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Sample records for ab-type rr lyrae

  1. The RR Lyrae variable population in the Phoenix dwarf galaxy

    SciTech Connect

    Ordoñez, Antonio J.; Sarajedini, Ata; Yang, Soung-Chul E-mail: ata@astro.ufl.edu

    2014-05-10

    We present the first detailed study of the RR Lyrae variable population in the Local Group dSph/dIrr transition galaxy, Phoenix, using previously obtained HST/WFPC2 observations of the galaxy. We utilize template light curve fitting routines to obtain best fit light curves for RR Lyrae variables in Phoenix. Our technique has identified 78 highly probable RR Lyrae stars (54 ab-type; 24 c-type) with about 40 additional candidates. We find mean periods for the two populations of (P {sub ab}) = 0.60 ± 0.03 days and (P{sub c} ) = 0.353 ± 0.002 days. We use the properties of these light curves to extract, among other things, a metallicity distribution function for ab-type RR Lyrae. Our analysis yields a mean metallicity of ([Fe/H]) = –1.68 ± 0.06 dex for the RRab stars. From the mean period and metallicity calculated from the ab-type RR Lyrae, we conclude that Phoenix is more likely of intermediate Oosterhoff type; however the morphology of the Bailey diagram for Phoenix RR Lyraes appears similar to that of an Oosterhoff type I system. Using the RRab stars, we also study the chemical enrichment law for Phoenix. We find that our metallicity distribution is reasonably well fitted by a closed-box model. The parameters of this model are compatible with the findings of Hidalgo et al., further supporting the idea that Phoenix appears to have been chemically enriched as a closed-box-like system during the early stage of its formation and evolution.

  2. RR Lyrae stars as standard candles

    NASA Technical Reports Server (NTRS)

    Lee, Young-Wook

    1992-01-01

    Recent developments in our understanding of RR Lyrae variables are discussed, with special emphasis on their role as distance indicators. The dependence of RR Lyrae luminosity on metallicity and horizontal-branch (HB) morphology is now well understood with many pieces of supporting evidence. This allows the determination of distances to several Local Group galaxies (LMC, M31, and M33) by constructing HB population models that reproduce the observed luminosity functions of RR Lyraes in these galaxies. The new RR Lyrae distances to M31 and M33 are some 15-37 percent larger than those adopted by de Vaucouleurs (1986) and by Aaronson et al. (1986), while they are in reasonable agreements with the recent results based on multicolor CCD photometry of classical Cepheids. This indicates that the large value of Hubble constant (90-100 km/s/Mpc) suggested by these authors may be due, at least in part, to the errors in distances to nearby calibrating galaxies.

  3. Abundances of 23 field RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Liu, Shu; Zhao, Gang; Chen, Yu-Qin; Takeda, Yoichi; Honda, Satoshi

    2013-11-01

    We present stellar parameters and abundances of 15 elements (Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, Y and Ba) for 23 field RR Lyrae variables based on high-resolution (R ~ 60 000) and high signal-to-noise (S/N~ 200) spectra obtained using the High Dispersion Spectrograph on the Subaru Telescope. Six stars in the sample have more than one spectrum observed at different pulsation phases. The derived abundance ratios of [X/Fe] for 14 elements (except for Ba) do not vary during the pulsation cycle. An interesting curve of [Ba/Fe] versus phase is detected for the first time and it shows decreasing [Ba/Fe] with increasing temperature at a given metallicity. Combining with data in the literature, abundances of most RR Lyrae stars as a function of [Fe/H] follow the same trends as those of dwarf stars, but [Sc/Fe] and [Y/Fe] ratios of RR Lyrae stars at solar metallicity are lower than those of dwarf stars. The kinematics of RR Lyrae stars indicate that three comparatively metal-rich RR Lyrae stars might originate from the thick disk and they show higher [α/Fe] ratios than RR Lyrae stars with thin disk kinematics. Among 23 RR Lyrae stars, two special objects are found with abnormal abundances; TV Lib has high [α/Fe], [Sc/Fe], [Y/Fe] and [Ba/Fe] ratios while TW Her has solar [α/Fe] but significantly lower [Sc/Fe], [Y/Fe] and [Ba/Fe] ratios as compared with other RR Lyrae stars.

  4. The magnificent past of RR Lyrae variables

    NASA Astrophysics Data System (ADS)

    Poretti, E.; Le Borgne, J.-F.; Klotz, A.; Audejean, M.; Hirosawa, K.

    2016-05-01

    We briefly review the results obtained by using the times of maximum brightness of RR Lyrae variables. They cover more than 120 years and have been used to study the evolutionary changes of the pulsational periods, the different shapes of the Blazhko effect among Galactic RRab stars, and the interplay between pulsational and Blazhko periods in the eponym of the class, RR Lyr. The data are stored in the GEOS database, continuously fed by contributions from professional and amateur astronomers.

  5. RR Lyrae Variables in Galactic Globular Clusters

    NASA Astrophysics Data System (ADS)

    Catelan, M.; Contreras, R.; Salinas, R.; Escobar, M. E.; Smith, H. A.; De Lee, N.; Pritzl, B. J.; Borissova, J.

    2004-12-01

    RR Lyrae variables are the cornerstone of the Population II distance scale, and yet our knowledge of the RR Lyrae variable star content in Galactic globular clusters is now known to be surprisingly incomplete. In the present paper, we present our new results in this area. Highlights of our work includes: i) The discovery of a vast number of variable stars in M62 (NGC 6266), making it one of the three most RR Lyrae-rich globular clusters known, and also placing it as Oosterhoff type I in spite of a blue horizontal branch morphology; ii) The determination of light curves and Oosterhoff types for globular clusters associated with the Sagittarius dSph galaxy, including NGC 5634, Arp 2, and Terzan 8; iii) A reassessment of the variable star content in the moderately metal-rich globular clusters M69 and NGC 6304; iv) The first theoretical calibration of the RR Lyrae period-luminosity-metallicity relation in I, J, and H, as well as an updated calibration of the K-band relation---along with comparisons against the empirical data, particularly in I. This project was supported in part by Proyecto Fondecyt Regular 1030954.

  6. RR Lyrae Variables in NGC 2808

    NASA Astrophysics Data System (ADS)

    Kunder, Andrea; Stetson, Peter B.; Catelan, Márcio; Amigo, Pía; de Propris, Roberto

    2011-08-01

    NGC 2808 is a unique globular cluster with not only a bimodal-horizontal branch (HB) but also with gaps on the blue horizontal branch. Adequate interpretation of the nature of the detected peculiarities in "bimodal" and "gap" clusters is of paramount importance for understanding the nature of the second parameter phenomenon and scenarios for the formation of the Galaxy. Although RR Lyrae variables are HB stars that can provide powerful constraints to models on the origin of bimodal HBs, unfortunately, until recently, only one RR Lyrae variable was known in this cluster. Here we present the first calibrated time-series CCD photometry for newly discovered fundamental mode RR Lyrae variables in NGC 2808, with observations over a range of twenty years. Investigations of RR Lyrae variable stars in this peculiar, bimodal-horizontal branch globular cluster are carried out to account for its formation, and the effects of helium enrichment and differential reddening. The Oosterhoff classification of NGC 2808, which has recently been associated with a previously unknown dwarf galaxy in Canis Major, is also discussed.

  7. Analysis of RR Lyrae stars of the Northern Sky Variability Survey

    NASA Astrophysics Data System (ADS)

    Kinemuchi, Karen

    RR Lyrae variable stars are important astronomical objects for the investigation of the structure and evolution of the Milky Way Galaxy. These pulsating stars are known to be found in old populations in our Galaxy and have the useful feature that we can readily derive distances from them. With a large survey of the Galaxy, the RR Lyrae stars can be used to map Galactic structures. The Northern Sky Variability Survey (NSVS), whose data was obtained through the Robotic Optical Transient Search Experiment (ROTSE-I) telescope, provides an opportunity to study RR Lyraes found near the Sun. The RR Lyrae stars can be detected up to 7-9 kiloparsecs from the Sun and can probe the inner halo and thick disk component of the Galaxy. This survey is an excellent complement to other Galactic surveys of the bulge and halo components. We have found that almost 90% of the RR Lyraes in the NSVS survey are not included in the General Catalog of Variable Stars (Kholopov 1985). Our sample of RR Lyraes consists of approximately 1430 ab-type RR Lyrae and 375 c-type RR Lyrae candidates. We have determined the periods and amplitudes, and have derived phased light curves for these stars. Metallicity ([Fe/H]) of these stars was derived from the photometric data using empirical methods developed by Jurcsik & Kovacs (1996) and Sandage (2004). To derive distances, we made use of an M V -[Fe/H] relation from Cacciari & Clementini (2003). We have also found that our sample of c-type RR Lyraes close to the plane is contaminated by other types of short period variable stars. RR Lyrae stars of both Oosterhoff I and II groups are present in the field population of RR Lyraes, but we find that the Oosterhoff I is dominant. A metal-rich group of stars was found in our ab-type RR Lyrae sample. These metal-rich stars were identified as belonging to the thick disk population. This metal-rich group was used to find the scale height of the thick disk. The result is approximately 0.4 kpc, which is lower than

  8. RR Lyrae stars in the Gaia era

    NASA Astrophysics Data System (ADS)

    Clementini, G.

    2016-05-01

    Gaia, the European Space Agency spacecraft successfully launched on 19 December 2013, entered into nominal science operations on 18 July 2014 after a few months of commissioning, and has been scanning the sky to a faint limit of G=20.7 mag since then. Gaia is expected to observe more than a hundred thousand RR Lyrae stars in the Galactic halo and bulge (most of which will be new discoveries), and to provide parallax measurements with about 10 muas uncertainty for those brighter than < V > ˜12-13 mag. Status and activities of the spacecraft since launch are briefly reviewed with emphasis on preliminary results obtained for RR Lyrae stars observed in the Large Magellanic Cloud during the first 28 days of science operations spent in Ecliptic Pole scanning mode and in light of the first Gaia data release which is scheduled for summer 2016.

  9. RR Lyrae to understand the Galactic halo

    NASA Astrophysics Data System (ADS)

    Fiorentino, Giuliana

    2016-08-01

    We present recent results obtained using old variable RR Lyrae stars on the Galactic halo structure and its connection with nearby dwarf galaxies. We compare the period and period-amplitude distributions for a sizeable sample of fundamental mode RR Lyrae stars (RRab) in dwarf spheroidals (~1300 stars) with those in the Galactic halo (~16'000 stars) and globular clusters (~1000 stars). RRab in dwarfs -as observed today- do not appear to follow the pulsation properties shown by those in the Galactic halo, nor they have the same properties as RRab in globulars. Thanks to the OGLE experiment we extended our comparison to massive metal-rich satellites like the dwarf irregular Large Magellanic Cloud (LMC) and the Sagittarius (Sgr) dwarf spheroidal. These massive and more metal-rich stellar systems likely have contributed to the Galactic halo formation more than classical dwarf spheroidals. Finally, exploiting the intrinsic nature of RR Lyrae as distance indicators we were able to study the period and period amplitude distributions of RRab within the Halo. It turned out that the inner and the outer Halo do show a difference that may suggest a different formation scenario (in situ vs accreted).

  10. MACHO RR lyrae in the inner halo and bulge

    SciTech Connect

    Drake, A.; Alcock, C.; Allsman, R. A.; Alves, D. R.; Axelrod, T.S.; Becker, A.; Bennett, D. P.; Cook, K. H.; Freeman, K. C.; Griest, K.; Lehner, M. J.; Marshall, S. L.; Minniti, D.; Peterson, B. A.; Pratt, M. R.; Quinn, P. J.; Rodgers, A. W.; Stubbs, C. W.; Sutherland, W.; Tomaney, A.; Vandehei, T.; Welch, D.

    1998-10-01

    The RR Lyrse in the bulge have been proposed to be the oldest populations in the Milky Way, tracers of how the galaxy formed. We study here the distribution of ?{approximately}1600 bulge RR Lyrae stars found by the MACHO Project. The RR Lyrae with 0.4 ? R ? 3 kpc show a density law that is well fit by the extension of the metal-poor stellar halo present in the outer regions of the Milky Way.

  11. The RR Lyrae stars: New perspectives

    SciTech Connect

    McNamara, D. H.; Barnes, J. E-mail: jonathan.barnes@slcc.edu

    2014-02-01

    We demonstrate that the Oosterhoff II (Oo II) RR Lyrae ab variables are hotter by ∼270 K, at the same period, than Oo I variables. Or, at the same ((B) – (V)){sub 0} value the Oo II variables have larger radii than Oo I variables. This accounts for the reason Oo II variables are brighter (0.12-0.20 mag) than Oo I variables. The dependence of the light amplitude of RR Lyrae variables on temperature is independent of Oo type. This makes it possible to derive an accurate set of equations to relate intrinsic (B – V){sub 0} color indices to light amplitudes, which in turn can be used to determine the interstellar reddening (E (B – V)). With just a few variables (∼5), it is possible to determine the E (B – V) to an accuracy of <0.01 mag in the absence of systematic photometric errors. We discuss the errors introduced in color excess determinations by including the Blazhko stars in a solution. A comparison of color excess values of 23 globular clusters and two regions of the Large Magellanic Cloud (LMC), determined with the aid of our newly developed equations, are found to compare favorably (∼0.01 mag) with color excess values found in the literature. Four new Oo III variables, some found in metal-poor clusters, are discussed. An analysis of the galactic-field variables indicates the majority are Oo I and Oo II variables, but a few short-period (log P < –0.36) metal-strong variables, so far not found in galactic globular clusters are evidently ∼0.30 mag fainter than Oo I variables. Oo III variables may also be present in the field. We conclude that the RR Lyrae ab variables are primarily restricted to four sequences or groups. If we assume that the Oo I variables' mean absolute magnitude is Mv = 0.61, the mean absolute magnitudes of the other three sequences are: short-period variables Mv ∼ 0.89 mag, Oo II Mv ∼ 0.43 mag, and Oo III Mv ∼ 0.29 mag. The Oo I fundamental RR Lyrae ab red edge (FRE) and fundamental blue edge (FBE) occur at approximately

  12. The RR Lyrae Stars: New Perspectives

    NASA Astrophysics Data System (ADS)

    McNamara, D. H.; Barnes, J.

    2014-02-01

    We demonstrate that the Oosterhoff II (Oo II) RR Lyrae ab variables are hotter by ~270 K, at the same period, than Oo I variables. Or, at the same (langBrang - langVrang)0 value the Oo II variables have larger radii than Oo I variables. This accounts for the reason Oo II variables are brighter (0.12-0.20 mag) than Oo I variables. The dependence of the light amplitude of RR Lyrae variables on temperature is independent of Oo type. This makes it possible to derive an accurate set of equations to relate intrinsic (B - V)0 color indices to light amplitudes, which in turn can be used to determine the interstellar reddening (E (B - V)). With just a few variables (~5), it is possible to determine the E (B - V) to an accuracy of <0.01 mag in the absence of systematic photometric errors. We discuss the errors introduced in color excess determinations by including the Blazhko stars in a solution. A comparison of color excess values of 23 globular clusters and two regions of the Large Magellanic Cloud (LMC), determined with the aid of our newly developed equations, are found to compare favorably (~0.01 mag) with color excess values found in the literature. Four new Oo III variables, some found in metal-poor clusters, are discussed. An analysis of the galactic-field variables indicates the majority are Oo I and Oo II variables, but a few short-period (log P < -0.36) metal-strong variables, so far not found in galactic globular clusters are evidently ~0.30 mag fainter than Oo I variables. Oo III variables may also be present in the field. We conclude that the RR Lyrae ab variables are primarily restricted to four sequences or groups. If we assume that the Oo I variables' mean absolute magnitude is Mv = 0.61, the mean absolute magnitudes of the other three sequences are: short-period variables Mv ~ 0.89 mag, Oo II Mv ~ 0.43 mag, and Oo III Mv ~ 0.29 mag. The Oo I fundamental RR Lyrae ab red edge (FRE) and fundamental blue edge (FBE) occur at approximately the following

  13. RR Lyrae Stars: Cosmic Lighthouses With a Twist

    NASA Astrophysics Data System (ADS)

    Kolenberg, K.

    2012-06-01

    Since their discovery over a century ago, RR Lyrae stars have proven to be valuable objects for the entire field of astrophysics. They are used as standard candles and witnesses of galactic evolution. Though the pulsations that cause their light variations are dominated by relatively “simple” radial modes, some aspects of RR Lyrae pulsation remain enigmatic. Besides the visual, photographic, and photometric observations of these stars that span several decades, spectroscopic data provide an in-depth view on the pulsations. In the past decade, particularly since the launch of the satellite missions with asteroseismology as part of their program (for example, MOST, CoRoT, and Kepler), several findings have helped us better understand the structure and pulsations of RR Lyrae stars. Nevertheless, ground-based observations and long-term monitoring of RR Lyrae stars, as done by the AAVSO members, remain of utmost importance.

  14. Charting Unexplored Dwarf Galaxy Territory with RR Lyrae

    NASA Astrophysics Data System (ADS)

    Baker, Mariah; Willman, Beth

    2015-11-01

    Observational biases against finding Milky Way (MW) dwarf galaxies at low Galactic latitudes (b ≲ 20°) and at low surface brightnesses ({μ }{{V,0}} ≳ 29 mag arcsec{}-2) currently limit our understanding of the faintest limits of the galaxy luminosity function. This paper is a proof-of-concept that groups of two or more RR Lyrae stars could reveal MW dwarf galaxies at d > 50 kpc in these unmined regions of parameter space, with only modest contamination from interloper groups when large halo structures are excluded. For example, a friends-of-friends (FOF) search with a 2D linking length of 500 pc could reveal dwarf galaxies more luminous than {M}{{V}} = -3.2 mag and with surface brightnesses as faint as 31 mag arcsec{}-2 (or even fainter, depending on RR Lyrae specific frequency). Although existing public RR Lyrae catalogs are highly incomplete at d > 50 kpc and/or include <1% of the MW halo’s volume, a FOF search reveals two known dwarfs (Boötes I and Sextans) and two dwarf candidate groups possibly worthy of follow-up. PanSTARRS 1 (PS1) may catalog RR Lyrae to 100 kpc (in the absence of Galactic extinction) which would include up to ˜15% of predicted MW dwarf galaxies. Groups of PS1 RR Lyrae should therefore reveal very low surface brightness and low Galactic latitude dwarfs within its footprint, if they exist. With sensitivity to RR Lyrae to d ≳ 600 kpc, LSST is the only planned survey that will be both wide-field and deep enough to use RR Lyrae to definitively measure the MW’s dwarf galaxy census to extremely low surface brightnesses, and through the Galactic plane.

  15. RR Lyrae stars in eclipsing systems -- historical candidates

    NASA Astrophysics Data System (ADS)

    Liška, J.; Skarka, M.; Hájková, P.; Auer, R. F.

    2016-03-01

    Discovery of binary systems among RR Lyrae stars belongs to challenges of present astronomy. So far, none of classical RR Lyrae stars was clearly confirmed, that it is a part of an eclipsing system. From this reason we studied two RR Lyrae stars, VX Her and RW Ari, in which changes assigned to eclipses were detected in sixties and seventies of the 20th century. In this paper our preliminary results based on analysis of new photometric measurements are presented as well as the results from the detailed analysis of original measurements. A new possible eclipsing system, RZ Cet was identified in the archive data. Our analysis rather indicates errors in measurements and reductions of the old data than real changes for all three stars.

  16. A machine learned classifier for RR Lyrae in the VVV survey

    NASA Astrophysics Data System (ADS)

    Elorrieta, Felipe; Eyheramendy, Susana; Jordán, Andrés; Dékány, István; Catelan, Márcio; Angeloni, Rodolfo; Alonso-García, Javier; Contreras-Ramos, Rodrigo; Gran, Felipe; Hajdu, Gergely; Espinoza, Néstor; Saito, Roberto K.; Minniti, Dante

    2016-11-01

    Variable stars of RR Lyrae type are a prime tool with which to obtain distances to old stellar populations in the Milky Way. One of the main aims of the Vista Variables in the Via Lactea (VVV) near-infrared survey is to use them to map the structure of the Galactic Bulge. Owing to the large number of expected sources, this requires an automated mechanism for selecting RR Lyrae, and particularly those of the more easily recognized type ab (i.e., fundamental-mode pulsators), from the 106-107 variables expected in the VVV survey area. In this work we describe a supervised machine-learned classifier constructed for assigning a score to a Ks-band VVV light curve that indicates its likelihood of being ab-type RR Lyrae. We describe the key steps in the construction of the classifier, which were the choice of features, training set, selection of aperture, and family of classifiers. We find that the AdaBoost family of classifiers give consistently the best performance for our problem, and obtain a classifier based on the AdaBoost algorithm that achieves a harmonic mean between false positives and false negatives of ≈7% for typical VVV light-curve sets. This performance is estimated using cross-validation and through the comparison to two independent datasets that were classified by human experts.

  17. A NEW CEMP-s RR LYRAE STAR

    SciTech Connect

    Kinman, T. D.; Beers, Timothy C.; Aoki, Wako; Brown, Warren R.

    2012-08-10

    We show that SDSS J170733.93+585059.7 (hereafter SDSS J1707+58), previously identified by Aoki and collaborators as a carbon-enhanced metal-poor star (with s-process-element enhancements, CEMP-s), on the assumption that it is a main-sequence turnoff star, is the RR Lyrae star VIII-14 identified by the Lick Astrograph Survey. Revised abundances for SDSS J1707+58 are [Fe/H] = -2.92, [C/Fe] = +2.79, and [Ba/Fe] = +2.83. It is thus one of the most metal-poor RR Lyrae stars known, and has more extreme [C/Fe] and [Ba/Fe] than the only other RR Lyrae star known to have a CEMP-s spectrum (TY Gru). Both stars are Oosterhoff II stars with prograde kinematics, in contrast to stars with [C/Fe] < + 0.7, such as KP Cyg and UY CrB, which are disk stars. Twelve other RR Lyrae stars with [C/Fe] {>=}+0.7 are presented as CEMP candidates for further study.

  18. RR Lyrae Atmospherics: Wrinkles Old and New. A Preview

    NASA Astrophysics Data System (ADS)

    Preston, George W.

    2011-01-01

    I report some results of an echelle spectroscopic survey of RR Lyrae stars begun in 2006 that I presented in my Henry Norris Lecture of 2010 January 4. Topics include (1) atmospheric velocity gradients, (2) phase-dependent envelope turbulence as it relates to Peterson's discoveries of axial rotation on the horizontal branch and to Stothers' explanation of the Blazhko effect, (3) the three apparitions of hydrogen emission during a pulsation cycle, (4) the occurrence of He I lines in emission and absorption, (5) detection of He II emission and metallic line doubling in Blazhko stars, and finally (6) speculation about what helium observations of RR Lyrae stars in omega Centauri might tell us about the putative helium populations and the horizontal branch of that strange globular cluster. This paper preserves the substance and style of remarks that accompanied the author's PowerPoint presentation of the 2009 Henry Norris Russell lecture.

  19. The Extinction Toward the Galactic Bulge from RR Lyrae Stars

    SciTech Connect

    Kunder, A; Popowski, P; Cook, K; Chaboyer, B

    2007-11-07

    The authors present mean reddenings toward 3525 RR0 Lyrae stars from the Galactic bulge fields of the MACHO Survey. These reddenings are determined using the color at minimum V-band light of the RR0 Lyrae stars themselves and are found to be in general agreement with extinction estimates at the same location obtained from other methods. Using 3256 stars located in the Galactic Bulge, they derive the selective extinction coefficient R{sub V,VR} = A{sub V}/E(V-R) = 4.2 {+-} 0.2. this value is what is expected for a standard extinction law with R{sub V,BV} = 3.1 {+-} 0.3

  20. RR LYRAE ATMOSPHERICS: WRINKLES OLD AND NEW. A PREVIEW

    SciTech Connect

    Preston, George W.

    2011-01-15

    I report some results of an echelle spectroscopic survey of RR Lyrae stars begun in 2006 that I presented in my Henry Norris Lecture of 2010 January 4. Topics include (1) atmospheric velocity gradients, (2) phase-dependent envelope turbulence as it relates to Peterson's discoveries of axial rotation on the horizontal branch and to Stothers' explanation of the Blazhko effect, (3) the three apparitions of hydrogen emission during a pulsation cycle, (4) the occurrence of He I lines in emission and absorption, (5) detection of He II emission and metallic line doubling in Blazhko stars, and finally (6) speculation about what helium observations of RR Lyrae stars in omega Centauri might tell us about the putative helium populations and the horizontal branch of that strange globular cluster.

  1. New systemic radial velocities of suspected RR Lyrae binary stars

    NASA Astrophysics Data System (ADS)

    Guggenberger, E.; Barnes, T. G.; Kolenberg, K.

    2016-05-01

    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.

  2. THE CHEMICAL COMPOSITIONS OF VARIABLE FIELD HORIZONTAL-BRANCH STARS: RR LYRAE STARS

    SciTech Connect

    For Biqing; Sneden, Christopher; Preston, George W.

    2011-12-01

    We present a detailed abundance study of 11 RR Lyrae ab-type variables: AS Vir, BS Aps, CD Vel, DT Hya, RV Oct, TY Gru, UV Oct, V1645 Sgr, WY Ant, XZ Aps, and Z Mic. High-resolution and high signal-to-noise ratio echelle spectra of these variables were obtained with the 2.5 m du Pont telescope at the Las Campanas Observatory. We obtained more than 2300 spectra, roughly 200 spectra per star, distributed more or less uniformly throughout the pulsational cycles. A new method has been developed to obtain the initial effective temperatures of our sample stars at a specific pulsational phase. We find that the abundance ratios are generally consistent with those of similar metallicity field stars in different evolutionary states and throughout the pulsational cycles for RR Lyrae stars. TY Gru remains the only n-capture enriched star among the RRab in our sample. A new relation is found between microturbulence and effective temperature among stars of the horizontal-branch population. In addition, the variation of microturbulence as a function of phase is empirically shown to be similar to the theoretical variation. Finally, we conclude that the derived T{sub eff} and log g values of our sample stars follow the general trend of a single mass evolutionary track.

  3. Physical parameter determination of seven RR Lyrae stars in Bootes

    NASA Astrophysics Data System (ADS)

    Peña, J. H.; Arellano, A.; Sareyan, J. P.; Peña, R.; Alvarez, M.

    2007-06-01

    uvbyβ photoelectric photometry of the RR Lyrae stars AE, RS, ST, TV, TW, UU, and XX Bootis has been acquired in order to determine the physical parameters of the stars. We used the correlation between the Fourier parameters derived from the light curves and the physical parameters such as the absolute magnitude M_v, intrinsic colour (B-V)_0 and metal abundance [Fe/H]. Once reddening has been determined, unreddened indices are obtained and T_{eff} and log g followed along the cycle, using a comparison with the theoretical models given for our determined metallicity.

  4. An Update on the Status of RR Lyrae Research - Report of the RRL2015 Meeting (October, Hungary) (Abstract)

    NASA Astrophysics Data System (ADS)

    Kolenberg, K.

    2016-06-01

    (Abstract only) In October 2015 we organized the first international meeting focused on RR Lyrae research, with the goal to discuss recent developments and future RR Lyrae plans. The Scientific rationale is the following:

  5. THE HORIZONTAL BRANCH OF NGC 1851: CONSTRAINTS FROM ITS RR LYRAE VARIABLES

    SciTech Connect

    Kunder, Andrea; De Propris, Roberto; Walker, Alistair; Salaris, Maurizio; Cassisi, Santi; Stetson, Peter B.; Catelan, Marcio; Amigo, Pia E-mail: mcatelan@astro.puc.cl

    2013-01-01

    We use the pulsational properties of the RR Lyrae variables in the globular cluster NGC 1851 to obtain detailed constraints of the various sub-stellar populations present along its horizontal branch. On the basis of detailed synthetic horizontal branch modeling, we find that minor helium variations (Y {approx} 0.248-0.280) are able to reproduce the observed periods and amplitudes of the RR Lyrae variables, as well as the frequency of fundamental and first-overtone RR Lyrae stars. Comparison of number ratios among the blue and red horizontal branch components and the two observed subgiant branches also suggest that the RR Lyrae variables originated from the progeny of the bright subgiant branch. The RR Lyrae variables with slightly enhanced helium (Y {approx} 0.270-0.280) have longer periods at a given amplitude, as is seen with Oosterhoff II (OoII) RR Lyrae variables, whereas the RR Lyrae variables with Y {approx} 0.248-0.270 have shorter periods, exhibiting properties of Oosterhoff I (OoI) variables. This correlation does suggest that the pulsational properties of RR Lyrae stars can be very useful for tracing the various subpopulations and can provide suitable constraints on the multiple population phenomenon. It appears to be of great interest to explore whether this conclusion can be generalized to other globular clusters hosting multiple populations.

  6. RR Lyrae stars in the outer region of the globular cluster M 3: A shortage of long periods at r ˜ 3.5 to 6 arcmin?

    NASA Astrophysics Data System (ADS)

    Butler, D. J.

    2004-06-01

    An analysis of the radial distribution of ab-type RR Lyrae star periods in the outer region of the globular cluster M 3 at r ≥0.83' has been performed. That analysis points towards a real shortage of stars with long periods in the radial distance range 3.5' to 6' (or about 7 to 12 core radii). A brief discussion is presented. The origin of the phenomenon remains an open question.

  7. THE RR LYRAE VARIABLES AND HORIZONTAL BRANCH OF NGC 6656 (M22) {sup ,}

    SciTech Connect

    Kunder, Andrea; Walker, Alistair R.; Paredes Alvarez, Leonardo; Stetson, Peter B.; Cassisi, Santi; Layden, Andrew; Bono, Giuseppe; Catelan, Márcio; Clem, James L.; Matsunaga, Noriyuki; Salaris, Maurizio; Lee, Jae-Woo; Chaboyer, Brian E-mail: mcatelan@astro.puc.cl

    2013-11-01

    The first calibrated broadband UBVI time-series photometry is presented for the RR Lyrae variable stars in NGC 6656 (M22), with observations spanning a range of 22 years. We have also redetermined the variability types and periods for the RR Lyrae stars identified previously by photographic observations, revising the number of fundamental-mode RR Lyrae variables (RR0) to 10 and the number of first-overtone variables (RR1) to 16. The mean periods of the RR0 and RR1 variables are (P) {sub RR0} = 0.66 ± 0.02 days and (P) {sub RR1} = 0.33 ± 0.01 days, respectively, supporting an Oosterhoff II classification for the cluster. The number ratio of RR1-type to all RR-type variables is N {sub 1}/N{sub RR} = 0.61, also consistent with an Oosterhoff II designation. Both the RR Lyrae stars' minimum light colors and the blue edge of the RR Lyrae instability strip suggest E( B – – V) = 0.36 ± 0.02 mag toward M22. Regarding the HB morphology of M22, we find (B-R)/(B+V+R) = +0.97 ± 0.1 and at least one ''gap'' located in an unusual part of the blue HB, in the middle of the so-called hot HB stars.

