Companion

Distribution by Scientific Domains

Kinds of Companion

  • brown dwarf companion
  • dwarf companion

  • Terms modified by Companion

  • companion animals
  • companion article
  • companion paper
  • companion star
  • companion study

  • Selected Abstracts


    Statin Use Is Associated With Improved Survival in Patients With Advanced Heart Failure Receiving Resynchronization Therapy

    CONGESTIVE HEART FAILURE, Issue 4 2009
    Andrew D. Sumner MD
    It is unknown whether statin use improves survival in patients with advanced chronic heart failure (HF) receiving cardiac resynchronization therapy (CRT). The authors retrospectively assessed the effect of statin use on survival in patients with advanced chronic HF receiving CRT alone (CRT-P) or CRT with implantable cardioverter-defibrillator therapy (CRT-D) in 1520 patients with advanced chronic HF from the Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION) trial database. Six hundred three patients (40%) were taking statins at baseline. All-cause mortality was 18% in the statin group and 22% in the no statin group (hazard ratio [HR] 0.85; confidence interval (CI), 0.67,1.07; P=.15). In a multivariable analysis controlling for significant baseline characteristics and use of CRT-P/CRT-D, statin use was associated with a 23% relative risk reduction in mortality (HR, 0.77; CI, 0.61,0.97; P=.03). Statin use is associated with improved survival in patients with advanced chronic HF receiving CRT. No survival benefit was seen in patients receiving statins and optimal pharmacologic therapy without CRT. [source]


    THE CONTINUUM COMPANION TO RELIGION AND FILM edited by William L. Blizek FILM, LACAN AND THE SUBJECT OF RELIGION: A PSYCHOANALYTIC APPROACH TO RELIGIOUS FILM ANALYSIS by Steve Nolan

    NEW BLACKFRIARS, Issue 1035 2010
    KEITH TESTER
    No abstract is available for this article. [source]


    Nuclear magnetic resonance data processing.

    CONCEPTS IN MAGNETIC RESONANCE, Issue 2 2003
    MestRe-C: A software package for desktop computers
    Abstract Magnetic Resonance Companion (MestRe-C) is a software package that offers state-of-the-art facilities for data processing, visualization, and analysis of high-resolution nuclear magnetic resonance (NMR) data, combined with a robust, user-friendly graphical interface that fully exploits the power and flexibility of the Windows platform. The program provides a variety of conversion facilities for most NMR spectrometer formats and includes all the conventional processing, displaying, and plotting capabilities of an NMR program, as well as more advanced processing techniques. A brief review of the basic concepts of NMR data processing is included also. 2003 Wiley Periodicals, Inc. Concepts Magn Reson Part A 19A: 80,96, 2003. [source]


    A Companion to the History of the Middle East Edited by Youssef M. Choueiri

    HISTORY, Issue 303 2006
    SPENCER MAWBY
    No abstract is available for this article. [source]


    A Reader's Companion to Against Prediction: A Reply to Ariela Gross, Yoram Margalioth, and Yoav Sapir on Economic Modeling, Selective Incapacitation, Governmentality, and Race

    LAW & SOCIAL INQUIRY, Issue 1 2008
    Bernard E. Harcourt
    From parole prediction instruments and violent sexual predator scores to racial profiling on the highways, instruments to predict future dangerousness, drug-courier profiles, and IRS computer algorithms to detect tax evaders, the rise of actuarial methods in the field of crime and punishment presents a number of challenging issues at the intersection of economic theory, sociology, history, race studies, criminology, social theory, and law. The three review articles of Against Prediction: Profiling, Policing, and Punishing in an Actuarial Age by Ariela Gross, Yoram Margalioth, and Yoav Sapir, raise these challenges in their very best light. Ranging from the heights of poststructuralist and critical race theory to the intricate details of mathematical economics and criminological analysis, the articles apply different disciplinary lenses to the analysis of the actuarial turn offered in Against Prediction and set forth both substantive and structural challenges to the book. By means of a detailed reply to the three reviews, this article provides a reader's companion to Against Prediction. [source]


