News tagged with galaxies
Black holes and star formation
(PhysOrg.com) -- It has long been recognized that galaxy mergers or even close interactions can play a vital role in shaping the morphology of galaxies. One way they can do so, it is thought, is by triggering ...
Feb 09, 2012 |
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Distorting the lens
(PhysOrg.com) -- One of the most bizarre predictions of Einstein's Theory of General Relativity is the existence of back holes, objects that are so dense that not even light can escape from their gravitational ...
Feb 09, 2012 |
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Samsung can continue selling Galaxy tabs in Germany: court
South Korea's Samsung Electronics can continue to sell its Galaxy Tab 10.1N tablet computer in Germany, a German court ruled Thursday, rejecting a bid by arch-rival Apple to have them banned.
Feb 09, 2012 |
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Astronomy team discovers nearby dwarf galaxy
(PhysOrg.com) -- A team led by UCLA research astronomer Michael Rich has used a unique telescope to discover a previously unknown companion to the nearby galaxy NGC 4449, which is some 12.5 million light years ...
Feb 08, 2012 |
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New images capture 'stealth merger' of dwarf galaxies
New images of a nearby dwarf galaxy have revealed a dense stream of stars in its outer regions, the remains of an even smaller companion galaxy in the process of merging with its host. The host galaxy, known ...
Feb 08, 2012 |
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NASA's Galaxy Evolution explorer in standby mode
(PhysOrg.com) -- NASA's Galaxy Evolution Explorer, or Galex, was placed in standby mode today as engineers prepare to end mission operations, nearly nine years after the telescope's launch. The spacecraft ...
Space & Earth / Space Exploration
Feb 08, 2012 |
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Scientists chart high-precision map of Milky Way's magnetic fields
(PhysOrg.com) -- Scientists at the Naval Research Laboratory (NRL) are part of an international team that has pooled their radio observations into a database, producing the highest precision map to date of ...
Feb 03, 2012 |
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Do black holes help stars form?
(PhysOrg.com) -- The center of just about every galaxy is thought to host a black hole, some with masses of thousands of millions of Suns and consequently strong gravitational pulls that disrupt material around ...
Feb 03, 2012 |
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Classic portrait of a barred spiral galaxy
(PhysOrg.com) -- The NASA/ESA Hubble Space Telescope has taken a picture of the barred spiral galaxy NGC 1073, which is found in the constellation of Cetus (The Sea Monster). Our own galaxy, the Milky Way, ...
Feb 03, 2012 |
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Hubble zooms in on a magnified galaxy
(PhysOrg.com) -- Thanks to the presence of a natural "zoom lens" in space, NASA's Hubble Space Telescope got a uniquely close-up look at the brightest "magnified" galaxy yet discovered.
Feb 02, 2012 |
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EU probes Samsung, Germany blocks its tablets
Samsung took a hit in its battle against arch-rival Apple on Tuesday, when the European Union announced it will investigate whether it is illegally trying to hinder competitors and Germany blocked sales of ...
Jan 31, 2012 |
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Blip in night sky tells story of cosmic catastrophe
(PhysOrg.com) -- NASAs Astronomy Picture of the Day, taken by Adam Block of the UAs Mt. Lemmon SkyCenter, shows the aftermath of a stellar explosion that happened 25 million years ago in an odd-shaped ...
Jan 30, 2012 |
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A galactic magnetic field in a lab bolsters astrophysical theory
Why is the universe magnetized? It's a question scientists have been asking for decades. Now, an international team of researchers including a University of Michigan professor have demonstrated that it could ...
Jan 25, 2012 |
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The wild early lives of today's most massive galaxies
(PhysOrg.com) -- Using the APEX telescope, a team of astronomers has found the strongest link so far between the most powerful bursts of star formation in the early Universe, and the most massive galaxies ...
Jan 25, 2012 |
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Verizon cuts price and memory storage of Droid Razr, as expected
One of my major complaints when I'm reviewing just about any top-of-the-line Android smartphone on Verizon is the price.
Electronics / Consumer & Gadgets
Jan 20, 2012 |
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Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The name is from the Greek root galaxias [γαλαξίας], meaning "milky," a reference to the Milky Way galaxy. Typical galaxies range from dwarfs with as few as ten million (107) stars up to giants with one trillion (1012) stars, all orbiting the galaxy's center of mass. Galaxies can also contain many multiple star systems, star clusters, and various interstellar clouds. The Sun is one of the stars in the Milky Way galaxy; the Solar System includes the Earth and all the other objects that orbit the Sun.
Historically, galaxies have been categorized according to their apparent shape (usually referred to as their visual morphology). A common form is the elliptical galaxy, which has an ellipse-shaped light profile. Spiral galaxies are disk-shaped assemblages with curving, dusty arms. Galaxies with irregular or unusual shapes are known as peculiar galaxies, and typically result from disruption by the gravitational pull of neighboring galaxies. Such interactions between nearby galaxies, which may ultimately result in galaxies merging, may induce episodes of significantly increased star formation, producing what is called a starburst galaxy. Small galaxies that lack a coherent structure could also be referred to as irregular galaxies.
There are probably more than 100 billion (1011) galaxies in the observable universe. Most galaxies are 1,000 to 100,000 parsecs in diameter and are usually separated by distances on the order of millions of parsecs (or megaparsecs). Intergalactic space (the space between galaxies) is filled with a tenuous gas of an average density less than one atom per cubic meter. The majority of galaxies are organized into a hierarchy of associations called clusters, which, in turn, can form larger groups called superclusters. These larger structures are generally arranged into sheets and filaments, which surround immense voids in the universe.
Although it is not yet well understood, dark matter appears to account for around 90% of the mass of most galaxies. Observational data suggests that supermassive black holes may exist at the center of many, if not all, galaxies. They are proposed to be the primary cause of active galactic nuclei found at the core of some galaxies. The Milky Way galaxy appears to harbor at least one such object within its nucleus.
For more information about Galaxy, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.