  8. Stellar evolution and period changes in RR Lyrae stars

    NASA Technical Reports Server (NTRS)

    Lee, Young-Wook

    1991-01-01

    The observed secular period changes of RR Lyrae stars in five globular clusters have been compared with those predicted by synthetic models of the horizontal branch (HB). It is shown that most of the observed number distributions of the period change rate beta could be attributed to evolutionary effects, if the random observational error is of order + or - 0.07 days/Myr in beta as suggested by the observers. The model calculations indicate that the mean rate of period change in RR Lyrae stars in globular clusters depends sensitively on their HB type, as is the case for the period shift at a given effective temperature. The distinct bias toward positive period changes in M15 and Omega Cen is evidence that most HB stars in the Oosterhoff group II clusters pass through the instability strip from blue to red toward the end of their core helium burning phase. If confirmed by future observations, this is strong support for the Lee et al. (1990) explanation of the Sandage (1957) period-shift effect.

  9. MACHO RR lyrae stars in the galactic bulge: the spatial distribution

    SciTech Connect

    Minniti, D.; Alcock, C.; Alves, D.

    1997-08-01

    We have analyzed a sample of 1150 type ab, and 550 type c RR Lyrae stars found in 24 bulge fields of the MACHO database. These fields cover a range in Galactocentric distances from 0.3 to 1.6 kpc. In combination with the data on the outer bulge fields of Alard (1997) and Wesselink (1987), here we present the surface density distribution of bulge RR Lyrae between 0.3 and 3 kpc. The distribution along the line of sight of the bulge RR Lyrae population was examined on the basis of the mean magnitudes, and it was shown that the bulk of the RR Lyrae population is not barred (Alcock et al. 1998). There is a hint of a bar only in the RR Lyrae of the inner fields closer to the Galactic center. The red giant clump stars in the MACHO fields, however, clearly show a barred distribution, confirming the results of previous studies (e.g. Dwek et al. 1995, Stanek et al. 1996). In the MACHO fields studied there are about 550 clump giants per RR Lyrae star. The RR Lyrae trace metal-poor stars, which are a minor component of the bulge population. The clump giants, however, should trace the bulk of the metal-rich population, foUowing underlying mass of the bulge more closely. Given the different spatial distribution, we concluded that the RR Lyrae and the clump giants trace two dif+erent populations (Alcock et al. 1998). The RR Lyrae would represent the inner extension of the Galactic halo in these fields (Minniti 1996). The observed surface distribution of RR Lyrae in the bulge fields was computed after discarding background RR Lyrae that belong to the Sgr dwarf galaxy (Alard 1996, Alcock et al. 1997). This distribution yields a power law density distribution. There is no turnover or flattening of this distribution even in the innermost fields, indicating that the RR Lyrae population is very concentrated, with core radius RC < 0.5 kpc. We also determine that the RR Lyrae surface distribution in the bulge fields is flattened, with b/a = 0.7.

  10. A Continued Search for CEMP RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    Reggiani, H. M.; Kennedy, C. R.; Rossi, S.; Beers, T. C.

    2014-10-01

    Among the stellar populations of the Galactic halo there is a class of stars known as carbon-enhanced metal-poor (CEMP) stars. These are metal-poor ([Fe/H] < 1.0) stars whose atmospheres exhibit large overabundances of carbon ([C/Fe] ≥ +0.7). The frequency of these stars increases with decreasing metallicity, and so by studying their abundance patterns, one can begin to uncover details of the origins of the elements. There exist a number of different classes of CEMP stars (Beers & Christlieb 2005) with specific abundance characteristics; one of them is the CEMP-s class, which exhibit evidence of s-process element enrichment, widely believed to be resultant of mass transfer from a companion low-metallicity asymptotic giant branch (AGB) star, where the production of carbon and s-process elements occurs. Recent spectroscopic observations of metal-poor RR Lyrae stars have revealed that their typical abundance patterns are consistent with very metal-poor (VMP) and extremely metal-poor (EMP) giants and dwarfs studied in the halo system of the Milky Way. Of particular interest is the recent discovery of a VMP RR Lyrae that has large overabundances of carbon and the s-process elements. In this work, we showed results obtained with WiFeS observations 2.3m Siding Spring Observatory telescope of a set of newly-identified CEMP stars that are known RR Lyr stars. We confirmed theses stars as CEMP stars (Kennedy et. al., in prep) and will, eventually, test their abundances against new stellar evolution simulations of CEMP stars.

  11. Seven new carbon-enhanced metal-poor RR Lyrae stars

    SciTech Connect

    Kennedy, Catherine R.; Stancliffe, Richard J.; Kuehn, Charles; Beers, Timothy C.; Kinman, T. D.; Placco, Vinicius M.; Reggiani, Henrique; Rossi, Silvia; Lee, Young Sun

    2014-05-20

    We report estimated carbon-abundance ratios, [C/Fe], for seven newly discovered carbon-enhanced metal-poor (CEMP) RR Lyrae stars. These are well-studied RRab stars that had previously been selected as CEMP candidates based on low-resolution spectra. For this pilot study, we observed eight of these CEMP RR Lyrae candidates with the Wide Field Spectrograph on the ANU 2.3 m telescope. Prior to this study, only two CEMP RR Lyrae stars had been discovered: TY Gru and SDSS J1707+58. We compare our abundances to new theoretical models of the evolution of low-mass stars in binary systems. These simulations evolve the secondary stars, post accretion from an asymptotic giant-branch (AGB) donor, all the way to the RR Lyrae stage. The abundances of CEMP RR Lyrae stars can be used as direct probes of the nature of the donor star, such as its mass, and the amount of material accreted onto the secondary. We find that the majority of the sample of CEMP RR Lyrae stars is consistent with AGB donor masses of around 1.5-2.0 M {sub ☉} and accretion masses of a few hundredths of a solar mass. Future high-resolution studies of these newly discovered CEMP RR Lyrae stars will help disentangle the effects of the proposed mixing processes that occur in such objects.

  12. The unique dynamical system underlying RR Lyrae pulsations

    NASA Astrophysics Data System (ADS)

    Kollath, Z.

    2016-05-01

    Hydrodynamic models of RR Lyrae pulsation display a very rich behaviour. Contrary to earlier expectations, high order resonances play a crucial role in the nonlinear dynamics representing the interacting modes. Chaotic attractors can be found at different time scales: both in the pulsation itself and in the amplitude equations shaping the possible modulation of the oscillations. Although there is no one-to-one connection between the nonlinear features found in the numerical models and the observed behaviour, the richness of the found phenomena suggests that the interaction of modes should be taken seriously in the study of the still unsolved puzzle of Blazhko effect. One of the main lessons of this complex system is that we should rethink the simple interpretation of the observed effect of resonances.

  13. Proper-Motion Based Kinematics Study of Galactic RR Lyraes

    NASA Astrophysics Data System (ADS)

    Dambis, Andrei K.; Berdnikov, Leonid N.; Rastorguev, Alexei S.; Zabolotskikh, Marina V.

    2016-08-01

    We use the UCAC4 and SDSS proper motions of about 7500 RR Lyrae type variables located within ~10 kpc from the Sun to study the dependence of their velocity ellipsoid on Galactocentric distance in the R G = 3-17 kpc interval. The radial velocity dispersion, σ VR , decreases from ~190 km/s at R G = 3.5-5.5 kpc down to ~100 km/s at R G = 13-15 kpc, and the σ VT /σ VR ratio remains virtually constant (σ VT /σ VR ~0.54-0.64) in the Galactocentric distance interval from R G = 4.5 kpc to R G = 10.5 kpc increasing to ~0.9 both toward the Galactic center and beyond R G = 11 kpc.

  14. Physical parameters of seven field RR Lyrae Stars in bootes

    NASA Astrophysics Data System (ADS)

    Peña, J. H.; Arellano Ferro, A.; Peña Miller, R.; Sareyan, J. P.; Álvarez, M.

    2009-10-01

    Strömgren uvby-β photometry is reported for the RR Lyrae stars AE, RS, ST, TV, TW, UU, and XX in Bootes. The physical parameters M/M_⊙, log(L/L_⊙), M_V, log T_{eff} and [Fe/H], have been estimated from the Fourier decomposition of the light curves and the empirical calibrations developed for this type of stars. The obtained [Fe/H] values are compared with those calculated from the Δ S index for some sample stars. It was found that reddening in the zone is negligible compared to that shown by several objects in the same sky zone. From that, distance to the stars was calculated. The variation of the unreddened indexes (b-y)_0 and c_1 along the pulsational cycle allows the direct comparison with the theoretical grids and, hence, an independent determination of T_{eff} and log g.

  15. DISTANCE SCALE ZERO POINTS FROM GALACTIC RR LYRAE STAR PARALLAXES

    SciTech Connect

    Benedict, G. Fritz; McArthur, Barbara E.; Barnes, Thomas G.; Feast, Michael W.; Harrison, Thomas E.; Bean, Jacob L.; Kolenberg, Katrien; Menzies, John W.; Laney, C. D.; Chaboyer, Brian; Fossati, Luca; Nesvacil, Nicole; Smith, Horace A.; Kochukhov, Oleg; Nelan, Edmund P.; Taylor, Denise; Shulyak, D. V.; Freedman, Wendy L.

    2011-12-15

    We present new absolute trigonometric parallaxes and proper motions for seven Population II variable stars-five RR Lyr variables: RZ Cep, XZ Cyg, SU Dra, RR Lyr, and UV Oct; and two type 2 Cepheids: VY Pyx and {kappa} Pav. We obtained these results with astrometric data from Fine Guidance Sensors, white-light interferometers on Hubble Space Telescope. We find absolute parallaxes in milliseconds of arc: RZ Cep, 2.12 {+-} 0.16 mas; XZ Cyg, 1.67 {+-} 0.17 mas; SU Dra, 1.42 {+-} 0.16 mas; RR Lyr, 3.77 {+-} 0.13 mas; UV Oct, 1.71 {+-} 0.10 mas; VY Pyx, 6.44 {+-} 0.23 mas; and {kappa} Pav, 5.57 {+-} 0.28 mas; an average {sigma}{sub {pi}}/{pi} = 5.4%. With these parallaxes, we compute absolute magnitudes in V and K bandpasses corrected for interstellar extinction and Lutz-Kelker-Hanson bias. Using these RR Lyrae variable star absolute magnitudes, we then derive zero points for M{sub V} -[Fe/H] and M{sub K} -[Fe/H]-log P relations. The technique of reduced parallaxes corroborates these results. We employ our new results to determine distances and ages of several Galactic globular clusters and the distance of the Large Magellanic Cloud. The latter is close to that previously derived from Classical Cepheids uncorrected for any metallicity effect, indicating that any such effect is small. We also discuss the somewhat puzzling results obtained for our two type 2 Cepheids.

  16. Database of candidates for RR Lyrae stars in binary systems - RRLyrBinCan

    NASA Astrophysics Data System (ADS)

    Liska, J.; Skarka, M.

    2016-05-01

    A new on-line database with RR Lyrae stars bound in binary systems is presented. Its purpose is to give a quick overview about known and suspected RR Lyrae stars in binaries on the basis of available literature. The first released version of the catalogue contains information about 61 double-star candidates, their orbital periods, method of detection, comments and active links to published papers.

  17. High-precision 2MASS JHK{sub s} light curves and other data for RR Lyrae star SDSS J015450 + 001501: Strong constraints for nonlinear pulsation models

    SciTech Connect

    Szabó, Róbert; Ivezić, Željko; Kiss, László L.; Kolláth, Zoltán; Jones, Lynne; Becker, Andrew C.; Davenport, James R. A.; Sesar, Branimir; Cutri, Roc M.

    2014-01-01

    We present and discuss an extensive data set for the non-Blazhko ab-type RR Lyrae star SDSS J015450+001501, including optical Sloan Digital Sky Survey ugriz light curves and spectroscopic data, LINEAR and Catalina Sky Survey unfiltered optical light curves, and infrared Two Micron All Sky Survey (2MASS) JHK{sub s} and Wide-field Infrared Survey Explorer W1 and W2 light curves. Most notable is that light curves obtained by 2MASS include close to 9000 photometric measures collected over 3.3 yr and provide an exceedingly precise view of near-infrared variability. These data demonstrate that static atmosphere models are insufficient to explain multiband photometric light-curve behavior and present strong constraints for nonlinear pulsation models for RR Lyrae stars. It is a challenge to modelers to produce theoretical light curves that can explain data presented here, which we make publicly available.

  18. RR Lyrae: the zero point of temperature and magnitude scales.

    NASA Astrophysics Data System (ADS)

    de Santis, R.

    1996-02-01

    We find that the position in the HR diagram of the RR Lyrae variables of type ab is strictly related to properties defined in the period-amplitude plane: that is, both temperature and V magnitude of the static star are tightly correlated with blue amplitude and period. Using this pulsational approach, we show that the equilibrium temperature derived by the Baade-Wesselink (BW) method, using V and K bands, connects observational data with both pulsational and evolutionary theories in a self consistent scenario for an original helium of Y=0.23 . In contrast, we wholly confirm the inconsistency between temperature and luminosity level as derived by the BW procedure with the luminosity being wrong. We use the pulsational properties to compare the distance modulus derived by RRab variables with that obtained by the isochrone fitting procedure for a sample of galactic globular clusters (GGCs). We find a convergence to within about 0.1mag of uncertainty: in turn, this means that ages derived by both the {DELTA}V(ZAHB-TO) and the {DELTA}(B-V) methods agree to within approximately 2Gyr. Finally, we point out the following: a) the metal poor GGCs M92, M68 and M15 appear coeval (20Gyr old); b) an age spread of =~6Gyr is found in our sample of clusters.

  19. The chemical compositions of RR Lyrae type c variable stars

    SciTech Connect

    Govea, Jose; Gomez, Thomas; Sneden, Christopher; Preston, George W. E-mail: chris@verdi.as.utexas.edu

    2014-02-20

    We present a detailed chemical abundance study of eight RR Lyrae variable stars of subclass c (RRc). The target RRc stars chosen for study exhibit 'Blazhko-effect' period and amplitude modulations to their pulsational cycles. Data for this study were gathered with the echelle spectrograph of the 100 inch du Pont telescope at Las Campanas Observatory. Spectra were obtained throughout each star's pulsation cycle. Atmospheric parameters—effective temperature, surface gravity, microturbulent velocity, and metallicity—were derived at multiple phase points. We found metallicities and element abundance ratios to be constant within observational uncertainties over the pulsational cycles of all stars. Moreover, the α-element and Fe-group abundance ratios with respect to iron are consistent with other horizontal-branch members (RRab, blue and red non-variables). Finally, we have used the [Fe/H] values of these eight RRc stars to anchor the metallicity estimates of a large-sample RRc snapshot spectroscopic study being conducted with the same telescope and instrument combination employed here.

  20. ON THE BLAZHKO EFFECT IN RR LYRAE STARS

    SciTech Connect

    Buchler, J. Robert; Kollath, Zoltan E-mail: kollath@konkoly.hu

    2011-04-10

    The Blazhko effect is a long-term, generally irregular modulation of the light curves that occurs in a sizeable number of RR Lyrae stars. The physical origin of the effect has been a puzzle ever since its discovery over a hundred years ago. We build here upon the recent observational and theoretical work of Szabo et al. on RRab stars who found with hydrodynamical simulations that the fundamental pulsation mode can get destabilized by a 9:2 resonant interaction with the 9th overtone. Alternating pulsation cycles arise, although these remain periodic, i.e., not modulated as in the observations. Here we use the amplitude equation formalism to study this nonlinear, resonant interaction between the two modes. We show that not only does the fundamental pulsation mode break up into a period-two cycle through the nonlinear, resonant interaction with the overtone, but that the amplitudes are modulated, and that in a broad range of parameters the modulations are irregular as in the observations. This irregular behavior is in fact chaotic and arises from a strange attractor in the dynamics.

  1. The effect of Livermore OPAL opacities on the evolutionary masses of RR Lyrae stars

    NASA Technical Reports Server (NTRS)

    Yi, Sukyoung; Lee, Young-Wook; Demarque, Pierre

    1993-01-01

    We have investigated the effect of the new Livermore OPAL opacities on the evolution of horizontal-branch (HB) stars. This work was motivated by the recent stellar pulsation calculations using the new Livermore opacities, which suggest that the masses of double-mode RR Lyrae stars are 0.1-0.2 solar mass larger than those based on earlier opacities. Unlike the pulsation calculations, we find that the effect of opacity change on the evolution of HB stars is not significant. In particular, the effect of the mean masses of RR Lyrae stars is very small, showing a decrease of only 0.01-0.02 solar mass compared to the models based on old Cox-Stewart opacities. Consequently, with the new Livermore OPAL opacities, both the stellar pulsation and evolution models now predict approximately the same masses for the RR Lyrae stars. Our evolutionary models suggest that the mean masses of the RR Lyrae stars are about 0.76 and about 0.71 solar mass for M15 (Oosterhoff group II) and M3 (group I), respectively. If (alpha/Fe) = 0.4, these values are decreased by about 0.03 solar mass. Variations of the mean masses of RR Lyrae stars with HB morphology and metallicity are also presented.

  2. PERIOD CHANGE SIMILARITIES AMONG THE RR LYRAE VARIABLES IN OOSTERHOFF I AND OOSTERHOFF II GLOBULAR SYSTEMS

    SciTech Connect

    Kunder, Andrea; Walker, Alistair; De Propris, Roberto; Stetson, Peter B.; Bono, Giuseppe; Di Cecco, Alessandra; Nemec, James M.; Monelli, Matteo; Cassisi, Santi; Andreuzzi, Gloria; Dall'Ora, Massimo; Zoccali, Manuela

    2011-01-15

    We present period change rates (dP/dt) for 42 RR Lyrae variables in the globular cluster IC 4499. Despite clear evidence of these period increases or decreases, the observed period change rates are an order of magnitude larger than predicted from theoretical models of this cluster. We find that there is a preference for increasing periods, a phenomenon observed in most RR Lyrae stars in Milky Way globular clusters. The period change rates as a function of position in the period-amplitude plane are used to examine possible evolutionary effects in OoI clusters, OoII clusters, field RR Lyrae stars, and the mixed-population cluster {omega} Centauri. It is found that there is no correlation between the period change rate and the typical definition of Oosterhoff groups. If the RR Lyrae period changes correspond with evolutionary effects, this would be in contrast to the hypothesis that RR Lyrae variables in OoII systems are evolved horizontal-branch stars that spent their zero-age horizontal-branch phase on the blue side of the instability strip. This may suggest that age may not be the primary explanation for the Oosterhoff types.

  3. La Silla quest RR Lyrae star survey: Region I

    SciTech Connect

    Zinn, R.; Miller, L.; Horowitz, B.; Baltay, C.; Ellman, N.; Hadjiyska, E.; Rabinowitz, D.; Vivas, A. K.

    2014-01-20

    A search for RR Lyrae stars (RRLSs) in ∼840 deg{sup 2} of the sky in right ascension 150°-210° and declination –10° to + 10° yielded 1013 type ab and 359 type c RRLS. This sample is used to study the density profile of the Galactic halo, halo substructures, and the Oosterhoff type of the halo over distances (d {sub ☉}) from ∼5 to ∼80 kpc. The halo is flattened toward the Galactic plane, and its density profile steepens in slope at galactocentric distances greater than ∼25 kpc. The RRLS in the stellar stream from the Sagittarius dwarf spheroidal (dSph) galaxy match well the model of Law and Majewski for the stars that were stripped 1.3-3.2 Gyr ago, but not for the ones stripped 3.2-5.0 Gyr ago. Over densities are found at the locations of the Virgo Overdensity and the Virgo Stellar Stream. Within 1° of 1220-1, which Jerjen et al. identify as a halo substructure at d {sub ☉} ∼ 24 kpc, there are four RRLS that are possibly members. Away from substructures, the RRLS are a mixture of Oosterhoff types I and II, but mostly OoI (∼73%). The accretion of galaxies resembling in RRLS content the most massive Milky Way satellites (LMC, SMC, For, Sgr) may explain this preponderance of OoI. Six new RRLS and three new anomalous Cepheids were found in the Sextans dSph galaxy.

  4. Determining a mid-infrared period-luminosity relation for Galactic globular cluster RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Neeley, J.; Marengo, M.; Bono, G.; Braga, V.; Dall'Ora, M.; CRRP Team

    2016-05-01

    We present new RR Lyrae variable period-luminosity (P-L) relations at mid-infrared wavelengths. Accurate photometry was obtained for 37 RR Lyrae variables in the globular cluster M4 (NGC 6121) using the Infrared Array Camera onboard the Spitzer Space Telescope. We obtained a very tight MIR P-L relation with 0.056 mag dispersion and 0.007 mag zero point dispersion. The P-L relation was calibrated by five Galactic RR Lyrae stars with parallaxes from HST. The resulting band averaged distance modulus for M4 is 11.399 +- 0.007(statistical) +- 0.080(systematic) +- 0.015(calibration) +- 0.020(extinction).

  5. VizieR Online Data Catalog: RR Lyrae in SDSS Stripe 82 (Suveges+, 2012)

    NASA Astrophysics Data System (ADS)

    Suveges, M.; Sesar, B.; Varadi, M.; Mowlavi, N.; Becker, A. C.; Ivezic, Z.; Beck, M.; Nienartowicz, K.; Rimoldini, L.; Dubath, P.; Bartholdi, P.; Eyer, L.

    2013-05-01

    We propose a robust principal component analysis framework for the exploitation of multiband photometric measurements in large surveys. Period search results are improved using the time-series of the first principal component due to its optimized signal-to-noise ratio. The presence of correlated excess variations in the multivariate time-series enables the detection of weaker variability. Furthermore, the direction of the largest variance differs for certain types of variable stars. This can be used as an efficient attribute for classification. The application of the method to a subsample of Sloan Digital Sky Survey Stripe 82 data yielded 132 high-amplitude delta Scuti variables. We also found 129 new RR Lyrae variables, complementary to the catalogue of Sesar et al., extending the halo area mapped by Stripe 82 RR Lyrae stars towards the Galactic bulge. The sample also comprises 25 multiperiodic or Blazhko RR Lyrae stars. (8 data files).

  6. Ursa Minor dSph galaxy: Updated census of RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Kinemuchi, K.; Grabowski, K.; Kuehn, C.; Nemec, J.

    2016-05-01

    We present our observations and photometric results of the Ursa Minor dwarf spheroidal galaxy (UMi dSph). Observations were taken at the Apache Point Observatory 0.5m ARCSAT telescope in 2014. We identify previously known RR Lyrae stars in the field of view, and also catalog other variable star candidates for which tentative classifications are provided. We have performed a period search for the known and new variable stars. Our ultimate goal is to create an updated catalog of variable stars in the UMi dSph and to compare the RR Lyrae stellar characteristics to other RR Lyrae stars found in Local Group dSph galaxies. The comparisons can give us insights to the near-field cosmology of the Local Group.

  7. RR Lyrae stars and color-magnitude diagram of the globular cluster NGC 6388

    NASA Technical Reports Server (NTRS)

    Silbermann, N. A.; Smith, Horace A.; Bolte, Michael; Hazen, Martha L.

    1994-01-01

    We present new V, B-V, and V, V-R color-magnitude diagrams for the bulge globular cluster NGC 6388. These diagrams indicate that NGC 6388 is a metal-rich globular cluster with color-magnitude morphology similar to that of 47 Tucanae. We have conducted a search for new variable stars close to NGC 6388, finding three new RR Lyrae stars. The membership of these and previously discovered RR Lyrae stars near NGC 6388 is discussed. There is reason for believing that some of these variables are nonmembers. Others, however, may belong to the cluster and may be similar to the RR Lyrae star V9 in 47 Tuc.

  8. Detailed chemical abundances of distant RR Lyrae stars in the Virgo Stellar Stream

    NASA Astrophysics Data System (ADS)

    Duffau, S.; Sbordone, L.; Vivas, A. K.; Hansen, C. J.; Zoccali, M.; Catelan, M.; Minniti, D.; Grebel, E. K.

    2016-05-01

    We present the first detailed chemical abundances for distant RR Lyrae stars members of the Virgo Stellar Stream (VSS), derived from X- Shooter medium-resolution spectra. Sixteen elements from carbon to barium have been measured in six VSS RR Lyrae stars, sampling all main nucleosynthetic channels. For the first time we will be able to compare in detail the chemical evolution of the VSS progenitor with those of Local Group dwarf spheroidal galaxies (LG dSph) as well as the one of the smooth halo.

  9. RR Lyrae stars in omega Centauri: Near-IR properties and period-luminosity relations

    NASA Astrophysics Data System (ADS)

    Navarrete, C.; Catelan, M.; Contreras Ramos, R.; Gran, F.; Alonso-Garcia, J.

    2016-05-01

    Omega Centauri contains a rich harvest of variable stars. Here we report on a deep, wide-field, near-infrared (IR) variability survey for this cluster, carried out using ESO's 4.1m VISTA telescope. Our time-series data includes more than 180 RR Lyrae light curves in both J and Ks, allowing us to derive an unprecedented homogeneous and complete near-IR catalog of RR Lyrae in the field of omega Cen. Near-IR period-luminosity relations are derived and used to determine an updated (pulsational) distance modulus for the cluster.

  10. EXPLORING THE SAGITTARIUS STREAM WITH SEKBO SURVEY RR LYRAE STARS

    SciTech Connect

    Prior, Sayuri L.; Da Costa, G. S.; Keller, Stefan C.

    2009-10-20

    A sample of RR Lyrae (RRL) variables from the Southern Edgeworth-Kuiper Belt Object survey in regions overlapping the expected position of debris from the interaction of the Sagittarius (Sgr) dwarf galaxy with the Milky Way (R.A. approx 20 and 21.5 hr; distance = 16-21 kpc) has been followed up spectroscopically and photometrically. The 21 photometrically confirmed type ab RRLs in this region have ([Fe/H]) = -1.79 +- 0.08 on our system, consistent with the abundances found for RRLs in a different portion of the Sgr tidal debris stream. The distribution of velocities in the Galactic standard of rest frame (V {sub GSR}) of the 26 RRLs in the region is not consistent with a smooth halo population. Upon comparison with the Sgr disruption models of Law et al., a prominent group of five stars having highly negative radial velocities (V {sub GSR} approx-175 km s{sup -1}) is consistent with predictions for old trailing debris when the Galactic halo potential is modeled as oblate. In contrast, the prolate model does not predict any significant number of Sgr stars at the locations of the observed sample. The observations also require that the recent trailing debris stream has a broader spread perpendicular to the Sgr plane than predicted by the models. We have also investigated the possible association of the Virgo Stellar Stream (VSS) with Sgr debris by comparing radial velocities for RRLs in the region with the same models, finding similarities in the velocity-position trends. As suggested by our earlier work, the stars in the VSS region with large negative V {sub GSR} values are likely to be old leading Sgr debris, but we find that while old trailing Sgr debris may well make a contribution at positive V {sub GSR} values, it is unlikely to fully account for the VSS feature. Overall we find that further modeling is needed, as trailing arm data generally favor oblate models while leading arm data favor prolate models, with no single potential fitting all the observed data.

  11. TRACING THE ORPHAN STREAM TO 55 kpc WITH RR LYRAE STARS

    SciTech Connect

    Sesar, Branimir; Cohen, Judith G.; Bellm, Eric C.; Levitan, David; Tang, Sumin; Waszczak, Adam; Kulkarni, Shrinivas R.; Prince, Thomas A.; Grillmair, Carl J.; Laher, Russ R.; Surace, Jason A.; Bhalerao, Varun B.; Ofek, Eran O.

    2013-10-10

    We report positions, velocities, and metallicities of 50 ab-type RR Lyrae (RRab) stars observed in the vicinity of the Orphan stellar stream. Using about 30 RRab stars classified as being likely members of the Orphan stream, we study the metallicity and the spatial extent of the stream. We find that RRab stars in the Orphan stream have a wide range of metallicities, from –1.5 dex to –2.7 dex. The average metallicity of the stream is –2.1 dex, identical to the value obtained by Newberg et al. using blue horizontal branch stars. We find that the most distant parts of the stream (40-50 kpc from the Sun) are about 0.3 dex more metal-poor than the closer parts (within ∼30 kpc), suggesting a possible metallicity gradient along the stream's length. We have extended the previous studies and have mapped the stream up to 55 kpc from the Sun. Even after a careful search, we did not identify any more distant RRab stars that could plausibly be members of the Orphan stream. If confirmed with other tracers, this result would indicate a detection of the end of the leading arm of the stream. We have compared the distances of Orphan stream RRab stars with the best-fit orbits obtained by Newberg et al. We find that model 6 of Newberg et al. cannot explain the distances of the most remote Orphan stream RRab stars, and conclude that the best fit to distances of Orphan stream RRab stars and to the local circular velocity is provided by potentials where the total mass of the Galaxy within 60 kpc is M{sub 60} ∼ 2.7 × 10{sup 11} M{sub ☉}, or about 60% of the mass found by previous studies. More extensive modeling that would consider non-spherical potentials and the possibility of misalignment between the stream and the orbit is highly encouraged.

  12. THE SWIFT UVOT STARS SURVEY. II. RR LYRAE STARS IN M3 AND M15

    SciTech Connect

    Siegel, Michael H.; Porterfield, Blair L.; Balzer, Benjamin G.; Hagen, Lea M. Z. E-mail: blp14@psu.edu E-mail: lea.zernow.hagen@gmail.com

    2015-10-15

    We present the first results of a near-ultraviolet (NUV) survey of RR Lyrae stars from the Ultraviolet Optical Telescope (UVOT) on board the Swift Gamma-ray Burst Mission. It is well-established that RR Lyrae stars have large amplitudes in the far- and near-ultraviolet. We have used UVOT’s unique wide-field NUV imaging capability to perform the first systematic NUV survey of variable stars in the Galactic globular clusters M3 and M15. We identify 280 variable stars, comprised of 275 RR Lyrae, 2 anomalous Cepheids, 1 classical Cepheid, 1 SX Phoenicis star, and 1 possible long-period or irregular variable. Only two of these are new discoveries. We compare our results to previous investigations and find excellent agreement in the periods with significantly larger amplitudes in the NUV. We map out, for the first time, an NUV Bailey diagram from globular clusters, showing the usual loci for fundamental mode RRab and first overtone RRc pulsators. We show the unique sensitivity of NUV photometry to both the temperatures and the surface gravities of RR Lyrae stars. Finally, we show evidence of an NUV period–metallicity–luminosity relationship. Future investigations will further examine the dependence of NUV pulsation parameters on metallicity and Oosterhoff classification.

  13. A HIGH-VELOCITY BULGE RR LYRAE VARIABLE ON A HALO-LIKE ORBIT

    SciTech Connect

    Kunder, Andrea; Storm, J.; Rich, R. M.; Hawkins, K.; Poleski, R.; Johnson, C. I.; Shen, J.; Li, Z.-Y.; Cordero, M. J.; Nataf, D. M.; Bono, G.; Walker, A. R.; Koch, A.; De Propris, R.; Udalski, A.; Szymanski, M. K.; Soszynski, I.; Pietrzynski, G.; Ulaczyk, K.; Wyrzykowski, Ł.; and others

    2015-07-20

    We report on the RR Lyrae variable star, MACHO 176.18833.411, located toward the Galactic bulge and observed within the data from the ongoing Bulge RR Lyrae Radial Velocity Assay, which has the unusual radial velocity of −372 ± 8 km s{sup −1} and true space velocity of −482 ± 22 km s{sup −1} relative to the Galactic rest frame. Located less than 1 kpc from the Galactic center and toward a field at (l, b) = (3, −2.5), this pulsating star has properties suggesting it belongs to the bulge RR Lyrae star population, yet a velocity indicating it is abnormal, at least with respect to bulge giants and red clump stars. We show that this star is most likely a halo interloper and therefore suggest that halo contamination is not insignificant when studying metal-poor stars found within the bulge area, even for stars within 1 kpc of the Galactic center. We discuss the possibility that MACHO 176.18833.411 is on the extreme edge of the bulge RR Lyrae radial velocity distribution, and also consider a more exotic scenario in which it is a runaway star moving through the Galaxy.

