Determining the Sources of the Zodiacal Cloud Using Relative Velocities of Dust Particles from High-Resolution Spectroscopy

The zodiacal cloud is the Solar System debris disk in which the Earth’s orbit is located. The dust that comprises the cloud comes from cometary, asteroidal, interstellar, and other source populations, but the relative ratios have proven hard to determine. However, asteroidal and cometary particles typically have different types of orbits, with asteroidal particles having more circular and lower inclination orbits than cometary particles. Accordingly, the relative velocities of these groups of particles with respect to Earth are also different, and measurements of these relative velocities can help distinguish between the sources. The spectrum of the zodiacal light contains solar absorption lines that are Doppler-shifted by moving dust particles. It is possible to determine dust particle velocities by observing the Doppler-shifted zodiacal light using the Wisconsin H-alpha Mapper (WHAM) — a specialized Fabry-Perot spectrometer. Focusing on a pair of scattered solar Mg I Fraunhofer lines, we have recently begun a three-year observing campaign with WHAM. In order to interpret these observations, we need to produce synthetic observations of how different orbital distributions of dust particles would shift and modify the observed spectral lines. Comparing these synthetic spectra to the actual observations will allow us to constrain the sources of the dust composing the zodiacal cloud. Here I present an overview of this new project and my work in analyzing the Ipatov et al (2008) code that will be altered to generate the synthetic spectra

Police Responses to a Course in Psychology

Although much police activity involves dealing with human behavior and mental health, policemen typically receive little training in behavioral science concepts and techniques. Recent events have dramatized the need for such training, and some efforts are being made to provide it.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67241/2/10.1177_001112877001600405.pd

Spatial and temporal variability of the snow environment in the Western Canadian Arctic

Snow cover in the Western Canadian Arctic is a significant input to the hydrological mass balance, it produces shelter and habitat for animals and humans, and supports interactions with vegetation and climate. The Arctic-tundra snow cover is greatly impacted by wind erosion, redistribution and deposition of snow during high wind events over the winter months. As a result, the end of winter snow cover is characterised by significant small-scale (on the order of a few meters) spatial variations in snow cover depth, density, and thus snow water equivalent (SWE), and runoff. Future climate related changes to snow cover depth and density will have significant consequences to the hydrology, ecology and climatology of the Arctic. This thesis reviews a multi-year record of snow studies in Siksik Creek, a sub-catchment of Trail Valley Creek (TVC) located in the western Canadian Arctic. TVC is located in the taiga-tundra transition zone, dominated by tundra, but with shrub and forest patches. Wind speed, snow depth, temperature and snowfall were measured over the full annual cycle, while end of winter snow accumulation was measured through ground based snow surveys and aerial imagery from an unmanned aerial system (UAS). The snow cover of TVC is highly influenced by its vegetation, topography and climate. Therefore, as the climate and vegetation continues to change in the coming decades, it is expected that there will be great changes in snow cover and, consequently, impacts on water resources, animal habitats and vegetation. The results from this thesis will provide information on improved methods to measure the snow environment, and the data sets needed to test snow models required for understanding future changes in snow

Determining the Sources of the Zodiacal Cloud Using Relative Velocities of Dust Particles From High-Resolution Spectroscopy

The zodiacal cloud is the Solar System debris disk in which the Earth’s orbit is located. The dust that comprises the cloud comes from cometary, asteroidal, interstellar, and other source populations, but the relative ratios have proven hard to determine. However, asteroidal and cometary particles typically have different types of orbits, with asteroidal particles having more circular and lower inclination orbits than cometary particles. Accordingly, the relative velocities of these groups of particles with respect to Earth are also different, and measurements of these relative velocities can help distinguish between the sources. The spectrum of the zodiacal light contains solar absorption lines that are Doppler-shifted by moving dust particles. It is possible to determine dust particle velocities by observing the Doppler-shifted zodiacal light using the Wisconsin H-alpha Mapper (WHAM) — a specialized Fabry-Perot spectrometer. Focusing on a pair of scattered solar Mg I Fraunhofer lines, we have recently begun a three-year observing campaign with WHAM. In order to interpret these observations we need to produce synthetic observations of how different orbital distributions of dust particles would shift and modify the observed spectral lines. Comparing these synthetic spectra to the actual observations will allow us to constrain the sources of the dust composing the zodiacal cloud. Here I present an overview of this new project and my work in analyzing the Ipatov et al (2008) code that will be altered to generate the synthetic spectra

Magnetic inflation and stellar mass. V. Intensification and saturation of M-dwarf absorption lines with Rossby number

In young Sun-like stars and field M-dwarf stars, chromospheric and coronal magnetic activity indicators such as Hα, X-ray, and radio emission are known to saturate with low Rossby number (Ro lesssim 0.1), defined as the ratio of rotation period to convective turnover time. The mechanism for the saturation is unclear. In this paper, we use photospheric Ti i and Ca i absorption lines in the Y band to investigate magnetic field strength in M dwarfs for Rossby numbers between 0.01 and 1.0. The equivalent widths of the lines are magnetically enhanced by photospheric spots, a global field, or a combination of the two. The equivalent widths behave qualitatively similar to the chromospheric and coronal indicators: we see increasing equivalent widths (increasing absorption) with decreasing Ro and saturation of the equivalent widths for Ro lesssim 0.1. The majority of M dwarfs in this study are fully convective. The results add to mounting evidence that the magnetic saturation mechanism occurs at or beneath the stellar photosphere.Published versio

A physically motivated and empirically calibrated method to measure effective temperature, metallicity, and Ti abundance of M dwarfs

