William Atkins
Thursday, 24 December 2009 21:38
Science -
Space
Page 2 of 3
And, the Local Fluff is held just outside of the heliosheath by the Sun’s magnetic field (through the solar wind).
The NASA article states that the:
“Solar wind inflates the bubble from the inside while the Local Fluff compresses it from the outside.”
The Local Fluff is about 30 light-years in width (where one light-year is the distance that light travels in a vacuum in one Earth-year). It contains a very tenuous mixture of hydrogen and helium atoms, all with a temperature of about 6,000 degrees Celsius (10,800 degrees Fahrenheit), generally about the same temperature as the Sun.
Astronomers believe that the Solar System entered the Local Fluff at some time between 44,000 and 150,000 years ago and it is expected to remain within this Local Interstellar Cloud for another 10,000 to 20,000 years.
The NASA article explains why the Local Fluff even exists. It states,
“The existential mystery of the Fluff has to do with its surroundings. About 10 million years ago, a cluster of supernovas exploded nearby, creating a giant bubble of million-degree gas. The Fluff is completely surrounded by this high-pressure supernova exhaust and should be crushed or dispersed by it.”
However, it has not been crushed or even destroyed (lucky for us!).
Dr. Opher explains:
"The observed temperature and density of the local cloud do not provide enough pressure to resist the 'crushing action' of the hot gas around it. "Voyager data show that the Fluff is much more strongly magnetized than anyone had previously suspected—between 4 and 5 microgauss (where micro stands for one-millionth, in this case one-millionth of one gauss). This magnetic field can provide the extra pressure required to resist destruction."
The unit of Gauss (abbreviated G) is a measurement for the magnetic field (or magnetic flux density). One gauss is defined as one maxwell per square centimeter.
Page three concludes with information on the Opher team, and their Nature paper.