  14. Lighthouses in the fog: Locating the faintest Milky Way satellites with RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Sesar, B.

    2016-05-01

    Almost every known low-luminosity Milky Way dwarf spheroidal (dSph) satellite galaxy contains at least one RR Lyrae star. Assuming that a fraction of distant (60 < dhelio < 100 kpc) Galactic halo RR Lyrae stars are members of yet to be discovered low-luminosity dSph galaxies, we perform a guided search for these low-luminosity dSph galaxies. In order to detect the presence of dSph galaxies, we combine stars selected from more than 123 sight- lines centered on RR Lyrae stars identified by the Palomar Transient Factory. We find that this method is sensitive enough to detect the presence of Segue 1- like galaxies (MV = -1.5+0.6-0.8, rh = 30 pc) even if only ~20 sightlines were occupied by such dSph galaxies. Yet, when our method is applied to the SDSS DR10 imaging catalog, no signal is detected. An application of our method to sightlines occupied by pairs of close (< 200 pc) horizontal branch stars, also did not yield a detection. Thus, we place upper limits on the number of low- luminosity dSph galaxies with half-light radii from 30 pc to 120 pc, and in the probed volume of the halo. Stronger constraints on the luminosity function may be obtained by applying our method to sightlines centered on RR Lyrae stars selected from the Pan-STARRS1 survey, and eventually, from LSST.

  15. A new Phi_31-period-metallicity relation for RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Martinez-Vazquez, C. E.; Monelli, M.; Bono, G.; Stetson, P. B.; Gallart, C.; Bernard, E. J.; Fiorentino, G.; Dall'Ora, M.

    2016-05-01

    We present a new calibration of the 31-period-metallicity relation based on cluster instead of field RR Lyrae stars. The novel approach relies on mean Fourier decomposition parameters of their optical light curves, mean periods and metal abundances rooted on a solid metallicity scale. The key advantage when compared with similar relations in the literature is that individual cluster samples cover a broad range in periods, and therefore the opportunity to fully characterize, at fixed metal content, their pulsational behaviour. To accomplish this goal, we used data for seven globular clusters hosting at least 20 RR Lyrae stars and covering a broad range in metallicity (from -2.3 to -1.1 dex). To further extend the metallicity range, we also included field RR Lyrae stars with a good sampling of the light curve (ASAS, Catalina), and for which iron measurements based on high-resolution spectra are available. We applied the new calibration to 167 fundamental RR Lyrae in the Sculptor dSph and we found a considerable spread in metallicity, thus confirming the fast early chemical evolution of this galaxy (Martinez-Vazquez et al. 2015).

  16. Observing globular cluster RR Lyraes with the BYU West Mountain Observatory

    NASA Astrophysics Data System (ADS)

    Jeffery, E. J.; Joner, M. D.; Walton, R. S.

    2016-05-01

    We have utilized the 0.9-meter telescope of the Brigham Young University West Mountain Observatory to secure data on six northern hemi- sphere globular clusters. Here we present observations of RR Lyrae stars located in these clusters. We compare light curves produced using both DAOPHOT and ISIS software packages. Light curve fitting is done with FITLC.

  17. DELTA SCUTI, SX PHOENICIS, AND RR LYRAE STARS IN GALAXIES AND GLOBULAR CLUSTERS

    SciTech Connect

    McNamara, D. H.

    2011-10-15

    The distances to four galaxies and two globular clusters which are derived with the aid of period-luminosity and period-color relations of {delta} Scuti and SX Phe stars are compared to the distances derived by other methods, in particular RR Lyrae stars. We examine the luminosities of horizontal branch or RR Lyrae stars in Oosterhoff I and II globular clusters. Observational data from a variety of sources indicate a discontinuous jump of {approx}0.2 mag in the luminosities of RR Lyrae variables at [Fe/H] {approx} -1.5 as we transition from Oosterhoff I to Oosterhoff II clusters. If Oosterhoff I clusters have RR Lyrae variables with average M{sub V} values of M{sub V} = 0.53 mag at [Fe/H] = -1.5, it implies that RR Lyrae stars in Oosterhoff II clusters average M{sub V} values are {approx}0.34 mag. Unlike the Oosterhoff I clusters which show an increase in the V luminosity of RR Lyrae stars as [Fe/H] becomes smaller, little or no change in the V luminosity of RR Lyrae variables is evident in Oosterhoff II clusters in the interval of [Fe/H] from -1.5 to -2.2. We find distance moduli found with RR Lyrae variables agree to {<=}0.04 mag with those found with the {delta} Scuti and/or SX Phe variables if the M{sub V} values of RR Lyrae stars above are adopted. We find evidence of recent star formation (presence of near solar-metallicity {delta} Scuti stars with ages of 150 Myr to 1 Gyr) in the Large Magellanic Cloud (LMC), Small Magellanic Cloud, and the central region of the Fornax (dSph) galaxies. We also find an older population of metal-poor {delta} Scuti variables (SX Phe stars) in the LMC and Fornax galaxies. The Carina dSph is unique in that only an old population of metal-poor {delta} Scuti variables is evident. No evidence of recent {delta} Scuti star formation is found. The minimum periods observed for the SX Phe variables (blue stragglers) in the globular clusters M55 and {omega} Cen indicate that they could have been formed in a burst of metal-poor single star

  18. Anomalous Double-Mode RR Lyrae Stars in the Magellanic Clouds

    NASA Astrophysics Data System (ADS)

    Soszyński, I.; Smolec, R.; Dziembowski, W. A.; Udalski, A.; Szymański, M. K.; Wyrzykowski, Ł.; Ulaczyk, K.; Poleski, R.; Pietrukowicz, P.; Kozłowski, S.; Skowron, D.; Skowron, J.; Mróz, P.; Pawlak, M.

    2016-08-01

    We report the discovery of a new subclass of double-mode RR Lyrae stars in the Large and Small Magellanic Clouds. The sample of 22 pulsating stars have been extracted from the latest edition of the OGLE collection of RR Lyrae variables in the Magellanic System. The stars pulsating simultaneously in the fundamental (F) and first-overtone (1O) modes have distinctly different properties than regular double-mode RR Lyrae variables (RRd stars). The P1O/PF period ratios of our anomalous RRd stars are within a range 0.725-0.738, while "classical" double-mode RR Lyrae variables have period ratios in the range 0.742-0.748. In contrast to the typical RRd stars, in the majority of the anomalous pulsators the F-mode amplitudes are higher than the 1O-mode amplitudes. The light curves associated with the F-mode in the anomalous RRd stars show different morphology than the light curves of, both, regular RRd stars and single-mode RRab stars. Most of the anomalous double-mode stars show long-term modulations of the amplitudes (Blazhko-like effect). Translating the period ratios into the abundance parameter, Z, we find for our stars Z ∈ (0.002, 0.005) - an order of magnitude higher values than typical for RR Lyrae stars. The mass range of the RRd stars inferred from the WI vs. PF diagram is (0.55 - 0.75) M⊙. These parameters cannot be accounted for with single star evolution assuming a Reimers-like mass loss. Much greater mass loss caused by interaction with other stars is postulated. We blame the peculiar pulsation properties of our stars to the parametric resonance instability of the 1O-mode to excitation of the F- and 2O-modes as with the inferred parameters of the stars 2ω1O ≈ ωF + ω2O.

  19. On the absolute magnitude of RR Lyrae stars - UU Ceti, RV Phoenicis, and W Tucanae

    NASA Astrophysics Data System (ADS)

    Cacciari, C.; Clementini, G.; Fernley, J. A.

    1992-09-01

    IR JHK light curves are presented for the RRab Lyrae stars UU Ceti, RV Phoenicis, and W Tucanae. These stars have similar periods and metallicities data, together with BVRI photometry and CORAVEL radial velocity data and Walraven photometry are used to derive absolute magnitudes for the stars using two formulations of the Baade-Wesselink method: (1) the infrared flux version and (2) the surface brightness version. The two methods are directly compared and their respective advantages and shortcomings are discussed. Finally, a comparison is made with previous results on the absolute magnitude of RR Lyrae variables.

  20. Fourier Analysis of First-Overtone RR Lyrae Variables in the LMC

    NASA Astrophysics Data System (ADS)

    Clement, C. M.; Muzzin, A. V.; Rowe, J. F.; MACHO Collaboration

    2002-05-01

    Simon's (1989, ApJ, 343, L17) Fourier decomposition technique has been applied to the V magnitudes of the first-overtone RR Lyrae (RR1) variables in 16 LMC fields observed by the MACHO collaboration. The Fourier coefficients R21 and φ 31 derived for these stars have been compared with the coefficients of RR1 variables in the galactic globular clusters Omega Centauri, M2, M3, M5, M68, M107 (NGC 6171) and NGC 6441. Our analysis indicates that the majority of the LMC RR1 variables have coefficients similar to those in the Oosterhoff type I (OoI) clusters M3 and M5 and to the OoI variables in Omega Centauri. In a study of hydrodynamic pulsation models of first overtone RR Lyrae variables, Simon & Clement (1993, ApJ, 410, 526) found that the Fourier phase parameter φ 31 depends essentially on mass and luminosity. From this, we conclude that the masses and luminosities of most of the RR1 variables in the LMC are comparable to those of the OoI RR1 variables in Omega Centauri, M3 and M5, a fact that should be considered when RR Lyrae variables are used for determining the distance to the LMC. The MACHO collaboration includes C. Alcock, R. A. Allsman, D. R. Alves, T. S. Axelrod, A. C. Becker, D. P. Bennet, K. H. Cook, A. J. Drake, K. C. Freeman, M. Geha, K. Griest, M. J. Lehner, S. L. Marshall, D. Minniti, C. A. Nelson, B. A. Peterson, P. Popowski, M. R. Pratt, P. J. Quinn, C. W. Stubbs, W. Sutherland, T. Vandehel and D. L. Welch. This research has been supported in part by the Natural Sciences and Engineering Research Council of Canada.

  1. Updated census of RR Lyrae stars in the globular cluster ω Centauri (NGC 5139)

    NASA Astrophysics Data System (ADS)

    Navarrete, C.; Contreras Ramos, R.; Catelan, M.; Clement, C. M.; Gran, F.; Alonso-García, J.; Angeloni, R.; Hempel, M.; Dékány, I.; Minniti, D.

    2015-05-01

    Aims: ω Centauri (NGC 5139) contains many variable stars of different types and, in particular, more than one hundred RR Lyrae stars. This enabled gathering a homogeneous sample (in terms of instrument, image quality, and time coverage) of high-quality near-infrared (NIR) RR Lyrae light curves by performing an extensive time-series campaign aimed at this object. We have conducted a variability survey of ω Cen in the NIR, using ESO's 4.1 m Visible and Infrared Survey Telescope for Astronomy (VISTA). This is the first paper of a series describing our results. Methods: ω Cen was observed using VIRCAM mounted on VISTA. A total of 42 epochs in J and 100 epochs in KS were obtained, distributed over a total timespan of 352 days. Point-spread function photometry was performed using DAOPHOT in the inner and DoPhot in the outer regions of the cluster. Periods of the known variable stars were improved when necessary using an ANOVA analysis. Results: We collected an unprecedented homogeneous and complete NIR catalog of RR Lyrae stars in the field of ω Cen, allowing us to study for the first time all the RR Lyrae stars associated with the cluster, except for four stars that are located far away from the cluster center. We derived membership status, subclassifications between RRab and RRc subtypes, periods, amplitudes, and mean magnitudes for all the stars in our sample. Additionally, four new RR Lyrae stars were discovered, two of which are very likely cluster members. We also discuss here the distribution of ω Cen stars in the Bailey (period-amplitude) diagram. We provide reference lines in this plane for both Oosterhoff Type I (OoI) and Oosterhoff Type II (OoII) components in J and KS. Conclusions: We clarify the status of many (candidate) RR Lyrae stars that have been reported as unclear in previous studies. This includes stars with anomalous positions in the color-magnitude diagram, uncertain periods or/and variability types, and possible field interlopers. We conclude

  2. HST/ACS Observations of RR Lyrae Stars in Six Ultra-Deep Fields of M31

    NASA Technical Reports Server (NTRS)

    Jeffery, E. J.; Smith, E.; Brown, T. M.; Sweigart, A. V.; Kalirai, J. S.; Ferguson, H. C.; Guhathakurta, P.; Renzini, A.; Rich, R. M.

    2010-01-01

    We present HST/ACS observations of RR Lyrae variable stars in six ultra deep fields of the Andromeda galaxy (M31), including parts of the halo, disk, and giant stellar stream. Past work on the RR Lyrae stars in M31 has focused on various aspects of the stellar populations that make up the galaxy s halo, including their distances and metallicities. This study builds upon this previous work by increasing the spatial coverage (something that has been lacking in previous studies) and by searching for these variable stars in constituents of the galaxy not yet explored. Besides the 55 RR Lyrae stars we found in our initial field located 11kpc from the galactic nucleus, we find additional RR Lyrae stars in four of the remaining five ultra deep fields as follows: 21 in the disk, 24 in the giant stellar stream, 3 in the halo field 21kpc from the galactic nucleus, and 5 in one of the halo fields at 35kpc. No RR Lyrae were found in the second halo field at 35kpc. The RR Lyrae populations of these fields appear to mostly be of Oosterhoff I type, although the 11kpc field appears to be intermediate or mixed. We will discuss the properties of these stars including period and reddening distributions. We calculate metallicities and distances for the stars in each of these fields using different methods and compare the results, to an extent that has not yet been done. We compare these methods not just on RR Lyrae in our M31 fields, but also on a data set of Milky Way field RR Lyrae stars.

  3. HST/ACS OBSERVATIONS OF RR LYRAE STARS IN SIX ULTRA-DEEP FIELDS OF M31

    SciTech Connect

    Jeffery, E. J.; Smith, E.; Brown, T. M.; Kalirai, J. S.; Ferguson, H. C.; Sweigart, A. V.; Rich, R. M.

    2011-05-15

    We present HST/ACS observations of RR Lyrae variable stars in six ultra-deep fields of the Andromeda galaxy (M31), including parts of the halo, disk, and giant stellar stream. Past work on the RR Lyrae stars in M31 has focused on various aspects of the stellar populations that make up the galaxy's halo, including their distances and metallicities. This study builds upon this previous work by increasing the spatial coverage (something that has been lacking in previous studies) and by searching for these variable stars in constituents of the galaxy not yet explored. Besides the 55 RR Lyrae stars we found in our initial field located 11 kpc from the galactic nucleus, we find additional RR Lyrae stars in four of the remaining five ultra-deep fields as follows: 21 in the disk, 24 in the giant stellar stream, three in the halo field 21 kpc from the galactic nucleus, and five in one of the halo fields at 35 kpc. No RR Lyrae stars were found in the second halo field at 35 kpc. The RR Lyrae populations of these fields appear to be mostly of Oosterhoff I type, although the 11 kpc field appears to be intermediate or mixed. We will discuss the properties of these stars including period and reddening distributions. We calculate metallicities and distances for the stars in each of these fields using different methods and compare the results, to an extent that has not yet been done. We compare these methods not just on RR Lyrae stars in our M31 fields, but also on a data set of Milky Way field RR Lyrae stars.

  4. RR-Lyrae-type pulsations from a 0.26-solar-mass star in a binary system.

    PubMed

    Pietrzyński, G; Thompson, I B; Gieren, W; Graczyk, D; Stępień, K; Bono, G; Moroni, P G Prada; Pilecki, B; Udalski, A; Soszyński, I; Preston, G W; Nardetto, N; McWilliam, A; Roederer, I U; Górski, M; Konorski, P; Storm, J

    2012-04-01

    RR Lyrae pulsating stars have been extensively used as tracers of old stellar populations for the purpose of determining the ages of galaxies, and as tools to measure distances to nearby galaxies. There was accordingly considerable interest when the RR Lyrae star OGLE-BLG-RRLYR-02792 (referred to here as RRLYR-02792) was found to be a member of an eclipsing binary system, because the mass of the pulsator (hitherto constrained only by models) could be unambiguously determined. Here we report that RRLYR-02792 has a mass of 0.26 solar masses M[symbol see text] and therefore cannot be a classical RR Lyrae star. Using models, we find that its properties are best explained by the evolution of a close binary system that started with M[symbol see text] and 0.8M[symbol see text]stars orbiting each other with an initial period of 2.9 days. Mass exchange over 5.4 billion years produced the observed system, which is now in a very short-lived phase where the physical properties of the pulsator happen to place it in the same instability strip of the Hertzsprung-Russell diagram as that occupied by RR Lyrae stars. We estimate that only 0.2 per cent of RR Lyrae stars may be contaminated by systems similar to this one, which implies that distances measured with RR Lyrae stars should not be significantly affected by these binary interlopers. PMID:22481359

  5. THE IMPACT OF CONTAMINATED RR LYRAE/GLOBULAR CLUSTER PHOTOMETRY ON THE DISTANCE SCALE

    SciTech Connect

    Majaess, D.; Turner, D.; Lane, D.; Gieren, W.

    2012-06-10

    RR Lyrae variables and the stellar constituents of globular clusters are employed to establish the cosmic distance scale and age of the universe. However, photometry for RR Lyrae variables in the globular clusters M3, M15, M54, M92, NGC 2419, and NGC 6441 exhibit a dependence on the clustercentric distance. For example, variables and stars positioned near the crowded high-surface brightness cores of the clusters may suffer from photometric contamination, which invariably affects a suite of inferred parameters (e.g., distance, color excess, absolute magnitude, etc.). The impetus for this study is to mitigate the propagation of systematic uncertainties by increasing awareness of the pernicious impact of contaminated and radial-dependent photometry.

  6. On the Sandage period shift effect among field RR Lyrae stars

    NASA Technical Reports Server (NTRS)

    Lee, Young-Wook

    1990-01-01

    The origin of the disagreement between the results of the synthetic horizontal branch (HB) model of Lee et al. (1990) and the Sandage (1990) analysis of Lub's (1977) data on a sample of field RR Lyrae stars is investigated, extending the original synthetic HB calculations of Lee et al. to all HB types over the metallicity range of the Galactic halo. It is shown that the period shifts of the RR Lyrae stars in globular clusters depend strongly on their HB type and metallicity. Results suggest that the disagreement between the slopes, Delta logP(Teff)/Delta Fe/H, obtained by Lee et al. and the ones obtained by Sandage can be explained by the fact that Lub's sample may have contained many highly evolved stars in the metallicity range of Fe/H between -2.0 and -1.6, since Lee's analysis did not include these stars.

  7. On the Sandage period shift effect among field RR Lyrae stars

    SciTech Connect

    Lee, Y. Victoria Univ. )

    1990-11-01

    The origin of the disagreement between the results of the synthetic horizontal branch (HB) model of Lee et al. (1990) and the Sandage (1990) analysis of Lub's (1977) data on a sample of field RR Lyrae stars is investigated, extending the original synthetic HB calculations of Lee et al. to all HB types over the metallicity range of the Galactic halo. It is shown that the period shifts of the RR Lyrae stars in globular clusters depend strongly on their HB type and metallicity. Results suggest that the disagreement between the slopes, Delta logP(Teff)/Delta Fe/H, obtained by Lee et al. and the ones obtained by Sandage can be explained by the fact that Lub's sample may have contained many highly evolved stars in the metallicity range of Fe/H between -2.0 and -1.6, since Lee's analysis did not include these stars. 48 refs.

  8. RR Lyrae stars as probes of the Milky Way structure and formation

    NASA Astrophysics Data System (ADS)

    Pietrukowicz, Pawel

    2016-08-01

    RR Lyrae stars being distance indicators and tracers of old population serve as excellent probes of the structure, formation, and evolution of our Galaxy. Thousands of them are being discovered in ongoing wide-field surveys. The OGLE project conducts the Galaxy Variability Survey with the aim to detect and analyze variable stars, in particular of RRab type, toward the Galactic bulge and disk, covering a total area of 3000 deg2. Observations in these directions also allow detecting background halo variables and unique studies of their properties and distribution at distances from the Galactic Center to even 40 kpc. In this contribution, we present the first results on the spatial distribution of the observed RRab stars, their metallicity distribution, the presence of multiple populations, and relations with the old bulge. We also show the most recent results from the analysis of RR Lyrae stars of the Sgr dwarf spheroidal galaxy, including its center, the globular cluster M54.

  9. DISTANCE TO THE SAGITTARIUS DWARF GALAXY USING MACHO PROJECT RR LYRAE STARS

    SciTech Connect

    Kunder, Andrea; Chaboyer, Brian E-mail: brian.chaboyer@dartmouth.edu

    2009-05-15

    We derive the distance to the northern extension of the Sagittarius (Sgr) dwarf spheroidal galaxy from 203 Sgr RR0 Lyrae stars found in the MACHO database. Their distances are determined differentially with respect to 288 Galactic bulge RR0 Lyrae stars also found in the MACHO data. We find a distance modulus difference of 2.41 mag at l = 5{sup 0} and b = -8{sup 0} and that the extension of the Sgr galaxy toward the galactic plane is inclined toward us. Assuming R {sub GC} = 8 kpc, this implies the distance to these stars is (m - M){sub 0} = 16.97 {+-} 0.07 mag, which corresponds to D = 24.8 {+-} 0.8 kpc. Although this estimate is smaller than previous determinations for this galaxy and agrees with previous suggestions that Sgr's body is truly closer to us, this estimate is larger than studies at comparable galactic latitudes.

  10. Observations and Analysis of Three Field RR Lyrae Stars Selected Using Single-epoch SDSS Data

    NASA Astrophysics Data System (ADS)

    Powell, W. L., Jr.; Jameson, S. N.; De lee, N.; Wilhelm, R. J.

    2015-08-01

    We present the results of our Johnson B and V observations of three RR Lyrae candidate stars that we identified as likely variable stars using SDSS data. The stars were selected based upon a single epoch of photometry and spectroscopy. The stars were observed at McDonald Observatory to obtain full light curves. We present full light curves, measured periods, and amplitudes, as well as the results of our Fourier analysis of the light curves.

  11. An RR Lyrae family portrait: 33 stars observed in Pisces with K2-E2

    NASA Astrophysics Data System (ADS)

    Molnár, L.; Szabó, R.; Moskalik, P. A.; Nemec, J. M.; Guggenberger, E.; Smolec, R.; Poleski, R.; Plachy, E.; Kolenberg, K.; Kolláth, Z.

    2015-10-01

    A detailed analysis is presented of 33 RR Lyrae stars in Pisces observed with the Kepler space telescope over the 8.9-d long K2 Two-Wheel Concept Engineering Test. The sample includes not only fundamental-mode and first-overtone (RRab and RRc) stars but the first two double-mode (RRd) stars that Kepler detected and the only modulated first-overtone star ever observed from space so far. The precision of the extracted K2 light curves made it possible to detect low-amplitude additional modes in all subtypes. All RRd and non-modulated RRc stars show the additional mode at PX/P1 ˜ 0.61 that was detected in previous space-based photometric measurements. A periodicity longer than the fundamental mode was tentatively identified in one RRab star that might belong to a gravity mode. We determined the photometric [Fe/H] values for all fundamental-mode stars and provide the preliminary results of our efforts to fit the double-mode stars with non-linear hydrodynamic pulsation models. The results from this short test run indicate that the K2 mission will be, and has started to be, an ideal tool to expand our knowledge about RR Lyrae stars. As a by-product of the target search and analysis, we identified 165 bona fide double-mode RR Lyrae stars from the Catalina Sky Survey observations throughout the sky, 130 of which are new discoveries.

  12. The identification of RR Lyrae and δ Scutti stars from variable galaxy evolution explorer ultraviolet sources

    SciTech Connect

    Kinman, T. D.; Brown, Warren R.

    2014-12-01

    We identify the RR Lyrae and δ Scuti stars in three catalogs of Galaxy Evolution Explorer (GALEX) variable sources. The NUV amplitude of RR Lyrae stars is about twice that in V, so we find a larger percentage of low-amplitude variables than catalogs such as Abbas et al. Interestingly, the (NUV – V){sub 0} color is sensitive to metallicity and can be used to distinguish between variables of the same period but differing [Fe/H]. This color is also more sensitive to T {sub eff} than optical colors and can be used to identify the red edge of the instability gap. We find 8 δ Scuti stars, 17 RRc stars, 1 RRd star, and 84 RRab stars in the GALEX variable catalogs of Welsh et al. and Wheatley et al. We also classify 6 δ Scuti stars, 5 RRc stars, and 18 RRab stars among the 55 variable GALEX sources identified as 'stars' or RR Lyrae stars in the catalog of Gezari et al. We provide ephemerides and light curves for the 26 variables that were not previously known.

  13. Probing Kinematic Substructures in the Virgo Overdensity using RR Lyrae from Recent Surveys

    NASA Astrophysics Data System (ADS)

    Farmer, John; Vivas, A. Katherina

    2015-01-01

    The Virgo Overdensity is one of the most intriguing features of the galactic halo, as it covers a large portion of the sky and seems to contain several kinematic substructures. It has been suggested that the remnants of several merger events coexist in this region. RR Lyrae stars are an excellent tracer for disentangling the different components of this overdensity, since they are excellent standard candles; by using both positions and pulsation-corrected radial velocities, we can identify distinct groups in phase space. In the last year, several surveys for RR Lyraes covering the Virgo region have become publicly available. We present analysis of ~300 spectra for ~200 stars in the Virgo overdensity region. This is a significant increase in the known sample of these stars in the region, spanning a significantly larger area of the sky than previous studies. Photometry for these data are taken primarily from the La Silla and Venezuela QUEST variability surveys with spectra provided by SDSS Data Release 10. Radial velocities for type ab RR Lyrae stars are corrected using the new set of template radial velocity curves for Balmer and metallic lines given by Sesar (2012). We combine data from QUEST, the Catalina Sky Survey, LINEAR, and spectroscopic observations from Duffau (2014) to give our full sample. A preliminary analysis reveals confirmation for several known stellar streams.

  14. The Identification of RR Lyrae and δ Scutti Stars from Variable Galaxy Evolution Explorer Ultraviolet Sources

    NASA Astrophysics Data System (ADS)

    Kinman, T. D.; Brown, Warren R.

    2014-12-01

    We identify the RR Lyrae and δ Scuti stars in three catalogs of Galaxy Evolution Explorer (GALEX) variable sources. The NUV amplitude of RR Lyrae stars is about twice that in V, so we find a larger percentage of low-amplitude variables than catalogs such as Abbas et al. Interestingly, the (NUV - V)0 color is sensitive to metallicity and can be used to distinguish between variables of the same period but differing [Fe/H]. This color is also more sensitive to T eff than optical colors and can be used to identify the red edge of the instability gap. We find 8 δ Scuti stars, 17 RRc stars, 1 RRd star, and 84 RRab stars in the GALEX variable catalogs of Welsh et al. and Wheatley et al. We also classify 6 δ Scuti stars, 5 RRc stars, and 18 RRab stars among the 55 variable GALEX sources identified as "stars" or RR Lyrae stars in the catalog of Gezari et al. We provide ephemerides and light curves for the 26 variables that were not previously known.

  15. The space photometry revolution and our understanding of RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Szabó, R.; Benkő, M. J.; Paparó, M.; Chapellier, E.; Poretti, E.; Baglin, A.; Weiss, W. W.; Kolenberg, K.; Guggenberger, E.; Le Borgne, J.-F.

    2015-09-01

    The study of RR Lyrae stars has recently been invigorated thanks to the long, uninterrupted, ultra-precise time series data provided by the Kepler and CoRoT space telescopes. We give a brief overview of the new observational findings concentrating on the connection between period doubling and the Blazhko modulation, and the omnipresence of additional periodicities in all RR Lyrae subtypes, except for non-modulated RRab stars. Recent theoretical results demonstrate that if more than two modes are present in a nonlinear dynamical system such as a high-amplitude RR Lyrae star, the outcome is often an extremely intricate dynamical state. Thus, based on these discoveries, an underlying picture of complex dynamical interactions between modes is emerging which sheds new light on the century-old Blazhko-phenomenon, as well. New directions of theoretical efforts, like multidimensional hydrodynamical simulations, future space photometric missions and detailed spectroscopic investigations will pave the way towards a more complete understanding of the atmospheric and pulsation dynamics of these enigmatic touchstone objects.

  16. The OGLE Collection of Variable Stars. Over 45 000 RR Lyrae Stars in the Magellanic System

    NASA Astrophysics Data System (ADS)

    Soszyński, I.; Udalski, A.; Szymański, M. K.; Wyrzykowski, Ł.; Ulaczyk, K.; Poleski, R.; Pietrukowicz, P.; Kozłowski, S.; Skowron, D. M.; Skowron, J.; Mróz, P.; Pawlak, M.

    2016-06-01

    We present the largest collection of RR Lyrae stars in the Magellanic System and in its foreground. The sample consists of 45 451 RR Lyr stars, of which 39 082 were detected toward the Large Magellanic Cloud and 6369 toward the Small Magellanic Cloud. We provide long-term time-series photometric measurements collected during the fourth phase of the Optical Gravitational Lensing Experiment (OGLE-IV). We discuss several potential astrophysical applications of our collection: investigation of the structure of the Magellanic Clouds and the Galactic halo, studies of the globular clusters in the Magellanic System, analysis of double-mode RR Lyr stars, and search for RR Lyr stars in eclipsing binary systems.

  17. Field 1: A First Look at the KELT RR Lyrae Project

    NASA Astrophysics Data System (ADS)

    De Lee, Nathan M.; Kinemuchi, Karen; Pepper, Joshua; Rodriguez, Joseph E.; Paegert, Martin

    2015-01-01

    In this poster we will discuss our ongoing program to use extant light curves from the Kilodegree Extremely Little Telescope (KELT) survey to find and characterize RR Lyrae (RRL) stars in the disk and inner halo of the Milky Way. We will focus on initial results from our testbed region, Field 1. RRL stars are of particular interest because they are standard candles and can be used to map out structure in the galaxy. The periods and shape of RRL light curves also contain information about their Oosterhoff type, which can probe galactic formation history, and metallicity respectively. Although there have been several large photometric surveys for RR Lyrae in the nearby galaxy (OGLE, NSVS, ASAS, and MACHO to name a few), they have each been limited in either sky coverage or number of epochs. The KELT survey represents a new generation of surveys that has many epochs over a large portion of the sky. KELT samples 60% of the sky in both northern and southern hemispheres, and has a long-time-baseline of 4-8 years with a very high cadence rate of less than 20 minutes. This translates into 4,000 to 9,000 epochs per light curve with completeness out to 3 kpc from the Sun.Recent results from both Kepler and ground based surveys results suggest that as many as 50% of RR Lyrae stars show long-term modulation of their light curve shapes (Blazhko effect). These stars combined with RRL stars that pulsate in more than one mode give a sample of objects that the KELT survey is uniquely suited to explore. This poster uses the RR Lyrae stars in Field 1 of the KELT survey to compare detection methods to previous variable star surveys of the same region. We also discuss the individual RR Lyrae found in Field 1. In particular, we focus on initial characterization of RRL light curves including those with amplitude-modulated or period-modulated light curves. We uses these initial results to discuss future plans for this survey.

