Modeling the Motion and Distribution of Interstellar Dust inside the Heliosphere

The interaction of dust grains originating from the local interstellar cloud with the environment inside the heliosphere is investigated. As a consequence of this interaction the spatial distribution of interstellar dust grains changes with time. Since dust grains are charged in the interplanetary plasma and radiation environment, the interaction of small grains with the heliosphere is dominated by their coupling to the solar wind magnetic field. The change of the field polarity with the solar cycle imposes a temporal variation of the spatial distribution and the flux of small (radius smaller than $0.4 \mu m$) interstellar dust grains in the Solar System, whereas the flux of large grains is constant because of their negligible coupling to the solar wind magnetic field. The flux variation observed by in-situ measurements of the Galileo and Ulysses spacecraft are reproduced by simulating the interaction of interstellar grains with charge-to-mass ratios between $0.5 C/kg^{-1}$ and $1.4 C/kg$ with the interplanetary environment.Comment: 18 pages, 9 figures (5 color figures are in separate jpeg-files), 2 tables, to appear in JGR Space physics special issue on interstellar dust and the heliospher

(WP 2011-07) Factoring Emerging Markets into the Relationship Between Global Liquidity and Commodities

What caused the mid-2000s world commodity price “bubble” and the recent commodity price growth during the economic recovery after the 2007-2009 recession? The classical “supply and demand” interpretation offered by some observers suggests that rapid global industrial growth over the past decade – the so-called “demand channel” – is the key driver of price growth. Others have argued that recent bouts of commodity price growth were directly related to central banks, especially the U.S. Federal Reserve, injecting too much money or “liquidity” into the financial system. They assert that high commodity prices are a result of excessively loose monetary policy. This paper extends the current research in this area by incorporating emerging economies, the BRIC (Brazil, Russia, India, and China) nations specifically, into global measures. It is hypothesized that factoring BRIC nations into the analysis provides useful information for examining the relationship between commodity prices and global liquidity that is not captured by advanced country data alone. The statistical model in this paper accounts for the two-way relationships that can exist between output, price, and monetary variables in a globally interconnected system. Various tests of the model consistently suggest that the “demand channel” plays a large part in explaining commodity price growth whether BRIC countries are included or excluded from the analysis. However, excess liquidity may also play a part in explaining price growth. In addition, factoring in BRIC country data leads to the conclusion that unexpected movements in liquidity eventually explain more of the variation in commodity prices than unexpected demand shocks. This specific result is not caught in the sample that only incorporates advanced economies. Therefore, policymakers and researchers should not ignore emerging markets when examining commodity prices and monetary factors in a global context. Studies that exclude these countries lose key information on the effects of global monetary fluctuations

Prediction of the In-Situ Dust Measurements of the Stardust Mission to Comet 81P/Wild 2

We predict the amount of cometary, interplanetary, and interstellar cosmic dust that is to be measured by the Cometary and Interstellar Dust Analyzer (CIDA) and the aerogel collector on-board the Stardust spacecraft during its fly-by of comet P/Wild 2 and during the interplanetary cruise phase. We give the dust flux on the spacecraft during the encounter with the comet using both, a radially symmetric and an axially symmetric coma model. At closest approach, we predict a total dust flux of $10^{6.0} m^{-2} s^{-1}$ for the radially symmetric case and $10^{6.5} m^{-2} s^{-1}$ for the axially symmetric case. This prediction is based on an observation of the comet at a heliocentric distance of $1.7 {\rm AU}$. We reproduce the measurements of the Giotto and VEGA missions to comet P/Halley using the same model as for the Stardust predictions. The planned measurements of {\em interstellar} dust by Stardust have been triggered by the discovery of interstellar dust impacts in the data collected by the Ulysses and Galileo dust detector. Using the Ulysses and Galileo measurements we predict that 25 interstellar particles, mainly with masses of about $10^{-12} g$, will hit the target of the CIDA experiment. The interstellar side of the aerogel collector will contain 120 interstellar particles, 40 of which with sizes greater than $1 \mu m$. We furthermore investigate the ``contamination'' of the CIDA and collector measurements by interplanetary particles during the cruise phase.Comment: 42 pages, 21 figures, 5 tables, uses LaTeX 2e and epsf.sty, to appear in Planetary and Space Scienc