Retired A Stars and Their Companions IV. Seven Jovian Exoplanets from Keck Observatory

We report precise Doppler measurements of seven subgiants from Keck Observatory. All seven stars show variability in their radial velocities consistent with planet-mass companions in Keplerian orbits. The host stars have masses ranging from 1.1 < Mstar/Msun < 1.9, radii 3.4 < Rstar/Rsun < 6.1, and metallicities -0.21 < [Fe/H] < +0.26. The planets are all more massive than Jupiter (Msini > 1 Mjup) and have semimajor axes > 1 AU. We present millimagnitude photometry from the T3 0.4m APT at Fairborn observatory for five of the targets. Our monitoring shows these stars to be photometrically stable, further strengthening the interpretation of the observed radial velocity variability. The orbital characteristics of the planets thus far discovered around former A-type stars are very different from the properties of planets around dwarf stars of spectral type F, G and K, and suggests that the formation and migration of planets is a sensitive function of stellar mass. Three of the planetary systems show evidence of long-term, linear trends indicative of additional distant companions. These trends, together with the high planet masses and increased occurrence rate, indicate that A-type stars are very promising targets for direct imaging surveys.Comment: PASP Accepted, final submission awaiting comments from the communit

The California Planet Survey II. A Saturn-Mass Planet Orbiting the M Dwarf Gl649

We report precise Doppler measurements of the nearby (d = 10.34 pc) M dwarf Gl649 that reveal the presence of a planet with a minimum mass Msini = 0.328 Mjup in an eccentric (e = 0.30), 598.3 day orbit. Our photometric monitoring reveals Gl649 to be a new variable star with brightness changes on both rotational and decadal timescales. However, neither of these timescales are consistent with the 600-day Doppler signal and so provide strong support for planetary reflex motion as the best interpretation of the observed radial velocity variations. Gl649b is only the seventh Doppler-detected giant planet around an M dwarf. The properties of the planet and host-star therefore contribute significant information to our knowledge of planet formation around low-mass stars. We revise and refine the occurrence rate of giant planets around M dwarfs based on the California Planet Survey sample of low-mass stars (M* < 0.6 Msun). We find that f = 3.4^{+2.2}_{-0.9}% of stars with M* < 0.6 Msun harbor planets with Msini > 0.3$ Mjup and a < 2.5 AU. When we restrict our analysis to metal-rich stars with [Fe/H] > +0.2 we find the occurrence rate is 10.7^{+5.9}_{-4.2}%.Comment: 8 pages, 4 figures, 3 tables, PASP accepte

Particle Movement and Separation Phenomena for a Gravity Separator: I. Development of a Markov Probability Model and Estimation of Model Parameters

The complexity of gravity separator mechanics precludes the use of a deterministic model for particle movement on a gravity separator. Particle movement is examined as a stochastic process; a distance-transition Markov probability model for particle movement is proposed. A linear programming method for estimation of the Markov model parameters is explained

Simulated Effects of Fertilizer Management on Nitrate Loss with Tile Drainage Water for Continuous Corn

A computer simulation model was used to estimate the impact of different fertilizer management practices for continuous corn production on the loss of nitrate-nitrogen with tile drainage water. Simulations using historical weather data were conducted for seven consecutive growing seasons for a location in Iowa. Currently, nitrogen management by most farmers in Iowa can be represented by a single application (usually NH3-N) of about 150 kg/ha. Management schemes tested to improve the efficiency of nitrogen use include fertilizer application rates, and timing and the number of applications. Model results indicate that lower application rates and multiple applications significantly decrease nitrate-nitrogen losses in both wet and dry years

Particle Movement and Separation Phenomena for a Gravity Separator: II. Experimental Data and Performance of Distance-Transition Markov Models

Linear programming procedures are used to fit stationary and nonstationary distance-transition Markov probability models to experimentally obtained particle distribution data from the deck of a gravity separator. Particle movement modeled is that of a light discard fraction. Performance of the models is examined by comparing predicted typical\u27\u27 particle pathways with observed particle pathways. The Markov process is found to be an appropriate model of particle movement

What Can You Do About a Wet Basement?

The main solution to the wet basement problem is to provide efficient drainage to remove excess water from the soil around basement walls to relieve the water from the soil around basement walls and to relieve the water pressure that builds up under the basement floor

Alpha Enhancement and the Metallicity Distribution Function of Plaut's Window

We present Fe, Si, and Ca abundances for 61 giants in Plaut's Window (l=-1,b=-8.5) and Fe abundances for an additional 31 giants in a second, nearby field (l=0,b=-8) derived from high resolution (R~25,000) spectra obtained with the Blanco 4m telescope and Hydra multifiber spectrograph. The median metallicity of red giant branch (RGB) stars in the Plaut field is ~0.4 dex lower than those in Baade's Window, and confirms the presence of an iron abundance gradient along the bulge minor axis. The full metallicity range of our (biased) RGB sample spans -1.5<[Fe/H]<+0.3, which is similar to that found in other bulge fields. We also derive a photometric metallicity distribution function for RGB stars in the (l=-1,b=-8.5) field and find very good agreement with the spectroscopic metallicity distribution. The radial velocity and dispersion data for the bulge RGB stars are in agreement with previous results of the BRAVA survey, and we find evidence for a decreasing velocity dispersion with increasing [Fe/H]. The [alpha/Fe] enhancement in Plaut field stars is nearly identical to that observed in Baade's window, and suggests that an [alpha/Fe] gradient does not exist between b=-4 and -8. Additionally, a subset of our sample (23 stars) appear to be foreground red clump stars that are very metal--rich, exhibit small metallicity and radial velocity dispersions, and are enhanced in alpha elements. While these stars likely belong to the Galactic inner disk population, they exhibit [alpha/Fe] ratios that are enhanced above the thin and thick disk.Comment: Accepted for publication in ApJ. 38 pages, 11 figures, and 2 tables. Requests for higher resolution figures and electronic versions of tables 1 and/or 2 in advance of publication may be sent to cijohnson[at]astro.ucla.ed

Nonlocalized modulation of periodic reaction diffusion waves: The Whitham equation

In a companion paper, we established nonlinear stability with detailed diffusive rates of decay of spectrally stable periodic traveling-wave solutions of reaction diffusion systems under small perturbations consisting of a nonlocalized modulation plus a localized perturbation. Here, we determine time-asymptotic behavior under such perturbations, showing that solutions consist to leading order of a modulation whose parameter evolution is governed by an associated Whitham averaged equation

Methodology of programming small watershed development

This is a study of some physical and economic aspects of planning for the conservation and development of soil and water resources on a small watershed basis. Specific problems covered are: (1) applying multipurpose concepts which have guided river-basin planning to the evaluation of conservation needs and development opportunities in much smaller drainages, (2) reconciling the economic objectives and management plans of farmers who control watershed uplands with the objectives and plans of other private or public economic subunits affected by upland use and (3) formulating optimal development programs for small watersheds, defined as programs that will maximize discounted net benefits without forcing any economic subunit to incur net losses. The study\u27s main objective was to treat these problems by illustrating procedures both for evaluating development possibilities and for devising alternative optimal development programs. Emphical investigations focused on the 480-acre Nepper Watershed, which includes parts of seven farms in Monona County of western Iowa and drains into the Maple, Little Sioux and Missouri rivers. Planning in the Nepper Watershed was directed toward determining particular combinations of land treatment and structural measures effective in achieving a community objective, or planning norm, from a complex of land, labor and capital resources available at a given point in time (specified as the year 1947). Potential beneficiaries of cooperative development were seven farm operating units, Monona County and the offsite area