The ability to perform detailed chemical analysis of Sun-like F-, G-, and K-type stars is a powerful tool with many applications including studying the chemical evolution of the Galaxy and constraining planet formation theories. Unfortunately, complications in modeling cooler stellar atmospheres hinders similar analysis of M-dwarf stars. Empirically-calibrated methods to measure M dwarf metallicity from moderate-resolution spectra are currently limited to measuring overall metallicity and rely on astrophysical abundance correlations in stellar populations. We present a new, empirical calibration of synthetic M dwarf spectra that can be used to infer effective temperature, Fe abundance, and Ti abundance. We obtained high-resolution (R~25,000), Y-band (~1 micron) spectra of 29 M dwarfs with NIRSPEC on Keck II. Using the PHOENIX stellar atmosphere modeling code (version 15.5), we generated a grid of synthetic spectra covering a range of temperatures, metallicities, and alpha-enhancements. From our observed and synthetic spectra, we measured the equivalent widths of multiple Fe I and Ti I lines and a temperature-sensitive index based on the FeH bandhead. We used abundances measured from widely-separated solar-type companions to empirically calibrate transformations to the observed indices and equivalent widths that force agreement with the models. Our calibration achieves precisions in Teff, [Fe/H], and [Ti/Fe] of 60 K, 0.1 dex, and 0.05 dex, respectively and is calibrated for 3200 K < Teff < 4100 K, -0.7 < [Fe/H] < +0.3, and -0.05 < [Ti/Fe] < +0.3. This work is a step toward detailed chemical analysis of M dwarfs at a similar precision achieved for FGK stars.Comment: accepted for publication in ApJ, all synthetic spectra available at http://people.bu.edu/mveyette/phoenix

Arkansas Symphony Orchestra

This is the program of the Arkansas Symphony Orchestra concert, directed by Philip Mann, featuring music by Dr. W. Francis McBeth, held on March 8, 2013, in the Jones Performing Arts Center

A Catalog of Cool Dwarf Targets for the Transiting Exoplanet Survey Satellite

We present a catalog of cool dwarf targets ($V-J>2.7$, $T_{\rm eff} \lesssim 4000 K$) and their stellar properties for the upcoming Transiting Exoplanet Survey Satellite (TESS), for the purpose of determining which cool dwarfs should be observed using two-minute observations. TESS has the opportunity to search tens of thousands of nearby, cool, late K and M-type dwarfs for transiting exoplanets, an order of magnitude more than current or previous transiting exoplanet surveys, such as {\it Kepler}, K2 and ground-based programs. This necessitates a new approach to choosing cool dwarf targets. Cool dwarfs were chosen by collating parallax and proper motion catalogs from the literature and subjecting them to a variety of selection criteria. We calculate stellar parameters and TESS magnitudes using the best possible relations from the literature while maintaining uniformity of methods for the sake of reproducibility. We estimate the expected planet yield from TESS observations using statistical results from the Kepler Mission, and use these results to choose the best targets for two-minute observations, optimizing for small planets for which masses can conceivably be measured using follow up Doppler spectroscopy by current and future Doppler spectrometers. The catalog is incorporated into the TESS Input Catalog and TESS Candidate Target List until a more complete and accurate cool dwarf catalog identified by ESA's Gaia Mission can be incorporated.Comment: Accepted to The Astronomical Journal. For the full catalog, please contact the corresponding autho

The gold standard: accurate stellar and planetary parameters for eight Kepler M dwarf systems enabled by parallaxes

We report parallaxes and proper motions from the Hawaii Infrared Parallax Program for eight nearby M dwarf stars with transiting exoplanets discovered by Kepler. We combine our directly measured distances with mass-luminosity and radius–luminosity relationships to significantly improve constraints on the host stars’ properties. Our astrometry enables the identification of wide stellar companions to the planet hosts. Within our limited sample, all the multi-transiting planet hosts (three of three) appear to be single stars, while nearly all (four of five) of the systems with a single detected planet have wide stellar companions. By applying strict priors on average stellar density from our updated radius and mass in our transit fitting analysis, we measure the eccentricity probability distributions for each transiting planet. Planets in single-star systems tend to have smaller eccentricities than those in binaries, although this difference is not significant in our small sample. In the case of Kepler-42bcd, where the eccentricities are known to be ≃0, we demonstrate that such systems can serve as powerful tests of M dwarf evolutionary models by working in L⋆ − ρ⋆ space. The transit-fit density for Kepler- 42bcd is inconsistent with model predictions at 2.1σ (22%), but matches more empirical estimates at 0.2σ (2%), consistent with earlier results showing model radii of M dwarfs are underinflated. Gaia will provide high-precision parallaxes for the entire Kepler M dwarf sample, and TESS will identify more planets transiting nearby, late-type stars, enabling significant improvements in our understanding of the eccentricity distribution of small planets and the parameters of late-type dwarfs.Support for Program number HST-HF2-51364.001-A was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555.Some of the data presented in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NNX09AF08G and by other grants and contracts. This paper includes data collected by the Kepler mission. Funding for the Kepler mission is provided by the NASA Science Mission directorate. The authors acknowledge the Texas Advanced Computing Center (TACC) at The University of Texas at Austin for providing HPC resources that have contributed to the research results reported within this paper. URL: http://www.tacc.utexas.edu. (HST-HF2-51364.001-A - NASA through Space Telescope Science Institute; NAS5-26555 - NASA; NNX09AF08G - NASA Office of Space Science; NASA Science Mission directorate