    A Feminist Companion to the Acts of the Apostles , Edited by Amy-Jill Levine with Marianne Blickenstaff

    RELIGIOUS STUDIES REVIEW, Issue 4 2008
    Jason J. Ripley
    No abstract is available for this article. [source]


    President Lincoln: The Duty of a Statesman by William Lee Miller and The Bedside, Bathtub & Armchair Companion to Mark Twain by Pam McAllister

    THE JOURNAL OF AMERICAN CULTURE, Issue 3 2008
    Ray B. Browne
    No abstract is available for this article. [source]


    Walter Mosley: A Critical Companion

    THE JOURNAL OF AMERICAN CULTURE, Issue 1 2004
    Ray B. Browne
    No abstract is available for this article. [source]


    Colorectal Surgery: A Companion to Specialist Surgical Practice (Fourth Edition)

    ANZ JOURNAL OF SURGERY, Issue 9 2010
    FRACS, Graham Hool MB BS
    No abstract is available for this article. [source]


    Australian Medicines Handbook Drug Choice Companion: Aged Care

    AUSTRALASIAN JOURNAL ON AGEING, Issue 1 2004
    Maureen M. Hendry Dip.
    [source]


    Therapy in Nephrology & Hypertension: Companion to Brenner & Rector's The Kidney

    BJU INTERNATIONAL, Issue 4 2010
    Blaithin McMahon
    No abstract is available for this article. [source]


    Colorectal Surgery: a Companion to Specialist Surgical Practice 2nd Edition

    COLORECTAL DISEASE, Issue 2 2004
    M. C. Winslet
    No abstract is available for this article. [source]


    "Prizeable Companions": Missing Friends in the Marquesan Accounts of William Crook, Edward Robarts, and Herman Melville

    LEVIATHAN, Issue 2 2009
    Vanessa Smith
    [source]


    Practical Reason and ,Companions in Guilt'

    PHILOSOPHICAL INVESTIGATIONS, Issue 4 2003
    James Harold
    First page of article [source]


    ART HISTORY: CONTEMPORARY PERSPECTIVES ON METHOD

    ART HISTORY, Issue 4 2009
    DANA ARNOLD
    Dana Arnold is Professor of Architectural History at the University of Southampton, UK. She was editor of Art History from 1997 to 2002 and edits the book series New Interventions in Art History; Companions to Art History; and Anthologies in Art History, all published by Wiley-Blackwell. Her recent monographs include: Rural Urbanism: London Landscapes in the Early Nineteenth Century (2006); Reading Architectural History (2002); Re-presenting the Metropolis: Architecture, Urban Experience and Social Life in London 1800,1840 (2000). Her edited and co-edited volumes include: Biographies and Space (2007); Rethinking Architectural Historiography (2006); Architecture as Experience (2004); Cultural Identities and the Aesthetics of Britishness (2004); Tracing Architecture: The Aesthetics of Antiquarianism (2003); Art and Thought (2003). She is the author of the bestselling Art History: A Very Short Introduction (2004) which has been translated into many languages, including Chinese, Russian, Arabic, Japanese and Spanish and has been reprinted several times. Her monograph on the Spaces of the Hospital is forthcoming from Routledge. Professor Arnold has held research fellowships at Yale University, the University of Cambridge and the Getty Research Institute, Los Angeles and has held numerous visiting Professorships. She was a member of the Research Panel for the Arts and Humanities Research Council (AHRC) and now sits on the Advisory Board of the joint Engineering and Physical Sciences/AHRC initiative Science and Heritage. [source]


    Brief exposure to the biological mother "potentiates" the isolation behavior of precocial Guinea pig pups

