Imaged sub-stellar companions: not as eccentric as they appear? The effect of an unseen inner mass on derived orbits

Increasing numbers of sub-stellar companions are now being discovered via direct imaging. Orbital elements for some of these objects have been derived using star--companion astrometry, and several of these appear to have eccentricities significantly greater than zero. We show that stellar motion caused by an undetected inner body may result in the companion elements derived in such a way being incorrect, which could lead to an overestimation of the eccentricity. The magnitude of this effect is quantified in several regimes and we derive the maximum eccentricity error a third body could introduce in a general form, which may be easily applied to any imaged system. Criteria for identifying systems potentially susceptible to this scenario are presented, and we find that around half of the planets/companion brown dwarfs currently imaged could be liable to these errors when their orbital elements are derived. In particular, this effect could be relevant for systems within 100 pc with companions at >50 AU, if they also harbour an unseen $\sim$ 10 Jupiter mass object at $\sim$ 10 AU. We use the Fomalhaut system as an example and show that a 10% error could be induced on the planet's eccentricity by an observationally allowed inner mass, which is similar in size to the current error from astrometry.Comment: Accepted for publication in MNRA

Profitability of Irrigated Improved Pecan Orchards in the Southern Plains

The objective was to determine if an irrigated improved pecan orchard is economical relative to agronomic systems commonly implemented by producers that have access to irrigation. Results show that the improved pecan orchard is more profitable than competitive enterprises after a twenty year time frame, but is sensitive to pecan price, pecan yield and attitude toward risk.Profitability, Irrigated, Pecan, Orchard, Southern Plains, Crop Production/Industries, Farm Management, Land Economics/Use, Production Economics, Risk and Uncertainty,

Implications of the Low Carbon Fuel Standard for State and National Ethanol Use

Resource /Energy Economics and Policy,

US BIOFUEL AND CLIMATE POLICIES DUEL OVER CELLULOSIC BIOMASS

Agricultural and Food Policy, Crop Production/Industries, Environmental Economics and Policy, International Relations/Trade, Resource /Energy Economics and Policy,

Biofuels: Impact of Selected Farm Bill Provisions and other Biofuel Policy Options

Agricultural and Food Policy, Resource /Energy Economics and Policy,

Predicting the frequencies of diverse exo-planetary systems

Extrasolar planetary systems range from hot Jupiters out to icy comet belts more distant than Pluto. We explain this diversity in a model where the mass of solids in the primordial circumstellar disk dictates the outcome. The star retains measures of the initial heavy-element (metal) abundance that can be used to map solid masses onto outcomes, and the frequencies of all classes are correctly predicted. The differing dependences on metallicity for forming massive planets and low-mass cometary bodies are also explained. By extrapolation, around two-thirds of stars have enough solids to form Earth-like planets, and a high rate is supported by the first detections of low-mass exo-planets.Comment: 5 pages, 2 figures; accepted by MNRA

EPA MANDATE WAIVERS CREATE NEW UNCERTAINTIES IN BIODIESEL MARKETS

Biodiesel, Biofuel Mandate, Waivers, Resource /Energy Economics and Policy, Q11, Q16, Q42, Q48,

Search for long lived charged massive particles in pp collisions at s-hat = 1.8TeV

We report a search for the production of long-lived charged massive particles in a data sample of 90   pb-1 of √s=1.8   TeV pp̅ collisions recorded by the Collider Detector at Fermilab. The search uses the muonlike penetration and anomalously high ionization energy loss signature expected for such a particle to discriminate it from backgrounds. The data are found to agree with background expectations, and cross section limits of O(1) pb are derived using two reference models, a stable quark and a stable scalar lepton