1,859 research outputs found

    Power Spectrum Analysis of Polarized Emission from the Canadian Galactic Plane Survey

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    Angular power spectra are calculated and presented for the entirety of the Canadian Galactic Plane Survey polarization dataset at 1.4 GHz covering an area of 1060 deg2^2. The data analyzed are a combination of data from the 100-m Effelsberg Telescope, the 26-m Telescope at the Dominion Radio Astrophysical Observatory, and the Synthesis Telescope at the Dominion Radio Astrophysical Observatory, allowing all scales to be sampled down to arcminute resolution. The resulting power spectra cover multipoles from ℓ≈60\ell \approx 60 to ℓ≈104\ell \approx 10^4 and display both a power-law component at low multipoles and a flattening at high multipoles from point sources. We fit the power spectrum with a model that accounts for these components and instrumental effects. The resulting power-law indices are found to have a mode of 2.3, similar to previous results. However, there are significant regional variations in the index, defying attempts to characterize the emission with a single value. The power-law index is found to increase away from the Galactic plane. A transition from small-scale to large-scale structure is evident at b=9∘b= 9^{\circ}, associated with the disk-halo transition in a 15∘^{\circ} region around l=108∘l=108^{\circ}. Localized variations in the index are found toward HII regions and supernova remnants, but the interpretation of these variations is inconclusive. The power in the polarized emission is anticorrelated with bright thermal emission (traced by Hα\alpha emission) indicating that the thermal emission depolarizes background synchrotron emission.Comment: Accepted to ApJ; 17 page

    The structured environments of embedded star-forming cores. PACS and SPIRE mapping of the enigmatic outflow source UYSO 1

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    The intermediate-mass star-forming core UYSO 1 has previously been found to exhibit intriguing features. While deeply embedded and previously only identified by means of its (sub-)millimeter emission, it drives two powerful, dynamically young, molecular outflows. Although the process of star formation has obviously started, the chemical composition is still pristine. We present Herschel PACS and SPIRE continuum data of this presumably very young region. The now complete coverage of the spectral energy peak allows us to precisely constrain the elevated temperature of 26 - 28 K for the main bulge of gas associated with UYSO1, which is located at the interface between the hot HII region Sh 2-297 and the cold dark nebula LDN 1657A. Furthermore, the data identify cooler compact far-infrared sources of just a few solar masses, hidden in this neighbouring dark cloud.Comment: accepted contribution for the forthcoming Herschel Special Issue of A&A, 5 pages (will appear as 4-page letter in the journal), 6 figure file

    Dust-temperature of an isolated star-forming cloud: Herschel observations of the Bok globule CB244

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    We present Herschel observations of the isolated, low-mass star-forming Bok globule CB244. It contains two cold sources, a low-mass Class 0 protostar and a starless core, which is likely to be prestellar in nature, separated by 90 arcsec (~ 18000 AU). The Herschel data sample the peak of the Planck spectrum for these sources, and are therefore ideal for dust-temperature and column density modeling. With these data and a near-IR extinction map, the MIPS 70 micron mosaic, the SCUBA 850 micron map, and the IRAM 1.3 mm map, we model the dust-temperature and column density of CB244 and present the first measured dust-temperature map of an entire star-forming molecular cloud. We find that the column-averaged dust-temperature near the protostar is ~ 17.7 K, while for the starless core it is ~ 10.6K, and that the effect of external heating causes the cloud dust-temperature to rise to ~ 17 K where the hydrogen column density drops below 10^21 cm^-2. The total hydrogen mass of CB244 (assuming a distance of 200 pc) is 15 +/- 5 M_sun. The mass of the protostellar core is 1.6 +/- 0.1 M_sun and the mass of the starless core is 5 +/- 2 M_sun, indicating that ~ 45% of the mass in the globule is participating in the star-formation process.Comment: Accepted for A&A Herschel Special Issue; 5 pages, 2 figure

    A knowledge-based expert system for scheduling of airborne astronomical observations

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    The Kuiper Airborne Observatory Scheduler (KAOS) is a knowledge-based expert system developed at NASA Ames Research Center to assist in route planning of a C-141 flying astronomical observatory. This program determines a sequence of flight legs that enables sequential observations of a set of heavenly bodies derived from a list of desirable objects. The possible flight legs are constrained by problems of observability, avoiding flyovers of warning and restricted military zones, and running out of fuel. A significant contribution of the KAOS program is that it couples computational capability with a reasoning system

    Modeling chemistry in and above snow at Summit, Greenland – Part 1: Model description and results

