10,590 research outputs found

    New systemic radial velocities of suspected RR Lyrae binary stars

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    Among the tens of thousands of known RR Lyrae stars there are only a handful that show indications of possible binarity. The question why this is the case is still unsolved, and has recently sparked several studies dedicated to the search for additional RR Lyraes in binary systems. Such systems are particularly valuable because they might allow to constrain the stellar mass. Most of the recent studies, however, are based on photometry by finding a light time effect in the timings of maximum light. This approach is a very promising and successful one, but it has a major drawback: by itself, it cannot serve as a definite proof of binarity, because other phenomena such as the Blazhko effect or intrinsic period changes could lead to similar results. Spectroscopic radial velocity measurements, on the other hand, can serve as definite proof of binarity. We have therefore started a project to study spectroscopically RR Lyrae stars that are suspected to be binaries. We have obtained radial velocity (RV) curves with the 2.1m telescope at McDonald observatory. From these we derive systemic RVs which we will compare to previous measurements in order to find changes induced by orbital motions. We also construct templates of the RV curves that can facilitate future studies. We also observed the most promising RR Lyrae binary candidate, TU UMa, as no recent spectroscopic measurements were available. We present a densely covered pulsational RV curve, which will be used to test the predictions of the orbit models that are based on the O-C variations.Comment: 4 pages, 1 figure, to appear in the No. 105 issue of the Communications from the Konkoly Observatory of the Hungarian Academy of Science

    The Cepheid Distance Scale: recent progress in fundamental techniques

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    This review examines progress on the Pop I, fundamental-mode Cepheid distance scale with emphasis on recent developments in geometric and quasi-geometric techniques for Cepheid distance determination. Specifically I examine the surface brightness method, interferometric pulsation method, and trigonometric measurements. The three techniques are found to be in excellent agreement for distance measures in the Galaxy. The velocity p-factor is of crucial importance in the first two of these methods. A comparison of recent determinations of the p-factor for Cepheids demonstrates that observational measures of p and theoretical predictions agree within their uncertainties for Galactic Cepheids.Comment: An invited review at the Santa Fe, NM, conference -- Stellar Pulsation: Challenges for Theory and Observation; May 31-June 5, 2009 10 pages, 8 figure

    SURVEY OF THE NUISANCE WILDLIFE CONTROL INDUSTRY WITH NOTES ON THEIR ATTITUDES AND OPINIONS

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    A total of 138 nuisance wildlife control operators (NWCO) attending a wildlife control operators short-course were surveyed for information about their business and attitudes regarding management of urban wildlife problems. One hundred and thirty-one (94.9% response rate) returned the survey. Seventy-two percent of the respondents operated a nuisance wildlife business. Of these respondents, 47.7% also operated a full-time pest control business. Over 65% of NWCO had been in business \u3c5 years and 89% reported their business was successful as a result of either increased nuisance animal problems, satisfied customers, a growing customer base, enjoyment of their work, or by providing a high level of service. Over 30% of NWCO had annual billings \u3e$ 100,000. Respondents based fees on either the animal species and number removed, on a contract or flat fee basis, or based on time and number of trips required to resolve the problem. A large majority of NWCO use live-trapping and releasing off-site as the preferred method of controlling wildlife pests because of customer desires or for public relations reasons. Over 95% of respondents did not believe euthanization should be required for all animal species, but a majority indicated euthanization should be required for pest birds. Fifty percent believed nuisance wildlife should not be released back into the environment because of the potential to spread disease. A small percentage felt wildlife should not be relocated for humane reasons, yet a majority felt that reduction of pain felt by an animal was very important. The majority felt NWCO should be certified or licensed and that in-service training, a trapper education course, an examination, and possession of general liability insurance should be required for operating as a NWCO. This information suggests: 1) that the NWCO industry is growing rapidly, 2) NWCO support state agency policy requiring education, licensing, and liability insurance, and 3) there are problems between NWCO actions and wildlife professionals regarding the fate of live-trapped nuisance wildlife

    Mammal Damage and Movements of Deer Mice in South Dakota Shelterbelts

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    A study was initiated to examine animal damage to new shelterbelts in Brookings County, South Dakota. Feeding preferences of deer mice (Peromyscus maniculatus) prairie voles (Microtus ochragaster), and cottontail rabbits (Sylvilagus floridanus) was conducted on 5 woody species that colIIIllonly occur in South Dakota shelterbelts. Movementsof deer mice were studied in a mature shelterbelt using a smoked kymograph tracking technique. Green ash (Fraxinus pennsylvanica Marsh.), tatarian honeysuckle (Lonicera tatarica L. ),, and common lilac (Syringa vulgaris L.) were the most common tree species encountered in this study. Of the trees examined, 398 (8. 9%) sustained animal damage over the winter. Dogwood (Cornus stolonifera Michx.), received significantly more damage than the other species. Conifer trees received significantly less damage than deciduous trees. Branch damage occurred on 170 of the damaged trees. Rabbits fed on 77. 8% of the trees that received damage. There was a significant difference in the amount of feeding between deer mice and prairie voles in laboratory studies. The rodents preferred honeysuckle and avoided ponderosa pine (Pinus ponderosa Laws. ) . Rabbits preferred Siberian elm (Ulmus pumila L.) and honeysuckle and avoided ponderosa pine. Average home range size was 0. 06 hectares. Movement occurred more on the ground and lower elevations in trees compared to levels at higher elevations. At higher elevations deer mice moved significantly more in green ash and hackberry (Celtis occidentalis L. ) than other tree species

    Origin and Dynamics of the Mutually Inclined Orbits of Upsilon Andromedae c and d

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    We evaluate the orbital evolution and several plausible origins scenarios for the mutually inclined orbits of Upsilon Andromedae c and d. These two planets have orbital elements that oscillate with large amplitudes and lie close to the stability boundary. This configuration, and in particular the observed mutual inclination, demands an explanation. The planetary system may be influenced by a nearby low-mass star, Upsilon And B, which could perturb the planetary orbits, but we find it cannot modify two coplanar orbits into the observed mutual inclination of ~30 deg. However, it could incite ejections or collisions between planetary companions that subsequently raise the mutual inclination to >30 deg. Our simulated systems with large mutual inclinations tend to be further from the stability boundary than Upsilon And, but we are able to produce similar systems. We conclude that scattering is a plausible mechanism to explain the observed orbits of Upsilon And c and d, but we cannot determine whether the scattering was caused by instabilities among the planets themselves or by perturbations from Upsilon And B. We also develop a procedure to quantitatively compare numerous properties of the observed system to our numerical models. Although we only implement this procedure to Upsilon And, it may be applied to any exoplanetary system.Comment: 19 pages, 5 figures, accepted to Astrophysical Journa

    Evidence for a Universal Slope of the Period-Luminosity Relation from Direct Distances to Cepheids in the LMC

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    We have applied the infrared surface brightness (ISB) technique to derive distances to 13 Cepheid variables in the LMC which have periods from 3-42 days. The corresponding absolute magnitudes define PL relations in VIWJK bands which agree exceedingly well with the corresponding Milky Way relations obtained from the same technique, and are in significant disagreement with the observed LMC Cepheid PL relations, by OGLE-II and Persson et al., in these bands. Our data uncover a systematic error in the p-factor law which transforms Cepheid radial velocities into pulsational velocities. We correct the p-factor law by requiring that all LMC Cepheids share the same distance. Re-calculating all Milky Way and LMC Cepheid distances with the revised p-factor law, we find that the PL relations from the ISB technique both in LMC and in the Milky Way agree with the OGLE-II and Persson et al. LMC PL relations, supporting the conclusion of no metallicity effect on the slope of the Cepheid PL relation in optical/near infrared bands.Comment: 4 pages, to appear in the proceedings of the "Stellar Pulsation and Evolution" conference, Monte Porzio Catone, June 200

    Stellar rotation, binarity, and lithium in the open cluster IC4756

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    An important aspect in the evolutionary scenario of cool stars is their rotation and the rotationally induced magnetic activity and interior mixing. Stars in open clusters are particularly useful tracers for these aspects because of their known ages. We aim to characterize the open cluster IC4756 and measure stellar rotation periods and surface differential rotation for a sample of its member stars. Thirty-seven cluster stars were observed continuously with the CoRoT satellite for 78 days in 2010. Follow-up high-resolution spectroscopy of the CoRoT targets and deep Str\"omgren uvbyβuvby\beta and Hα\alpha photometry of the entire cluster were obtained with our robotic STELLA facility and its echelle spectrograph and wide-field imager, respectively. We determined high-precision photometric periods for 27 of the 37 CoRoT targets and found values between 0.155 and 11.4 days. Twenty of these are rotation periods. Twelve targets are spectroscopic binaries of which 11 were previously unknown; orbits are given for six of them. Six targets were found that show evidence of differential rotation with ΔΩ/Ω\Delta\Omega/\Omega in the range 0.04-0.15. Five stars are non-radially pulsating stars with fundamental periods of below 1d, two stars are semi-contact binaries, and one target is a micro-flaring star that also shows rotational modulation. Nine stars in total were not considered members because of much redder color(s) and deviant radial velocities with respect to the cluster mean. Hα\alpha photometry indicates that the cluster ensemble does not contain magnetically over-active stars. The cluster average metallicity is -0.08±\pm0.06 (rms) and its logarithmic lithium abundance for 12 G-dwarf stars is 2.39±\pm0.17 (rms). [...]Comment: A&A, in pres