    DEVELOPMENTAL PSYCHOBIOLOGY, Issue 8 2006
    Michael B. Hennessy
    Abstract When isolated rat pups are briefly reunited with a lactating female, her subsequent removal leads to a dramatic increase in the emission of ultrasonic vocalizations, but not other behaviors. Whether this socially induced augmentation of isolation behavior (i.e., "potentiation") is characteristic only of altricial rodents is not known. Therefore, we examined precocial guinea pig pups in a potentiation paradigm. Ten-day-old guinea pigs were isolated in a test cage for 10 min, at which time they were then placed into a second cage for 5 min that either contained a companion or, for controls, was empty. Pups were then isolated again in the test cage for a second 10-min period. Control pups showed a significant reduction in vocalizing and locomotor activity from the first to second isolation period. Exposure to the biological mother prevented the decline in both behaviors (Experiment 1), whereas exposure to a familiar littermate (Experiment 2) had no effect, and exposure to an unfamiliar lactating female (Experiment 3) had only a minimal effect on locomotor activity. The results show that potentiation of isolation behaviors is not limited to altricial rodents, and suggest that specific characteristics of the effect (i.e., its magnitude, the specific behaviors affected, and the selectivity of the response to particular social partners) varies with the abilities and requirements of the young, as well as the behavioral ecology of the species in question. 2006 Wiley Periodicals, Inc. Dev Psychobiol 48: 653,659, 2006. [source]


    Inelastic spectra for infilled reinforced concrete frames

    EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 15 2004
    Matja
    Abstract In two companion papers a simplified non-linear analysis procedure for infilled reinforced concrete frames is introduced. In this paper a simple relation between strength reduction factor, ductility and period (R,,T relation) is presented. It is intended to be used for the determination of inelastic displacement ratios and of inelastic spectra in conjunction with idealized elastic spectra. The R,,T relation was developed from results of an extensive parametric study employing a SDOF mathematical model composed of structural elements representing the frame and infill. The structural parameters, used in the proposed R,,T relation, in addition to the parameters used in a usual (e.g. elasto-plastic) system, are ductility at the beginning of strength degradation, and the reduction of strength after the failure of the infills. Formulae depend also on the corner periods of the elastic spectrum. The proposed equations were validated by comparing results in terms of the reduction factors, inelastic displacement ratios, and inelastic spectra in the acceleration,displacement format, with those obtained by non-linear dynamic analyses for three sets of recorded and semi-artificial ground motions. A new approach was used for generating semi-artificial ground motions compatible with the target spectrum. This approach preserves the basic characteristics of individual ground motions, whereas the mean spectrum of the whole ground motion set fits the target spectrum excellently. In the parametric study, the R,,T relation was determined by assuming a constant reduction factor, while the corresponding ductility was calculated for different ground motions. The mean values proved to be noticeably different from the mean values determined based on a constant ductility approach, while the median values determined by the different procedures were between the two means. The approach employed in the study yields a R,,T relation which is conservative both for design and performance assessment (compared with a relation based on median values). Copyright 2004 John Wiley & Sons, Ltd. [source]


    Effect of paddock vs. stall housing on 24 hour gastric pH within the proximal and ventral equine stomach

    EQUINE VETERINARY JOURNAL, Issue 4 2008
    L. HUSTED
    Summary Reasons for performing study: Stall housing has been suggested as a risk factor for ulcer development in the equine stomach; however, the exact pathogenesis for this has not been established. Objectives: To investigate the effect of 3 environmental situations (grass paddock, stall alone or stall with adjacent companion) on pH in the proximal and the ventral stomach. Methods: Six horses with permanently implanted gastric cannulae were used in a randomised, cross-over, block design. Each horse rotated through each of three 24 h environmental situations. Horses remained on their normal diet (grass hay ad libitum and grain b.i.d.) throughout the study. Intragastric pH was measured continuously for 72 h just inside the lower oesophageal sphincter (proximal stomach) and via a pH probe in the gastric cannula (ventral stomach). Results: Neither proximal nor ventral 24 h gastric pH changed significantly between the 3 environmental situations. Mean hourly proximal gastric pH decreased significantly in the interval from 01.00,09.00 h compared to the interval from 13.00,20.00 h, regardless of environmental situation. Median hourly proximal pH only differed in the interval from 06.00,07.00 h compared to the interval 14.00,19.00 h. Neither mean nor median hourly ventral gastric pH varied significantly with the time of day. Conclusions: The change in housing status used in the current study did not affect acid exposure within either region of the equine stomach. The pH in the ventral stomach was uniformly stable throughout the study, while the proximal pH demonstrated a 24 h circadian pattern. Potential relevance: Since stall housing was not associated with prolonged acid exposure to the proximal stomach, this aspect alone does not explain the increased risk of squamous ulcer development. The circadian rhythm associated with proximal intragastric pH warrants further investigation. [source]


