Numerous Hydrogen Clouds discovered lurking among our galactic neighbours

This combined graphic shows new, high-resolution GBT imaging (in box) of recently discovered hydrogen clouds between M31 (upper right) and M33 (bottom left). 

Credit: Bill Saxton, NRAO/AUI/NSF

In a dark, starless patch of intergalactic space, astronomers have discovered a never-before-seen cluster of hydrogen clouds strewn between two nearby galaxies, Andromeda (M31) and Triangulum (M33).

The researchers speculate that these rarefied blobs of gas—each about as massive as a dwarf galaxy—condensed out of a vast and as-yet undetected reservoir of hot, ionized gas, which could have accompanied an otherwise invisible band of dark matter.

The astronomers detected these objects using the National Science Foundation's Green Bank Telescope (GBT) at the National Radio Astronomy Observatory (NRAO) in Green Bank, W.Va. The results were published in the journal Nature.

Spencer Wolfe

"We have known for some time that many seemingly empty stretches of the Universe contain vast but diffuse patches of hot, ionized hydrogen," said Spencer Wolfe of West Virginia University in Morgantown.

"Earlier observations of the area between M31 and M33 suggested the presence of colder, neutral hydrogen, but we couldn't see any details to determine if it had a definitive structure or represented a new type of cosmic feature."

"Now, with high-resolution images from the GBT, we were able to detect discrete concentrations of neutral hydrogen emerging out of what was thought to be a mainly featureless field of gas."

Astronomers are able to observe neutral atomic hydrogen, which is referred to as HI (H and the Roman numeral one), because of the characteristic signal it emits at radio wavelengths, which can be detected by radio telescopes on Earth.

Though this material is abundant throughout the cosmos, in the space between galaxies it can be very tenuous and the faint signal it emits can be extremely difficult to detect.



The animation demonstrates the difference in resolution from the original Westerbork Radio Telescope data (Braun & Thilker, 2004) and the finer resolution imaging of GBT, which revealed the hydrogen clouds between M31 and M33. 

Credit: Bill Saxton, NRAO/AUI/NSF.

A little more than a decade ago, astronomers had the first speculative hints that a previously unrecognized reservoir of hydrogen lay between M31 and M33.

The signal from this gas, however, was too faint to draw any firm conclusions about its nature, origin, or even certain existence.

Last year, preliminary data taken with the GBT confirmed that there was indeed hydrogen gas, and a lot of it, smeared out between the galaxies.

These preliminary observations, however, lacked the necessary sensitivity to see any fine-grain structure in the gas or deduce whence it came and what it signified.

The most likely explanation at the time was that a few billion years earlier, these two galaxies had a close encounter and the resulting gravitational perturbations pulled off some wispy puffs of gas, leaving a tenuous bridge between the two.

Mysterious electron Cluster found hidden among Van Allen belts

This NASA rendering depicts Earth's Van Allen radiation belts and the path of the Van Allen Probe spacecraft, which were launched in August 2012. 

Data from the spacecraft have confirmed a never-before-seen phenomenon-a long-lived zone of high-energy electrons residing between the inner and outer radiation belts. (Credit: NASA illustration)

U.S. researchers, including a trio from Los Alamos National Laboratory, have witnessed the mysterious appearance of a relatively long-lived zone of high-energy electrons stored between Earth's Van Allen radiation belts.

The surprising findings, discovered by NASA's Van Allen Probes (formerly known as the Radiation Belt Storm Probes), were outlined Thursday in Science Express and during a press conference at NASA headquarters in Washington, D.C.

The research was led by Dan Baker of the University of Colorado, Boulder, Laboratory for Atmospheric and Space Physics.

"Nature keeps on surprising us by producing long-lived harsh environments in space in regions not previously considered," said Los Alamos plasma physicist Reiner Friedel of LANL's Intelligence and Space Research Division. "This finding may impact the planning of future space missions."

The Van Allen radiation belts - named in honor James Van Allen, who discovered them nearly 50 years ago - are a pair of donut shaped zones of charged particles that surround Earth and occupy the inner region of our planet's Magnetosphere.

The outer belt contains extremely high-energy electrons, while the inner belt is comprised of energetic protons and electrons.

The belts have been studied extensively since the dawn of the Space Age, because the high-energy particles in the outer ring can cripple or disrupt spacecraft. Long-term observation of the belts have hinted that the belts can act as efficient and powerful particle accelerators; the recent observations by the Van Allen Probes-a pair of spacecraft launched in August 2012-now seem to confirm this.

Shortly after launch, the spacecraft activated their Relativistic Electron-Proton Telescope (REPT) instruments to measure particles within the belts and their immediate environs.

The instrument immediately detected on September 1, 2012, the presence of a stable zone of high-energy electrons residing between the belts. This donut-shaped third ring nestled between the belts existed for nearly a month before being obliterated by a powerful shockwave of particles emanating from center of the solar system.

Such a distinct, long-lasting ring of high-energy electrons had never before been seen by any prior instrument in space or on Earth.

The findings suggest that the Van Allen Belts somehow capture and store energetic electrons in a circular path around our home planet, perhaps in much the same way as a cyclotron can capture and store charged particles here on Earth.

"One of the main reasons the Van Allen Probe instruments are seeing these new features are their unprecedented sensitivity and rejection of backgrounds," Friedel said.

"As the mission proceeds, we expect further surprises that will challenge our conventional wisdom on the transport, loss and energization processes in these highly energetic electron radiation regions."

Iceland Eyjafjallajokull Volcano: Images of a river of ash among the clouds

After more than a week of relatively subdued activity in late April, Iceland’s Eyjafjallajokull Volcano began a fresh round of explosive ash eruptions in the first week of May.

Picture available from ESA Earth Observatory site

On the morning of May 6, 2010, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this view of a thick plume of ash blowing east and then south from the volcano.

Click Here for Live Webcam Views

Clouds bracket the edges of the scene, but the dark blue waters of the Atlantic Ocean show in the middle, and above them, a rippling, brownish-yellow river of ash.

MORE: ESA plans new instruments to monitor volcanic ash clouds on future Earth Observation spacecraft.

WEBCAM View: Eyjafjallajokull volcano, including Infrared views

In Liquid and Air, Scientists Find Order Among the Chaos - NYTimes.com

In Liquid and Air, Scientists Find Order Among the Chaos - NYTimes.com

Assisted by instruments that can track in fine detail how parcels of fluid move, and by low-cost computers that can crunch vast amounts of data quickly, researchers have found hidden structures beyond Monterey Bay, structures that explain why aircraft meet unexpected turbulence, why the air flow around a car causes drag and how blood pumps from the heart's ventricles. In December, the journal Chaos will highlight the research under way to track the moving skeletons embedded in complex flows, known as Lagrangian coherent structures.

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