    Wildflowers and Ferns of Kentucky

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    Since Kentucky is situated at a biological crossroads in eastern North America, citizens and visitors to this beautiful state are likely to be greeted by an astonishing variety of wildflowers. This non-technical guide—featuring more than five hundred dazzling full-color photographs by award-winning photographer Thomas G. Barnes—is the state’s indispensable guide to the most common species in the Commonwealth. With this book, readers will learn to identify and appreciate Kentucky wildflowers and ferns by matching photographs and leaf line drawings to the more than six hundred and fifty species of flowers covered in the book. Extremely practical and simple to use, the guide’s color photographs and line drawings appear with plant descriptions for easy identification, and plants are grouped by flower color and blooming season. Each species listing includes the plant’s common and scientific name, plant family, habitat, frequency, and distribution throughout Kentucky, with similar species listed in the notes. There is no other volume that covers the flora of Kentucky with such ease of identification. The first new statewide guide to appear in thirty years, with its combination of high quality photographs, illustrations, portability, and easy organization of information, Wildflowers and Ferns of Kentucky is an essential addition to the library or field pack of the wildflower enthusiast, naturalist, and anyone else who loves the outdoors. Thomas G. Barnes, an extension professor of forestry and wildlife specialist in the Department of Forestry, College of Agriculture at the University of Kentucky, is the author of Kentucky’s Last Great Places. Former naturalist S. Wilson Francis, Ph.D., is park superintendent at Natural Bridge State Resort Park in Kentucky. An essential addition to the library or field pack of the wildflower enthusiast or naturalist. —Kentucky Alumni A striking volume, memorable not only for its color photographs and plant descriptions but also for its introductory exposition of such pertinent matters as finding a good definition for \u27wildflower\u27 and one for \u27weed.\u27 —Mountain Eagle There isn\u27t a gardener on your gift list who wouldn\u27t be delighted by this book. Don\u27t forget-you need a copy too. —Southsider Wildflowers and Ferns of Kentucky is an extraordinarily beautiful, helpful, full color, 344-page guide showing 634 of the most common species of native ferns and seed-bearing wildflowers in Kentucky. —State Magazine Utilizes strong artistic compositions without compromising the identifiable characteristics of the plant. —Burpee Museum of Natural History This book is an excellent choice for professionals and general readers interested in the flora of Kentucky, adjacent states, and the northeastern US. . . . Highly recommended. —Choice Contains superb color photographs that make identifying the ferns and flowers much easier. —Modern Mountain Magazine A must-have for Kentuckiana gardeners. . . . A beautiful book that is easy to use (and carry) as a field guide. —Perry County News An astonishing variety of plant life exists in Kentucky\u27s diverse geography, and the book represents the impressive mix. . . . Even a botanical novice will benefit from perusing this delightfully blooming book. —Southern Livinghttps://uknowledge.uky.edu/upk_plant_sciences/1005/thumbnail.jp

    Infrared Surface Brightness Distances to Cepheids: a comparison of Bayesian and linear-bisector calculations

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    We have compared the results of Bayesian statistical calculations and linear-bisector calculations for obtaining Cepheid distances and radii by the infrared surface brightness method. We analyzed a set of 38 Cepheids using a Bayesian Markov Chain Monte Carlo method that had been recently studied with a linear-bisector method. The distances obtained by the two techniques agree to 1.5 \pm 0.6% with the Bayesian distances being larger. The radii agree to 1.1% \pm 0.7% with the Bayesian determinations again being larger. We interpret this result as demonstrating that the two methods yield the same distances and radii. This implies that the short distance to the LMC found in recent linear-bisector studies of Cepheids is not caused by deficiencies in the mathematical treatment. However, the computed uncertainties in distance and radius for our dataset are larger in the Bayesian calculation by factors of 1.4-6.7. We give reasons to favor the Bayesian computations of the uncertainties. The larger uncertainties can have a significant impact upon interpretation of Cepheid distances and radii obtained from the infrared surface brightness method.Comment: 27 pages with 9 figure

    The (In)Stability of Planetary Systems

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    We present results of numerical simulations which examine the dynamical stability of known planetary systems, a star with two or more planets. First we vary the initial conditions of each system based on observational data. We then determine regions of phase space which produce stable planetary configurations. For each system we perform 1000 ~1 million year integrations. We examine upsilon And, HD83443, GJ876, HD82943, 47UMa, HD168443, and the solar system (SS). We find that the resonant systems, 2 planets in a first order mean motion resonance, (HD82943 and GJ876) have very narrow zones of stability. The interacting systems, not in first order resonance, but able to perturb each other (upsilon And, 47UMa, and SS) have broad regions of stability. The separated systems, 2 planets beyond 10:1 resonance, (we only examine HD83443 and HD168443) are fully stable. Furthermore we find that the best fits to the interacting and resonant systems place them very close to unstable regions. The boundary in phase space between stability and instability depends strongly on the eccentricities, and (if applicable) the proximity of the system to perfect resonance. In addition to million year integrations, we also examined stability on ~100 million year timescales. For each system we ran ~10 long term simulations, and find that the Keplerian fits to these systems all contain configurations which may be regular on this timescale.Comment: 37 pages, 49 figures, 13 tables, submitted to Ap
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