  18. Evidence for Distinct Components of the Galactic Stellar Halo from 838 RR Lyrae Stars Discovered in the LONEOS-I Survey

    SciTech Connect

    Miceli, A; Rest, A; Stubbs, C W; Hawley, S L; Cook, K H; Magnier, E A; Krisciunas, K; Bowell, E; Koehn, B

    2007-02-23

    We present 838 ab-type RR Lyrae stars from the Lowell Observatory Near Earth Objects Survey Phase I (LONEOS-I). These objects cover 1430 deg{sup 2} and span distances ranging from 3-30kpc from the Galactic Center. Object selection is based on phased, photometric data with 28-50 epochs. We use this large sample to explore the bulk properties of the stellar halo, including the spatial distribution. The period-amplitude distribution of this sample shows that the majority of these RR Lyrae stars resemble Oosterhoff type I, but there is a significant fraction (26%) which have longer periods and appear to be Oosterhoff type II. We find that the radial distributions of these two populations have significantly different profiles ({rho}{sub OoI} {approx} R{sup -2.26{+-}0.07} and {rho}{sub OoII} {approx} R{sup -2.88{+-}0.11}). This suggests that the stellar halo was formed by at least two distinct accretion processes and supports dual-halo models.

  19. Finest light curve details, physical parameters, and period fluctuations of CoRoT RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Benkő, J. M.; Szabó, R.; Derekas, A.; Sódor, Á.

    2016-08-01

    The CoRoT satellite supplied the scientific community with a huge data base of variable stars. Among them the RR Lyrae stars have intensively been discussed in numerous papers in the last few years, but the latest runs have not been checked to find RR Lyrae stars up to now. Our main goal was to fill this gap and complete the CoRoT RR Lyrae sample. We found nine unstudied RR Lyrae stars. Seven of them are new discoveries. We identified three new Blazhko stars. The Blazhko effect shows non-strictly repetitive nature for all stars. The frequency spectrum of the Blazhko star CoRoT 104948132 contains second overtone frequency with the highest known period ratio. The harmonic amplitude and phase declines with the harmonic order were studied for non-Blazhko stars. We found a period dependent but similar shape amplitude decline for all stars. We discovered significant random period fluctuation for one of the two oversampled target, CM Ori. After a successful transformation of the CoRoT band parameters to the Johnson V values we estimated the basic physical properties such as mass, luminosity, metallicity. The sample can be divided into two subgroups with respect to the metallicity but otherwise the physical parameters are in the canonical range of RR Lyrae stars.

  20. KELT RR Lyrae Variable Stars Observed by the NKU Schneider Observatory

    NASA Astrophysics Data System (ADS)

    De Lee, Nathan M.; Russell, Neil; Kinemuchi, Karen; Pepper, Joshua; Rodriguez, Joseph E.; Paegert, Martin

    2016-01-01

    In this poster we will discuss our ongoing program to use extant light curves from the Kilodegree Extremely Little Telescope (KELT) survey to find and characterize RR Lyrae (RRL) stars in the disk and inner halo of the Milky Way. RRL stars are of particular interest because they are standard candles and can be used to map out structure in the galaxy. The periods and shape of RRL light curves also contain information about their Oosterhoff type, which can probe galactic formation history, and metallicity respectively. Although there have been several large photometric surveys for RR Lyrae in the nearby galaxy (OGLE, NSVS, ASAS, and MACHO to name a few), they have each been limited in either sky coverage or number of epochs. The KELT survey represents a new generation of surveys that has many epochs over a large portion of the sky. KELT samples over 60% of the sky in both northern and southern hemispheres, and has a long-time-baseline of 4-10 years with a very high cadence rate of less than 20 minutes. This translates into 4,000 to 10,000+ epochs per light curve with completeness out to 3 kpc from the Sun. This poster will present follow-up data taken of RR Lyrae candidate stars found in the KELT survey. These stars were observed using an 11inch telescope at the NKU Schneider Observatory. We will discuss photometric accuracies, cadence, and initial analysis of these stars. We will also discuss the capabilities of our new observatory as well as future follow-up and analysis plans.

  1. Period-color and amplitude-color relations for RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Kanbur, S.; Bhardwaj, A.; Singh, H. P.; Ngeow, C. C.

    2016-05-01

    We use published OGLE LMC/SMC data to present comprehensive period-color (PC) and amplitude-color (AC) relations for both fundamental and overtone stars. For fundamental mode stars, we confirm earlier work that the minimum light extinction corrected PC relation in V - I has a shallow slope but with considerable scatter (LMC: [0.093+-0.019] with a standard deviation about this line of 0.116, SMC: [0.055+-0.058] with a standard deviation about this line of 0.099). We note the high scatter about this line for both the LMC and SMC: either there is some source of uncertainty in extinction or some other physical parameter is responsible for this dispersion. We compare with previous results and discuss some possible causes for this scatter. In contrast, RRc overtone stars do not obey a flat PC relation at minimum light (LMC: [0.604+-0.041] with a standard deviation about this line of 0.109, SMC: [0.472+-0.265] with a standard deviation about this line of 0.091). The fact that fundamental mode RR Lyrae stars obey a flat relation at minimum light and overtone RR Lyrae stars do not is consistent with the interaction of the stellar photosphere and hydrogen ionization front. We compare these results with PC relations for fundamental mode and first overtone Cepheids. The fact that the PC relations change significantly as a function of phase indicates strongly that Cepheid and RR Lyrae relations can only be understood at mean light when their properties as a function of phase are determined.

  2. Deep CCD Photometry and RR Lyrae Survey for the Outer-Halo Globular Cluster NGC 6229

    NASA Astrophysics Data System (ADS)

    Catelan, M.; Borissova, J.; Spassova, N.; Ferraro, F. R.; Buonanno, R.; Sweigart, A. V.

    1997-12-01

    Deep BV CCD photometry for a large field covering the outer-halo Galactic globular cluster NGC 6229 is presented. For the first time, a color-magnitude diagram (CMD) reaching below the main-sequence turnoff has been obtained for this cluster. Previous results regarding the overall morphology of the horizontal and giant branches are confirmed. In addition, several candidate blue straggler stars are identified. However, a preliminary analysis of the cluster's CMD suggests that the putative extreme horizontal branch population suggested by Borissova et al. (1997, AJ, 113, 692) may not be present. Unfortunately, the innermost cluster regions could not be studied due to crowding. Comparison of the cluster CMD locus with the latest isochrones from VandenBerg (1997, private communication) is also presented, as is a study of the cluster age relative to a few well-studied reference globulars, using both the ``horizontal" and ``vertical" methods. We also report on an investigation of the variable stars in NGC 6229. We obtained new light curves and re-derived the periods, amplitudes and mean V and B-V magnitudes for 17 RR Lyrae stars listed in Sawyer Hogg's (1973, Publ. David Dunlap Obs., 3, No. 6) catalog. We obtained the first light curves for the RR Lyrae candidates No. 155 and No. 88 (Carney et al. 1991, AJ, 101, 1699), and confirm variability of their star No. 134, as well as of the RR Lyrae stars V3, V8 and V12 suspected by Borissova et al. (1997). A search for variable stars in our 5 x 5 arcmin field does not lead to any new variable candidates.

  3. AH Cam: A metal-rich RR Lyrae star with the shortest known Blazhko period

    NASA Technical Reports Server (NTRS)

    Smith, Horace A.; Matthews, Jaymie M.; Lee, Kevin M.; Williams, Jeffrey; Silbermann, N. A.; Bolte, Michael

    1994-01-01

    Analysis of 746 new V-band observations of the RR Lyrae star AH Cam obtained during 1989 - 1992 clearly show that its light curve cannot be described by a single period. In fact, at first glance, the Fourier spectrum of the photometry resembles that of a double-mode pulsator, with peaks at a fundamental period of 0.3686 d and an apparent secondary period of 0.2628 d. Nevertheless, the dual-mode solution is a poor fit to the data. Rather, we believe that AH Cam is a single-mode RR Lyrae star undergoing the Blazhko effect: periodic modulation of the amplitude and shape of its light curve. What was originally taken to be the period of the second mode is instead the 1-cycle/d alias of a modulation sidelobe in the Fourier spectrum. The data are well described by a modulation period of just under 11 d, which is the shortest Blazhko period reported to date in the literature and confirms the earlier suggestion by Goranskii. A low-resolution spectrum of AH Cam indicates that it is relatively metal rich, with delta-S less than or = 2. Its high metallicity and short modulation period may provide a critical test of at least one theory for the Blazhko effect. Moskalik's internal resonance model makes specific predictions of the growth rate of the fundamental model vs fundamental period. AH Cam falls outside the regime of other known Blazhko variables and resonance model predictions, but these are appropriate for metal-poor RR Lyrae stars. If the theory matches the behavior of AH Cam for a metal-rich stellar model, this would bolster the resonance hypothesis.

  4. A new overview of secular period changes of RR Lyrae stars in M5

    NASA Astrophysics Data System (ADS)

    Arellano Ferro, A.; Ahumada, J. A.; Kains, N.; Luna, A.

    2016-09-01

    Secular period variations, β =dot{P}, in 76 RR Lyrae stars in the globular cluster M5 are analysed using our most recent CCD V photometry and the historical photometric data base available in the literature since 1889. This provides a time baseline of up to 118 yr for these variables. The analysis was performed using two independent approaches: first, the classical O - C behaviour of the time of maximum light, and second, via a grid (P, β), where the solution producing the minimum scatter in the phased light curve is chosen. The results of the two methods agree satisfactorily. This allowed a new interpretation of the nature of the period changes in many RR Lyrae stars in M5. It is found that in 96 per cent of the stars studied no irregular or stochastic variations need to be claimed, but that 66 per cent of the population shows steady period increases or decreases, and that 34 per cent of the periods seem to have been stable over the last century. The lack of systematic positive or negative period variations in RR Lyrae stars in other globular clusters is addressed, and the paradigm of period changes being a consequence of stellar evolution is discussed in terms of chemical variations near the stellar core and of multiple stellar populations. In M5 we found a small positive average value of β and a small surplus of RRab stars with a period increase. Nevertheless, in M5 we have been able to isolate a group of likely evolved stars that systematically show positive, and in some cases large, period change rates.

  5. Metal-rich or misclassified? The case of four RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Molnar, L.; Juhasz, A. L.; Plachy, E.; Szabo, R.

    2016-06-01

    We analysed the light curve of four, apparently extremely metal-rich fundamenta-mode RR Lyrae stars. We identified two stars, MT Tel and ASAS J091803-3022.6 as RRc (first-overtone) pulsators that were misclassified as RRab ones in the ASAS survey. In the case of the other two stars, V397 Gem and ASAS J075127-4136.3, we could not decide conclusively, as they are outliers in the period-Fourier-coefficient space from the loci of both classes, but their photometric metallicities also favour the RRc classification.

  6. CHEMICAL ABUNDANCES OF METAL-POOR RR LYRAE STARS IN THE MAGELLANIC CLOUDS

    SciTech Connect

    Haschke, Raoul; Grebel, Eva K.; Duffau, Sonia; Frebel, Anna; Hansen, Camilla J.; Koch, Andreas

    2012-09-01

    We present for the first time a detailed spectroscopic study of chemical element abundances of metal-poor RR Lyrae stars in the Large and Small Magellanic Cloud (LMC and SMC). Using the MagE echelle spectrograph at the 6.5 m Magellan telescopes, we obtain medium resolution (R {approx} 2000-6000) spectra of six RR Lyrae stars in the LMC and three RR Lyrae stars in the SMC. These stars were chosen because their previously determined photometric metallicities were among the lowest metallicities found for stars belonging to the old populations in the Magellanic Clouds. We find the spectroscopic metallicities of these stars to be as low as [Fe/H]{sub spec} = -2.7 dex, the lowest metallicity yet measured for any star in the Magellanic Clouds. We confirm that for metal-poor stars, the photometric metallicities from the Fourier decomposition of the light curves are systematically too high compared to their spectroscopic counterparts. However, for even more metal-poor stars below [Fe/H]{sub phot} < -2.8 dex this trend is reversed and the spectroscopic metallicities are systematically higher than the photometric estimates. We are able to determine abundance ratios for 10 chemical elements (Fe, Na, Mg, Al, Ca, Sc, Ti, Cr, Sr, and Ba), which extend the abundance measurements of chemical elements for RR Lyrae stars in the Clouds beyond [Fe/H] for the first time. For the overall [{alpha}/Fe] ratio, we obtain an overabundance of 0.36 dex, which is in very good agreement with results from metal-poor stars in the Milky Way halo as well as from the metal-poor tail in dwarf spheroidal galaxies. Comparing the abundances with those of the stars in the Milky Way halo we find that the abundance ratios of stars of both populations are consistent with another. Therefore, we conclude that from a chemical point of view early contributions from Magellanic-type galaxies to the formation of the Galactic halo as claimed in cosmological models are plausible.

  7. Observing Globular Cluster RR Lyraes with the BYU West Mountain Observator

    NASA Astrophysics Data System (ADS)

    Jeffery, Elizabeth; Joner, Michael D.

    2016-01-01

    We have utilized the 0.9-meter telescope of the Brigham Young University West Mountain Observatory to secure data on six northern hemisphere globular clusters. Here we present observations of RR Lyrae stars located in these clusters, including light curves. We compare light curves produced using both DAOPHOT and ISIS software packages. Light curve fitting is done with FITLC. We acknowledge continued support from the Brigham Young University College of Physical and Mathematical sciences for operation of the West Mountain Observatory. Some of the observations included in this presentation were secured within the term of NSF grant AST-0618209.

  8. Observing Globular Cluster RR Lyrae Variables with the BYU West Mountain Observatory

    NASA Astrophysics Data System (ADS)

    Jeffery, E. J.; Joner, M. D.

    2016-06-01

    We have utilized the 0.9-meter telescope of the Brigham Young University West Mountain Observatory to secure data on six northern hemisphere globular clusters. Here we present representative observations of RR Lyrae stars located in these clusters, including light curves. We compare light curves produced using both DAOPHOT and ISIS software packages. Light curve fitting is done with FITLC. We find that for well-separated stars, DAOPHOT and ISIS provide comparable results. However, for stars within the cluster core, ISIS provides superior results. These improved techniques will allow us to better measure the properties of cluster variable stars.

  9. A Swift/UVOT Survey of RR Lyrae Stars in the M2 and Omega Centauri Globular Clusters

    NASA Astrophysics Data System (ADS)

    Siegel, Michael; Balzer, Benjamin

    2016-01-01

    We present new results from our ongoing Near Ultraviolet (UV) survey of RR Lyrae variable stars in globular clusters using the Swift Ultraviolet Optical Telescope (UVOT). Our previous investigations have shown that RR Lyrae have strong pulsations in the UV. The pulsational parameters show correlations similar to those seen in the optical/IR, including a strong period-shift, period-amplitude relationship and period-temperature relationship. We have also seen a period-luminosity relationship that has a strong dependence on metallicity. We now examine the NUV properties of RR Lyrae in two additional clusters, M2 and Omega Centauri. We show that these two clusters follow the same paradigm and shed new light on the period-luminosity relationship.

  10. THE DYNAMICAL DISTANCE, RR LYRAE ABSOLUTE MAGNITUDE, AND AGE OF THE GLOBULAR CLUSTER NGC 6266

    SciTech Connect

    McNamara, Bernard J.; McKeever, Jean E-mail: jeanm12@nmsu.edu

    2011-11-15

    The internal proper motion dispersion of NGC 6266 was measured using Hubble Space Telescope Wide Field Planetary Camera 2 images with an epoch difference of eight years. The dispersion was found to be 0.041 {+-} 0.001 arcsec century{sup -1}. This value was then equated to the cluster's radial velocity dispersion of 13.7 {+-} 1.1 km s{sup -1} to yield a distance to NGC 6266 of 7054 {+-} 583 pc. Based on this distance we find that the NGC 6266 RR Lyrae stars have M{sub V} = 0.51 {+-} 0.18 mag. This magnitude is in good agreement with that predicted by the M{sub V} versus [Fe/H] relation found by Benedict et al. Using an average [Fe/H] of -1.25 for NGC 6266, their relation predicts M{sub V} = 0.49 {+-} 0.06. Based on the RR Lyrae M{sub V} versus age relation determined by Chaboyer et al., we estimate that NGC 6266 has an age of 11.4 {+-} 2.2 Gyr.

  11. Discovery of RR Lyrae Stars in the Nuclear Bulge of the Milky Way

    NASA Astrophysics Data System (ADS)

    Minniti, Dante; Contreras Ramos, Rodrigo; Zoccali, Manuela; Rejkuba, Marina; Gonzalez, Oscar A.; Valenti, Elena; Gran, Felipe

    2016-10-01

    Galactic nuclei, such as that of the Milky Way, are extreme regions with high stellar densities, and in most cases, the hosts of a supermassive black hole. One of the scenarios proposed for the formation of the Galactic nucleus is merging of primordial globular clusters. An implication of this model is that this region should host stars that are characteristically found in old Milky Way globular clusters. RR Lyrae stars are primary distance indicators, well known representatives of old and metal-poor stellar populations, and therefore are regularly found in globular clusters. Here we report the discovery of a dozen RR Lyrae type ab stars in the vicinity of the Galactic center, i.e., in the so-called nuclear stellar bulge of the Milky Way. This discovery provides the first direct observational evidence that the Galactic nuclear stellar bulge contains ancient stars (>10 Gyr old). Based on this we conclude that merging globular clusters likely contributed to the build-up of the high stellar density in the nuclear stellar bulge of the Milky Way.

  12. ON THE MODULATION OF RR LYRAE STARS IN THE GLOBULAR CLUSTER M3

    SciTech Connect

    Jurcsik, J.; Smitola, P.; Nuspl, J.; Hajdu, G.

    2014-12-10

    New, extended time-series photometry of M3 RR Lyrae stars has revealed that 4 of the 10 double-mode stars show large-amplitude Blazhko modulation of both radial modes. The first, detailed analysis of the peculiar behavior of the unique, Blazhko RRd stars is given. While the P1/P0 period ratio is normal, and the overtone mode is dominant in the other RRd stars of the cluster, the period ratio is anomalous and the fundamental mode has a larger (or similar) mean amplitude than the overtone has in Blazhko RRd stars. The modulations of the fundamental and overtone modes are synchronized only in one of the Blazhko RRd stars. No evidence of any connection between the modulations of the modes in the other three stars is found. The Blazhko modulation accounts, at least partly, for the previously reported amplitude and period changes of these stars. Contrary to the ∼50% Blazhko statistics of RRab and RRd stars, Blazhko modulation occurs only in 10% of the overtone variables in M3. Four of the five Blazhko RRc stars are bright, evolved objects, and one has a period and brightness similar to those of Blazhko RRd stars. The regions of the instability strip with high and low occurrence rates of the Blazhko modulation overlap with the regions populated by first- and second-generation stars according to theoretical and observational studies, raising up the possibility that the Blazhko modulation occurs preferentially in first-generation RR Lyrae stars.

  13. VizieR Online Data Catalog: Field RR Lyrae stars (Liska+, 2016)

    NASA Astrophysics Data System (ADS)

    Liska, J.; Skarka, M.; Zejda, M.; Mikulasek, Z.; de Villiers, S. N.

    2016-05-01

    Differential photometry for VX Her in 'table1.dat' file. New photometric measurements for VX Her were performed at Masaryk University Observatory, Brno, Czech Republic during 13 nights (April-August 2014) with 0.6-m (24-inch) Newtonian telescope, CCD G2-0402, in BVRI bands. CCD images were calibrated in a standard way (dark frame and flat field corrections). The C-Munipack software (Motl 2009) was used for this processing as well as for differential photometry. TYC 1510-269-1 and TYC 1510-149-1 were used as comparison and check stars, respectively. Differential photometry for AT Ser and SS Leo is in 'table2.dat' file. New photometric measurements for these two stars were obtained using 1-inch refractor (a photographic lens Sonnar 4/135mm, lens focal ratio/focal length) and ATIK 16IC CCD camera with green photometric filter with similar throughput as the Johnson V filter. Exposures were 30s and each five frames were combined to a single image to achieve a better signal-to-noise ratio. The time resolution of a such combined frame is about 170s. The comparison stars were HD 142799 for AT Ser and HD 100763 for SS Leo. List with candidates for binaries with RR Lyrae component - RRLyrBinCan database (version 2016 May 5) is in 'table3.dat' file. 'table4.dat' file contains false-positives binary candidates among RR Lyrae stars. 'table5.dat' and 'table6.dat' files contain used maxima timings given in GEOS RR Lyr database, or newly determined in this study. (7 data files).

  14. Ground-Based BVRI Time-Series Follow-Up Observations for the RR Lyrae stars in Kepler Field

    NASA Astrophysics Data System (ADS)

    Jeon, Young-Beom; Ngeow, Chow-Choong; Nemec, James M.

    2015-09-01

    Time series observations for the 41 RR Lyrae stars in Kepler's fields were carried out in 2010 to 2013 using a number of meter class (or smaller) telescopes. These telescopes include the 1-m and 41-cm telescopes of Lulin Observatory (LOT and SLT respectively, Taiwan), the 81-cm telescope of Tenagra-II Observatory (TNG, Arizona, USA), the 1-m telescope at the Mt. Lemmon Optical Astronomy Observatory (LOAO, Arizona, USA), the 1.8-m and 15-cm telescopes at the Bohyunsan Optical Astronomy Observatory (BOAO, Korea), and the 61-cm telescope at the Sobaeksan Optical Astronomy Observatory (SOAO, Korea). All of these telescopes were equipped with commercial available CCD imagers, and the observations were done in standard BVRI filters. Photometric calibration of the RR Lyrae light curves was done with standard stars listed in Landolt standard stars [1]. Observations of selected Landolt standard stars (centered on SA 107-456 & SA 110-232) in Johnson-Kron-Cousins BVRI filters, spanning three distinct airmasses, were done with the 81-cm Tenagra II telescope on 25 June 2011. Raw imaging data were reduced with IRAF in the same manner as in the case of the RR Lyrae, and astrometric calibrated with astrometry.net [2]. We calibrated BVRI magnitudes for 40 RR Lyrae stars.

  15. The CRRP and SMHASH programs: Mapping the Milky Way and its neighbours with RR Lyraes in the mid IR

    NASA Astrophysics Data System (ADS)

    Scowcroft, Victoria; Freedman, Wendy L.; Johnston, Kathryn V.; Madore, Barry; Crrp Team, Smhash Team

    2015-01-01

    The CRRP and SMHASH programs are Spitzer Warm mission programs studying RR Lyrae in the Milky Way and its nearest neighbors.The calibration program (CRRP) studies individual calibrator RR Lyrae stars that will be observed by Gaia, in addition to 45 MW and LMC globular clusters and 36 fields in the MW bulge and halo. These observations provide the calibration of the RR Lyrae mid-IR PL relation, allow us to measure metallicity effects using objects such as ω Cen, and will allow us to study the structure of the MW itself.Our follow-on program, SMHASH, builds on the CRRP foundation to do a larger scale structural study of the MW. In this program we have targeted the Sagittarius dwarf, Sagittarius and Orphan Streams and several dwarf galaxies neighboring the MW.I will discuss the two programs, giving preliminary results showing the first measurements of the RR Lyrae mid-IR PL relation from full phase coverage observations. I will show how the measurements from CRRP/SMHASH are critical for both the structural studies of the MW and for an independent measure of the distance to the LMC, providing a complementary test of the Cepheid distance ladder.

  16. THREE-DIMENSIONAL MAPS OF THE MAGELLANIC CLOUDS USING RR LYRAE STARS AND CEPHEIDS. II. THE SMALL MAGELLANIC CLOUD

    SciTech Connect

    Haschke, Raoul; Grebel, Eva K.; Duffau, Sonia

    2012-10-01

    We use data on variable stars from the Optical Gravitational Lensing Experiment survey to determine the three-dimensional structure of the Small Magellanic Cloud (SMC). Deriving individual distances to RR Lyrae stars and Cepheids, we investigate the distribution of these tracers of the old and young populations in the SMC. Photometrically estimated metallicities are used to determine the distances to 1494 RR Lyrae stars, which have typical ages greater than 9 Gyr. For 2522 Cepheids, with ages of a few tens to a few hundred Myr, distances are calculated using their period-luminosity relation. Individual reddening estimates from the intrinsic color of each star are used to obtain high precision three-dimensional maps. The distances of RR Lyrae stars and Cepheids are in very good agreement with each other. The median distance of the RR Lyrae stars is found to be 61.5 {+-} 3.4 kpc. For the Cepheids, a median distance of 63.1 {+-} 3.0 kpc is obtained. Both populations show an extended scale height, with 2.0 {+-} 0.4 kpc for the RR Lyrae stars and 2.7 {+-} 0.3 kpc for the Cepheids. This confirms the large depth of the SMC suggested by a number of earlier studies. The young population is very differently oriented than the old stars. While we find an inclination angle of 7 Degree-Sign {+-} 15 Degree-Sign and a position angle of 83 Degree-Sign {+-} 21 Degree-Sign for the RR Lyrae stars, for the Cepheids an inclination of 74 Degree-Sign {+-} 9 Degree-Sign and a position angle of 66 Degree-Sign {+-} 15 Degree-Sign is obtained. The RR Lyrae stars show a fairly homogeneous distribution, while the Cepheids roughly follow the distribution of the bar, with their northeastern part being closer to us than the southwestern part of the bar. Interactions between the SMC, Large Magellanic Cloud, and Milky Way are presumably responsible for the tilted, elongated structure of the young population of the SMC.

  17. THREE-DIMENSIONAL MAPS OF THE MAGELLANIC CLOUDS USING RR LYRAE STARS AND CEPHEIDS. I. THE LARGE MAGELLANIC CLOUD

    SciTech Connect

    Haschke, Raoul; Grebel, Eva K.; Duffau, Sonia

    2012-10-01

    The new data for Cepheids and RR Lyrae stars of the Optical Gravitational Lensing Experiment (OGLE III) survey allow us to study the three-dimensional distribution of stars corresponding to young (a few tens to a few hundreds of millions of years) and old (typically older than {approx}9 Gyr) populations of the Large Magellanic Cloud (LMC) traced by these variable stars. We estimate the distance to 16,949 RR Lyrae stars by using their photometrically estimated metallicities. Furthermore, the periods of 1849 Cepheids are used to determine their distances. Three-dimensional maps are obtained by using individual reddening estimates derived from the intrinsic color of these stars. The resulting median distances of the RR Lyrae stars and Cepheids appear to resolve the long and short distance scale problem for our sample. With median distances of 53.1 {+-} 3.2 kpc for the RR Lyrae stars and 53.9 {+-} 1.8 kpc for the Cepheids, these two distance indicators are in very good agreement with each other in contrast to a number of earlier studies. Individual reddening estimates allow us to resolve the distance discrepancies often observed while comparing Cepheids and RR Lyrae stars. For both stellar populations we find the inclination angle of the LMC to be 32 Degree-Sign {+-} 4 Degree-Sign and the mean position angle to be 115 Degree-Sign {+-} 15 Degree-Sign . The position angle increases with galactocentric radius, indicative of mild twisting. Within the innermost 7 Degree-Sign of the LMC covered by OGLE III, the change in position angle amounts to more than 10 Degree-Sign . The depth of the Cepheids is found to be 1.7 {+-} 0.2 kpc. The bar stands out as an overdensity both in RR Lyrae stars and in Cepheids. In RR Lyrae stars the bar can be traced as a protruding overdensity with a line-of-sight depth of almost 5 kpc in front of the main body of the disk.

  18. Study of the period changes in SW Dor, an RR Lyrae type star with Blazhko effect

    NASA Astrophysics Data System (ADS)

    Berdnikov, L. N.; Kniazev, A. Y.; Dambis, A. K.; Kravtsov, V. V.; Sefako, R.

    2016-09-01

    In 2012-2014 we acquired 1569 CCD BVIc frames for the RR Lyrae type variable SW Dor with the 76-cm telescope of the South African Astronomical Observatory (SAAO) and 1-m telescopes of Las Cumbres Observatory Global Telescope network (LCOGT). Our observations showed a large scatter in the resulting phased light curve, especially near maximum brightness, which allowed us to reveal the Blazhko effect with a period of ˜80.9d. To study the pulsation period changes, we used all the available observations including the 1299 magnitude estimates from the digitized plate library of Harvard University (the DASCH project), which allowed us to construct the O-C diagram spanning a 125-year long time interval and discover for the first time at least three abrupt changes of the pulsation period.

  19. Evidence for an old Galactic bulge from RR Lyrae stars in Baade's window - Implications for the formation of the Galaxy and the age of the universe

    NASA Technical Reports Server (NTRS)

    Lee, Young-Wook

    1992-01-01

    Recent abundance measurements of RR Lyrae variables in the Baade's window field of the Galactic nuclear bulge are examined, and the observed metallicity distributions of the RR Lyraes in different Galactic radial zones are compared with those predicted for the HB population models. It is shown that the observed systematic variation with Galactocentric distance is only explained if the age of the stellar population increases, in the mean, with decreasing R(G). Thus, the oldest stellar population, the RR Lyraes in the Galactic nuclear bulge, is indeed older than that in the halo.

  20. A PRELIMINARY CALIBRATION OF THE RR LYRAE PERIOD-LUMINOSITY RELATION AT MID-INFRARED WAVELENGTHS: WISE DATA

    SciTech Connect

    Madore, Barry F.; Freedman, Wendy L.; Kollmeier, Juna A.; Monson, Andy; Eric Persson, S.; Rich, Jeff A. Jr.; Scowcroft, Victoria; Seibert, Mark; Hoffman, Douglas E-mail: wendy@obs.carnegiescience.edu E-mail: amonson@obs.carnegiescience.edu E-mail: jrich@obs.carnegiescience.edu E-mail: mseibert@obs.carnegiescience.edu

    2013-10-20

    Using time-resolved, mid-infrared data from the Wide-field Infrared Survey Explorer (WISE) and geometric parallaxes from the Hubble Space Telescope for four Galactic RR Lyrae variables, we derive the following Population II period-luminosity (PL) relations for the WISE [W1], [W2], and [W3] bands at 3.4, 4.6, and 12 μm, respectively: The slopes and the scatter around the fits are consistent with a smooth extrapolation of those same quantities from previously published K-band observations at 2.2 μm, where the asymptotic (long-wavelength) behavior is consistent with a period-radius relation with a slope of 0.5. No obvious correlation with metallicity (spanning 0.4 dex in [Fe/H]) is found in the residuals of the four calibrating RR Lyrae stars about the mean PL regression line.

