TDE), donde las fuerzas de una marea debido a la gravedad de un agujero negro pueden destruir un objeto – como una estrella – que pasa demasiado cerca. Durante un TDE, algunos de los escombros estelares se lanzan hacia fuera a altas velocidades, mientras que el resto cae hacia el agujero negro. A medida que se desplaza hacia el interior para ser ingerido por el agujero negro, el material se calienta a millones de grados y genera una llamarada de rayos X distinta.
"Hemos sido testigos de la espectacular y prolongada desaparición de una estrella." dijo Daching Lin, de la Universidad de New Hampshire en Durham, quien dirigió el estudio. "Decenas de eventos de interrupción de las mareas se han detectado desde la década de los 90, pero ninguno permaneció brillante durante tanto tiempo como este".
La extraordinaria y larga fase luminosa de este evento que se extiende a lo largo de diez años significa que, entre los TDEs observados, esta fue la estrella más masiva que se desgarró por completo durante uno de estos eventos o la primera donde una estrella más pequeña se desgarró por completo.
La fuente de rayos X que contiene este agujero negro alimentado a la fuerza, conocido por su nombre abreviado de XJ1500 + 0154, se encuentra en una pequeña galaxia a unos 1.800 millones de años luz de la Tierra.
 
Concepto artístico de lo que los astrónomos llaman un "evento de interrupción de mareas" (TDE). Credits: Illustration: CXC/M. Weiss; X-ray: NASA/CXC/UNH/D. Lin et al, Optical: CFHT
NASA
Guillermo Gonzalo Sánchez Achutegui
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domingo, 23 de noviembre de 2014

NASA : Swift Gamma-Ray Burst Mission Marks Ten Years of Discovery.- La Misión Swift Gamma-Ray Burst marca 10 años de descubrimientos

Hola amigos: A VUELO DE UN QUINDE  EL BLOG., hemos recibido de la Agencia Espacial NASA, la información del satélite llamado : "NASA's Swift spacecraft " que viajó a bordo del cohete Boing Delta II, que fue lanzado desde la Base Espacial Cabo Cañaveral el 20 de noviembre del 2004, cuya misión fue identificar el origen y estallido de los Rayos Gamma, que se observan como explosiones luminosas en el Cosmos; su origen se cree que se produce cuando una estrella se queda sin su combustible nuclear y colapsa bajo su propio peso; y forma lo que conocemos como los Agujeros Negros, que impulsa chorros de partículas de la estrella en colapso y estallan en el espacio casi a la velocidad de la luz.
NASA... nos dice .."El 20 de noviembre de 2004, la nave espacial Swift de la NASA despegó a bordo de un cohete Boeing Delta II desde Cabo Cañaveral, Florida., Comenzando su misión de estudiar los estallidos de rayos gamma e identificar su origen. Estallidos de rayos gamma son las explosiones más luminosas en el cosmos. La mayoría se cree que se activará cuando el núcleo de una estrella masiva se queda sin combustible nuclear, se colapsa bajo su propio peso, y forma un agujero negro. El agujero negro luego impulsa chorros de partículas que perforan todo el camino a través de la estrella en colapso y estallan al espacio a casi la velocidad de la luz..............."

Swift Gamma-Ray Burst Mission Marks Ten Years of Discovery
On Nov. 20, 2004, NASA's Swift spacecraft lifted off aboard a Boeing Delta II rocket from Cape Canaveral Air Force Station, Fla., beginning its mission to study gamma-ray bursts and identify their origins. Gamma-ray bursts are the most luminous explosions in the cosmos. Most are thought to be triggered when the core of a massive star runs out of nuclear fuel, collapses under its own weight, and forms a black hole. The black hole then drives jets of particles that drill all the way through the collapsing star and erupt into space at nearly the speed of light.
Astronomers at NASA and Pennsylvania State University used Swift to create the most detailed ultraviolet light surveys ever of the Large and Small Magellanic Clouds, the two closest major galaxies. Nearly a million ultraviolet sources appear in this mosaic of the Large Magellanic Cloud, which was assembled from 2,200 images taken by Swift's Ultraviolet/Optical Telescope (UVOT) and released on June 3, 2013. The 160-megapixel image required a cumulative exposure of 5.4 days. The image includes light from 1,600 to 3,300 angstroms -- UV wavelengths largely blocked by Earth's atmosphere -- and has an angular resolution of 2.5 arcseconds at full size. The Large Magellanic Cloud is about 14,000 light-years across.
Viewing in the ultraviolet allows astronomers to suppress the light of normal stars like the sun, which are not very bright at such higher energies, and provides a clearer picture of the hottest stars and star-formation regions. No telescope other than UVOT can produce such high-resolution wide-field multicolor surveys in the ultraviolet.
Pennsylvania State University manages the Swift Mission Operations Center, which controls Swift's science and flight operations. Goddard manages Swift, which was launched in November 2004. The satellite is operated in collaboration with Penn State, the Los Alamos National Laboratory in New Mexico and Orbital Sciences Corp. in Dulles, Va. International collaborators are in the United Kingdom and Italy, and the mission includes contributions from Germany and Japan.
Image Credit: NASA/Swift/S. Immler (Goddard) and M. Siegel (Penn State)
NASA
Guillermo Gonzalo Sánchez Achutegui
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sábado, 11 de enero de 2014

NASA : NASA's Swift Catches X-ray Action at Milky Way's Center


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This sequence from the X-ray Telescope aboard NASA’s Swift shows changes in the central region of the Milky Way galaxy from 2006 through 2013. Watch for flares from binary systems containing a neutron star or black hole and the changing brightness of Sgr A* (center), the galaxy’s monster black hole.
Image Credit: NASA/Swift/N. Degenaar (Univ. of Michigan)
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Recent observations by NASA's Swift spacecraft have provided scientists a unique glimpse into the activity at the center of our galaxy and led to the discovery of a rare celestial entity that may help them test predictions of Albert Einstein's theory of general relativity.

This week, at the annual meeting of the American Astronomical Society in National Harbor, Md., scientists presented their research into images captured by Swift, explaining how these images will help decipher the physical nature of X-ray flares and enabled their discovery of a rare subclass of neutron star.
This X-ray image of the galactic center merges Swift XRT observations through 2013. Sgr A* is at center. Low-energy X-rays (300 to 1,500 electron volts) are shown in red, medium-energy (1,500 to 3,000 eV) in green, and high-energy (3,000 to 10,000 eV) in blue. The total exposure time is 12.6 days.
Image Credit: NASA/Swift/N. Degenaar (Univ. of Michigan)
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Swift's seven-year campaign to monitor the center of the Milky Way has doubled the number of images available to scientists of bright X-ray flares occurring at the galaxy's central black hole, dubbed Sagittarius A* (Sgr A*).
Sgr A* sits in the center of the Milky Way's innermost region, 26,000 light-years away in the direction of the constellation Sagittarius. Its mass is at least 4 million times that of the sun. Despite its considerable size, it is not nearly as bright as it could be if it was more active, according to one expert.
"Given its size, this supermassive black hole is about a billion times fainter than it could be," said Nathalie Degenaar, principal investigator on the Swift galactic center campaign and an astronomer at the University of Michigan in Ann Arbor. "Though it's sedate now, it was quite active in the past and still regularly produces brief X-ray flares today."
To better understand the black hole's behavior over time, the Swift team began making regular observations of the Milky Way's center in February 2006. Every few days, the Swift spacecraft turns toward the innermost region of the galaxy and takes a 17-minute-long snapshot with its X-ray Telescope (XRT).
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This simulation shows the future behavior of the G2 gas cloud now approaching Sgr A*, the supermassive black hole at the center of the Milky Way. X-ray emission from the cloud’s tidal interaction with the black hole is expected sometime this spring.
Image Credit: ESO/MPE/M.Schartmann
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To date, Swift's XRT has detected six bright flares during which the black hole's X-ray emission was as much as 150 times brighter for a couple of hours. These new detections enabled the team to estimate that similar flares occur every five to 10 days. Scientists will look at differences between the outbursts to decipher their physical nature.
The Swift XRT team expects 2014 to be a banner year for the campaign. A cold gas cloud named G2, about three times the mass of Earth, will pass near Sgr A* and already is being affected by tides from the black hole's powerful gravitational field. Astronomers expect G2 will swing so close to the black hole during the second quarter of the year that it will heat up to the point where it produces X-rays.
If some of the cloud's gas actually reaches Sgr A*, astronomers may witness a significant increase in activity from the black hole. The event will unfold over the next few years, giving scientists a front-row seat to study the phenomena.
"Astronomers around the world are eagerly awaiting the first sign that this interaction has begun," said Jamie Kennea, a team member at Pennsylvania State University in University Park, Pa. "With the invaluable help of Swift, our monitoring program may well provide that indicator."
Scientists saw what they thought was a sign in April, when Swift detected a powerful high-energy burst and a dramatic rise in the X-ray brightness of the Sgr A* region. They were excited to discover the activity came from separate source very near the black hole: a rare subclass of neutron star.
A neutron star is the crushed core of a star destroyed by a supernova explosion, packing the equivalent mass of a half-million Earths into a sphere no wider than Washington. The neutron star, named SGR J1745-29, is a magnetar, meaning its magnetic field is thousands of times stronger than an average neutron star. Only 26 magnetars have been identified to date.
The discovery of SGR J1745-29 may aid scientists in their exploration of important properties of the Sgr A* black hole. As it spins, the magnetar emits regular X-ray and radio pulses. As it orbits Sgr A*, astronomers could detect subtle changes in the pulse timing because of the black hole's gravitational field, a prediction of Einstein’s theory of general relativity.
"This long-term program has reaped many scientific rewards, and due to a combination of the spacecraft's flexibility and the sensitivity of its XRT, Swift is the only satellite that can carry out such a campaign," said Neil Gehrels, the mission's principal investigator at NASA's Goddard Space Flight Center in Greenbelt, Md.
Goddard manages Swift, which was launched in November 2004. Goddard operates the spacecraft in collaboration with Pennsylvania State University, the Los Alamos National Laboratory in New Mexico and Orbital Sciences Corp. in Dulles, Va. International collaborators are located in the United Kingdom and Italy. The mission includes contributions from Germany and Japan.
For more about the Swift mission, visit:
http://www.nasa.gov/swift
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Guillermo Gonzalo Sánchez Achutegui

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