    Sickness and Aggressive Behavior in Dominant and Subordinate Mice,

    ETHOLOGY, Issue 2 2009
    Daniel W. H. Cohn
    Sick animals show a set of organized behavioral changes (sickness behavior), which is the result of a motivational re-organization of the behavior as a whole. Sickness behavior display can be influenced by the social context. In this work, we sought to investigate the regulation of sickness behavior within a pair of mice in the presence of an intruder mouse. Dominant and subordinate mice were treated with the bacterial endotoxin lipopolysaccharide (LPS) and were challenged with the presence of an intruder mouse. LPS effects depended on ranking and social context. Even though dominant mice displayed more agonistic interaction towards the intruder, subordinate mice displayed agonistic behavior towards the intruder when their dominant companion was treated with LPS. The results show that, not only sickness behavior is differentially expressed among different social ranks, but also that sickness behavior is related to different reactions among surrounding animals. These data are relevant for a biological approach to the relation between sickness behavior and social behavior. [source]


    Transient heat conduction in a medium with multiple circular cavities and inhomogeneities

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 11 2009
    Elizaveta Gordeliy
    Abstract A two-dimensional transient heat conduction problem of multiple interacting circular inhomogeneities, cavities and point sources is considered. In general, a non-perfect contact at the matrix/inhomogeneity interfaces is assumed, with the heat flux through the interface proportional to the temperature jump. The approach is based on the use of the general solutions to the problems of a single cavity and an inhomogeneity and superposition. Application of the Laplace transform and the so-called addition theorem results in an analytical transformed solution. The solution in the time domain is obtained by performing a numerical inversion of the Laplace transform. Several numerical examples are given to demonstrate the accuracy and the efficiency of the method. The approximation error decreases exponentially with the number of the degrees of freedom in the problem. A comparison of the companion two- and three-dimensional problems demonstrates the effect of the dimensionality. Copyright 2009 John Wiley & Sons, Ltd. [source]


    A Reader's Companion to Against Prediction: A Reply to Ariela Gross, Yoram Margalioth, and Yoav Sapir on Economic Modeling, Selective Incapacitation, Governmentality, and Race

    LAW & SOCIAL INQUIRY, Issue 1 2008
    Bernard E. Harcourt
    From parole prediction instruments and violent sexual predator scores to racial profiling on the highways, instruments to predict future dangerousness, drug-courier profiles, and IRS computer algorithms to detect tax evaders, the rise of actuarial methods in the field of crime and punishment presents a number of challenging issues at the intersection of economic theory, sociology, history, race studies, criminology, social theory, and law. The three review articles of Against Prediction: Profiling, Policing, and Punishing in an Actuarial Age by Ariela Gross, Yoram Margalioth, and Yoav Sapir, raise these challenges in their very best light. Ranging from the heights of poststructuralist and critical race theory to the intricate details of mathematical economics and criminological analysis, the articles apply different disciplinary lenses to the analysis of the actuarial turn offered in Against Prediction and set forth both substantive and structural challenges to the book. By means of a detailed reply to the three reviews, this article provides a reader's companion to Against Prediction. [source]


    The determination of planetary structure in tidally relaxed inclined systems

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2010
    Rosemary A. Mardling
    ABSTRACT The recent discovery of a transiting short-period planet on a slightly non-circular orbit with a massive highly eccentric companion orbiting the star HAT-P-13 offers the possibility of probing the structure of the short-period planet. The ability to do this relies on the system being in a quasi-equilibrium state in the sense that the eccentricities are constant on the usual secular time-scale (typically, a few thousand years), and decay on a time-scale which is much longer than the age of the system. Since the equilibrium eccentricity is effectively a function only of observable system parameters and the unknown Love number of the short-period planet, the latter can be determined with accurate measurements of the planet's eccentricity and radius. However, this analysis relies on the assumption that the system is coplanar, a situation which seems unlikely given the high eccentricity of the outer planet. Here we generalize our recent analysis of this fixed-point phenomenon to mutually inclined systems in which the outer body dominates the total angular momentum, and show that (1) the fixed point of coplanar systems is replaced by a limit cycle in eb,, space, where eb is the eccentricity of the inner planet and , is the angle between the periapse lines, with the average value of eb, e(av)b, decreasing and its amplitude of variation increasing with increasing mutual inclination. This behaviour significantly reduces the ability to unambiguously determine the Love number of the short-period planet if the mutual inclination is higher than around 10. (2) We show that for Q -values less than 106, the HAT-P-13 system cannot have a mutual inclination between 54 and 126 because Kozai oscillations coupled with tidal dissipation would act to quickly move the inclination outside this range, and (3) that the behaviour of retrograde systems is the mirror image of that for prograde systems in the sense that (almost) identical limit cycles exist for a given mutual inclination and , minus this value. (4) We derive a relationship between e(av)b, the equilibrium radius of the short-period planet, its Q -value and its core mass, and show that given current estimates of eb and the planet radius, as well as the lower bound placed on the Q -value by the decay rate of e(av)b, the HAT-P-13 system is likely to be close to prograde coplanar, or have a mutual inclination between 130 and 135. Lower rather than higher core masses are favoured. (5) An expression for the time-scale for decay of the mutual inclination is derived, revealing that it evolves towards a non-zero value as long as eb > 0 on a time-scale which is much longer than the age of the system. (6) We conclude with a scattering scenario for the origin of the HAT-P-13 system and show that almost identical initial conditions can result in significantly different outer planet eccentricities, stellar obliquities and planet radii. The implications for systems with high stellar obliquities such as HAT-P-7 and WASP-17 are briefly discussed. [source]


    The dust-free symbiotic Mira K4,46 = LL Cas

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2010
    U. Munari
    ABSTRACT Accurate BVRCIC light and colour curves of the Mira variable in the dust-free symbiotic system K4,46 are presented and discussed. They cover several consecutive pulsations cycles. The Mira mean period is 284.2 d, the reddening sums to E(B,V) = 0.35 and the distance is 10 kpc. Absolute spectrophotometry at both maximum and minimum brightness of the Mira is presented. The rich emission line and continuum spectrum of the H ii region ionized by the hard radiation of the white dwarf dominates at Mira minimum. From its photoionization analysis, it is found that the H ii region extends to a radius of 210 au, has a mass 1.8 10,4 M, and it is ionized by a white dwarf of 158 000 K temperature and 0.06 R, radius, stably burning hydrogen at its surface. The derived [Fe/H]=,0.45 well match the ambient metallicity expected at K4,46 at its 15 kpc galactocentric distance, and the overabundances in N, Ne and He are those expected if the H ii region is fed by the wind of the Mira and polluted by nuclearly processed material lost by the white dwarf companion. [source]


    PG 1258+593 and its common proper motion magnetic white dwarf counterpart

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2010
    J. Girven
    ABSTRACT We confirm SDSS J130033.48+590407.0 as a common proper motion companion to the well-studied hydrogen-atmosphere (DA) white dwarf PG 1258+593 (GD322). The system lies at a distance of 68 3 pc, where the angular separation of 16.1 0.1 arcsec corresponds to a minimum binary separation of 1091 7 au. SDSS J1300+5904 is a cool (Teff= 6300 300 K) magnetic white dwarf (B, 6 mG). PG 1258+593 is a DA white dwarf with Teff= 14790 77 K and log g= 7.87 0.02. Using the white dwarf mass,radius relation implies the masses of SDSS J1300+5904 and PG 1258+593 are 0.54 0.06 and 0.54 0.01 M,, respectively, and therefore a cooling age difference of 1.67 0.05 Gyr. Adopting main-sequence lifetimes from stellar models, we derive an upper limit of 2.2 M, for the mass of the progenitor of PG 1258+593. A plausible range of initial masses is 1.4,1.8 M, for PG 1258+593 and 2,3 M, for SDSS J1300+5904. Our analysis shows that white dwarf common proper motion binaries can potentially constrain the white dwarf initial mass,final mass relation and the formation mechanism for magnetic white dwarfs. The magnetic field of SDSS J1300+5904 is consistent with an Ap progenitor star. A common envelope origin of the system cannot be excluded, but requires a triple system as progenitor. [source]


    The Monitor project: the search for transits in the open cluster NGC 2362

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008
    Adam A. Miller
    ABSTRACT We present the results of a systematic search for transiting planets in a ,5 Myr open cluster, NGC 2362. We observed ,1200 candidate cluster members, of which ,475 are believed to be genuine cluster members, for a total of ,100 h. We identify 15 light curves with reductions in flux that pass all our detection criteria, and six of the candidates have occultation depths compatible with a planetary companion. The variability in these six light curves would require very large planets to reproduce the observed transit depth. If we assume that none of our candidates are, in fact, planets then we can place upper limits on the fraction of stars with hot Jupiters (HJs) in NGC 2362. We obtain 99 per cent confidence upper limits of 0.22 and 0.70 on the fraction of stars with HJs (fp) for 1,3 and 3,10 d orbits, respectively, assuming all HJs have a planetary radius of 1.5RJup. These upper limits represent observational constraints on the number of stars with HJs at an age ,10 Myr, when the vast majority of stars are thought to have lost their protoplanetary discs. Finally, we extend our results to the entire Monitor project, a survey searching young, open clusters for planetary transits, and find that the survey as currently designed should be capable of placing upper limits on fp near the observed values of fp in the solar neighbourhood. [source]


    Near-infrared spectroscopy of the very low mass companion to the hot DA white dwarf PG 1234+482

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007
    P. R. Steele
    ABSTRACT We present a near-infrared spectrum of the hot (Teff, 55 000 K) hydrogen atmosphere (DA) white dwarf PG 1234+482. We confirm that a very low mass companion is responsible for the previously recognized infrared photometric excess. We compare spectra of M and L dwarfs, combined with an appropriate white dwarf model, to the data to constrain the spectral type of the secondary. We find that uncertainties in the Two-Micron All-Sky Survey HK photometry of the white dwarf prevent us from distinguishing whether the secondary is stellar or substellar, and assign a spectral type of L01 (M9,L1).Therefore, this is the hottest and youngest (,106 yr) DA white dwarf with a possible brown dwarf companion. [source]


    Establishing the nature of companion candidates to X-ray-emitting late B-type stars,

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007
    S. Hubrig
    ABSTRACT The most favoured interpretation for the detection of X-ray emission from late B-type stars is that these stars have a yet undiscovered late-type companion (or an unbound nearby late-type star) that produces the X-rays. Several faint infrared objects at (sub)arcsecond separation from B-type stars have been uncovered in our earlier adaptive optics imaging observations, and some of them have been followed up with the high spatial resolution of the Chandra X-ray observatory, pinpointing the X-ray emitter. However, firm conclusions on their nature require a search for spectroscopic signatures of youth. Here we report on our recent ISAAC observations carried out in low-resolution spectroscopic mode. Equivalent widths have been used to obtain information on spectral types of the companions. All eight X-ray-emitting systems with late B-type primaries studied contain dwarf-like companions with spectral types later than A7. The only system in the sample where the companion turns out to be of early spectral type is not an X-ray source. These results are consistent with the assumption that the observed X-ray emission from late B-type stars is produced by an active pre-main-sequence companion star. [source]


    Very high contrast integral field spectroscopy of AB Doradus C: 9-mag contrast at 0.2 arcsec without a coronagraph using spectral deconvolution,

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007
    Niranjan Thatte
    ABSTRACT We present an extension of the spectral deconvolution (SD) method to achieve very high contrast at small inner working radii. We apply the method to the specific case of ground-based adaptive optics fed integral field spectroscopy (without a coronagraph). Utilizing the wavelength dependence of the Airy and speckle patterns, we make an accurate estimate of the point spread function that can be scaled and subtracted from the data cube. The residual noise in the resulting spectra is very close to the photon noise from the starlight halo. We utilize the technique to extract a very high signal-to-noise ratio H - and K -band spectrum of AB Doradus (AB Dor) C, the low-mass companion to AB Dor A. By effectively eliminating all contamination from AB Dor A, the extracted spectrum retains both continuum and spectral features. The achieved 1, contrast is 9 mag at 0.2 arcsec, 11 mag at 0.5 arcsec, in 20 min exposure time, at an effective spectral bandwidth of 5.5 nm, proving that the method is applicable even in low-Strehl regimes. The SD method clearly demonstrates the efficacy of image slicer based integral field units in achieving very high contrast imaging spectroscopy at small angular separations, validating their use as high-contrast spectrographs/imagers for extreme adaptive optics systems. [source]


    A fast hybrid algorithm for exoplanetary transit searches

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2006
    A. Collier Cameron
    ABSTRACT We present a fast and efficient hybrid algorithm for selecting exoplanetary candidates from wide-field transit surveys. Our method is based on the widely used SysRem and Box Least-Squares (BLS) algorithms. Patterns of systematic error that are common to all stars on the frame are mapped and eliminated using the SysRem algorithm. The remaining systematic errors caused by spatially localized flat-fielding and other errors are quantified using a boxcar-smoothing method. We show that the dimensions of the search-parameter space can be reduced greatly by carrying out an initial BLS search on a coarse grid of reduced dimensions, followed by Newton,Raphson refinement of the transit parameters in the vicinity of the most significant solutions. We illustrate the method's operation by applying it to data from one field of the SuperWASP survey, comprising 2300 observations of 7840 stars brighter than V= 13.0. We identify 11 likely transit candidates. We reject stars that exhibit significant ellipsoidal variations caused indicative of a stellar-mass companion. We use colours and proper motions from the Two Micron All Sky Survey and USNO-B1.0 surveys to estimate the stellar parameters and the companion radius. We find that two stars showing unambiguous transit signals pass all these tests, and so qualify for detailed high-resolution spectroscopic follow-up. [source]


    Analysis of , Librae including Hipparcos astrometry

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2006
    V. Bak
    ABSTRACT New spectroscopy of the classical Algol system , Lib, combined with high-quality optical and infrared photometry, provides the basis for a good understanding of the close binary system's main parameters. Detailed analysis of the photometry reveals the significant role of a third light source, pointing to the existence of a companion to the eclipsing system of mass ,1 M,. We review the methodology of applying high-accuracy positional information, available from the Hipparcos Intermediate Astrometric Data archive, to stars that may have such companions. Analysis of the astrometry of , Lib also points to a third star similar to the one already identified by Worek from radial-velocity data, although with slightly revised parameters. O,C data do not contradict this, but their general precision (while confirming the close pair's Algol status) fails to allow a decision on the third orbit parameters: Worek's or revised ones. Taking the photometry, spectroscopy and astrometry together, however, the existence of a third star of comparable mass to the Sun, as a relatively close companion to the eclipsing binary (,4 au), is confirmed. [source]