  1. ON THE PERIOD DISTRIBUTION OF CLUSTER RR LYRAE STARS TO CONSTRAIN THEIR HELIUM CONTENT: THE CASE OF {omega} CENTAURI

    SciTech Connect

    Marconi, M.; Bono, G.; Caputo, F.; Piersimoni, A. M.; Pietrinferni, A.; Stellingwerf, R. F. E-mail: giuseppe.bono@roma2.infn.it E-mail: piersimoni@oa-teramo.inaf.it E-mail: rfs@swcp.com

    2011-09-01

    We present new sets of nonlinear, time-dependent convective hydrodynamical models of RR Lyrae stars assuming two metal (Z = 0.0005, Z = 0.001) and three helium abundances (Y = 0.24, 0.30, 0.38). For each chemical composition, we constructed a grid of fundamental and first overtone models covering a broad range of stellar masses and luminosities. To constrain the impact of the helium content on RR Lyrae properties, we adopted two observables-period distribution and luminosity amplitudes-that are independent of distance and reddening. The current predictions confirm that the helium content has a marginal effect on the pulsation properties. The key parameter causing the difference between canonical and He-enhanced observables is the luminosity. We compared current predictions with the sample of 189 RR Lyrae stars in {omega} Cen and found that the period range of He-enhanced models is systematically longer than observed. These findings apply to metal-poor and metal-intermediate He-enhanced models. To further constrain the impact of He-enhanced structures on the period distribution, we also computed a series of synthetic horizontal branch (HB) models and found that the predicted period distribution, based on a Gaussian sampling in mass, agrees quite well with observations. This applies not only to the minimum fundamentalized period of RR Lyrae stars (0.39 versus 0.34 days) but also to the fraction of Type II Cepheids (2% versus 3%). We also computed a series of synthetic HB models assuming a mixed HB population in which the 80% is made of canonical HB structures, while the 20% is made of He-enhanced (Y = 0.30) HB structures. We found that the fraction of Type II Cepheids predicted by these models is almost a factor of two larger than observed (5% versus 3%). This indicates that the fraction of He-enhanced structures in {omega} Cen cannot be larger than 20%.

  2. On the Period Distribution of Cluster RR Lyrae Stars to Constrain Their Helium Content: The Case of ω Centauri

    NASA Astrophysics Data System (ADS)

    Marconi, M.; Bono, G.; Caputo, F.; Piersimoni, A. M.; Pietrinferni, A.; Stellingwerf, R. F.

    2011-09-01

    We present new sets of nonlinear, time-dependent convective hydrodynamical models of RR Lyrae stars assuming two metal (Z = 0.0005, Z = 0.001) and three helium abundances (Y = 0.24, 0.30, 0.38). For each chemical composition, we constructed a grid of fundamental and first overtone models covering a broad range of stellar masses and luminosities. To constrain the impact of the helium content on RR Lyrae properties, we adopted two observables—period distribution and luminosity amplitudes—that are independent of distance and reddening. The current predictions confirm that the helium content has a marginal effect on the pulsation properties. The key parameter causing the difference between canonical and He-enhanced observables is the luminosity. We compared current predictions with the sample of 189 RR Lyrae stars in ω Cen and found that the period range of He-enhanced models is systematically longer than observed. These findings apply to metal-poor and metal-intermediate He-enhanced models. To further constrain the impact of He-enhanced structures on the period distribution, we also computed a series of synthetic horizontal branch (HB) models and found that the predicted period distribution, based on a Gaussian sampling in mass, agrees quite well with observations. This applies not only to the minimum fundamentalized period of RR Lyrae stars (0.39 versus 0.34 days) but also to the fraction of Type II Cepheids (2% versus 3%). We also computed a series of synthetic HB models assuming a mixed HB population in which the 80% is made of canonical HB structures, while the 20% is made of He-enhanced (Y = 0.30) HB structures. We found that the fraction of Type II Cepheids predicted by these models is almost a factor of two larger than observed (5% versus 3%). This indicates that the fraction of He-enhanced structures in ω Cen cannot be larger than 20%.

  3. Lyra

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    (the Lyre; abbrev. Lyr, gen. Lyrae; area 286 sq. deg.) A northern constellation which lies between Hercules and Cygnus, and culminates at midnight in early July. It is an ancient constellation pattern, which was associated with an eagle or vulture in the Indian subcontinent and Arab countries, and with the mythical lyre invented by Hermes and given by Apollo to Orpheus in ancient Greece. Its brig...

  4. Macho project photometry of RR Lyrae stars in the Sagittarius dwarf galaxy

    SciTech Connect

    Alcock, C. |; Allsman, R.A. |; Alves, D.R. |; Axelrod, T.S. |; Becker, A.C. |; Bennett, D.P.; Cook, K.H. |; Freeman, K.C.; Griest, K. |; Guern, J.A.; Lehner, M.J.; Marshall, S.L.; Minniti, D.; Peterson, B.A.; Pratt, M.R.

    1997-01-01

    We report the discovery of 30 type a, b RR Lyrae (RRab) stars that are likely members of the Sagittarius dwarf galaxy (Sgr). Accurate positions, periods, amplitudes, and magnitudes are presented. Their distances are determined with respect to RRab stars in the Galactic bulge found also in the MACHO 1993 data. For R{sub {circle_dot}}=8kpc, the mean distance to these stars is D=22{plus_minus}1kpc, smaller than previous determinations for this galaxy. This indicates that Sgr has an elongated main body extending for more than 10 kpc, which is inclined along the line of sight, with its northern part (in Galactic coordinates) closer to us. The size and shape of Sgr give clues about the past history of this galaxy. If the shape of Sgr follows the direction of its orbit, the observed spatial orientation suggests that Sgr is moving away from the Galactic plane. Also, Sgr stars may be the sources of some of the microlensing events seen toward the bulge. {copyright} {ital 1997} {ital The American Astronomical Society}

  5. The visual surface brightness relation and the absolute magnitudes of RR Lyrae stars. I - Theory

    NASA Technical Reports Server (NTRS)

    Manduca, A.; Bell, R. A.

    1981-01-01

    A theoretical relation analogous to the Barnes-Evans relation between stellar surface brightness and V-R color is derived which is applicable to the temperatures and gravities appropriate to RR Lyrae stars. Values of the visual surface brightness and V-R colors are calculated for model stellar atmospheres with effective temperatures between 6000 and 8000 K, log surface gravities from 2.2 to 3.5, and A/H anbundance ratios from -0.5 to -3.0. The resulting relation is found to be in reasonable agreement with the empirical relation of Barnes, Evans and Moffet (1978), with, however, small sensitivities to gravity and metal abundance. The relation may be used to derive stellar angular diameters from (V,R) photometry and to derive radii, distances, and absolute magnitudes for variable stars when combined with a radial velocity curve. The accuracies of the radii and distances (within 10%) and absolute magnitudes (within 0.25 magnitudes) compare favorably with those of the Baade-Wesselink method currently in use.

  6. Chemical and structural analysis of the Large Magellanic Cloud using the fundamental mode RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Deb, Sukanta; Singh, Harinder P.

    2014-03-01

    We present a careful and detailed light-curve analysis of publicly available I-band data on fundamental mode RR Lyrae (RRab) stars of the Large Magellanic Cloud (LMC) obtained by the Optical Gravitational Lensing Experiment phase-III project. Using the Fourier parameters of 13 095 RRab stars, metallicities and absolute magnitudes of individual stars are obtained. The representation of stars on the P-φ _{31}V plane shows the existence of three significant metallicity groups with mean metallicities as -1.20 ± 0.12, -1.57 ± 0.10 and -1.89 ± 0.09 dex. The corresponding absolute magnitudes of these three groups are obtained as 0.70 ± 0.08, 0.59 ± 0.06 and 0.49 ± 0.08 mag, respectively. Distribution of these three groups as a function of vertical |z| distance indicates that the formation of the LMC disc predates the formation of the inner halo. Issue of the existence of a metallicity gradient as a function of galactocentric distances has also been addressed. Approximating the structure of the LMC disc as a triaxial ellipsoid, the inclination angle (i) relative to the plane of the sky and the position angle of the line of nodes (θlon) were estimated as 24.20° and 176.01°, respectively. The axes ratios and the eccentricity were also determined using the principal axis transformation method.

  7. RR LYRAE VARIABLES IN THE LOCAL GROUP DWARF GALAXY NGC 147

    SciTech Connect

    Yang, S-C.; Sarajedini, Ata E-mail: ata@astro.ufl.ed

    2010-01-01

    We investigate the RR Lyrae (RRL) population in NGC 147, a dwarf satellite galaxy of M31 (Andromeda). We used both Thuan-Gunn g-band ground-based photometry from the literature and Hubble Space Telescope Wide Field Planetary Camera 2 archival data in the F555W and F814W passbands to investigate the pulsation properties of RRL variable candidates in NGC 147. These data sets represent the two extreme cases often found in RRL studies with respect to the phase coverage of the observations and the quality of the photometric measurements. Extensive artificial variable star tests for both cases were performed. We conclude that neither data set is sufficient to confidently determine the pulsation properties of the NGC 147 RRLs. Thus, while we can assert that NGC 147 contains RRL variables, and therefore a population older than approx10 Gyr, it is not possible at this time to use the pulsation properties of these RRLs to study other aspects of this old population. Our results provide a good reference for gauging the completeness of RRL variable detection in future studies.

  8. NO EXCESS OF RR LYRAE STARS IN THE CANIS MAJOR OVERDENSITY

    SciTech Connect

    Mateu, Cecilia; Vivas, A. Katherina; Abad, Carlos; Zinn, Robert; Miller, Lissa R. E-mail: vivas@cida.ve E-mail: robert.zinn@yale.edu

    2009-05-15

    Our multi-epoch survey of {approx}20 deg{sup 2} of the Canis Major (CMa) overdensity has detected only 10 RR Lyrae stars (RRLS). We show that this number is consistent with the number expected from the Galactic halo and thick disk populations alone, leaving no excess that can be attributed to the dwarf spheroidal (dSph) galaxy that some authors have proposed as the origin of the CMa overdensity. If this galaxy resembles the dSph satellites of the Milky Way (MW) and of M31 and has the putative M{sub V} {approx} -14.5, our survey should have detected several tens of RRLS. Even if M{sub V} {approx}< -12, the expected excess is {approx}>10, which is not observed. Either the old stellar population of this galaxy has unique properties or, as others have argued before, the CMa overdensity is produced by the thin and thick disk and spiral arm populations of the MW and not by a collision with a dSph satellite galaxy.

  9. Harmonizing the RR Lyrae and Clump Distance Scales-Stretching the Short Distance Scale to Intermediate Ranges?

    SciTech Connect

    Popowski, P.

    2000-01-31

    I explore the consequences of making the RR Lyrae and clump giant distance scales consistent in the solar neighborhood, Galactic bulge and Large Magellanic Cloud (LMC). I employ two major assumptions: (1) that the absolute magnitude -metallicity, M{sub V}(RR) - [Fe/H], relation for RR Lyrae stars is universal, and (2) that absolute I-magnitudes of clump giants, M{sub I}(RC), in Baade's Window can be inferred from the local Hipparcos calibration of clump giants' magnitudes. A comparison between the solar neighborhood and Baade's Window sets M{sub V}(RR) at [Fe/H] = -1.6 in the range (0.59 {+-} 0.05, 0.70 {+-} 0.05), somewhat brighter than the statistical parallax solution. A comparison between Baade's Window and the LMC sets the M{sub I}{sup LMC}(RC) in the range (-0.33 {+-} 0.09, -0.53 {+-} 0.09). The distance modulus to the LMC is {mu}{sup LMC} {element_of} (18.24 {+-} 0.08, 18.44 {+-} 0.07). I argue that the currently available information slightly favors the short distance scale but is insufficient to select the correct solutions with high confidence.

  10. Chemical abundances in a high-velocity RR Lyrae star near the bulge

    NASA Astrophysics Data System (ADS)

    Hansen, C. J.; Rich, R. M.; Koch, A.; Xu, S.; Kunder, A.; Ludwig, H.-G.

    2016-05-01

    Low-mass variable high-velocity stars are interesting study cases for many aspects of Galactic structure and evolution. Until recently, the only known high- or hyper-velocity stars were young stars thought to originate from the Galactic center. Wide-area surveys such as APOGEE and BRAVA have found several low-mass stars in the bulge with Galactic rest-frame velocities higher than 350 km s-1. In this study we present the first abundance analysis of a low-mass RR Lyrae star that is located close to the Galactic bulge, with a space motion of ~-400 km s-1. Using medium-resolution spectra, we derived abundances (including upper limits) of 11 elements. These allowed us to chemically tag the star and discuss its origin, although our derived abundances and metallicity, at [Fe/H] =-0.9 dex, do not point toward one unambiguous answer. Based on the chemical tagging, we cannot exclude that it originated in the bulge. However, its retrograde orbit and the derived abundances combined suggest that the star was accelerated from the outskirts of the inner (or even outer) halo during many-body interactions. Other possible origins include the bulge itself, or the star might have been stripped from a stellar cluster or the Sagittarius dwarf galaxy when it merged with the Milky Way. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  11. WEAK GALACTIC HALO-DWARF SPHEROIDAL CONNECTION FROM RR LYRAE STARS

    SciTech Connect

    Fiorentino, Giuliana; Bono, Giuseppe; Monelli, Matteo; Gallart, Carme; Martínez-Vásquez, Clara E.; Tolstoy, Eline; Salaris, Maurizio; Bernard, Edouard J.

    2015-01-01

    We discuss the role that dwarf galaxies may have played in the formation of the Galactic halo (Halo) using RR Lyrae stars (RRL) as tracers of their ancient stellar component. The comparison is performed using two observables (periods, luminosity amplitudes) that are reddening and distance independent. Fundamental mode RRL in 6 dwarf spheroidals (dSphs) and 11 ultra faint dwarf galaxies (∼1300) show a Gaussian period distribution well peaked around a mean period of (Pab) = 0.610 ± 0.001 days (σ = 0.03). The Halo RRL (∼15,000) are characterized by a broader period distribution. The fundamental mode RRL in all the dSphs apart from Sagittarius are completely lacking in High Amplitude Short Period (HASP) variables, defined as those having P ≲ 0.48 days and A{sub V} ≥ 0.75 mag. Such variables are not uncommon in the Halo and among the globular clusters and massive dwarf irregulars. To further interpret this evidence, we considered 18 globulars covering a broad range in metallicity (–2.3 ≲ [Fe/H] ≲ –1.1) and hosting more than 35 RRL each. The metallicity turns out to be the main parameter, since only globulars more metal-rich than [Fe/H] ∼ –1.5 host RRL in the HASP region. This finding suggests that dSphs similar to the surviving ones do not appear to be the major building-blocks of the Halo. Leading physical arguments suggest an extreme upper limit of ∼50% to their contribution. On the other hand, massive dwarfs hosting an old population with a broad metallicity distribution (Large Magellanic Cloud, Sagittarius) may have played a primary role in the formation of the Halo.

  12. ON A NEW THEORETICAL FRAMEWORK FOR RR LYRAE STARS. I. THE METALLICITY DEPENDENCE

    SciTech Connect

    Marconi, M.; Coppola, G.; Musella, I.; Ripepi, V.; Bono, G.; Braga, V.; Buonanno, R.; Pietrinferni, A.; Castellani, M.; Stellingwerf, R. F. E-mail: giuseppe.bono@roma2.infn.it E-mail: adriano@oa-teramo.inaf.it E-mail: rfs@swcp.com

    2015-07-20

    We present new nonlinear, time-dependent convective hydrodynamical models of RR Lyrae stars computed assuming a constant helium-to-metal enrichment ratio and a broad range in metal abundances (Z = 0.0001–0.02). The stellar masses and luminosities adopted to construct the pulsation models were fixed according to detailed central He-burning horizontal-branch evolutionary models. The pulsation models cover a broad range in stellar luminosity and effective temperatures and the modal stability is investigated for both fundamental (FU) and first overtone polsators (FOs). We predict the topology of the instability strip (IS) as a function of the metal content and new analytical relations for the edges of the IS in the observational plane. Moreover, a new analytical relation to constrain the pulsation mass of double pulsators as a function of the period ratio and the metal content is provided. We derive new Period–Radius–Metallicity relations for FU and FO pulsators. They agree quite well with similar empirical and theoretical relations in the literature. From the predicted bolometric light curves, transformed into optical (UBVRI) and near-infrared (NIR; JHK) bands, we compute the intensity-averaged mean magnitudes along the entire pulsation cycle and in turn new and homogenous metal-dependent (RIJHK) Period–Luminosity relations. Moreover, we compute new dual and triple-band optical, optical–NIR, and NIR Period–Wesenheit–Metallicity relations. Interestingly, we find that the optical Period-W(V, B–V) is independent of the metal content and that the accuracy of individual distances is a balance between the adopted diagnostics and the precision of photometric and spectroscopic data sets.

  13. On a New Theoretical Framework for RR Lyrae Stars. I. The Metallicity Dependence

    NASA Astrophysics Data System (ADS)

    Marconi, M.; Coppola, G.; Bono, G.; Braga, V.; Pietrinferni, A.; Buonanno, R.; Castellani, M.; Musella, I.; Ripepi, V.; Stellingwerf, R. F.

    2015-07-01

    We present new nonlinear, time-dependent convective hydrodynamical models of RR Lyrae stars computed assuming a constant helium-to-metal enrichment ratio and a broad range in metal abundances (Z = 0.0001-0.02). The stellar masses and luminosities adopted to construct the pulsation models were fixed according to detailed central He-burning horizontal-branch evolutionary models. The pulsation models cover a broad range in stellar luminosity and effective temperatures and the modal stability is investigated for both fundamental (FU) and first overtone polsators (FOs). We predict the topology of the instability strip (IS) as a function of the metal content and new analytical relations for the edges of the IS in the observational plane. Moreover, a new analytical relation to constrain the pulsation mass of double pulsators as a function of the period ratio and the metal content is provided. We derive new Period-Radius-Metallicity relations for FU and FO pulsators. They agree quite well with similar empirical and theoretical relations in the literature. From the predicted bolometric light curves, transformed into optical (UBVRI) and near-infrared (NIR; JHK) bands, we compute the intensity-averaged mean magnitudes along the entire pulsation cycle and in turn new and homogenous metal-dependent (RIJHK) Period-Luminosity relations. Moreover, we compute new dual and triple-band optical, optical-NIR, and NIR Period-Wesenheit-Metallicity relations. Interestingly, we find that the optical Period-W(V, B-V) is independent of the metal content and that the accuracy of individual distances is a balance between the adopted diagnostics and the precision of photometric and spectroscopic data sets.

  14. RR Lyrae in XSTPS: The halo density profile in the north galactic cap

    SciTech Connect

    Faccioli, L.; Smith, M. C.; Yuan, H.-B.; Liu, X.-W.; Zhang, H.-H.; Zhao, H.-B.; Yao, J.-S. E-mail: msmith@shao.ac.cn

    2014-06-20

    We present a catalog of RR Lyrae stars (RRLs) observed by the Xuyi Schmidt Telescope Photometric Survey (XSTPS). The area we consider is located in the north Galactic cap, covering ≈376.75 deg{sup 2} at α ≈ 150° and δ ≈ 27° down to a magnitude limit of i ≈ 19. Using the variability information afforded by the multi-epoch nature of our XSTPS data, combined with colors from the Sloan Digital Sky Survey, we are able to identify candidate RRLs. We find 318 candidates, derive distances to them, and estimate the detection efficiency. The majority of our candidates have more than 12 observations, and for these we are able to calculate periods. These also allow us to estimate our contamination level, which we predict is between 30% and 40%. Finally, we use the sample to probe the halo density profile in the 9-49 kpc range and find that it can be well fitted by a double power law. We find good agreement between this model and the models derived for the south Galactic cap using the Watkins et al. and Sesar et al. RRL data sets, after accounting for possible contamination in our data set from Sagittarius stream members. We consider non-spherical double power-law models of the halo density profile and again find agreement with literature data sets, although we have limited power to constrain the flattening due to our small survey area. Much tighter constraints will be placed by current and future wide-area surveys, most notably ESA's astrometric Gaia mission. Our analysis demonstrates that surveys with a limited number of epochs can effectively be mined for RRLs. Our complete sample is provided as accompanying online material; as an example the first few entries of each electronic table are shown in the text.

  15. PROBING THE OUTER GALACTIC HALO WITH RR LYRAE FROM THE CATALINA SURVEYS

    SciTech Connect

    Drake, A. J.; Djorgovski, S. G.; Graham, M. J.; Mahabal, A.; Donalek, C.; Williams, R.; Catelan, M.; Torrealba, G.; Belokurov, V.; Koposov, S. E.; Prieto, J. L.; Larson, S.; Christensen, E.; Beshore, E.

    2013-01-20

    We present analysis of 12,227 type-ab RR Lyraes (RRLs) found among the 200 million public light curves in Catalina Surveys Data Release 1. These stars span the largest volume of the Milky Way ever surveyed with RRLs, covering {approx}20,000 deg{sup 2} of the sky (0 Degree-Sign < {alpha} < 360 Degree-Sign , -22 Degree-Sign < {delta} < 65 Degree-Sign ) to heliocentric distances of up to 60 kpc. Each of the RRLs is observed between 60 and 419 times over a six-year period. Using period finding and Fourier fitting techniques we determine periods and apparent magnitudes for each source. We find that the periods are generally accurate to {sigma} = 0.002% in comparison to 2842 previously known RRLs and 100 RRLs observed in overlapping survey fields. We photometrically calibrate the light curves using 445 Landolt standard stars and show that the resulting magnitudes are accurate to {approx}0.05 mag using Sloan Digital Sky Survey (SDSS) data for {approx}1000 blue horizontal branch stars and 7788 RRLs. By combining Catalina photometry with SDSS spectroscopy, we analyze the radial velocity and metallicity distributions for >1500 of the RRLs. Using the accurate distances derived for the RRLs, we show the paths of the Sagittarius tidal streams crossing the sky at heliocentric distances from 20 to 60 kpc. By selecting samples of Galactic halo RRLs, we compare their velocity, metallicity, and distance with predictions from a recent detailed N-body model of the Sagittarius system. We find that there are some significant differences between the distances and structures predicted and our observations.

  16. METAL ABUNDANCES, RADIAL VELOCITIES, AND OTHER PHYSICAL CHARACTERISTICS FOR THE RR LYRAE STARS IN THE KEPLER FIELD

    SciTech Connect

    Nemec, James M.; Cohen, Judith G.; Sesar, Branimir; Ripepi, Vincenzo; Derekas, Aliz; Moskalik, Pawel; Chadid, Merieme; Bruntt, Hans E-mail: jmn@isr.bc.ca E-mail: bsesar@astro.caltech.edu E-mail: derekas@konkoly.hu E-mail: chadid@marseille.fr

    2013-08-20

    Spectroscopic iron-to-hydrogen ratios, radial velocities, atmospheric parameters, and new photometric analyses are presented for 41 RR Lyrae stars (and one probable high-amplitude {delta} Sct star) located in the field-of-view of the Kepler space telescope. Thirty-seven of the RR Lyrae stars are fundamental-mode pulsators (i.e., RRab stars) of which sixteen exhibit the Blazhko effect. Four of the stars are multiperiodic RRc pulsators oscillating primarily in the first-overtone mode. Spectroscopic [Fe/H] values for the 34 stars for which we were able to derive estimates range from -2.54 {+-} 0.13 (NR Lyr) to -0.05 {+-} 0.13 dex (V784 Cyg), and for the 19 Kepler-field non-Blazhko stars studied by Nemec et al. the abundances agree will with their photometric [Fe/H] values. Four non-Blazhko RR Lyrae stars that they identified as metal-rich (KIC 6100702, V2470 Cyg, V782 Cyg and V784 Cyg) are confirmed as such, and four additional stars (V839 Cyg, KIC 5520878, KIC 8832417, KIC 3868420) are also shown here to be metal-rich. Five of the non-Blazhko RRab stars are found to be more metal-rich than [Fe/H] {approx}-0.9 dex while all of the 16 Blazhko stars are more metal-poor than this value. New P-{phi}{sub 31}{sup s}-[Fe/H] relationships are derived based on {approx}970 days of quasi-continuous high-precision Q0-Q11 long- and short-cadence Kepler photometry. With the exception of some Blazhko stars, the spectroscopic and photometric [Fe/H] values are in good agreement. Several stars with unique photometric characteristics are identified, including a Blazhko variable with the smallest known amplitude and frequency modulations (V838 Cyg)

  17. Near-Field Cosmology with RR Lyrae Variable Stars: A First View of Substructure in the Southern Sky

    NASA Astrophysics Data System (ADS)

    Navarrete, C.; Duffau, S.; Vivas, A. K.; Catelan, M.; Hajdu, G.; Torrealba, G.; Cortés, C.; Belokurov, V.; Koposov, S.; Drake, A. J.

    2016-08-01

    We present the current status of the spectroscopic follow-up of a large number of RR Lyrae (RRL) halo overdensity candidates recently found by Torrealba et al. (2015) using southern-hemisphere data from the Catalina Real-time Transient Survey (CRTS). Characterizing the individual RRL stars in these overdensities is crucial to confirm them as real halo substructures. Low-resolution spectra have been obtained for RRL stars in 11 different overdensities, using the SOAR and Magellan telescopes. Radial velocities and metallicities have been derived so far for 123 and 99 RRL stars, respectively.

  18. Observing RR Lyrae Variables in the M3 Globular Cluster with the BYU West Mountain Observatory (Abstract)

    NASA Astrophysics Data System (ADS)

    Joner, M. D.

    2016-06-01

    (Abstract only) We have utilized the 0.9-meter telescope of the Brigham Young University West Mountain Observatory to secure data on the northern hemisphere globular cluster NGC 5272 (M3). We made 216 observations in the V filter spaced between March and August 2012. We present light curves of the M3 RR Lyrae stars using different techniques. We compare light curves produced using DAOPHOT and ISIS software packages for stars in both the halo and core regions of this globular cluster. The light curve fitting is done using FITLC.

  19. Finding, characterizing and classifying variable sources in multi-epoch sky surveys: QSOs and RR Lyraes in PS1 3Pi

    NASA Astrophysics Data System (ADS)

    Hernitschek, N.; Schlafly, E. F.; Sesar, B.; Rix, H.-W.; Hogg, D. W.; Ivezic, Z.; Grebel, E. K.

    2016-05-01

    We develop a new approach for quantifying statistical properties of non-simultaneous, sparse, multi-color light curves through light-curve structure functions. Using PS1 data on SDSS Stripe 82 as "ground truth", a Random Forest Classifier identifies QSOs and RR Lyrae stars based on their variability and mean PS1 and WISE colors. We find that, aside from the Galactic plane, QSO and RR Lyrae samples of purity 75% and completeness 92% can be selected. On this completeness and purity basis we have identified a QSO candidate sample of a million objects, including many at low latitudes. We have assembled an unprecedentedly large and deep sample of 150 000 likely RR Lyrae candidates, with distances from 10 kpc to 120 kpc. We provide a catalog of 2.6 x 107 likely variable point sources. This work illustrates the power of time- domain surveys to identify variable objects and opens up enormous follow-up possibilities.

  20. Time-series Photometry of Globular Clusters: M62 (NGC 6266), the Most RR Lyrae-rich Globular Cluster in the Galaxy?

    NASA Astrophysics Data System (ADS)

    Contreras, R.; Catelan, M.; Smith, H. A.; Pritzl, B. J.; Borissova, J.; Kuehn, C. A.

    2010-12-01

    We present new time-series CCD photometry, in the B and V bands, for the moderately metal-rich ([Fe/H] ~= -1.3) Galactic globular cluster M62 (NGC 6266). The present data set is the largest obtained so far for this cluster and consists of 168 images per filter, obtained with the Warsaw 1.3 m telescope at the Las Campanas Observatory and the 1.3 m telescope of the Cerro Tololo Inter-American Observatory, in two separate runs over the time span of 3 months. The procedure adopted to detect the variable stars was the optimal image subtraction method (ISIS v2.2), as implemented by Alard. The photometry was performed using both ISIS and Stetson's DAOPHOT/ALLFRAME package. We have identified 245 variable stars in the cluster fields that have been analyzed so far, of which 179 are new discoveries. Of these variables, 133 are fundamental mode RR Lyrae stars (RRab), 76 are first overtone (RRc) pulsators, 4 are type II Cepheids, 25 are long-period variables (LPVs), 1 is an eclipsing binary, and 6 are not yet well classified. Such a large number of RR Lyrae stars places M62 among the top two most RR Lyrae-rich (in the sense of total number of RR Lyrae stars present) globular clusters known in the Galaxy, second only to M3 (NGC 5272) with a total of 230 known RR Lyrae stars. Since this study covers most but not all of the cluster area, it is not unlikely that M62 is in fact the most RR Lyrae-rich globular cluster in the Galaxy. In like vein, thanks to the time coverage of our data sets, we were also able to detect the largest sample of LPVs known so far in a Galactic globular cluster. We analyze a variety of Oosterhoff type indicators for the cluster, including mean periods, period distribution, Bailey diagrams, and Fourier decomposition parameters (as well as the physical parameters derived therefrom). All of these indicators clearly show that M62 is an Oosterhoff type I system. This is in good agreement with the moderately high metallicity of the cluster, in spite of its

  1. TIME-SERIES PHOTOMETRY OF GLOBULAR CLUSTERS: M62 (NGC 6266), THE MOST RR LYRAE-RICH GLOBULAR CLUSTER IN THE GALAXY?

    SciTech Connect

    Contreras, R.; Catelan, M.; Smith, H. A.; Kuehn, C. A.; Pritzl, B. J.; Borissova, J.

    2010-12-15

    We present new time-series CCD photometry, in the B and V bands, for the moderately metal-rich ([Fe/H] {approx_equal} -1.3) Galactic globular cluster M62 (NGC 6266). The present data set is the largest obtained so far for this cluster and consists of 168 images per filter, obtained with the Warsaw 1.3 m telescope at the Las Campanas Observatory and the 1.3 m telescope of the Cerro Tololo Inter-American Observatory, in two separate runs over the time span of 3 months. The procedure adopted to detect the variable stars was the optimal image subtraction method (ISIS v2.2), as implemented by Alard. The photometry was performed using both ISIS and Stetson's DAOPHOT/ALLFRAME package. We have identified 245 variable stars in the cluster fields that have been analyzed so far, of which 179 are new discoveries. Of these variables, 133 are fundamental mode RR Lyrae stars (RRab), 76 are first overtone (RRc) pulsators, 4 are type II Cepheids, 25 are long-period variables (LPVs), 1 is an eclipsing binary, and 6 are not yet well classified. Such a large number of RR Lyrae stars places M62 among the top two most RR Lyrae-rich (in the sense of total number of RR Lyrae stars present) globular clusters known in the Galaxy, second only to M3 (NGC 5272) with a total of 230 known RR Lyrae stars. Since this study covers most but not all of the cluster area, it is not unlikely that M62 is in fact the most RR Lyrae-rich globular cluster in the Galaxy. In like vein, thanks to the time coverage of our data sets, we were also able to detect the largest sample of LPVs known so far in a Galactic globular cluster. We analyze a variety of Oosterhoff type indicators for the cluster, including mean periods, period distribution, Bailey diagrams, and Fourier decomposition parameters (as well as the physical parameters derived therefrom). All of these indicators clearly show that M62 is an Oosterhoff type I system. This is in good agreement with the moderately high metallicity of the cluster, in spite

  2. RR Lyrae variables in the Small Magellanic Cloud - II. The extended area: chemical and structural analysis

    NASA Astrophysics Data System (ADS)

    Kapakos, E.; Hatzidimitriou, D.

    2012-11-01

    We have performed the Fourier decomposition analysis of 8- and 13-yr V-band light curves of a carefully selected sample of 454 fundamental-mode RR Lyrae variables (RRab type), detected in an ≃14 square degree area of the Small Magellanic Cloud (SMC) and listed in the Optical Gravitational Lensing Experiment, phase III, Catalogue of Variable Stars. The Fourier decomposition parameters were used to derive metal abundances and distance moduli, following the methodology described by Kapakos, Hatzidimitriou & Soszyński. The average metal abundance of the RRab stars on the new scale of Carretta et al. was found to be <[Fe/H]C09> = -1.69 ± 0.41 dex (std, with a standard error of 0.02 dex). A tentative metallicity gradient of -0.013 ± 0.007 dex kpc-1 was detected, with increasing metal abundance towards the dynamical centre of the SMC, but selection effects are also discussed. The distance modulus of the SMC was re-estimated and was found to be <μ> = 19.13 ± 0.19 (std) in a distance scale where the distance modulus of the Large Magellanic Cloud (LMC) is μLMC = 18.52 ± 0.06 (std). The average 1σ line-of-sight depth was found to be σ int =5.3±0.4 kpc (std), while spatial variations of the depth were detected. The SMC was found to be deeper in the north-eastern region, while metal-richer and metal-poorer objects in the sample seem to belong to different dynamical structures. The former have smaller scale height and may constitute a thick disc, its width being 10.40 ± 0.02 kpc, and a bulge whose size (radius) is estimated to be 2.09 ± 0.81 kpc. The latter seem to belong to a halo structure with a maximum depth along the line of sight extending over 16 kpc in the SMC central region and falling to ˜12 kpc in the outer regions.

  3. Variaciones seculares de período en las RR Lyrae de ω~Centauri

    NASA Astrophysics Data System (ADS)

    Marraco, H. G.; Milesi, G. E.

    Utilizando 689 observaciones de 35 estrellas RR Lyrae del cúmulo globular ω Centauri hemos obtenido nuevas determinaciones de sus períodos y sus correspondientes variaciones seculares. Las observaciones fueron obtenidas de la literatura con la excepción de un grupo 66 determinaciones que se presentan por vez primera aquí. Utilizando el parámetro testigo σ descripto en Marraco & Muzzio (Publ. Astron. Soc. Pacific 92, 700, 1980), hemos realizado un ajuste bidimensional en P y β (donde β es la variación secular del período). Con este fin la totalidad de las 689 observaciones fueron llevadas a un sistema fotométrico común. Para esto se realizó un cuidadoso análisis de los numerosos errores en la identificación de las estrellas de las series de comparación. Los resultados de los ajustes bidimensionales fueron analizados utilizando técnicas de procesamiento de imágenes. Con este fin el parámetro de ajuste σ fue representado como función de P y β. En las imágenes resultantes se buscaron los mínimos y al menor de ellos se lo aceptó como período instantáneo verdadero y su variación secular β. La determinación precisa de cada parámetro se realizó mediante ajuste de gaussianas y se determinaron sus errores. A modo de ejemplo la variable #8 fue analizada en una matriz de 501 × 501 elementos representando el parámetro σ para valores comprendidos entre 0,521034 < P < 0,521534 dias y -150×10-10 < β < +150×10-10 dias/dia. El mejor período instantáneo (correspondiente a la época DJ=2.426.908) y su variación secular son P = 0,5212859±0,0000001 días y β 14,012±,010×10-10 días/día respectivamente. Con estos valores el parámetro testigo resulta σ= 0,127 . Si no se tiene en cuenta la variación secular del período y se busca aquél de mejor ajuste para β = 0, se obtiene P = 0,5212960 días, pero entonces el parámetro de ajuste resulta tan alto como σ = 0,23 .

  4. Properties of RR Lyrae stars in the inner regions of the Large Magellanic Cloud. III. Near-infrared study

    NASA Astrophysics Data System (ADS)

    Borissova, J.; Rejkuba, M.; Minniti, D.; Catelan, M.; Ivanov, V. D.

    2009-08-01

    Context: RR Lyrae variable stars are the primary Population II distance indicator. Likewise, the Large Magellanic Cloud (LMC) constitutes a key step in the extragalactic distance scale. Aims: By combining near-IR photometry and spectroscopically measured metallicities for a homogeneous sample of 50 RR Lyr stars in the LMC, we investigate the metallicity dependence of the period-luminosity relation in the near-infrared (IR), use the newly derived relations to re-derive the distance to the LMC, and compare the distance moduli obtained from RR Lyr and red clump stars. Methods: This paper presents new (single-epoch) J-band and (multi-epoch) K_s-band photometry of RR Lyr stars in 7 different LMC fields, observed with the near-IR camera SOFI at ESO's New Technology Telescope. Additional K_s-band data for another two LMC fields were taken with the ISPI infrared array at CTIO's Blanco 4m telescope. The near-IR photometry was cross-correlated with the MACHO and OGLE databases, resulting in a catalog of 62 RR Lyr stars with BVRIJKs photometry. A subsample of 50 stars also has spectroscopically measured metallicities. Results: In the deep JK color-magnitude diagrams of 7 fields, red giant branch, red clump and RR Lyr stars are detected. The majority of RR Lyr stars are located within the instability strip with near-IR colors between 0.14 ≤ (J-K_s)_0<0.32. The period-luminosity relation only has a very mild dependence on metallicity in the K band, consistent with no dependence: MKs =2.11(± 0.17) log{P} + 0.05(± 0.07) [Fe/H] - 1.05. In the J band the currently available data do not allow firm conclusions regarding the metallicity dependence of the period-luminosity relation. Conclusions: The distance modulus of the LMC, derived using our near-IR period-luminosity-metallicity relation for RR Lyr stars, is (m-M)_0=18.53 ± 0.13, in very good agreement with the distance modulus from the red clump stars, 18.46 ± 0.07. However, LMC modulus derived from the RR Lyrae stars

  5. THE OPTICAL GRAVITATIONAL LENSING EXPERIMENT: ANALYSIS OF THE BULGE RR LYRAE POPULATION FROM THE OGLE-III DATA

    SciTech Connect

    Pietrukowicz, P.; Udalski, A.; Soszynski, I.; Wyrzykowski, L.; Poleski, R.; Kozlowski, S.; Szymanski, M. K.; Kubiak, M.; Pietrzynski, G.; Ulaczyk, K.; Nataf, D. M.

    2012-05-10

    We have analyzed the data on 16,836 RR Lyrae (RR Lyr) variables observed toward the Galactic bulge during the third phase of the Optical Gravitational Lensing Experiment (OGLE-III), which took place in 2001-2009. Using these standard candles, we show that the ratio of total-to-selective extinction toward the bulge is given by R{sub I} = A{sub I} /E(V - I) = 1.080 {+-} 0.007 and is independent of color. We demonstrate that the bulge RR Lyr stars form a metal-uniform population, slightly elongated in its inner part. The photometrically derived metallicity distribution is sharply peaked at [Fe/H] = -1.02 {+-} 0.18, with a dispersion of 0.25 dex. In the inner regions (|l| < 3 Degree-Sign , |b| < 4 Degree-Sign ) the RR Lyr tend to follow the barred distribution of the bulge red clump giants. The distance to the Milky Way center inferred from the bulge RR Lyr is R{sub 0} = 8.54 {+-} 0.42 kpc. We report a break in the mean density distribution at a distance of {approx}0.5 kpc from the center indicating its likely flattening. Using the OGLE-III data, we assess that (4-7) Multiplication-Sign 10{sup 4} type ab RR Lyr variables should be detected toward the bulge area of the ongoing near-IR VISTA Variables in the Via Lactea (VVV) survey, where the uncertainty partially results from the unknown RR Lyr spatial density distribution within 0.2 kpc from the Galactic center.

  6. EXPLORING THE VARIABLE SKY WITH LINEAR. II. HALO STRUCTURE AND SUBSTRUCTURE TRACED BY RR LYRAE STARS TO 30 kpc

    SciTech Connect

    Sesar, Branimir; Ivezic, Zeljko; Morgan, Dylan M.; Becker, Andrew C.; Stuart, J. Scott; Sharma, Sanjib; Palaversa, Lovro; Juric, Mario; Wozniak, Przemyslaw; Oluseyi, Hakeem

    2013-08-01

    We present a sample of {approx}5000 RR Lyrae stars selected from the recalibrated LINEAR data set and detected at heliocentric distances between 5 kpc and 30 kpc over {approx}8000 deg{sup 2} of sky. The coordinates and light curve properties, such as period and Oosterhoff type, are made publicly available. We analyze in detail the light curve properties and Galactic distribution of the subset of {approx}4000 type ab RR Lyrae (RRab) stars, including a search for new halo substructures and the number density distribution as a function of Oosterhoff type. We find evidence for the Oosterhoff dichotomy among field RR Lyrae stars, with the ratio of the type II and I subsamples of about 1:4, but with a weaker separation than for globular cluster stars. The wide sky coverage and depth of this sample allow unique constraints for the number density distribution of halo RRab stars as a function of galactocentric distance: it can be described as an oblate ellipsoid with an axis ratio q = 0.63 and with either a single or a double power law with a power-law index in the range -2 to -3. Consistent with previous studies, we find that the Oosterhoff type II subsample has a steeper number density profile than the Oosterhoff type I subsample. Using the group-finding algorithm EnLink, we detected seven candidate halo groups, only one of which is statistically spurious. Three of these groups are near globular clusters (M53/NGC 5053, M3, M13), and one is near a known halo substructure (Virgo Stellar Stream); the remaining three groups do not seem to be near any known halo substructures or globular clusters and seem to have a higher ratio of Oosterhoff type II to Oosterhoff type I RRab stars than what is found in the halo. The extended morphology and the position (outside the tidal radius) of some of the groups near globular clusters are suggestive of tidal streams possibly originating from globular clusters. Spectroscopic follow-up of detected halo groups is encouraged.

  7. Pulsations and period changes of the non-Blazhko RR lyrae variable Y oct observed from Dome A, Antarctica

    SciTech Connect

    Zhihua, Huang; Jianning, Fu; Weikai, Zong; Lingzhi, Wang; Zonghong, Zhu; M, Macri Lucas; Lifan, Wang; Ashley, Michael C. B.; S, Lawrence Jon; Daniel, Luong-Van; Xiangqun, Cui; Long-Long, Feng; Xuefei, Gong; Qiang, Liu; Huigen, Yang; Xiangyan, Yuan; Xu, Zhou; Zhenxi, Zhu; R, Pennypacker Carl; G, York Donald

    2015-01-01

    During the operation of the Chinese Small Telescope Array (CSTAR) in Dome A of Antarctica in the years 2008, 2009, and 2010, large amounts of photometric data have been obtained for variable stars in the CSTAR field. We present here the study of one of six RR Lyrae variables, Y Oct, observed with CSTAR in Dome A, Antarctica. Photometric data in the i band were obtained in 2008 and 2010, with a duty cycle (defined as the fraction of time representing scientifically available data to CSTAR observation time) of about 44% and 52%, respectively. In 2009, photometric data in the g and r bands were gathered for this star, with a duty cycle of 65% and 60%, respectively. Fourier analysis of the data in the three bands only shows the fundamental frequency and its harmonics, which is characteristic of the non-Blazhko RR Lyrae variables. Values of the fundamental frequency and the amplitudes, as well as the total pulsation amplitude, are obtained from the data in the three bands separately. The amplitude of the fundamental frequency and the total pulsation amplitude in the g band are the largest, and those in the i band the smallest. Two-hundred fifty-one times of maximum are obtained from the three seasons of data, which are analyzed together with 38 maximum times provided in the GEOS RR Lyrae database. A period change rate of −0.96 ± 0.07 days Myr{sup −1} is then obtained, which is a surprisingly large negative value. Based on relations available in the literature, the following physical parameters are derived: [Fe/H] = −1.41 ± 0.14, M{sub V} = 0.696 ± 0.014 mag, V−K = 1.182 ± 0.028 mag, logT{sub eff} = 3.802 ± 0.003 K, logg = 2.705 ± 0.004, logL/L{sub ⊙} = 1.625 ± 0.013, and logM/M{sub ⊙} = −0.240 ± 0.019.

  8. The Interstellar Extinction Towards the Milky Way Bulge with Planetary Nebulae, Red Clump, and RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    Nataf, David M.

    2016-06-01

    I review the literature covering the issue of interstellar extinction towards the Milky Way bulge, with emphasis placed on findings from planetary nebulae, RR Lyrae, and red clump stars. I also report on observations from HI gas and globular clusters. I show that there has been substantial progress in this field in recent decades, most particularly from red clump stars. The spatial coverage of extinction maps has increased by a factor ~ 100 × in the past 20 yr, and the total-to-selective extinction ratios reported have shifted by ~ 20-25%, indicative of the improved accuracy and separately, of a steeper-than-standard extinction curve. Problems remain in modelling differential extinction, explaining anomalies involving the planetary nebulae, and understanding the difference between bulge extinction coefficients and `standard' literature values.

  9. VizieR Online Data Catalog: 33 RR Lyrae observed in Pisces with K2-E2 (Molnar+, 2015)

    NASA Astrophysics Data System (ADS)

    Molnar, L.; Szabo, R.; Moskalik, P. A.; Nemec, J. M.; Guggenberger, E.; Smolec, R.; Poleski, R.; Plachy, E.; Kolenberg, K.; Kollath, Z.

    2016-03-01

    Kepler observed a stellar field around the vernal equinox point in Pisces (centre coordinates: RA=359°, DE=-2°) between 2014 February 04 and 13. The primary goal of this K2 Two-Wheel Concept Engineering Test (hereafter K2-E2) was to test the performance of the telescope in fine guidance mode. As well, the observations of nearly 2000 targets were made available for the scientific community. We identified 33 potential RR Lyrae stars in the K2-E2 sample and extracted their photometric data with the pyke software, developed for the Kepler mission by the Kepler Guest Observer Office (Still & Barclay, 2012, Astrophysics Source Code Library record ascl:1208.004). (6 data files).

  10. ANCIENT STARS BEYOND THE LOCAL GROUP: RR LYRAE VARIABLES AND BLUE HORIZONTAL BRANCH STARS IN SCULPTOR GROUP DWARF GALAXIES

    SciTech Connect

    Da Costa, G. S.; Jerjen, H.; Rejkuba, M.; Grebel, E. K.

    2010-01-10

    We have used Hubble Space Telescope Advanced Camera for Surveys images to generate color-magnitude diagrams that reach below the magnitude of the horizontal branch in the Sculptor Group dwarf galaxies ESO294-010 and ESO410-005. In both diagrams, blue horizontal branch stars are unambiguously present, a signature of the existence of an ancient stellar population whose age is comparable to that of the Galactic halo globular clusters. The result is reinforced by the discovery of numerous RR Lyrae variables in both galaxies. The occurrence of these stars is the first direct confirmation of the existence of ancient stellar populations beyond the Local Group and indicates that star formation can occur at the earliest epochs even in low-density environments.

  11. Cyclic variations in O-C diagrams of field RR Lyrae stars as a result of LiTE

    NASA Astrophysics Data System (ADS)

    Liška, J.; Skarka, M.; Zejda, M.; Mikulášek, Z.; de Villiers, S. N.

    2016-07-01

    This paper presents an extensive overview of known and proposed RR Lyrae stars in binaries. The aim is to revise and extend the list with new Galactic field systems. We utilized maxima timings for 11 RRab type stars with suspicious behaviour from the GEOS data base, and determined maxima timings from data of sky surveys and our own observations. This significantly extended the number of suitable maxima timings. We modelled the proposed Light Time Effect (LiTE) in O-C diagrams to determine orbital parameters for these systems. In contrast to recent studies, our analysis focused on decades-long periods instead of periods in the order of years. Secondary components were found to be predominantly low-mass objects. However, for RZ Cet and AT Ser the mass of the suspected companion of more than one solar mass suggests that it is a massive white dwarf, a neutron star or even a black hole. We found that the semimajor axes of the proposed orbits are between 1 and 20 au. Because the studied stars belong to the closest RR Lyraes, maximal angular distances between components during orbit should at least be between 1 and 13 mas and this improves the chance to detect both stars using current telescopes. However, our interpretation of the O-C diagrams as a consequence of the LiTE should be considered as preliminary without reliable spectroscopic measurements. On the other hand, our models give a prediction of the period and radial velocity evolution which should be sufficient for plausible proof of binarity.

  12. Optical and Near-Infrared UBVRIJHK Photometry for the RR Lyrae Stars in the Nearby Globular Cluster M4 (NGC 6121)

    NASA Astrophysics Data System (ADS)

    Stetson, P. B.; Braga, V. F.; Dall'Ora, M.; Bono, G.; Buonanno, R.; Ferraro, I.; Iannicola, G.; Marengo, M.; Neeley, J.

    2014-06-01

    We present optical and near-infrared UBVRIJHK photometry of stars in the Galactic globular cluster M4 (NGC 6121) based upon a large corpus of observations obtained mainly from public astronomical archives. We concentrate on the RR Lyrae variable stars in the cluster, and make a particular effort to accurately reidentify the previously discovered variables. We have also discovered two new probable RR Lyrae variables in the M4 field: one of them by its position on the sky and its photometric properties is a probable member of the cluster, and the second is a probable background (bulge?) object. We provide accurate equatorial coordinates for all 47 stars identified as RR Lyraes, new photometric measurements for 46 of them, and new period estimates for 45. We have also derived accurate positions and mean photometry for 34 more stars previously identified as variable stars of other types, and for an additional five non-RR Lyrae variable stars identified for the first time here. We present optical and near-infrared color-magnitude diagrams for the cluster and show the locations of the variable stars in them. We present the Bailey (period-amplitude) diagrams and the period-frequency histogram for the RR Lyrae stars in M4 and compare them to the corresponding diagrams for M5 (NGC 5904). We conclude that the RR Lyrae populations in the two clusters are quite similar in all the relevant properties that we have considered. The mean periods, pulsation-mode ratios, and Bailey diagrams of these two clusters show support for the recently proposed "Oosterhoff-neutral" classification. Based in part on data obtained from the ESO Science Archive Facility under multiple requests by the authors; in part on data obtained from the Isaac Newton Group Archive, which is maintained as part of the CASU Astronomical Data Centre at the Institute of Astronomy, Cambridge; and in part upon data distributed by the NOAO Science Archive. NOAO is operated by the Association of Universities for

  13. Image-Subtraction Photometry of the Globular Cluster M3: Identification of New Double-Mode RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    Clementini, Gisella; Corwin, T. Michael; Carney, Bruce W.; Sumerel, Andrew N.

    2004-02-01

    We have applied the image subtraction method of Alard and Lupton to the extensive M3 data set previously analyzed by Corwin and Carney using DAOPHOT and ALLSTAR. This new analysis has produced light curves and periods for 15 variables not found in the previous study but already known to be variables, and it has also resulted in improved periods for several other variables. The additional variables recovered with the image subtraction analysis are in the very central region of M3, where crowding is severe and the photometry was not of sufficient quality that it could be put on the standard system. The present study brings to 222 the total number of RR Lyrae variables in Corwin and Carney's M3 data set for which light curves and periods are available. Among them we have identified three new candidate double-mode pulsating variables (V13, V200, and V251), reported here for the first time. This brings to eight the total number of double-mode RR Lyrae (RRd's) identified in M3. Of the newly discovered RRd's V13 is unusual in that it has the fundamental as the dominant pulsation mode. M3 is unique among the globular clusters in having RRd variables with a dominant fundamental mode. Two of the new candidate RRd's (V13 and V200) have period ratios as low as 0.738-0.739. They lie well separated from all previously known double-mode variable stars in the Petersen diagram in positions implying a large spread in mass and/or, less likely, in heavy element mass fraction, among the M3 horizontal-branch (HB) stars. We explore mass transfer and helium enhancement as possible explanations for the apparent spread in HB masses. We also note that the masses derived from the double-mode analyses now favor little mass loss on the red giant branch. We find that V200 has changed its dominant pulsation mode from fundamental to first overtone, while V251 has changed its dominant mode from first overtone to fundamental in the interval 1992 to 1993. Together with M3-V166 this is the first time

  14. RR Lyrae Luminosity Differences between Oosterhoff Group I and II Cluster Systems and the Origin of the Oosterhoff Dichotomy

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Woo; Carney, Bruce W.

    1999-09-01

    We present a comparative study of the Oosterhoff II cluster M2 and the Oosterhoff I cluster M3. Both have similar metallicities, [Fe/H]=-1.62 for M2 and -1.66 for M3, but very different horizontal-branch (HB) morphologies (B-R)/(B+V+R)=0.92 for M2 and 0.08 for M3. A period shift analysis and main-sequence fitting show that RRab variables in M2 are about 0.2 mag brighter than those in M3. Comparisons of the M2 period shift with Oosterhoff I clusters NGC 3201 and NGC 7006 also yield similar results, while a comparison between M2 and the Oosterhoff II cluster NGC 5986 reveals that the RR Lyrae luminosities are very similar. The luminosity difference is thought to be due to the evolutionary effect described in 1990 by Lee, Demarque, & Zinn: the M2 RRab variables have evolved away from the zero-age horizontal branch (ZAHB), while most M3 RRab variables lie near the ZAHB. A comparison of the mean period change rates of two clusters supports this hypothesis. Our relative age estimation using the difference in color between the base of giant branch and turn-off point shows that M2 is about 2 Gyr older than M3. Our result strongly suggests that the Oosterhoff dichotomy is due to age differences between Oosterhoff group I and II. This is consistent with the idea that the global second parameter is age. We discuss the kinematic differences between Oosterhoff group I and II clusters. Our result shows that the Oosterhoff group I clusters have zero or retrograde rotation with =-68+/-56 km s^-1 and sigma_los=131+/-28 km s^-1, while the Oosterhoff group II clusters have prograde rotation with =+94+/-47 km s^-1 and sigma_los=115+/-29 km s^-1, confirming a similar conclusion of van den Bergh. The difference in kinematics and ages between Oosterhoff group I and II clusters suggests that they may have different origins: The Oosterhoff II clusters were formed very early in the proto-Galaxy while the Oosterhoff I clusters were formed at different locations and at a later

  15. Finding, Characterizing, and Classifying Variable Sources in Multi-epoch Sky Surveys: QSOs and RR Lyrae in PS1 3π data

    NASA Astrophysics Data System (ADS)

    Hernitschek, Nina; Schlafly, Edward F.; Sesar, Branimir; Rix, Hans-Walter; Hogg, David W.; Ivezić, Željko; Grebel, Eva K.; Bell, Eric F.; Martin, Nicolas F.; Burgett, W. S.; Flewelling, H.; Hodapp, K. W.; Kaiser, N.; Magnier, E. A.; Metcalfe, N.; Wainscoat, R. J.; Waters, C.

    2016-01-01

    In area and depth, the Pan-STARRS1 (PS1) 3π survey is unique among many-epoch, multi-band surveys and has enormous potential for the all-sky identification of variable sources. PS1 has observed the sky typically seven times in each of its five bands (grizy) over 3.5 years, but unlike SDSS, not simultaneously across the bands. Here we develop a new approach for quantifying statistical properties of non-simultaneous, sparse, multi-color light curves through light curve structure functions, effectively turning PS1 into a ∼35-epoch survey. We use this approach to estimate variability amplitudes and timescales (ωr, τ) for all point sources brighter than rP1 = 21.5 mag in the survey. With PS1 data on SDSS Stripe 82 as “ground truth,” we use a Random Forest Classifier to identify QSOs and RR Lyrae based on their variability and their mean PS1 and WISE colors. We find that, aside from the Galactic plane, QSO and RR Lyrae samples of purity ∼75% and completeness ∼92% can be selected. On this basis we have identified a sample of ∼1,000,000 QSO candidates, as well as an unprecedentedly large and deep sample of ∼150,000 RR Lyrae candidates with distances from ∼10 to ∼120 kpc. Within the Draco dwarf spheroidal, we demonstrate a distance precision of 6% for RR Lyrae candidates. We provide a catalog of all likely variable point sources and likely QSOs in PS1, a total of 25.8 × 106 sources.

  16. The Araucaria Project: The Distance to the Carina Dwarf Galaxy from Infrared Photometry of RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    Karczmarek, Paulina; Pietrzyński, Grzegorz; Gieren, Wolfgang; Suchomska, Ksenia; Konorski, Piotr; Górski, Marek; Pilecki, Bogumił; Graczyk, Dariusz; Wielgórski, Piotr

    2015-09-01

    We obtained single-phase near-infrared (NIR) magnitudes in the J- and K-band for a sample of 33 RR Lyrae (RRL) stars in the Carina dSph galaxy. Applying different theoretical and empirical calibrations of the NIR period–luminosity–metallicity relation for RRL stars, we find consistent results and obtain a true, reddening-corrected distance modulus of 20.118 ± 0.017 (statistical) ± 0.11 (systematic) mag. This value is in excellent agreement with the results obtained in the context of the Araucaria Project from NIR photometry of red clump stars (20.165 ± 0.015) and the tip of red giant branch (20.09 ± 0.03 ± 0.12 mag in the J band, 20.14 ± 0.04 ± 0.14 mag in the K band), as well as with most independent distance determinations to this galaxy. The NIR RRL method proved to be a reliable tool for accurate distance determination at the 5% level or better, particularly for galaxies and globular clusters that lack young standard candles, like Cepheids. Based on data collected with the VLT/HAWK-I instrument at ESO Paranal Observatory, Chile, as a part of a program 082.D-0123(B).

  17. RR Lyrae stars in the SDSS Stripe 82 region: period-color and amplitude-color relations

    NASA Astrophysics Data System (ADS)

    Ngeow, C.-C.; Kanbur, S.; Bhardwaj, A.; Singh, H.

    2016-05-01

    Investigation of period-color (PC) and amplitude-color (AC) relations at the maximum and minimum light for RR Lyrae (RRL) stars can be used to probe the interaction of the hydrogen ionization front with photosphere at the atmosphere for this type of pulsating variables. For example, theoretical calculation indicated that such interaction would occur at the minimum light for RRL stars and caused a flat PC relation. In the past, the PC and AC relations have been investigated by using either the (V - R) or (V - I) colors. Here, we extend previous works to multi-bands by analyzing the RRL stars in SDSS (Sloan Digitized Sky Survey) Stripe 82 region, at which multi-epoch data are available for RRL stars located within the footprint of Stripe 82 region in ugriz bands. We present the PC and AC relations in four colors after correcting for extinction. We found that the structure of PC and AC relations for this sample of RRL stars is more complicated than a linear regression fit.

  18. THE ARAUCARIA PROJECT: THE DISTANCE TO THE CARINA DWARF GALAXY FROM INFRARED PHOTOMETRY OF RR LYRAE STARS

    SciTech Connect

    Karczmarek, Paulina; Pietrzynski, Grzegorz; Suchomska, Ksenia; Konorski, Piotr; Górski, Marek; Pilecki, Bogumił; Wielgórski, Piotr; Gieren, Wolfgang; Graczyk, Dariusz E-mail: ksenia@astrouw.edu.pl E-mail: pilecki@astrouw.edu.pl E-mail: pietrzyn@astrouw.edu.pl E-mail: mgorski@astrouw.edu.pl

    2015-09-15

    We obtained single-phase near-infrared (NIR) magnitudes in the J- and K-band for a sample of 33 RR Lyrae (RRL) stars in the Carina dSph galaxy. Applying different theoretical and empirical calibrations of the NIR period–luminosity–metallicity relation for RRL stars, we find consistent results and obtain a true, reddening-corrected distance modulus of 20.118 ± 0.017 (statistical) ± 0.11 (systematic) mag. This value is in excellent agreement with the results obtained in the context of the Araucaria Project from NIR photometry of red clump stars (20.165 ± 0.015) and the tip of red giant branch (20.09 ± 0.03 ± 0.12 mag in the J band, 20.14 ± 0.04 ± 0.14 mag in the K band), as well as with most independent distance determinations to this galaxy. The NIR RRL method proved to be a reliable tool for accurate distance determination at the 5% level or better, particularly for galaxies and globular clusters that lack young standard candles, like Cepheids.

  19. VizieR Online Data Catalog: Double-mode RR Lyrae stars in LINEAR (Poleski+, 2014)

    NASA Astrophysics Data System (ADS)

    Poleski, R.

    2014-11-01

    The LINEAR survey operated between 1998 and 2009 using two 1m telescopes. Each of the mosaic cameras had a 2deg2 field of view with a 2.25" pixel scale. Observations were collected without a filter and sometimes in nonphotometric conditions. On average, 250 epochs were collected per field, and the number rises to 500 for targets close to the ecliptic plane. Such a dataset is suitable for a search for periodic variable stars. The catalog of such objects was presented by Palaversa et al. (2013AJ....146..101P, Cat. J/AJ/146/101). It includes more than 7000 stars, most of which are RR Lyr pulsators. There are 2923 RRab and 990 RRc stars. We performed the search for other radial modes in RR Lyr type stars. (2 data files).

  20. Globular cluster distances from the RR Lyrae log(period)-infrared magnitude relation

    NASA Astrophysics Data System (ADS)

    Longmore, A. J.; Dixon, R.; Skillen, I.; Jameson, R. F.; Fernley, J. A.

    1990-12-01

    The present determinations of log(period)-2.2 micron IR relationship for RR Lyr stars in eight clusters indicate no sign of scatter in the relation apart from observational error. It is suggested that very accurate relative distances, insensitive to both reddening errors and the effects of metallicity, are obtainable, although mass differences between variables in different clusters may still introduce relative distance uncertainties. A comparison of the absolute calibration of K magnitudes of two field stars obtained with an IR-flux method form of the Baade-Wesselink analysis to three other sets of distance measurements shows good agreement with those of Richer and Fahlman (1987).

  1. The early chemical enrichment histories of two Sculptor group dwarf galaxies as revealed by RR lyrae variables

    SciTech Connect

    Yang, Soung-Chul; Kim, Sang Chul; Kyeong, Jaemann; Wagner-Kaiser, Rachel; Sarajedini, Ata

    2014-03-20

    We present the results of our analysis of the RR Lyrae (RRL) variable stars detected in two transition-type dwarf galaxies (dTrans), ESO294-G010 and ESO410-G005 in the Sculptor group, which is known to be one of the closest neighboring galaxy groups to our Local Group. Using deep archival images from the Advanced Camera for Surveys on board the Hubble Space Telescope, we have identified a sample of RRL candidates in both dTrans galaxies (219 RRab (RR0) and 13 RRc (RR1) variables in ESO294-G010; 225 RRab and 44 RRc stars in ESO410-G005). The metallicities of the individual RRab stars are calculated via the period-amplitude-[Fe/H] relation derived by Alcock et al. This yields mean metallicities of ([Fe/H]){sub ESO294} = –1.77 ± 0.03 and ([Fe/H]){sub ESO410} = –1.64 ± 0.03. The RRL metallicity distribution functions (MDFs) are investigated further via simple chemical evolution models; these reveal the relics of the early chemical enrichment processes for these two dTrans galaxies. In the case of both galaxies, the shapes of the RRL MDFs are well described by pre-enrichment models. This suggests two possible channels for the early chemical evolution for these Sculptor group dTrans galaxies: (1) the ancient stellar populations of our target dwarf galaxies might have formed from the star forming gas which was already enriched through 'prompt initial enrichment' or an 'initial nucleosynthetic spike' from the very first massive stars, or (2) this pre-enrichment state might have been achieved by the end products from more evolved systems of their nearest neighbor, NGC 55. We also study the environmental effects of the formation and evolution of our target dTrans galaxies by comparing their properties with those of 79 volume limited (D {sub ☉} < 2 Mpc) dwarf galaxy samples in terms of the luminosity-metallicity relation and the H I gas content. The presence of these RRL stars strongly supports the idea that although the Sculptor Group galaxies have a considerably

  2. RR Lyrae stars - A theoretical study of Bailey type c variables

    NASA Technical Reports Server (NTRS)

    Hubickyj, Olenka; Stothers, Richard B.

    1986-01-01

    New theoretical models of stars pulsating in the first overtone have been constructed to simulate RR Lyr variables of Bailey type c. Despite the use of different opacities, these new models agree very well with earlier models built by Christy and Stellingwerf. Quantitative comparisons using empirical light curves and velocity curves of metal-poor type c variables confirm the validity of the models. Masses of 0.55-0.65 solar mass and luminosities of 40-50 solar luminosities derived here for the type c variables, are consistent with previous results obtained for type ab variables. A Christy echo of the kind normally associated with fundamental-mode pulsators was detected in the interior velocity structure of one first-overtone model that happens to have a large velocity amplitude.

  3. The MACHO Project Large Magellanic Cloud Variable Star Inventory. XIII. Fourier Parameters for the First Overtone RR Lyrae Variables and the LMC Distance

    SciTech Connect

    Alcock, C; Alves, D; Axelrod, T; Becker, A; Bennett, D; Clement, C; Cook, K; Drake, A; Freeman, K; Geha, M; Griest, K; Lehner, M; Marshall, S; Minniti, D; Muzzin, A; Nelson, C; Peterson, B; Popowski, P; Pratt, M; Quinn, P; Rodgers, A; Rowe, J; Sutherland, W; Vandehei, T; Welch, D

    2003-12-31

    Shapes of RR Lyrae light curves can be described in terms of Fourier coefficients which past research has linked with physical characteristics such as luminosity, mass and temperature. Fourier coefficients have been derived for the V and R light curves of 785 overtone RR Lyrae variables in 16 MACHO fields near the bar of the LMC. In general, the Fourier phase differences {phi}{sub 21}, {phi}{sub 31} and {phi}{sub 41} increase and the amplitude ratio R{sub 21} decreases with increasing period. The coefficients for both the V and R magnitudes follow these patterns, but the phase differences for the R curves are on average slightly greater, and their amplitudes are about 20% smaller, than the ones for the V curves. The {phi}{sub 31} and R{sub 21} coefficients have been compared with those of the first overtone RR Lyrae variables in the Galactic globular clusters NGC 6441, M107, M5, M3, M2, {omega} Centauri and M68. The results indicate that many of the LMC variables have properties similar to the ones in M2, M3, M5 and the Oosterhoff type I variables in {omega} Cen, but they are different from the Oosterhoff type II variables in {omega} Cen. Equations derived from hydrodynamic pulsation models have been used to calculate the luminosity and temperature for the 330 bona fide first-overtone variables. The results indicate that they have Log L in the range 1.6 to 1.8 L{sub {center_dot}} and log T{sub eff} between 3.85 and 3.87. Based on these temperatures, a mean color excess E(V-R) = 0.08 mag, equivalent to E(B-V) = 0.14 mag, has been estimated for these 330 stars. The 80 M5-like variables (selected according to their location in the {phi}{sub 31} - log P plot) are used to determine an LMC distance. After correcting for the effects of extinction and crowding, a mean apparent magnitude < V{sub 0} > = 18.99 {+-} 0.02 (statistical) {+-} 0.16 (systematic) has been estimated for these 80 stars. Combining this with a mean absolute magnitude M{sub V} = 0.56 {+-} 0.06 for M5

  4. Peculiar double-periodic pulsation in RR Lyrae stars of the OGLE collection - I. Long-period stars with dominant radial fundamental mode

    NASA Astrophysics Data System (ADS)

    Smolec, R.; Prudil, Z.; Skarka, M.; Bakowska, K.

    2016-09-01

    We present the discovery of a new, peculiar form of double-periodic pulsation in RR Lyrae stars. In four, long-period (P > 0.6 d) stars observed by the Optical Gravitational Lensing Experiment, and classified as fundamental mode pulsators (RRab), we detect additional, low-amplitude variability, with period shorter than fundamental mode period. The period ratios fall in a range similar to double-mode fundamental and first overtone RR Lyrae stars (RRd), with the exception of one star, in which the period ratio is significantly lower and nearly exactly equals 0.7. Although period ratios are fairly different for the four stars, the light-curve shapes corresponding to the dominant, fundamental mode are very similar. The peak-to-peak amplitudes and amplitude ratios (Fourier parameters R21 and R31) are among the highest observed in RRab stars of similar period, while Fourier phases (ϕ21 and ϕ31) are among the lowest observed in RRab stars. If the additional variability is interpreted as due to radial first overtone, then, the four stars are the most extreme RRd variables of the longest pulsation periods known. Indeed, the observed period ratios can be well modelled with high-metallicity pulsation models. However, at such long pulsation periods, first overtone is typically damped. Five other candidates, with weak signature of additional variability, sharing the same characteristics, were also detected and are briefly discussed.

  5. An optimized method to identify RR Lyrae stars in the SDSS×Pan-STARRS1 overlapping area using a bayesian generative technique

    SciTech Connect

    Abbas, Mohamad; Grebel, Eva K.; Martin, N. F.; Kaiser, N.; Burgett, W. S.; Huber, M. E.; Waters, C.

    2014-07-01

    We present a method for selecting RR Lyrae (RRL) stars (or other types of variable stars) in the absence of a large number of multi-epoch data and light curve analyses. Our method uses color and variability selection cuts that are defined by applying a Gaussian Mixture Bayesian Generative Method (GMM) on 636 pre-identified RRL stars instead of applying the commonly used rectangular cuts. Specifically, our method selects 8115 RRL candidates (heliocentric distances < 70 kpc) using GMM color cuts from the Sloan Digital Sky Survey (SDSS) and GMM variability cuts from the Panoramic Survey Telescope and Rapid Response System 1 3π survey (PS1). Comparing our method with the Stripe 82 catalog of RRL stars shows that the efficiency and completeness levels of our method are ∼77% and ∼52%, respectively. Most contaminants are either non-variable main-sequence stars or stars in eclipsing systems. The method described here efficiently recovers known stellar halo substructures. It is expected that the current completeness and efficiency levels will further improve with the additional PS1 epochs (∼3 epochs per filter) that will be observed before the conclusion of the survey. A comparison between our efficiency and completeness levels using the GMM method to the efficiency and completeness levels using rectangular cuts that are commonly used yielded a significant increase in the efficiency level from ∼13% to ∼77% and an insignificant change in the completeness levels. Hence, we favor using the GMM technique in future studies. Although we develop it over the SDSS×PS1 footprint, the technique presented here would work well on any multi-band, multi-epoch survey for which the number of epochs is limited.

  6. Constraints on the Distance Moduli, Helium and Metal Abundances, and Ages of Globular Clusters from their RR Lyrae and Non-variable Horizontal-branch Stars. I. M3, M15, and M92

    NASA Astrophysics Data System (ADS)

    VandenBerg, Don A.; Denissenkov, P. A.; Catelan, Márcio

    2016-08-01

    Up-to-date isochrones, zero-age horizontal-branch (ZAHB) loci, and evolutionary tracks for core He-burning stars are applied to the color-magnitude diagrams of M3, M15, and M92, focusing in particular on their RR Lyrae populations. Periods for the ab- and c-type variables are calculated using the latest theoretical calibrations of {log} {P}{ab} and {log} {P}c as a function of luminosity, mass, effective temperature ({T}{{eff}}), and metallicity. Our models are generally able to reproduce the measured periods to well within the uncertainties implied by the stellar properties on which pulsation periods depend, as well as the mean periods and cluster-to-cluster differences in < {P}{ab}> and < {P}c> , on the assumption of well-supported values of E(B-V), {(m-M)}V, and [Fe/H]. While many of RR Lyrae in M3 lie close to the same ZAHB that fits the faintest horizontal-branch (HB) stars at bluer or redder colors, the M92 variables are all significantly evolved stars from ZAHB locations on the blue side of the instability strip. M15 appears to contain a similar population of HB stars as M92, along with additional helium-enhanced populations not present in the latter which comprise most of its RR Lyrae stars. The large number of variables in M15 and the similarity of the observed values of < {P}{ab}> and < {P}c> in M15 and M92 can be explained by HB models that allow for variations in Y. Similar ages (˜12.5 Gyr) are found for all three clusters, making them significantly younger than the field halo subgiant HD 140283. Our analysis suggests a preference for stellar models that take diffusive processes into account.

  7. Constraints on the Distance Moduli, Helium and Metal Abundances, and Ages of Globular Clusters from their RR Lyrae and Non-variable Horizontal-branch Stars. I. M3, M15, and M92

    NASA Astrophysics Data System (ADS)

    VandenBerg, Don A.; Denissenkov, P. A.; Catelan, Márcio

    2016-08-01

    Up-to-date isochrones, zero-age horizontal-branch (ZAHB) loci, and evolutionary tracks for core He-burning stars are applied to the color–magnitude diagrams of M3, M15, and M92, focusing in particular on their RR Lyrae populations. Periods for the ab- and c-type variables are calculated using the latest theoretical calibrations of {log} {P}{ab} and {log} {P}c as a function of luminosity, mass, effective temperature ({T}{{eff}}), and metallicity. Our models are generally able to reproduce the measured periods to well within the uncertainties implied by the stellar properties on which pulsation periods depend, as well as the mean periods and cluster-to-cluster differences in < {P}{ab}> and < {P}c> , on the assumption of well-supported values of E(B-V), {(m-M)}V, and [Fe/H]. While many of RR Lyrae in M3 lie close to the same ZAHB that fits the faintest horizontal-branch (HB) stars at bluer or redder colors, the M92 variables are all significantly evolved stars from ZAHB locations on the blue side of the instability strip. M15 appears to contain a similar population of HB stars as M92, along with additional helium-enhanced populations not present in the latter which comprise most of its RR Lyrae stars. The large number of variables in M15 and the similarity of the observed values of < {P}{ab}> and < {P}c> in M15 and M92 can be explained by HB models that allow for variations in Y. Similar ages (˜12.5 Gyr) are found for all three clusters, making them significantly younger than the field halo subgiant HD 140283. Our analysis suggests a preference for stellar models that take diffusive processes into account.

  8. On the Distance of the Globular Cluster M4 (NGC 6121) Using RR Lyrae Stars. II. Mid-infrared Period-luminosity Relations.

    NASA Astrophysics Data System (ADS)

    Neeley, J. R.; Marengo, M.; Bono, G.; Braga, V. F.; Dall'Ora, M.; Stetson, P. B.; Buonanno, R.; Ferraro, I.; Freedman, W. L.; Iannicola, G.; Madore, B. F.; Matsunaga, N.; Monson, A.; Persson, S. E.; Scowcroft, V.; Seibert, M.

    2015-07-01

    New mid-infrared (MIR) period-luminosity (PL) relations are presented for RR Lyræ variables in the globular cluster M4 (NGC 6121). Accurate photometry was obtained for 37 RR Lyræ variables using observations from the Infrared Array Camera on board the Spitzer Space Telescope. The dispersion of M4's PL relations is 0.056, and the uncertainty in the slope is 0.11 mag. Additionally, we established calibrated PL relations at 3.6 and 4.5 μm using published Hubble Space Telescope geometric parallaxes of five Galactic RR Lyræ stars. The resulting band-averaged distance modulus for M4 is μ =11.399+/- 0.007({stat}) ± 0.080({syst}) ± 0.015({cal})+/- 0.020({ext}). The systematic uncertainty will be greatly reduced when parallaxes of more stars become available from the GAIA mission. Optical and infrared period-color (PC) relations are also presented, and the lack of an MIR PC relation suggests that RR Lyræ stars are not affected by CO absorption in the 4.5 μm band.

  9. ON THE DISTANCE OF THE GLOBULAR CLUSTER M4 (NGC 6121) USING RR LYRAE STARS. I. OPTICAL AND NEAR-INFRARED PERIOD-LUMINOSITY AND PERIOD-WESENHEIT RELATIONS

    SciTech Connect

    Braga, V. F.; Bono, G.; Buonanno, R.; Dall'Ora, M.; Coppola, G.; Marconi, M.; Stetson, P. B.; Ferraro, I.; Iannicola, G.; Marengo, M.; Neeley, J.; Persson, S. E.; Freedman, W.; Madore, B. F.; Monson, A.; Rich, J.; Scowcroft, V.; Seibert, M.; Matsunaga, N.

    2015-02-01

    We present new distance determinations to the nearby globular M4 (NGC 6121) based on accurate optical and near-infrared (NIR) mean magnitudes for fundamental (FU) and first overtone (FO) RR Lyrae variables (RRLs), and new empirical optical and NIR period-luminosity (PL) and period-Wesenheit (PW) relations. We have found that optical-NIR and NIR PL and PW relations are affected by smaller standard deviations than optical relations. The difference is the consequence of a steady decrease in the intrinsic spread of cluster RRL apparent magnitudes at fixed period as longer wavelengths are considered. The weighted mean visual apparent magnitude of 44 cluster RRLs is =13.329 ± 0.001 (standard error of the mean) ±0.177 (weighted standard deviation) mag. Distances were estimated using RR Lyr itself to fix the zero-point of the empirical PL and PW relations. Using the entire sample (FU+FO) we found weighted mean true distance moduli of 11.35 ± 0.03 ± 0.05 mag and 11.32 ± 0.02 ± 0.07 mag. Distances were also evaluated using predicted metallicity dependent PLZ and PWZ relations. We found weighted mean true distance moduli of 11.283 ± 0.010 ± 0.018 mag (NIR PLZ) and 11.272 ± 0.005 ± 0.019 mag (optical-NIR and NIR PWZ). The above weighted mean true distance moduli agree within 1σ. The same result is found from distances based on PWZ relations in which the color index is independent of the adopted magnitude (11.272 ± 0.004 ± 0.013 mag). These distances agree quite well with the geometric distance provided by Kaluzny et al. based on three eclipsing binaries. The available evidence indicates that this approach can provide distances to globulars hosting RRLs with a precision better than 2%-3%.

  10. On the Distance of the Globular Cluster M4 (NGC 6121) Using RR Lyrae Stars. I. Optical and Near-infrared Period-Luminosity and Period-Wesenheit Relations

    NASA Astrophysics Data System (ADS)

    Braga, V. F.; Dall'Ora, M.; Bono, G.; Stetson, P. B.; Ferraro, I.; Iannicola, G.; Marengo, M.; Neeley, J.; Persson, S. E.; Buonanno, R.; Coppola, G.; Freedman, W.; Madore, B. F.; Marconi, M.; Matsunaga, N.; Monson, A.; Rich, J.; Scowcroft, V.; Seibert, M.

    2015-02-01

    We present new distance determinations to the nearby globular M4 (NGC 6121) based on accurate optical and near-infrared (NIR) mean magnitudes for fundamental (FU) and first overtone (FO) RR Lyrae variables (RRLs), and new empirical optical and NIR period-luminosity (PL) and period-Wesenheit (PW) relations. We have found that optical-NIR and NIR PL and PW relations are affected by smaller standard deviations than optical relations. The difference is the consequence of a steady decrease in the intrinsic spread of cluster RRL apparent magnitudes at fixed period as longer wavelengths are considered. The weighted mean visual apparent magnitude of 44 cluster RRLs is =13.329 ± 0.001 (standard error of the mean) ±0.177 (weighted standard deviation) mag. Distances were estimated using RR Lyr itself to fix the zero-point of the empirical PL and PW relations. Using the entire sample (FU+FO) we found weighted mean true distance moduli of 11.35 ± 0.03 ± 0.05 mag and 11.32 ± 0.02 ± 0.07 mag. Distances were also evaluated using predicted metallicity dependent PLZ and PWZ relations. We found weighted mean true distance moduli of 11.283 ± 0.010 ± 0.018 mag (NIR PLZ) and 11.272 ± 0.005 ± 0.019 mag (optical-NIR and NIR PWZ). The above weighted mean true distance moduli agree within 1σ. The same result is found from distances based on PWZ relations in which the color index is independent of the adopted magnitude (11.272 ± 0.004 ± 0.013 mag). These distances agree quite well with the geometric distance provided by Kaluzny et al. based on three eclipsing binaries. The available evidence indicates that this approach can provide distances to globulars hosting RRLs with a precision better than 2%-3%.

  11. VVV SURVEY NEAR-INFRARED PHOTOMETRY OF KNOWN BULGE RR LYRAE STARS: THE DISTANCE TO THE GALACTIC CENTER AND ABSENCE OF A BARRED DISTRIBUTION OF THE METAL-POOR POPULATION

    SciTech Connect

    Dékány, I.; Minniti, D.; Catelan, M.; Zoccali, M.; Hempel, M.; Saito, R. K.

    2013-10-20

    We have combined optical and near-infrared data of known RR Lyrae (RRL) stars in the bulge in order to study the spatial distribution of its metal-poor component by measuring precise reddening values and distances of 7663 fundamental-mode RRL stars with high-quality photometry. We obtain a distance to the Galactic center of R {sub 0} = 8.33 ± 0.05 ± 0.14 kpc. We find that the spatial distribution of the RRL stars differs from the structures traced by the predominantly metal-rich red clump (RC) stars. Unlike the RC stars, the RRL stars do not trace a strong bar, but have a more spheroidal, centrally concentrated distribution, showing only a slight elongation in its very center. We find a hint of bimodality in the density distribution at high southern latitudes (b < –5°), which needs to be confirmed by extending the areal coverage of the current census. The different spatial distributions of the metal-rich and metal-poor stellar populations suggest that the Milky Way has a composite bulge.

  12. AMPLITUDE FINE STRUCTURE IN THE CEPHEID P-L RELATION. I. AMPLITUDE DISTRIBUTION ACROSS THE RR LYRAE INSTABILITY STRIP MAPPED USING THE ACCESSIBILITY RESTRICTION IMPOSED BY THE HORIZONTAL BRANCH

    SciTech Connect

    Sandage, Allan

    2010-10-10

    The largest amplitude light curves for both RR Lyrae (RRL) variables and classical Cepheids with periods less than 10 days and greater than 20 days occur at the blue edge of the respective instability strips. It is shown that the equation for the decrease in amplitude with penetration into the strip from the blue edge, and hence the amplitude fine structure within the strip, is the same for RRL and the Cepheids despite their metallicity differences. However, the manifestation of this identity is different between the two classes of variables because the sampling of the RRL strip is restricted by the discrete strip positions of the horizontal branch, a restriction that is absent for the Cepheids in stellar aggregates with a variety of ages. To show the similarity of the strip amplitude fine structure for RRL and Cepheids, we make a grid of lines of constant amplitude in the H-R diagram of the strip using amplitude data for classical Cepheids in the Galaxy, LMC, and SMC. The model implicit in the grid, that also contains lines of constant period, is used to predict the correlations between period, amplitude, and color for the two Oosterhoff RRL groups in globular clusters. The good agreement of the predictions with the observations using the classical Cepheid amplitude fine structure also for the RRL shows one aspect of the unity of the pulsation processes between the two classes of variables.

  13. RW Arietis, an Eclipsing RR Lyrae Star?

    NASA Astrophysics Data System (ADS)

    Odell, Andrew P.; Sreedhar, Y. Harsha

    2016-08-01

    RW Arietis is an RRc star which has long been thought to undergo eclipses. We set out to answer the question posed in the title by utilizing extensive datasets, both archival and original, but found nothing, thus effectively answering in the negative. Instead we present the highest quality light curve to date, the first radial velocity curve, and the first successful ephemeris. The pulsation period changed abruptly in 2012, and seems to have changed at least twice before that.

  14. RR Lyrae stars in the Andromeda satellite galaxies

    NASA Astrophysics Data System (ADS)

    Cusano, F.; Garofalo, A.; Clementini, G.

    2016-05-01

    In this contribution we summarize results on the search for variable stars and the study of the resolved stellar populations in four dwarf spheroidal satellites of the Andromeda galaxy that we have observed with the Large Binocular Cameras (LBC) at the Large Binocular Telescope (LBT).

  15. Dynamical investigation of modulated Kepler RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Plachy, E.; Benkő, J. M.; Kolláth, Z.; Szabó, R.; Molnár, L.

    2015-09-01

    We performed a non-linear dynamical analysis on the Blazhko modulation for the first time. Our results suggest that the detection of chaotic nature behind the phenomenon is limited by the instrumental effects and the data processing problems of the Kepler pipeline concerning high-amplitude variable stars.

  16. LYRA Mid-Term Periodicities

    NASA Astrophysics Data System (ADS)

    Wauters, L.; Dominique, M.; Dammasch, I. E.

    2016-08-01

    The spectra of the PROBA2/LYRA data, similarly to every other solar time series, show predominant periodicities that can be of solar or instrumental origin. In this article, we compare the main periodicities characterizing the LYRA spectrum to those found in the sunspot number, in the 10.7 cm flux, in an X-ray flare index, and in the sunspot area evolution. We focused on the 2010 to 2014 time range, for which the LYRA data are available, although we also briefly address the evolution of the main periodicities in the longer range. The mid-term periodicities at {˜} 28, {˜} 44, {˜} 54, {˜} 59, {˜} 100, {˜} 110, and {˜} 150 days appear as highly significant in several analyzed datasets. The consistency of distinct periodicities between datasets provides characteristics for the global Sun. This consistency also strengthens the reliability of LYRA data.

  17. From Algol to Beta Lyrae

    NASA Astrophysics Data System (ADS)

    Plavec, M. J.

    Recognizing that the structure and evolutionary status of Beta Lyrae are much more complicated than for Algol, some of the problems of revealing its structure are discussed. The best model available at present considers Beta Lyrae as an Algol-type semi-detached system in a phase of fairly rapid mass transfer, i.e., younger than typical Algols. It is concluded that Beta Lyrae is not so special as it appears; some characteristics that are so puzzling in Beta Lyrae already appear in such classical Algols as U Cephei and RW Tauri. The mass-accreting components in these systems are surrounded by a hot, turbulent layer which probably expands and which is the seat of emission lines of fairly high ionization discovered in the far ultraviolet. In Beta Lyrae and the so-called W Serpenis stars, the circumstellar hot turbulent shell is much more extensive and probably also denser - a kind of 'superchromosphere'. In Beta Lyrae, a thick disk probably completely surrounds and hides the accreting star proper.

  18. Pseudosymmetric features of non-centrosymmetric AB type crystals

    NASA Astrophysics Data System (ADS)

    Gazhulina, A. P.; Marychev, M. O.

    2016-07-01

    This work is supplement to our previous investigation (Gazhulina and Marychev, 2015) [1]. We have considered pseudosymmetric features with respect to the operation of inversion (pseudoinversion) for 340 non-centrosymmetric AB type crystals. Analysis of the features of particular structure types allowed us to determine the positions of pseudoinversion centers, subdivide them into separate types, and classify the entire set of crystals studied with respect to the types of pseudoinversion centers and peculiarities of the behavior of the degree of pseudoinversion depending on the ratio of atomic numbers of A and B components. For each group of crystals, average values and lower boundaries of the maximum pseudoinversion are determined and distribution with respect to the degree of pseudoinversion is constructed.

  19. RR photons

    NASA Astrophysics Data System (ADS)

    Cámara, Pablo G.; Ibáñez, Luis E.; Marchesano, Fernando

    2011-09-01

    Type II string compactifications to 4d generically contain massless Ramond-Ramond U(1) gauge symmetries. However there is no massless matter charged under these U(1)'s, which makes a priori difficult to measure any physical consequences of their existence. There is however a window of opportunity if these RR U(1)'s mix with the hypercharge U(1) Y (hence with the photon). In this paper we study in detail different avenues by which U(1) RR bosons may mix with D-brane U(1)'s. We concentrate on Type IIA orientifolds and their M-theory lift, and provide geometric criteria for the existence of such mixing, which may occur either via standard kinetic mixing or via the mass terms induced by Stückelberg couplings. The latter case is particularly interesting, and appears whenever D-branes wrap torsional p-cycles in the compactification manifold. We also show that in the presence of torsional cycles discrete gauge symmetries and Aharanov-Bohm strings and particles appear in the 4d effective action, and that type IIA Stückelberg couplings can be understood in terms of torsional (co)homology in M-theory. We provide examples of Type IIA Calabi-Yau orientifolds in which the required torsional cycles exist and kinetic mixing induced by mass mixing is present. We discuss some phenomenological consequences of our findings. In particular, we find that mass mixing may induce corrections relevant for hypercharge gauge coupling unification in F-theory SU(5) GUT's.

  20. PULSATION PERIOD VARIATIONS IN THE RRc LYRAE STAR KIC 5520878

    SciTech Connect

    Hippke, Michael; Learned, John G.; Zee, A.; Edmondson, William H.; Lindner, John F.; Kia, Behnam; Ditto, William L.; Stevens, Ian R. E-mail: jgl@phys.hawaii.edu E-mail: w.h.edmondson@bham.ac.uk E-mail: wditto@hawaii.edu E-mail: irs@star.sr.bham.ac.uk

    2015-01-01

    Learned et al. proposed that a sufficiently advanced extra-terrestrial civilization may tickle Cepheid and RR Lyrae variable stars with a neutrino beam at the right time, thus causing them to trigger early and jogging the otherwise very regular phase of their expansion and contraction. This would turn these stars into beacons to transmit information throughout the galaxy and beyond. The idea is to search for signs of phase modulation (in the regime of short pulse duration) and patterns, which could be indicative of intentional, omnidirectional signaling. We have performed such a search among variable stars using photometric data from the Kepler space telescope. In the RRc Lyrae star KIC 5520878, we have found two such regimes of long and short pulse durations. The sequence of period lengths, expressed as time series data, is strongly autocorrelated, with correlation coefficients of prime numbers being significantly higher (p = 99.8%). Our analysis of this candidate star shows that the prime number oddity originates from two simultaneous pulsation periods and is likely of natural origin. Simple physical models elucidate the frequency content and asymmetries of the KIC 5520878 light curve. Despite this SETI null result, we encourage testing of other archival and future time-series photometry for signs of modulated stars. This can be done as a by-product to the standard analysis, and can even be partly automated.

  1. Pulsation Period Variations in the RRc Lyrae Star KIC 5520878

    NASA Astrophysics Data System (ADS)

    Hippke, Michael; Learned, John G.; Zee, A.; Edmondson, William H.; Lindner, John F.; Kia, Behnam; Ditto, William L.; Stevens, Ian R.

    2015-01-01

    Learned et al. proposed that a sufficiently advanced extra-terrestrial civilization may tickle Cepheid and RR Lyrae variable stars with a neutrino beam at the right time, thus causing them to trigger early and jogging the otherwise very regular phase of their expansion and contraction. This would turn these stars into beacons to transmit information throughout the galaxy and beyond. The idea is to search for signs of phase modulation (in the regime of short pulse duration) and patterns, which could be indicative of intentional, omnidirectional signaling. We have performed such a search among variable stars using photometric data from the Kepler space telescope. In the RRc Lyrae star KIC 5520878, we have found two such regimes of long and short pulse durations. The sequence of period lengths, expressed as time series data, is strongly autocorrelated, with correlation coefficients of prime numbers being significantly higher (p = 99.8%). Our analysis of this candidate star shows that the prime number oddity originates from two simultaneous pulsation periods and is likely of natural origin. Simple physical models elucidate the frequency content and asymmetries of the KIC 5520878 light curve. Despite this SETI null result, we encourage testing of other archival and future time-series photometry for signs of modulated stars. This can be done as a by-product to the standard analysis, and can even be partly automated.

  2. Multi-Filter Photometric Analysis of Three β Lyrae-type Eclipsing Binary Stars

    NASA Astrophysics Data System (ADS)

    Gardner, T.; Hahs, G.; Gokhale, V.

    2015-12-01

    We present light curve analysis of three variable stars, ASAS J105855+1722.2, NSVS 5066754, and NSVS 9091101. These objects are selected from a list of β- Lyrae candidates published by Hoffman et al. (2008). Light curves are generated using data collected at the the 31-inch NURO telescope at the Lowell Observatory in Flagstaff, Arizona in three filters: Bessell B, V, and R. Additional observations were made using the 14-inch Meade telescope at the Truman State Observatory in Kirksville, Missouri using Baader R, G, and B filters. In this paper, we present the light curves for these three objects and generate a truncated eight-term Fourier fit to these light curves. We use the Fourier coefficients from this fit to confirm ASAS J105855+1722.2 and NSVS 5066754 as β Lyrae type systems, and NSVS 9091101 to possibly be a RR Lyrae-type system. We measure the O'Connell effect observed in two of these systems (ASAS J105855+1722.2 and NSVS 5066754), and quantify this effect by calculating the "Light Curve Asymmetry" (LCA) and the "O'Connell Effect Ratio" (OER).

  3. Classification of octet AB-type binary compounds using dynamical charges: A materials informatics perspective

    PubMed Central

    Pilania, G.; Gubernatis, J. E.; Lookman, T.

    2015-01-01

    The role of dynamical (or Born effective) charges in classification of octet AB-type binary compounds between four-fold (zincblende/wurtzite crystal structures) and six-fold (rocksalt crystal structure) coordinated systems is discussed. We show that the difference in the dynamical charges of the fourfold and sixfold coordinated structures, in combination with Harrison’s polarity, serves as an excellent feature to classify the coordination of 82 sp–bonded binary octet compounds. We use a support vector machine classifier to estimate the average classification accuracy and the associated variance in our model where a decision boundary is learned in a supervised manner. Finally, we compare the out-of-sample classification accuracy achieved by our feature pair with those reported previously. PMID:26631979

  4. Classification of octet AB-type binary compounds using dynamical charges: A materials informatics perspective

    DOE PAGES

    Pilania, G.; Gubernatis, J. E.; Lookman, T.

    2015-12-03

    The role of dynamical (or Born effective) charges in classification of octet AB-type binary compounds between four-fold (zincblende/wurtzite crystal structures) and six-fold (rocksalt crystal structure) coordinated systems is discussed. We show that the difference in the dynamical charges of the fourfold and sixfold coordinated structures, in combination with Harrison’s polarity, serves as an excellent feature to classify the coordination of 82 sp–bonded binary octet compounds. We use a support vector machine classifier to estimate the average classification accuracy and the associated variance in our model where a decision boundary is learned in a supervised manner. Lastly, we compare the out-of-samplemore » classification accuracy achieved by our feature pair with those reported previously.« less

  5. Classification of octet AB-type binary compounds using dynamical charges: A materials informatics perspective

    SciTech Connect

    Pilania, G.; Gubernatis, J. E.; Lookman, T.

    2015-12-03

    The role of dynamical (or Born effective) charges in classification of octet AB-type binary compounds between four-fold (zincblende/wurtzite crystal structures) and six-fold (rocksalt crystal structure) coordinated systems is discussed. We show that the difference in the dynamical charges of the fourfold and sixfold coordinated structures, in combination with Harrison’s polarity, serves as an excellent feature to classify the coordination of 82 sp–bonded binary octet compounds. We use a support vector machine classifier to estimate the average classification accuracy and the associated variance in our model where a decision boundary is learned in a supervised manner. Lastly, we compare the out-of-sample classification accuracy achieved by our feature pair with those reported previously.

  6. Classification of octet AB-type binary compounds using dynamical charges: A materials informatics perspective

    NASA Astrophysics Data System (ADS)

    Pilania, G.; Gubernatis, J. E.; Lookman, T.

