Energy ribbon at solar system's edge a 'cosmic roadmap'

A model of the interstellar magnetic fields which would otherwise be straight -- warping around the outside of our heliosphere, based on data from NASA's Interstellar Boundary Explorer. The red arrow shows the direction in which the solar system moves through the galaxy.NASA/IBEX/UNH

Cosmic ray intensities (left) compared with predictions (right) from NASA's IBEX spacecraft. The similarity between these observations and predictions supports the local galactic magnetic field direction determined from IBEX observations made from particles at vastly lower energies than the cosmic ray observations shown here. The blue area represents regions of lower fluxes of cosmic rays. The gray and white lines separate regions of different energiesâlower energies above the lines, high energies below.Nathan Schwadron/UNH-EOS

A strange ribbon of energy and particles at the edge of the solar system first spotted by a NASA spacecraft appears to serve as a sort of "roadmap in the sky" for the interstellar magnetic field, scientists say.

By comparing ground-based studies and in-space observations of solar system's mysterious energy ribbon, which was first discovered by NASA's Interstellar Boundary Explorer (IBEX) in 2009, scientists are learning more details about the conditions at the solar system's edge. The study also sheds light into the sun's environment protects the solar system from high-energy cosmic rays. [Photos and Images from NASA's IBEX Spacecraft]

"What I always have been trying to do was to establish a clear connection between the very high-energy cosmic rays we're seeing [from the ground] and what IBEX is seeing," study leader Nathan Schwadron, a physicist at the University of New Hampshire, told Space.com.

Previously, maps from ground-based observatories showed researchers that clusters of cosmic rays — extremely high-energy particles that originate from supernovas — are correlated with the IBEX ribbon. The ribbon is roughly perpendicular to the interstellar magnetic field while cosmic rays stream, on average, along the interstellar magnetic field. (The particles themselves are created from interactions between the solar wind and interstellar matter.)

In the longer term, Schwadron said work like this will help scientists better understand more about the boundary between our solar system and interstellar space. This is a region that only one mission — NASA's Voyager 1 spacecraft — has reached so far, and scientists know little about what that environment is like.

Travelling through the transition zone
The sun's sphere of influence in the solar system is known as the heliosphere. The sun's "solar wind" of high-energy particles flows within the heliosphere and pushes back against high-energy cosmic rays originating in interstellar space. The transition zone between these two regions is called the heliosheath.

Here's where a mystery arises: Voyager 1's measurements of the magnetic field from the edge of interstellar space show a starkly different direction of the magnetic field inferred in the IBEX ribbon, Schwadron said.

"At that point, you say to yourself what’s wrong? What could possibly be the issue? It seems like we now have good independent confirmation that the IBEX ribbon is ordered by the interstellar magnetic field, and we know that Voyager 1 takes fairly good measurements," Schwadron said.

The few studies examining this issue, showing little consensus. An October paper co-authored by Schwadron in Astrophysical Journal Letters argued that Voyager 1 could be measuring interstellar plasma coming in through magnetic field lines, but may still be in the heliosheath itself. This stands in contrast to findings from NASA and other science groups saying Voyager 1 is definitively in interstellar space.

The researchers noted that Voyager 1 is picking up its information "at a specific time and place," but IBEX's data is collected and averaged across vast distances, so that could also lead to discrepancies.

"What is really missing here is our understanding of the physics," Schwadron said, adding that reconnection between magnetic field lines could be an example of something that changes the conditions of the boundary region.

The research was published Thursday in the journal Science Express and includes participation from several United States research institutions.

View the original article here

Mysterious Ultra-Red Galaxies May Be Cosmic 'Missing Link' (SPACE.com)

Scientists have spied a new type of ultra-red galaxy lurking at the far reaches of the universe, a new study reports.

Using NASA's Spitzer space telescope, the astronomers spotted four remarkably red galaxies nearly 13 billion light-years from Earth — meaning it's taken their light about 13 billion years to reach us. So researchers are seeing the galaxies as they were in the early days of the universe, which itself is about 13.7 billion years old.

NASA's Hubble space telescope has imaged even more ancient galaxies, but the four ruddy objects seen by Spitzer are a breed apart, researchers said.

"Hubble has shown us some of the first protogalaxies that formed, but nothing that looks like this," study co-author Giovanni Fazio, of the Harvard-Smithsonian Center for Astrophysics, said in a statement. "In a sense, these galaxies might be a 'missing link' in galactic evolution."

The four newfound galaxies shine much more brightly in infrared light than in visible wavelengths, which is how the infrared-sensitive Spitzer was able to detect them. The research team still isn't sure why they're so strikingly red.

There are three main reasons why a galaxy may appear red, researchers said. First, it may be extremely dusty. Second, it could contain many old, red stars. Or third, the galaxy may be extremely distant, in which case the expansion of the universe has stretched its light to very long (and very red) wavelengths.

All three of these factors may be in play in the newfound galaxies' case, researchers said. But they're not sure, since much about them remains mysterious.

"We've had to go to extremes to get the models to match our observations," said study lead author Jiasheng Huang, also of the CfA.

The four galaxies are grouped together and appear to be physically associated, rather than constituting a chance alignment of like objects, researchers said.

The team hopes to study the galaxies further, perhaps employing powerful ground-based instruments such as the Atacama Large Millimeter Array in Chile. And they'd like to find more examples of this new type of galactic "species."

"There's evidence for others in other regions of the sky," Fazio said. "We'll analyze more Spitzer and Hubble observations to track them down."

The astronomers reported their results online in the Astrophysical Journal.

Follow SPACE.com for the latest in space science and exploration news on Twitter @Spacedotcom and on Facebook.

View the original article here

New Look at Exploding Stars Provides Cosmic Yardstick (SPACE.com)

Nola Taylor Redd, SPACE.com Contributor
Space.com Nola Taylor Redd, Space.com Contributor
space.com – Thu Aug 11, 2:14 pm ET

In universe spanning more than a billion light-years, distance can't be measured with a ruler. To judge how far away objects are, astronomers must rely on other objects whose properties are already known — such as certain kinds of exploding stars called supernova.  

New research is shedding light on the identity of one of these "standard candles," so-called because their brightness is standard enough that their true distance can be deduced from it.

Astronomers are hoping that analyzing one specific type of supernova explosion will give them a better understanding of how frequently it differs from another type. That, in turn, should allow for even more precise measurements of distance in the universe.

One dwarf or two

When a compact, dying star known as a white dwarf orbits another star closely enough, its strong gravitational pull can ultimately rip its partner apart. But the massive survivor can pack only so much material onto its surface. When its critical point is reached, it explodes as a Type 1a supernova.  

These events can be divided into two categories. One involves only the single white dwarf and its victim. The other involves two white dwarfs, with one destroying the other.  New research, published in the Aug. 12 issue of the journal Science, takes a look at just how commonplace the single-white-dwarf version of a Type 1a supernova may be. [Video: Supernovas – Destroyers and Creators]

When two white dwarfs are orbiting one another and the smaller one moves too close, it is almost instantly torn apart, creating a disk to orbit its destructive companion.

Almost immediately, the disk falls onto the remaining star, pushing it over the critical mass threshold and causing an explosion.

But when the second star in a pair isn't a white dwarf, things move slower. The stars don't get as close, and tidal forces manage to pull away only some of the gas from the near side of the second star. The white dwarf feeds on the material until it eventually reaches the critical mass, exploding as a supernova.

"Both models agree that the explosion is an accreting white dwarf," the lead author of the study, Assaf Sternberg at the Weizmann Institute of Science in Israel, told SPACE.com via email. "The disagreement is on the origin of the accreted material."

It is this material that interested Sternberg and his team. When the destroyed star is a white dwarf, the material is quickly consumed, but when it is not, traces of the gas linger even after the explosion.

The international team of astronomers used the Keck telescope in Hawaii  and the Magellan telescope in Chile to study the sodium in gas clouds around 41 Type 1a supernovas. Sodium is an element found in most stars but not in white dwarfs.

From the sample taken, the team determined that at least 24 percent of the explosions did not involve white dwarfs as the companion.

This number was a lower limit: Half or even all of the pairings could involve only one white dwarf star. The researchers couldn't specifically target which explosions contain white dwarfs and which do not. Instead, they looked for a distribution. They found more systems with sodium than would be found if there were an equal number of double-white-dwarf and single-white-dwarf systems.

Judging distances

Josh Simon, of the Carnegie Institute, explained how this event helps determine distances in the universe.

"If you know that the light bulb is 60 watts, then you can figure out how far away the light is from you by measuring how bright it looks," he told SPACE.com by email.

But the second star in the set could be a number of things. Simon likened the different pairings to light bulbs of varying wattage.

"You can't tell the difference between a 50-watt bulb nearby, a 60-watt bulb a bit further away, or a 100-watt bulb even farther away than that," Simon said.

Follow SPACE.com for the latest in space science and exploration news on Twitter @Spacedotcom and on Facebook.

View the original article here