3,024 research outputs found

    Herschel Observations of Cataclysmic Variables

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    We have used the PACS instrument on the Herschel Space Observatory to observe eight cataclysmic variables at 70 and 160 μm. Of these eight objects, only AM Her was detected. We have combined the Herschel results with ground-based, Spitzer, and WISE observations to construct spectral energy distributions for all of the targets. For the two dwarf novae in the sample, SS Cyg and U Gem, we find that their infrared luminosities are completely dominated by their secondary stars. For the two highly magnetic "polars" in our survey, AM Her and EF Eri, we find that their mid-infrared excesses, previously attributed to circumbinary dust emission, can be fully explained by cyclotron emission. The WISE light curves for both sources show large, orbitally modulated variations that are identically phased to their near-IR light curves. We propose that significant emission from the lowest cyclotron harmonics (n ≤ 3) is present in EF Eri and AM Her. Previously, such emission would have been presumed to be optically thick, and not provide significant orbitally modulated flux. This suggests that the accretion onto polars is more complicated than assumed in the simple models developed for these two sources. We develop a model for the near-/mid-IR light curves for WZ Sge with an L2 donor star that shows that the ellipsoidal variations from its secondary star are detected. We conclude that none of the targets surveyed have dusty circumbinary disks

    Low State, Phase-Resolved IR Spectroscopy of VV Puppis

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    We present phase-resolved low resolution JHKJHK and higher resolution KK-band spectroscopy of the polar VV Pup. All observations were obtained when VV Pup was in a low accretion state having a K magnitude near 15. The low resolution observations reveal cyclotron emission in the JJ band during some phases, consistent with an origin near the active 30.5 MG pole on the white dwarf. The secondary in VV Pup appears to be a normal M7V star and we find that the HH and KK band fluxes are entirely due to this star at all orbital phases during the low accretion state. We use our higher resolution Keck spectroscopy to produce the first KK-band radial velocity curve for VV Pup. Our orbital solution yields K2K_2=414±27\pm27 km sec−1^{-1} and leads to mass estimates of M1_1=0.73±\pm0.05 M⊙_{\odot} and M2_2=0.10±\pm0.02 M⊙_{\odot}. We find that the mass accretion rates during the normal low states of the polars VV Pup, EF Eri, and EQ Cet are near 10−13^{-13} M⊙_{\odot} yr−1^{-1}. The fact that \.M is not zero in low state polars indicates active secondary stars in these binary systems, including the sub-stellar donor star present in EF Eri.Comment: Accepted in Astronomical Journal 5 figure

    2016-2017 Illinois waterfowl hunter report: harvest, youth hunts, and zone option preferences

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    To survey waterfowl (duck, goose, and coot) hunters annually to determine their activities, harvest, characteristics, attitudes, and opinions.Department of Natural Resources, Division of Wildlife; U.S. Fish & Wildlife Service; and Illinois Natural History Survey; Federal Aid in Wildlife Restoration W-112-R-26unpublishednot peer reviewedOpe

    Impact of Canadian tobacco packaging policy on quitline reach and reach equity

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    AbstractObjectiveTo examine the impact of the new Canadian tobacco package warning labels with a quitline toll-free phone number for seven provincial quitlines, focusing on treatment reach and reach equity in selected vulnerable groups.MethodsA quasi-experimental design assessed changes in new incoming caller characteristics, treatment reach for selected vulnerable sub-populations and the extent to which this reach is equitable, before and after the introduction of the labels in June, 2012. Administrative call data on smokers were collected at intake. Pre- and post-label treatment reach and reach equity differences were analysed by comparing the natural logarithms of the reach and reach equity statistics.ResultsDuring the six months following the introduction of the new warning labels, 86.4% of incoming new callers indicated seeing the quitline number on the labels. Treatment reach for the six-month period significantly improved compared to the same six-month period the year before from .042% to .114% (p<.0001) and reach equity significantly improved for young males (p<.0001) and those with high school education or less (p=.004).ConclusionsThe introduction of the new tobacco warning labels with a quitline toll-free number in Canada was associated with an increase in treatment reach. The toll-free number on tobacco warning labels aided in reducing tobacco related inequalities, such as improved reach equity for young males and those with high school or less education

    Cyclotron modeling phase-resolved infrared spectroscopy of polars I: EF Eridani

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    We present phase-resolved low resolution infrared spectra of the polar EF Eridani obtained over a period of 2 years with SPEX on the IRTF. The spectra, covering the wavelength range 0.8 to 2.4 microns, are dominated by cyclotron emission at all phases. We use a ``Constant Lambda'' prescription to attempt to model the changing cyclotron features seen in the spectra. A single cyclotron emission component with B = 12.6 MG, and a plasma temperature of kT = 5.0 keV, does a reasonable job in matching the features seen in the H and K bands, but fails to completely reproduce the morphology shortward of 1.6 microns. We find that a two component model, where both components have similar properties, but whose contributions differ with viewing geometry, provides an excellent fit to the data. We discuss the implications of our models and compare them with previously published results. In addition, we show that a cyclotron model with similar properties to those used for modeling the infrared spectra, but with a field strength of B = 115 MG, can explain the GALEX observations of EF Eri.Comment: 25 pages, 5 figures, to appear in Ap

    No effect of seed source on multiple aspects of ecosystem functioning during ecological restoration: cultivars compared to local ecotypes of dominant grasses

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    Genetic principles underlie recommendations to use local seed, but a paucity of information exists on the genetic distinction and ecological consequences of using different seed sources in restorations. We established a field experiment to test whether cultivars and local ecotypes of dominant prairie grasses were genetically distinct and differentially influenced ecosystem functioning. Whole plots were assigned to cultivar and local ecotype grass sources. Three subplots within each whole plot were seeded to unique pools of subordinate species. The cultivar of the increasingly dominant grass, Sorghastrum nutans, was genetically different than the local ecotype, but genetic diversity was similar between the two sources. There were no differences in aboveground net primary production, soil carbon accrual, and net nitrogen mineralization rate in soil between the grass sources. Comparable productivity of the grass sources among the species pools for four years shows functional equivalence in terms of biomass production. Subordinate species comprised over half the aboveground productivity, which may have diluted the potential for documented trait differences between the grass sources to influence ecosystem processes. Regionally developed cultivars may be a suitable alternative to local ecotypes for restoration in fragmented landscapes with limited gene flow between natural and restored prairie and negligible recruitment by seed

    GALEX, Optical and IR Light Curves of MQ Dra: UV Excesses at Low Accretion Rates

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    Ultraviolet light curves constructed from NUV and FUV detectors on GALEX reveal large amplitude variations during the orbital period of the Low Accretion Rate Polar MQ Dra (SDSSJ1553+55). This unexpected variation from a UV source is similar to that seen and discussed in the Polar EF Eri during its low state of accretion, even though the accretion rate in MQ Dra is an order of magnitude lower than even the low state of EF Eri. The similarity in phasing of the UV and optical light curves in MQ Dra imply a similar location for the source of light. We explore the possibilities of hot spots and cyclotron emission with simple models fit to the UV, optical and IR light curves of MQ Dra. To match the GALEX light curves with a single temperature circular hot spot requires different sizes of spots for the NUV and FUV, while a cyclotron model that can produce the optical harmonics with a magnetic field near 60 MG requires multipoles with fields > 200 MG to match the UV fluxes.Comment: accepted for ApJ; 15 pages, 7 tables, 8 fig
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