January 31, 2012
New ‘Alien’ Particles Have Entered Our Solar System
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Researchers have measured neutral "alien" particles that have entered our solar system from interstellar space.
The team used NASA's Interstellar Boundary Explorer (IBEX) spacecraft to find the neutral particles, which make up about half the material outside the heliosphere.
The heliosphere is the bubble in which our Sun and planets reside and is formed by the interaction between the solar wind and the interstellar medium.
Electrically charged particles cannot penetrate the boundary between these two bodies, but neutral particles are able to flow freely through it.
Ulysses is the only other spacecraft that has been able to directly detect these neutral particles.
IBEX's low-energy energetic neutral atom camera has measured interstellar neutral particles that Ulysses was unable to detect.
The spacecraft's data reveals that interstellar neutrals enter the heliosphere at a speed of about 52,000 miles per hour.
IBEX discovered that the solar wind is about 7,000 miles per hour slower than previously thought, which indicates that our solar system is in the "local interstellar cloud."
The scientists have performed the first detailed analyses of samples of captured interstellar neutral atoms. The team said the findings are important because the interstellar gas surrounding us can affect the strength of the Sun's heliosphere.
The astronomers say that we will transition into a different region at any time within a few thousand years where conditions will change and affect the heliosphere's protective capability for better or for worse.
As the solar system travels around the Milky Way through cosmic time, the nature of the heliosphere has likely had implications on the evolution of life on Earth, as varying levels of radiation spurred genetic mutations, and extinctions.
A deeper understanding of our heliosphere could help scientists explore astrospheres that surround other stars through the Milky Way.
IBEX found neutral atoms in 2009 and 2010, but the new discovery is the most complete glimpse of the material.
"We've directly measured four separate types of atoms from interstellar space and the composition just doesn't match up with what we see in the solar system," Eric Christian, mission scientist for IBEX at NASA's Goddard Space Flight Center in Greenbelt, Md, said in a press release. "IBEX's observations shed a whole new light on the mysterious zone where the solar system ends and interstellar space begins."
These new measurements help give clues about how and where our solar system formed, the forces that physically shape our solar system, and even the history of other stars in the Milky Way.
The scientists wrote in The Astrophysical Journal that for every 20 neon atoms in the galactic wind, there are 74 oxygen atoms.
However, in our own solar system, for every 20 neon atoms there are 111 oxygen atoms. This translates to more oxygen in any given part of the solar system than in the local interstellar space.
"Our solar system is different than the space right outside it and that suggests two possibilities," David McComas, the principal investigator for IBEX at the Southwest Research Institute in San Antonio, Texas, said in a statement. "Either the solar system evolved in a separate, more oxygen-rich part of the galaxy than where we currently reside or a great deal of critical, life-giving oxygen lies trapped in interstellar dust grains or ices, unable to move freely throughout space."
Scientists are able to find out information about how our solar system interacts with the rest of space by studying the galactic winds.
IBEX's main goal is to study the helios health, which is the boundary of the solar system's heliosphere.
"Measuring the pressure on our heliosphere from the material in the galaxy and from the magnetic fields out there, will help determine the size and shape of our solar system as it travels through the galaxy," Christian said in a press release.
The new results also hold information about the history of the material in the universe. Knowing the amounts of elements in space can help map out how the galaxy evolved and changed over time.
"This set of papers provide many of the first direct measurements of the interstellar medium around us," McComas said in a press release. "We've been trying to understand our galaxy for a long time, and with all of these observations together, we are taking a major step forward in knowing what the local part of the galaxy is like."
Image 1: NASA's Interstellar Boundary Explorer (IBEX) studies the outer boundaries of the solar system where particles from the solar wind collide with particles from the galactic wind. Credit: NASA
Image 2: The galactic wind streams toward the sun from the direction of Scorpio and IBEX has found that it travels at 52,000 miles an hour. The speed of the galactic wind and its subsequent pressure on the outside of the solar system's boundary affects the shape of the heliosphere as it travels through space. Credit: NASA/Goddard Scientific Visualization Studio
Image 3: NASA's Interstellar Boundary Explorer (IBEX) has found that there's more oxygen in our solar system than there is in the nearby interstellar material. That suggests that either the sun formed in a different part of the galaxy or that outside our solar system life-giving oxygen lies trapped in dust or ice grains unable to move freely in space. Credit: NASA/Goddard
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