Subscribe free to our newsletters via your
. 24/7 Space News .




STELLAR CHEMISTRY
STEREO Creates First Images of the Solar System's Invisible Frontier
by Staff Writers
Berkeley CA (SPX) Jul 03, 2008


Hot ions in the inner heliosheath are uniquely traced by energetic neutral atoms (ENAs) and are more intense (indicated by color code) around the nose of the heliosphere. Credit: University of California, Berkeley; L. Wang

NASA's sun-focused STEREO spacecraft unexpectedly detected particles from the edge of the solar system last year, allowing University of California, Berkeley, scientists to map for the first time the energized particles in the region where the hot solar wind slams into the cold interstellar medium.

Mapping the region by means of neutral, or uncharged, atoms instead of light "heralds a new kind of astronomy using neutral atoms," said Robert Lin, UC Berkeley professor of physics and lead for the suprathermal electron sensor aboard STEREO. "You can't get a global picture of this region, one of the last unexplored regions of the heliosphere, any other way because it is too tenuous to be seen by normal optical telescopes."

The heliosphere is a volume over which the effects of the solar wind extend, stretching from the sun to more than twice the distance of Pluto. Beyond its edge, called the heliopause, lies the relative quiet of interstellar space, at about 100 astronomical units (AU) - 100 times the Earth-sun distance.

The results, reported in the July 3 issue of the journal Nature, clear up a discrepancy in the amount of energy dumped into space by the decelerating solar wind that was discovered last year when Voyager 2 crossed the solar system's termination shock and entered the surrounding heliosheath.

The termination shock is the region of the heliosphere where the supersonic solar wind slows to subsonic speed as it merges with the interstellar medium. The heliosheath is the region of roiled plasma between the shock front and the interstellar medium.

The newly discovered population of ions in the heliosheath contains about 70 percent of the energy dissipated in the termination shock, exactly the amount unaccounted for by Voyager 2's instruments, the UC Berkeley physicists concluded. The Voyager 2 results are reported in the same issue of Nature.

The twin STEREO spacecraft were launched in 2006 into Earth's orbit about the sun to obtain stereo pictures of the sun's surface and to measure magnetic fields and ion fluxes associated with solar explosions.

Between June and October 2007, however, the suprathermal electron sensor in the IMPACT (In-situ Measurements of Particles and CME Transients) suite of instruments on board each STEREO spacecraft detected neutral atoms originating from the same spot in the sky: the shock front and the heliosheath beyond, where the sun plunges through the interstellar medium.

"The suprathermal electron sensors were designed to detect charged electrons, which fluctuate in intensity depending on the magnetic field," said lead author Linghua Wang, a graduate student in UC Berkeley's Department of Physics. "We were surprised that these particle intensities didn't depend on the magnetic field, which meant they must be neutral atoms."

UC Berkeley physicists concluded that these energetic neutral atoms were originally ions heated up in the termination that lost their charge to cold atoms in the interstellar medium and, no longer hindered by magnetic fields, flowed back toward the sun and into the suprathermal electron sensors on STEREO.

"This is the first mapping of energetic neutral particles from beyond the heliosphere," Lin said. "These neutral atoms tell us about the hot ions in the heliosheath. The ions heated in the termination shock exchange charge with the cold, neutral atoms in the interstellar medium to become neutral, and then flow back in."

According to Lin, the neutral atoms are probably hydrogen, since most of the particles in the local interstellar medium are hydrogen.

The charge exchange between hot ions and neutral atoms to generate energetic neutral atoms is well known around the sun and planets, including Earth and Jupiter, and has been used by spacecraft such as IMAGE and Cassini as a means of remotely measuring the energy in ion plasmas, since neutral atoms travel much farther than ions.

A new NASA mission, the Interstellar Boundary Explorer (IBEX), is planned for launch later this year to map more thoroughly the lower-energy energetic ions in the heliosheath by means of energetic neutral atoms to discover the structure of the termination shock and how hydrogen ions are accelerated there.

.


Related Links
Stellar Chemistry, The Universe And All Within It






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle








STELLAR CHEMISTRY
Siamese Twin Galaxies In A Gravitational Embrace
La Serena, Chile (SPX) Jun 27, 2008
In what appears to be a masterful illusion, astronomers at Gemini Observatory have imaged two nearly identical spiral galaxies in Virgo, 90 million light years distant, in the early stages of a gentle gravitational embrace. The new image was obtained at the Gemini South telescope in Chile using GMOS, the Gemini Multi-Object Spectrograph. Like two skaters grabbing hands while passing ... read more


STELLAR CHEMISTRY
Looking For Early Earth...On The Moon

Moon-Bound NASA Spacecraft Passes Major Preflight Tests

Northrop Grumman Completes LCROSS Thermal Vacuum Testing

NASA Study Provides Next Step To Establishing Lunar Outpost

STELLAR CHEMISTRY
Phoenix To Bake Ice-Rich Sample Next Week

Rain Showers On Mars

Mars Sample Return: The Next Step In Exploring The Red Planet

New Soil Analysis Suggests It Rained On Mars Long Ago

STELLAR CHEMISTRY
Analex Awarded Three-Year Option On NASA Expendable Launch Vehicles Integrated Support

Russia seals agreement with private investor for space tourism

Fly me to the Moon: Japan firm offers weddings in space

NASA Goddard Has More Than A Dozen Exciting Missions In Next Year

STELLAR CHEMISTRY
China's Shot Heard Around The Galaxy

Shenzhou VII Research Crew Ready To Set Out For Launch Center

A Better Focus On Shenzhou

Gallup Poll Shows Americans Unconcerned About China Space Program

STELLAR CHEMISTRY
NASA plans two ISS spacewalks next week

Discovery undocks from ISS

Shuttle astronauts bid farewell to space station crew

Shuttle Astronauts Bid Farewell To Space Station Crew

STELLAR CHEMISTRY
Russia Launches Rocket With Military Satellite

Inmarsat And ILS Set August 14 For Proton Flight With Inmarsat Satellite

Payload Integration Complete For Arianespace's Fourth Mission Of 2008

Successful Ariane 5 Solid Rocket Booster Test Firing

STELLAR CHEMISTRY
Chemical Clues Point To Dusty Origin For Earth-Like Planets

Astronomers discover clutch of 'super-Earths'

Vanderbilt Astronomers Getting Into Planet-Finding Game

NASA Selects MIT-Led Team To Develop Planet-Searching Satellite

STELLAR CHEMISTRY
NASA Considers Development Of Student-Led Satellite Initiative

SATLYNX Completes 300 Site SCADA Network Rollout For EDF Energy

Herschel Undergoes Acoustic And Vibration Tests

Russian-US Launch Firm To Put Satellite In Orbit In August




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement