Washington: Our solar system is floating through interstellar clouds of gases slower than expected, a new study has revealed.
A NASA robotic probe sampling particles flowing into our solar system from the galactic neighborhood revealed that we are residing in a cloud and will probably stay that way for another hundreds or even thousands of years.
The measurements from NASA’s Interstellar Boundary Explorer, or IBEX, spacecraft include the first direct samplings of hydrogen, oxygen and neon that did not come from the sun or anywhere else in the solar system, the Discovery News reported.
Instead, the gases, along with helium, which was earlier detected by NASA’s Ulysses spacecraft, streamed into our solar system from the galactic neighbourhood, which currently includes a tenuous wispy cloud.
The gush of interstellar particles is slower than expected, but is still cruising along at 52,000 mph, and coming from a somewhat different direction than formerly thought.
That has quite a lot of implications, including a new assessment that the sun and its brood of planets, asteroids, comets and everything else within the sun’s protective, pressurized cocoon - a structure known as the heliosphere – will not be leaving the cloud that has been our home for the last 45,000 years or so anytime soon.
The slower flow also implies that the heliosphere faces less pressure from the outside, making it more susceptible to external magnetic forces.
Subsequently, it has a different shape than previously thought, more like a squashed beach ball than a speeding bullet.
“The heliosphere is essentially the balance between outward-moving solar wind and the compression from the gas and dust that surround it, so if you're in a different interstellar medium environment, you're going to create a different heliospheric structure,” said astronomer Seth Redfield with Wesleyan University.
That in turn determines how efficiently the heliosphere shields the solar system from galactic cosmic rays and other high-energy radiation.
The new results also give rise to questions about where the solar system came from. Analysis of the interstellar gases collected by IBEX indicated a shortage of oxygen, relative to the amount of neon.
“The local cloud is actually somewhat different in composition than the sun and the Milky Way as a whole,” said University of New Hampshire physicist Eberhard Mobius.
“That leaves us with a puzzle for now. Could it be that some of this oxygen is locked up in the cosmic dust? Or does it tell us how different our neighborhood is compared to the sun's birthplace?” he added.
The study has been published in Astrophysical Journal.
First Published: Thursday, February 02, 2012, 19:05