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Sunday, March 8, 2015

NASA's Chandra Observatory Finds Cosmic Showers Halt Galaxy Growth

NASA's Chandra Observatory Finds Cosmic Showers Halt Galaxy Growth:

This galaxy cluster comes from a sample of over 200 that were studied to determine how giant black holes at their centers affect the growth and evolution of their host galaxy, as reported in our latest press release. This study revealed that an unusual form of cosmic precipitation enables a feedback loop of cooling and heating, stifling star formation in the middle of these galaxy clusters.

Abell 2597, shown here, is a galaxy cluster located about one billion light years from Earth. This image contains X-rays from NASA's Chandra X-ray Observatory (blue), optical data from the Hubble Space Telescope and the Digitized Sky Survey (yellow) and emission from hydrogen atoms (red) from the Walter Baade Telescope in Chile.

According to this new study, the regulation of the largest black hole and their host galaxies works as follows: in some galaxies, such as NGC 2597, hot gas is able to quickly cool through radiation and energy loss, in a process called precipitation. The clouds of cool gas that result then fall into the central supermassive black hole, producing jets that heat the gas and prevent further cooling.

The researchers used Chandra data to estimate how long it should take for the gas to cool at different distances from the black holes in the study. Using that information, they were able to accurately predict the "weather" around each of the black holes.

They found that the precipitation feedback loop driven by energy produced by the black hole jets prevents the showers of cold clouds from getting too strong. The Chandra data indicate that the regulation of this precipitation has been going on for the last 7 billion years or more.

More information at http://chandra.harvard.edu/photo/2015/a2597/index.html

-Megan Watzke, CXC

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The National Aeronautics and Space Administration (NASA) is the United States government agency responsible for the civilian space program as well as aeronautics and aerospace research. President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA's predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

UFO SIGHTINGS PHOTO PHOTOGRAPHY

The Oxford English Dictionary defines a UFO as "An unidentified flying object; a 'flying saucer'." The first published book to use the word was authored by Donald E. Keyhoe. The acronym "UFO" was coined by Captain Edward J. Ruppelt, who headed Project Blue Book, then the USAF's official investigation of UFOs. He wrote, "Obviously the term 'flying saucer' is misleading when applied to objects of every conceivable shape and performance. For this reason the military prefers the more general, if less colorful, name: unidentified flying objects. UFO (pronounced Yoo-foe) for short." Other phrases that were used officially and that predate the UFO acronym include "flying flapjack", "flying disc", "unexplained flying discs", "unidentifiable object", and "flying saucer". The phrase "flying saucer" had gained widespread attention after the summer of 1947. On June 24, a civilian pilot named Kenneth Arnold reported seeing nine objects flying in formation near Mount Rainier. Arnold timed the sighting and estimated the speed of discs to be over 1,200 mph (1,931 km/h). At the time, he described the objects' shape as being somewhat disc-like or saucer-like, leading to newspaper accounts of "flying saucers" and "flying discs". In popular usage the term UFO came to be used to refer to claims of alien spacecraft. and because of the public and media ridicule associated with the topic, some investigators prefer to use such terms as unidentified aerial phenomenon (or UAP) or anomalous phenomena, as in the title of the National Aviation Reporting Center on Anomalous Phenomena (NARCAP).

UFO PHOTO PHOTOGRAPHY

UFO - Unidentified Flying Object An unidentified flying object, or UFO, in its most general definition, is any apparent anomaly in the sky that is not identifiable as a known object or phenomenon. Culturally, UFOs are associated with claims of visitation by extraterrestrial life or government-related conspiracy theories, and have become popular subjects in fiction. While UFOs are often later identified, sometimes identification may not be possible owing to the usually low quality of evidence related to UFO sightings (generally anecdotal evidence and eyewitness accounts). Stories of fantastical celestial apparitions have been told since antiquity, but the term "UFO" (or "UFOB") was officially created in 1953 by the United States Air Force (USAF) to serve as a catch-all for all such reports. In its initial definition, the USAF stated that a "UFOB" was "any airborne object which by performance, aerodynamic characteristics, or unusual features, does not conform to any presently known aircraft or missile type, or which cannot be positively identified as a familiar object." Accordingly, the term was initially restricted to that fraction of cases which remained unidentified after investigation, as the USAF was interested in potential national security reasons and/or "technical aspects" (see Air Force Regulation 200-2). During the late 1940s and through the 1950s, UFOs were often referred to popularly as "flying saucers" or "flying discs". The term UFO became more widespread during the 1950s, at first in technical literature, but later in popular use. UFOs garnered considerable interest during the Cold War, an era associated with a heightened concern for national security. Various studies have concluded that the phenomenon does not represent a threat to national security nor does it contain anything worthy of scientific pursuit (e.g., 1951 Flying Saucer Working Party, 1953 CIA Robertson Panel, USAF Project Blue Book, Condon Committee).