Tag Archives | Galaxy

Our Milky Way Galaxy Devours Its Small Neighboring Galaxies

Milky WayVia PhysOrg:

A team of astronomers led by Sergey Koposov and Vasily Belokurov of Cambridge University recently discovered two streams of stars in the Southern Galactic hemisphere [of the Milky Way] that were torn off the Sagittarius dwarf galaxy. This discovery came from analysing data from the latest Sloan Digital Sky Survey (SDSS-III) and was announced in a paper released that connects these new streams with two previously known streams in the Northern Galactic hemisphere.

“We have long known that when small dwarf galaxies fall into bigger galaxies, elongated streams, or tails, of stars are pulled out of the dwarf by the enormous tidal field,” said Sergey Koposov.

The Sagittarius dwarf galaxy used to be one of the brightest of the Milky Way satellites. Its disrupted remnant now lies on the other side of the Galaxy, breaking up as it is crushed and stretched by huge tidal forces. It is so small that it has lost half of its stars and all its gas over the last billion years.

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Black Hole Hosts Universe’s Most Massive Water Cloud

Photo: NASA

Photo: NASA

A giant quasar billions of light-years away is surrounded by water vapor that could fill Earth’s oceans over 140 trillion times. Via National Geographic:

In a galaxy 12 billion light-years away resides the most distant and most massive cloud of water yet seen in the universe, astronomers say.

Weighing in at 40 billion times the mass of Earth, the giant cloud of mist swaddles a type of actively feeding supermassive black hole known as a quasar.

Among the brightest and most energetic objects in the universe, quasars are black holes at the centers of galaxies that are gravitationally consuming surrounding disks of material while burping back out powerful energy jets.

“As this disk of material is consumed by the central black hole, it releases energy in the form of x-ray and infrared radiation, which in turn can heat the surrounding material, resulting in the observed water vapor,” said study co-author Eric Murphy, an astronomer with the Carnegie Observatories in Pasadena, California.

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Asteroid Travels Close To Earth Today

Photo: NASA/JPL-Caltech

Photo: NASA/JPL-Caltech

Sometimes asteroids come very close to home, about every six years. The latest asteroid to come closer to Earth than our own satellites appears today. Via Space.com:

An asteroid the size of a tour bus will fly past Earth today (June 27) so closely it will be beneath some of the planet’s satellites.

The rock, named asteroid 2011 MD will zoom by just 7,500 miles (12,000 km) above the planet, making a sharp turn forced by Earth’s gravity before winging off into space again. The flyby will occur at about 1 p.m. EDT (1700 GMT).

There is no risk of an impact, NASA scientists said. The space rock, estimated to be between 29 to 98 feet (9 to 30 meters) wide, is likely too small to survive a plunge through our atmosphere anyway. An asteroid this size, if it were mostly stony, would break apart and burn up before hitting the surface.

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‘Magnetic Bubbles’ Found Around Solar System Edge

Photo: NASA

A digital image of the newly theorized 'foam zone'.

Is our solar system a ‘cosmic jacuzzi filled with magnetic bubbles’? The outer shield of our solar system was thought to be smooth, like soda gone flat, but new theory believes it may foam-like filled with “bubbles.” From National Geographic:

The edge of the solar system may be a frothy sea of giant magnetic “bubbles,” a new NASA study says.

The new findings may mean that our system’s magnetic barrier—once thought to be a smooth shield—may be letting in more harmful cosmic rays and energetic particles than previously thought.

The new “foam zone” theory is based on a computer model created using data from NASA’s twin Voyager spacecraft, both launched in 1977 and currently about 10 billion miles (16 billion kilometers) from Earth.

In 2007 Voyager 1 recorded dramatic dips and rises in the amount of electrons it encountered as the craft traveled through the heliosphere—the “force field” that surrounds the entire solar system and is created by the sun’s magnetic field.

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Astronomers Discover Oldest Galaxy Yet

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European Southern Observatory

What’s the farthest we can see from Earth? Galaxy UDFy_38135539, 13.1 billion light years away, thanks to Europe’s Very Large telescope. Daily Mail reports:

Astronomers have discovered the oldest and most distant object in the universe – a galaxy so far away that its light has taken 13.1 billion years to reach the Earth.

The galaxy, which was spotted by Europe’s Very Large telescope in Chile, is the most remote cluster of stars, gas and dust ever measured.

It is so distant, scientists are observing it when the universe was in its infancy – aged just 00 million years old, or four per cent of its present age.

Dr. Nicole Nesvadba of the Institute of Space Astrophysics in Paris said: ‘Measuring the most distant galaxy so far is very exciting in itself, but the astrophysical implication of this detection are even more important.

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Supermassive Black Hole Is Hurled Out Of Galaxy

A Hubble Space Telescope image of the galaxy studied by Marianne Heida. The white circle marks the centre of the galaxy and the red circle marks the position of the suspected offset black hole. Image: STScI / NASA

A Hubble Space Telescope image of the galaxy studied by Marianne Heida. The white circle marks the centre of the galaxy and the red circle marks the position of the suspected offset black hole. Image: STScI / NASA

This is shock and awe. Report from BBC News:

A supermassive black hole may have been observed in the process of being hurled from its parent galaxy at high speed.

The finding comes from analysis of data collected by the US Chandra space X-ray observatory. However, there are alternative explanations for the observation.

The work, by an international team of astronomers, has been published in the journal Monthly Notices of the Royal Astronomical Society.

Normally, each galaxy contains a supermassive black hole at its centre. Given that these objects can have masses equivalent to one billion Suns, it takes a special set of conditions to cause this to happen.

High-speed exit

The authors believe this could be the result of the merger of two smaller black holes.

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Supernova Winds Shape Galaxies

The Crab Nebula is a pulsar wind nebula associated with the 1054 supernova.From Discovery News:

The explosions of massive stars may be responsible for the formation of galaxies.

After years of struggling to understand how to properly assemble a galaxy, astronomers have discovered that the answer is blowin’ in the wind. The supernova wind, that is.

New computer simulations show that winds generated by supernovas, which are the explosions of massive stars, can push stars out from the center of a dwarf galaxy. This simulation of supernova winds redistributes both ordinary matter and invisible dark matter in a way that almost perfectly matches observations of the way matter is distributed in actual dwarf galaxies. Fabio Governato of the University of Washington in Seattle and his colleagues describe their simulations in the Jan. 14 Nature.

Previous attempts to model galaxy formation based on the highly successful theory of cold dark matter — which states that invisible material must account for 85 percent of the mass of the universe — have done “an awesome job” of explaining such global properties as where, when and how many galaxies should form, notes Governato.

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