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    Sun-lit snow is increasingly recognized as a chemical reactor that plays an active role in uptake, transformation, and release of atmospheric trace gases. Snow is known to influence boundary layer air on a local scale, and given the large global surface coverage of snow may also be significant on regional and global scales. We present a new detailed one-dimensional snow chemistry module that has been coupled to the 1-D atmospheric boundary layer model MISTRA. The new 1-D snow module, which is dynamically coupled to the overlaying atmospheric model, includes heat transport in the snowpack, molecular diffusion, and wind pumping of gases in the interstitial air. The model includes gas phase chemical reactions both in the interstitial air and the atmosphere. Heterogeneous and multiphase chemistry on atmospheric aerosol is considered explicitly. The chemical interaction of interstitial air with snow grains is simulated assuming chemistry in a liquid-like layer (LLL) on the grain surface. The coupled model, referred to as MISTRA-SNOW, was used to investigate snow as the source of nitrogen oxides (NOx) and gas phase reactive bromine in the atmospheric boundary layer in the remote snow covered Arctic (over the Greenland ice sheet) as well as to investigate the link between halogen cycling and ozone depletion that has been observed in interstitial air. The model is validated using data taken 10 June–13 June, 2008 as part of the Greenland Summit Halogen-HOx experiment (GSHOX). The model predicts that reactions involving bromide and nitrate impurities in the surface snow can sustain atmospheric NO and BrO mixing ratios measured at Summit, Greenland during this period

    Integration of Sexuality Content into an Occupational Therapy Curriculum

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    Sexuality is a broad term that can be used to encompass other terms such as sexual expression and sexual functioning, and can be defined as a holistic concept of the individual that is more than just physical sexual behavior but also relates to thoughts and feelings of everyday life (Couldrick, 1998a). Sexuality and sexual functioning are considered an activity of daily living (ADL) by the Occupational Therapy Practice Framework: Domain and Process (2008); however, it is a topic that is not being routinely addressed with clients by occupational therapists or other healthcare professionals (Hattjar, 2012). Studies show there is a significant lack of information given to clients in regard to sexuality, as well as dissatisfaction with the services that are provided for sexuality. This information implies an increase in knowledge, experience, and comfort levels with sexuality needs to be addressed with occupational therapists and occupational therapy students in order to treat clients in a holistic and client-centered manner. A comprehensive literature review was completed to identify key aspects of sexuality. The literature review revealed a significant lack in student and practitioner confidence and competence in addressing sexuality in a clinical setting. After an extensive search regarding the topic of sexuality within the profession of occupational therapy it was found that much of the limited literature stems from the late 1980’s to early 1990’s, yet the literature from the 2000’s continue to address the same issues. Due to the reported low levels of comfort for occupational therapy students and practitioners regarding sexuality and the role occupational therapists play in addressing the subject with clients, the following product was developed. There was a dearth of the information and no evidenced-based articles were located regarding sexuality or how to teach about the topic. The product created includes lesson plans that address different aspects of physical and/or psychosocial impairments that may impact sexuality. The product lesson plans consist of varying lectures, readings and activities, to be incorporated into several courses throughout the duration of an occupational therapy professional program. The goal of this product is to increase exposure to issues of sexuality and sexual functioning throughout the curricula of a Midwestern professional occupational therapy program in order to create competent and comfortable practitioners within the field

    Fast deuterium fractionation in magnetized and turbulent filaments

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    Deuterium fractionation is considered as an important process to infer the chemical ages of prestellar cores in filaments. We present here the first magneto-hydrodynamical simulations including a chemical network to study deuterium fractionation in magnetized and turbulent filaments and their substructures. The filaments typically show widespread deuterium fractionation with average values ≳0.01\gtrsim0.01. For individual cores of similar age, we observe the deuteration fraction to increase with time, but also to be independent of their average properties such as density, virial or mass-to-magnetic flux ratio. We further find a correlation of the deuteration fraction with core mass, average H2_2 density and virial parameter only at late evolutionary stages of the filament and attribute this to the lifetime of the individual cores. Specifically, chemically old cores reveal higher deuteration fractions. Within the radial profiles of selected cores, we notice differences in the structure of the deuteration fraction or surface density, which we can attribute to their different turbulent properties. High deuteration fractions of the order 0.01−0.10.01-0.1 may be reached within approximately 200200~kyrs, corresponding to two free-fall times, as defined for cylindrical systems, of the filamentsComment: submitted to MNRAS. Comments welcom

    Anomaluos RR Lyrae (V-I)_0 colors in Baade's Window

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    We compare (V-I)_0-(V-K)_0 color-color and (V-I)_0-log P period-color diagrams for Baade's Window and local RRab Lyrae stars. We find that for a fixed log P the Baade's Window RR Lyrae stars are ~0.17 magnitudes redder in (V-I)_0 than the local RR Lyrae stars. We also show that there is no such effect observed in (V-K)_0. We argue that an extinction misestimate towards Baade's Window is not a plausible explanation of the discrepancy. Unlike Baade's Window RR Lyrae stars, the local ones follow a black-body color-color relation and are well approximated by theoretical models. We test two parameters, metallicity and surface gravity, and find that their effects are too small to explain the (V-I)_0 discrepancy between the two groups of stars. We do not provide any explanation for the anomalous (V-I)_0 behavior of the Baade's Window RR Lyrae stars. We note that a similar effect for clump giant stars has been recently reported by Paczynski and we caution that RR Lyrae stars and clump giants, often used as standard candles, can be subject to the same type of systematics.Comment: 10 pages, 7 figures, submitted to Ap
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