    2015-12-01

    The role of dynamical (or Born effective) charges in classification of octet AB-type binary compounds between four-fold (zincblende/wurtzite crystal structures) and six-fold (rocksalt crystal structure) coordinated systems is discussed. We show that the difference in the dynamical charges of the fourfold and sixfold coordinated structures, in combination with Harrison’s polarity, serves as an excellent feature to classify the coordination of 82 sp-bonded binary octet compounds. We use a support vector machine classifier to estimate the average classification accuracy and the associated variance in our model where a decision boundary is learned in a supervised manner. Finally, we compare the out-of-sample classification accuracy achieved by our feature pair with those reported previously.

  7. Verbesserte Elemente der RR-Lyrae-Sterne SX Trianguli und WW Bootis

    NASA Astrophysics Data System (ADS)

    Maintz, Gisela

    2016-03-01

    CCD observations of SX Tri and WW Boo, variable stars of type RRab, were taken at my private observatory over several years. Because of this long time span a revision of their elements was placed here. I derived the new elements of these stars as: Star Max period +- JD [d] [d] SX Tri 2457296.4745 0.7429652 0.0000003 WW Boo 2453897.4157 0.479263 0.000001

  8. RR Lyrae stars and the horizontal branch of NGC 5904 (M5)

    NASA Astrophysics Data System (ADS)

    Arellano Ferro, A.; Luna, A.; Bramich, D. M.; Giridhar, Sunetra; Ahumada, J. A.; Muneer, S.

    2016-05-01

    We report the distance and [Fe/H] value for the globular cluster NGC 5904 (M5) derived from the Fourier decomposition of the light curves of selected RRab and RRc stars. The aim in doing this was to bring these parameters into the homogeneous scales established by our previous work on numerous other globular clusters, allowing a direct comparison of the horizontal branch luminosity in clusters with a wide range of metallicities. Our CCD photometry of the large variable star population of this cluster is used to discuss light curve peculiarities, like Blazhko modulations, on an individual basis. New Blazhko variables are reported.

  9. The ultraviolet spectrum of Beta Lyrae

    NASA Technical Reports Server (NTRS)

    Mazzali, Paolo A.

    1987-01-01

    The high-resolution UV spectrum of Beta Lyrae observed with the IUE satellite between 1980 and 1986 is analyzed. A complete list of line identifications for the entire spectral range of the IUE (1225-3125 A) is presented. The main spectral features are P Cygni profiles of resonance lines of high ionization states typical of stellar winds, some of which are combined with a broad emission feature due probably to an accretion disk; P Cygni profiles due to moderately ionized atoms in the iron group (mostly Fe III and Ni III); and absorption lines of elements in lower ionization stages, such as S II, Si II (higher multiplets), Ni II, and a large number of Fe II lines.

  10. LYRA, a webserver for lymphocyte receptor structural modeling.

    PubMed

    Klausen, Michael Schantz; Anderson, Mads Valdemar; Jespersen, Martin Closter; Nielsen, Morten; Marcatili, Paolo

    2015-07-01

    The accurate structural modeling of B- and T-cell receptors is fundamental to gain a detailed insight in the mechanisms underlying immunity and in developing new drugs and therapies. The LYRA (LYmphocyte Receptor Automated modeling) web server (http://www.cbs.dtu.dk/services/LYRA/) implements a complete and automated method for building of B- and T-cell receptor structural models starting from their amino acid sequence alone. The webserver is freely available and easy to use for non-specialists. Upon submission, LYRA automatically generates alignments using ad hoc profiles, predicts the structural class of each hypervariable loop, selects the best templates in an automatic fashion, and provides within minutes a complete 3D model that can be downloaded or inspected online. Experienced users can manually select or exclude template structures according to case specific information. LYRA is based on the canonical structure method, that in the last 30 years has been successfully used to generate antibody models of high accuracy, and in our benchmarks this approach proves to achieve similarly good results on TCR modeling, with a benchmarked average RMSD accuracy of 1.29 and 1.48 Å for B- and T-cell receptors, respectively. To the best of our knowledge, LYRA is the first automated server for the prediction of TCR structure.

  11. LYRA, a webserver for lymphocyte receptor structural modeling

    PubMed Central

    Klausen, Michael Schantz; Anderson, Mads Valdemar; Jespersen, Martin Closter; Nielsen, Morten; Marcatili, Paolo

    2015-01-01

    The accurate structural modeling of B- and T-cell receptors is fundamental to gain a detailed insight in the mechanisms underlying immunity and in developing new drugs and therapies. The LYRA (LYmphocyte Receptor Automated modeling) web server (http://www.cbs.dtu.dk/services/LYRA/) implements a complete and automated method for building of B- and T-cell receptor structural models starting from their amino acid sequence alone. The webserver is freely available and easy to use for non-specialists. Upon submission, LYRA automatically generates alignments using ad hoc profiles, predicts the structural class of each hypervariable loop, selects the best templates in an automatic fashion, and provides within minutes a complete 3D model that can be downloaded or inspected online. Experienced users can manually select or exclude template structures according to case specific information. LYRA is based on the canonical structure method, that in the last 30 years has been successfully used to generate antibody models of high accuracy, and in our benchmarks this approach proves to achieve similarly good results on TCR modeling, with a benchmarked average RMSD accuracy of 1.29 and 1.48 Å for B- and T-cell receptors, respectively. To the best of our knowledge, LYRA is the first automated server for the prediction of TCR structure. PMID:26007650

  12. Complex infrared emission features in the spectrum of beta Lyrae

    NASA Technical Reports Server (NTRS)

    Morgan, T. H.; Potter, A. E.; Kondo, Y.

    1974-01-01

    Spectra of beta Lyrae over the spectral region from 5800 to 11,000 per cm (1.76 to 0.9 micron) at two different phases have been obtained. They show a remarkable emission-absorption complex at 9231 per cm, a highly structured emission at P beta, and several additional broad weak emissions.

  13. The hot white dwarf in the cataclysmic variable MV Lyrae

    NASA Technical Reports Server (NTRS)

    Hoard, D. W.; Linnell, A. P.; Szkody, Paula; Fried, Robert E.; Sion, Edward M.; Hubeny, Ivan; Wolfe, M. A.

    2003-01-01

    We have obtained the first far-ultraviolet spectrum of the novalike cataclysmic variable MV Lyrae using the Far Ultraviolet Spectroscopic Explorer. We also obtained contemporaneous optical light curves and spectra. All data are from a deep faint accretion state of MV Lyr.

  14. Temporal integration in the echolocating bat, Megaderma lyra.

    PubMed

    Wiegrebe, L; Schmidt, S

    1996-12-01

    Temporal integration is a crucial feature of auditory temporal processing. We measured the psychophysical temporal integration of acoustic intensity in the echolocating bat Megaderma lyra using a two-alternative forced-choice procedure. A measuring paradigm was chosen in which the absolute threshold for pairs of short tone pips was determined as a function of the temporal separation between the pips. The time constants determined with this paradigm are a crucial characteristic of the sonar system of M. lyra, a species orientating in its environment by very short broadband sonar calls emitted at high rates. Two different carrier frequencies for the tone pips were used to obtain data from the lower and the higher half of the hearing area of M. lyra. Both in the lower and in the higher frequency range, M. lyra showed very short time constants of about 220 microseconds. Our results are comparable to data from the echolocating dolphin, Tursiops truncatus, showing click integration times of about 260 microseconds and to estimates of auditory temporal integration in the context of echo clutter interference in the big brown bat.

  15. Drosophila Lyra mutations are gain-of-function mutations of senseless

    NASA Technical Reports Server (NTRS)

    Nolo, R.; Abbott, L. A.; Bellen, H. J.

    2001-01-01

    The Lyra mutation was first described by Jerry Coyne in 1935. Lyra causes recessive pupal lethality and adult heterozygous Lyra mutants exhibit a dominant loss of the anterior and posterior wing margins. Unlike many mutations that cause loss of wing tissue (e.g., scalloped, Beadex, cut, and apterous-Xasta), Lyra wing discs do not exhibit increased necrotic or apoptotic cell death, nor do they show altered BrdU incorporation. However, during wing disc eversion, loss of the anterior and posterior wing margins is apparent. We have previously shown that senseless, a gene that is necessary and sufficient for peripheral nervous system (PNS) development, is allelic to Lyra. Here we show by several genetic criteria that Lyra alleles are neomorphic alleles of senseless that cause ectopic expression of SENSELESS in the wing pouch. Similarly, overexpression of SENSELESS in the wing disc causes loss of wing margin tissue, thereby mimicking the Lyra phenotype. Lyra mutants display aberrant expression of DELTA, VESTIGIAL, WINGLESS, and CUT. As in Lyra mutants, overexpression of SENSELESS in some areas of the wing pouch also leads to loss of WINGLESS and CUT. In summary, our data indicate that overexpression of SENSELESS causes a severe reduction in NOTCH signaling that in turn may lead to decreased transcription of several key genes required for wing development, leading to a failure in cell proliferation and loss of wing margin tissue.

  16. OAO-2 observations of beta Lyrae and a provisional interpretation

    NASA Technical Reports Server (NTRS)

    Kondo, Y.; Mccluskey, G. E., Jr.; Houck, T. E.

    1972-01-01

    Six-color ultraviolet photoelectric observations of beta Lyrae obtained with OAO-2 are presented. These observations, made at 1380, 1500, 1920, 2460, 2980 and 3330 A, represent the first truly continual coverage of the light changes of beta Lyrae during one orbital revolution and were obtained in November 1970. The photometric data are supplemented by spectral scans in the wavelength intervals 3800-1800 A and 2000-1050 A; the latter interval was scanned at 10 A resolution once during every OAO-2 orbit, i.e., about 100 minutes. Anomalous features, such as asymmetries and short and long term variations, are present in the light curves. A tentative discussion of solutions of the light curves is given.

  17. Copernicus spectra of beta Lyrae. [in far UV

    NASA Technical Reports Server (NTRS)

    Hack, M.; Hutchings, J. B.; Kondo, Y.; Mccluskey, G. E.; Plavec, M.; Polidan, R. S.

    1974-01-01

    The observations reported were made in August and September 1973. The principal data were scans in the low resolution mode at phases nearly coincident with the two light minima. Shorter scans were obtained at the two quadrature phases. The data show that the secondary component of beta Lyrae is a hotter object than the visible B8 star. The velocity amplitude of the lines suggests that the secondary is the more massive object, by a factor of several times.

  18. First detection of multi-shocks in RR Lyrae stars from Antarctica : A possible explanation of the Blazhko effect

    SciTech Connect

    Chadid, M.; Vernin, J.; Zalian, C.; Pouzenc, C.; Abe, L.; Agabi, A.; Aristidi, E.; Mékarnia, D.; Preston, G.; Liu, L.Y.; Trinquet, H.

    2014-11-01

    We present the first detection of multi-shocks propagating through the atmosphere of the Blazhko star S Arae using uninterrupted, accurate optical photometric data collected during one polar night, 150 days from Antarctica at Dome C, with the Photometer AntarctIca eXtinction (PAIX). We acquired 89,736 CCD frames during 323 pulsation cycles and 3 Blazhko cycles. We detected two new light curve properties in the PAIX light curve, jump and rump, which we associated with two new post-maximum shock waves Sh{sub PM1} and Sh{sub PM2}. jump, lump, rump, bump, and hump are induced by five shock waves, with different amplitudes and origins, Sh{sub PM1}, Sh{sub PM}, Sh{sub PM2}, Sh{sub PM3}, and the main shock Sh{sub H+He}. Correlations between the length of rise time and light amplitude and Sh{sub PM3} are monotonous during three Blazhko cycles, but the pulsation curve is double peaked. We discuss the physical mechanisms driving the modulation of these quantities. Finally, we hypothesize that the origin of the Blazhko effect is a dynamical interaction between a multi-shock structure and an outflowing wind in a coronal structure.

  19. VizieR Online Data Catalog: QSOs and RR Lyrae in Pan-STARRS1 3π Data (Hernitschek+ 2016)

    NASA Astrophysics Data System (ADS)

    Hernitschek, N.; Schlafly, E. F.; Sesar, B.; Rix, H.-W.; Hogg, D. W.; Ivezic, Z.; Grebel, E. K.; Bell, E. F.; Martin, N. F.; Burgett, W. S.; Flewelling, H.; Hodapp, K. W.; Kaiser, N.; Magnier, E. A.; Metcalfe, N.; Wainscoat, R. J.; Waters, C.

    2016-04-01

    In area and depth, the Pan-STARRS1 (PS1) 3π survey is unique among many-epoch, multi-band surveys and has enormous potential for the all-sky identification of variable sources. PS1 has observed the sky typically seven times in each of its five bands (grizy) over 3.5 years, but unlike SDSS, not simultaneously across the bands. We developed a new approach for quantifying statistical properties of non-simultaneous, sparse, multi-color light curves through light curve structure functions, effectively turning PS1 into a {sim}35-epoch survey. We use this approach to estimate variability amplitudes and timescales for point sources brighter than rP1=21.5 mag in the survey. On this basis we provide a catalog of all likely variable point sources and likely QSOs in PS1. (2 data files).

  20. Synthesis of biobased polyurethane from oleic and ricinoleic acids as the renewable resources via the AB-type self-condensation approach.

    PubMed

    Palaskar, Dnyaneshwar V; Boyer, Aurélie; Cloutet, Eric; Alfos, Carine; Cramail, Henri

    2010-05-10

    Polyurethane (PU) from methyl oleate (derived from sunflower oil) and ricinoleic acid (derived from castor oil) was synthesized using the AB-type self-polycondensation approach for the first time. In the present work, three novel AB-type monomers, namely, a mixture of 10-hydroxy-9-methoxyoctadecanoyl azide/9-hydroxy-10-methoxyoctadecanoyl azide (HMODAz), 12-hydroxy-9-cis-octadecenoyl azide (HODEAz) and methyl-N-11-hydroxy-9-cis-heptadecen carbamate (MHHDC) were synthesized from methyl oleate and ricinoleic acid using simple reaction steps. Out of these, HMODAz and HODEAz monomers were polymerized by the acyl-azido and hydroxyl AB-type self-condensation approach, while MHHDC monomer was polymerized through AB-type self-condensation via transurethane reaction. The acyl-azido and hydroxyl self-condensations were carried out at various temperatures (50, 60, 80. and 110 degrees C) in bulk with and without catalyst. A FTIR study of the polymerization, using HMODAz at 80 degrees C without catalyst, indicates in situ formation of an intermediate isocyanate group in the first 15-30 min, and further onward, the molar mass increases as observed by SEC analysis. In the case of the MHHDC monomer, a transurethane reaction was used to obtain a similar PU (which was obtained by AB-type acyl-azido and hydroxyl self-condensation of HODEAz) in the presence of titanium tetrabutoxide as a catalyst at 130 degrees C. HMODAz, HODEAz, MHHDC, and corresponding polyurethanes were characterized by FTIR, (1)H NMR, (13)C NMR, and MALDI-TOF mass spectroscopy. Differential scanning calorimetric analysis of polyurethanes derived from HMODAz, HODEAz, and MHHDC showed two different glass transition temperatures for soft segments (at lower temperature) and hard segments (at higher temperature), indicating phase-separated morphology. PMID:20402498

  1. GEOMETRICAL CONSTRAINTS ON THE HOT SPOT IN BETA LYRAE

    SciTech Connect

    Lomax, Jamie R.; Hoffman, Jennifer L.; Elias II, Nicholas M.; Bastien, Fabienne A.; Holenstein, Bruce D. E-mail: Jennifer.Hoffman@du.edu E-mail: fabienne.a.bastien@vanderbilt.edu

    2012-05-01

    We present results from six years of recalibrated and new spectropolarimetric data taken with the University of Wisconsin's Half-Wave Spectropolarimeter and six years of new data taken with the photoelastic modulating polarimeter at the Flower and Cook Observatory of beta Lyrae. Combining these data with polarimetric data from the literature allows us to characterize the intrinsic BVRI polarized light curves. A repeatable discrepancy of 0.245 days (approximately 6 hr) between the secondary minima in the total light curve and the polarization curve in the V band, with similar behavior in the other bands, may represent the first direct evidence for an accretion hot spot on the disk edge.

  2. A search for Lyman-alpha emission in beta Lyrae from Copernicus

    NASA Technical Reports Server (NTRS)

    Kondo, Y.; Mccluskey, G. E., Jr.

    1974-01-01

    High-resolution (0.2 A) spectrophotometric observations of the complex eclipsing binary beta Lyrae were obtained with the Princeton Telescope Spectrometer on the Copernicus satellite. We discuss the search for L-alpha emission in beta Lyrae and compare the Copernicus results with the OAO-2 observations of the same binary system. The possible L-alpha emission features observed from OAO-2 are identified as blends of the emission lines of other elements in the vicinity of L-alpha.

  3. High temperature plasma in beta Lyrae, observed from Copernicus

    NASA Technical Reports Server (NTRS)

    Kondo, Y.; Hack, M.; Hutchings, J. B.; Mccluskey, G. E., Jr.; Plavec, M.; Polidan, R. S.

    1975-01-01

    High-resolution UV spectrophotometry of the complex close binary system beta Lyrae was performed with a telescope spectrometer on board Copernicus. Observations were made at phases 0.0, 0.25, 0.5, and 0.75 with resolutions of 0.2 A (far-UV) and 0.4 A (mid-UV). The far-UV spectrum is completely dominated by emission lines indicating the existence of a high-temperature plasma in this binary. The spectrum of this object is unlike that of any other object observed from Copernicus. It is believed that this high-temperature plasma results from dynamic mass transfer taking place in the binary. The current results are compared with OAO-2 observations and other observational results. The possibility that the secondary component is a collapsed object is also discussed; the Copernicus observations are consistent with the hypothesis that the spectroscopically invisible secondary component is a black hole.

  4. Implications of the β Lyrae accretion disk rim Teff

    NASA Astrophysics Data System (ADS)

    Linnell, A. P.

    2000-12-01

    Photometric evidence indicates that the massive gainer in the β Lyrae system is hidden from the observer by a thick accretion disk (Linnell, Hubeny, & Harmanec, 1998, ApJ, 509, 379). It is believed that the gainer approximates a main sequence star of Teff= 30000K. Spectroscopic analysis by Balachrandan et al. (1986, MNRAS, 219, 479) establishes a Teff of 13,300K for the donor. System synthetic spectra, fitted via the BINSYN suite to spectrophotometric scan data and IUE spectra, establish a mean rim Teff of 9000K. Assuming conservative mass transfer, Harmanec & Scholz (1993, A&A, 279, 131) use the rate of period change to derive a mass transfer rate of 20x10-6M⊙ yr-1. Connecting the rim Teff to the accretion disk face Teff with the Hubeny theory (Hubeny & Plavec 1991, AJ, 102, 1156) and using the standard accretion disk relations (Frank, King & Raine), the adopted mass transfer rate predicts a rim Teff of 4500K. The BINSYN-derived 9000K rim Teff would require a mass transfer rate 30 times larger than the adopted value. The observed rate of period change excludes such a large mass transfer rate. The bolometric luminosity of the rim, from the BINSYN model, is 5.6x1036erg sec-1. The bolometric luminosity of the gainer, on the adopted model, is 9.8x1037erg sec-1. Thus, the luminosity of the rim is 6% of the luminosity of the gainer. On the BINSYN model, the accretion disk covers 26% of the sky, as seen by the gainer. Absorption of radiation from the gainer, and its reradiation by the accretion disk, could explain the derived Teff of the rim. The conclusion is that the β Lyrae accretion disk structure must be strongly affected by radiation from the hot gainer (unseen by the observer) at the center of the accretion disk.

  5. Variable Stars in the Unusual, Metal-Rich Globular Cluster NGC-6441

    NASA Technical Reports Server (NTRS)

    Pritzl, Barton J.; Smith, Horace A.; Catelan, Marcio; Sweigart, Allen V.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We have undertaken a search for variable stars in the metal-rich globular cluster NGC 6441 using time-series BV photometry. The total number of variables found near NGC 6441 has been increased to approx. 104, with 48 new variables being found in this survey. A significant number of the variables are RR Lyrae stars (approx. 46), most of which are probable cluster members. As was noted by Layden et al. (1999), the periods of the fundamental mode RR Lyrae are unusually long compared to field stars of similar metallicity. The existence of these long period RRab stars is consistent with Sweigart & Catelan's (1998) prediction that the horizontal branch of NGC 6441 is unusually bright. This result implies that the metallicity-luminosity relationship for RR Lyrae stars is not universal. We discuss the difficulty in determining the Oosterhoff classification of NGC 6441 due to the unusual nature of its RR Lyrae. A number of ab-type RR Lyrae are found to be both brighter and redder than the other probable RRab found along the horizontal branch, which may be a result of blending with stars of redder color. A smaller than usual gap is found between the shortest period fundamental mode and the longest period first-overtone mode RR Lyrae. We determine the reddening of the cluster to be E(B - V) = 0.51 +/- 0.02 mag, with substantial differential reddening across the face of the cluster. The mean V magnitude of the RR Lyrae is found to be 17.51 +/- 0.02 resulting in a distance of 10.4 to 11.9 kpc, for a range of assumed values of < M(sub V)> for RR Lyrae stars. The possibility that stars in NGC 6441 may span a range in [Fe/H] is also discussed.

  6. Perception of complex tones and its analogy to echo spectral analysis in the bat, Megaderma lyra.

    PubMed

    Krumbholz, K; Schmidt, S

    1999-02-01

    The gleaning bat Megaderma lyra emits broadband echolocation sounds consisting of multiple frequency components. The present study investigates into which perceptual qualities the spectral characteristics of echoes may be translated in the auditory system of M. lyra. Three bats were trained in a 2-AFC behavioral experiment to classify nine complex tones, which spectrally resembled M. lyra's sonar calls, into two perceptual categories. Then the bats' spontaneous responses to unknown complex tones were recorded. The results show that the animals based their classifications of the complex tones on a sound quality which was mediated by their broadband frequency spectra. The bats used the training stimuli as spectral templates and classified the test stimuli according to their broadband spectral similarity with the learned patterns. Assuming that passive hearing and echo processing are governed by similar perceptual qualities and subject to similar limitations, the perceptual mode which was used by the bats to compare the multicomponent spectral patterns in the reported experiments could serve as a powerful tool for the spectral analysis of M. lyra's multicomponent echoes. The analogy between the perception of complex tones and echo spectral analysis in M. lyra is theoretically elaborated in the "formant-mode" model.

  7. Random variations in the ultraviolet spectrum of Beta Lyrae

    NASA Technical Reports Server (NTRS)

    Bless, R. C.; Eaton, J. A.; Meade, M. R.

    1977-01-01

    Spectrophotometric scans of Beta Lyrae over the wavelength range from 1100 to 3700 A are analyzed which were obtained at different times with different resolutions by the OAO 2 satellite and from the ground. A model atmosphere with normal H and He abundances, an electron temperature of 11,000 K, and log g of 3.0 is found to fit the visual region of the spectrum well but to be a poor representation in the Balmer continuum. It is shown that a large complex emission feature dominates the spectrum from about 1700 to 2200 A, that there is a very pronounced strengthening of the spectrum just shortward of the 1550-A C IV feature at phase 0.69, and that the overall level of the spectrum shortward of 1400 A is quite high in comparison with the broad emission feature. A model is discussed in which the light from a disk-shaped secondary is highly concentrated toward the polar regions.

  8. Multicenter evaluation of the Quidel Lyra Direct C. difficile nucleic acid amplification assay.

    PubMed

    Beck, Eric T; Buchan, Blake W; Riebe, Katherine M; Alkins, Brenda R; Pancholi, Preeti; Granato, Paul A; Ledeboer, Nathan A

    2014-06-01

    Clostridium difficile is a Gram-positive bacterium commonly found in health care and long-term-care facilities and is the most common cause of antibiotic-associated diarrhea. Rapid detection of this bacterium can assist physicians in implementing contact precautions and appropriate antibiotic therapy in a timely manner. The purpose of this study was to compare the clinical performance of the Quidel Lyra Direct C. difficile assay (Lyra assay) (Quidel, San Diego, CA) to that of a direct cell culture cytotoxicity neutralization assay (CCNA) and enhanced toxigenic culture. This study was performed at three geographically diverse laboratories within the United States using residual stool specimens submitted for routine C. difficile testing. Residual samples were tested using the Lyra assay on three real-time PCR platforms, and results were compared to those for direct CCNA and enhanced toxigenic culture. The test results for all platforms were consistent across all three test sites. The sensitivity and specificity of the Lyra assay on the SmartCycler II, ABI 7500 Fast DX, and ABI QuantStudio DX instruments compared to CCNA were 90.0% and 93.3%, 95.0% and 94.2%, and 93.8% and 95.0%, respectively. Compared to enhanced toxigenic culture, the sensitivity and specificity of the Lyra assay on the SmartCycler II, ABI 7500, and QuantStudio instruments were 82.1% and 96.9%, 89.3% and 98.8%, and 85.7% and 99.0%, respectively. Overall, the Lyra assay is easy to use and versatile and compares well to C. difficile culture methods.

  9. Five dimensional cosmological models in Lyra geometry with time dependent displacement field

    NASA Astrophysics Data System (ADS)

    Mohanty, G.; Mahanta, K. L.; Bishi, B. K.

    2007-08-01

    In this paper exact solutions of the five-dimensional vacuum cosmological field equations based on Lyra geometry are obtained. Further it is shown that neither dust distribution nor perfect fluid distributions survive for the model. Some properties of the vacuum model are also discussed.

  10. A redetermination of the luminosity, distance, and reddening of Beta Lyrae

    NASA Astrophysics Data System (ADS)

    Dobias, J. J.; Plavec, M. J.

    1985-05-01

    The authors have redetermined the distance to β Lyrae and found that it probably lies between 345 and 400 pc, with the most likely value being 370 pc. With the corresponding true distance modulus of 7.8 mag, they find that the eclipsing system of β Lyrae has a maximum absolute visual magnitude of -4.7 mag. Using Wilson's model, the authors conclude that the average absolute visual magnitude of the primary component is -4.1 mag, so that the star is best classified as B8.5 or B9 II-Ib. The visual absolute magnitude of the secondary component is -3.3 mag. The color excess is small, E(B-V) = 0.04 mag. These data are based on optical and IUE scans of the brightest visual companion to β Lyrae, HD 174664, and on an analysis of the hydrogen line profiles in its spectrum. The authors find that the star is mildly evolved within the main-sequence band. Its effective temperature (14250K) and surface gravity (log g ≅ 4.0) correspond most closely to those of stars classified as B6 V. This conclusion creates a certain evolutionary dilemma, since the age of HD 174664 should not exceed 20 - 30 million years if the basic model of β Lyrae as an Algol-type binary is correct while the authors' result is 48×106yr.

  11. Automatic detection of atrial fibrillation using the coefficient of variation and density histograms of RR and deltaRR intervals.

    PubMed

    Tateno, K; Glass, L

    2001-11-01

    The paper describes a method for the automatic detection of atrial fibrillation, an abnormal heart rhythm, based on the sequence of intervals between heartbeats. The RR interval is the interbeat interval, and deltaRR is the difference between two successive RR intervals. Standard density histograms of the RR and deltaRR intervals were prepared as templates for atrial fibrillation detection. As the coefficients of variation of the RR and deltaRR intervals were approximately constant during atrial fibrillation, the coefficients of variation in the test data could be compared with the standard coefficients of variation (CV test). Further, the similarities between the density histograms of the test data and the standard density histograms were estimated using the Kolmogorov-Smirnov test. The CV test based on the RR intervals showed a sensitivity of 86.6% and a specificity of 84.3%. The CV test based on the deltaRR intervals showed that the sensitivity and the specificity are both approximately 84%. The Kolmogorov-Smirnov test based on the RR intervals did not improve on the result of the CV test. In contrast, the Kolmogorov-Smirnov test based on the ARR intervals showed a sensitivity of 94.4% and a specificity of 97.2%.

  12. 20. BLUEPRINT, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY L.% MI. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. BLUEPRINT, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY L.% MI. S of MS. 50 Proposed bridge, by Phoenis Bridge Co., Phoenixville, Pa. 218-foot turn span, with load bearing. 21 May 1914. Act. size: 16X35 in. Credit: Columbus and Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. Sept 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  13. 18. BLUEPRINT, RR BRIDGE Tombigbee R. MISSISSIPPI, CLAY CO., WAVERLY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. BLUEPRINT, RR BRIDGE Tombigbee R. MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS 50 Detail: 'Georgia Pacific Rwy. -- Tombigbee River Bridge Elevation' with river profile, May 16, 1888. Credit: Columbus and Greenville Rr, Columbus, Ms. DWG = S-3-342. Sarcone Photography, Columbus, Ms Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  14. 14. ALABAMA, SUMTER CO., EPES RAILROAD BRIDGE Southern RR at ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. ALABAMA, SUMTER CO., EPES RAILROAD BRIDGE Southern RR at Epes Alabama Great Southern RR bridge. View from S. Copy of photo taken in 1922 by Jack Donnell, Columbus, Ms. Sarcone Photography, Columbus, Ms., Sep 1978. - Bridges of the Upper Tombigbee River Valley, Cochrane, Pickens County, AL

  15. A redetermination of the luminosity, distance, and reddening of Beta Lyrae

    NASA Technical Reports Server (NTRS)

    Dobias, J. J.; Plavec, M. J.

    1985-01-01

    The most likely distance to the Beta Lyrae system is redetermined to lie at 370 pc, corresponding to a distance modulus of 7.8 mag, while the correct modulus value probably lies in the 7.7-8.0 mag range, corresponding to a distance range between 345 and 400 pc. On the basis of Wilson's (1974) model, the phase-averaged absolute visual magnitude of the primary component is -4.1 mag; this star is therefore a very luminous giant, classifiable as B8.5 or B9, with a luminosity class of II-Ib. The present data are based on optical and IUE scans of the brightest visual companion to Beta Lyrae, HD 174664, together with an analysis of the H line profiles in its spectrum.

  16. Light-induced COP9 signalosome expression in the Indian false vampire bat Megaderma lyra.

    PubMed

    Rajan, K Emmanuvel; Rajkumar, R; Liao, Chen-Chug; Ganesh, A; Marimuthu, G

    2010-01-01

    The COP9 signalosome (CSN) is a multi-subunit protein complex conserved in plants and animals. CSN subunits have been identified as light-mediated master regulators of eukaryotic circadian clocks from fungi to animals. The Indian false vampire bat Megaderma lyra is completely adapted to an anthropic biotope and behavioral studies have reported that M. lyra exhibits light-sampling behavior to assess environmental light. LC-MS-MS results for a 36 kDa protein were analyzed using the Sequest search engine, and COP9 signalosome subunit 5 (CSN5) was pinpointed as having the highest score with 6 matching peptides. To confirm the presence of CSN5, up-regulated cDNA was amplified, sequenced, and identified as CSN5. Furthermore, semi-quantitative RT-PCR analysis demonstrated that the level of induction of CSN5 was regulated by environmental light. We estimated the level of expression across a light-dark cycle and observed a higher level of expression at the end of the light phase. Similarly, when the animal was shifted from continuous dark to light, CSN5 expression was induced. Correspondingly, we detected the similar pattern of translated protein with JAB1 antibody. Knowledge about the circadian rhythm and its molecular mechanism in Chiroptera is very limited and this study suggests that CSN5 might be involved in the M. lyra light-signaling process.

  17. The absence of spatial echo suppression in the echolocating bats Megaderma lyra and Phyllostomus discolor.

    PubMed

    Schuchmann, Maike; Hübner, Matthias; Wiegrebe, Lutz

    2006-01-01

    Acoustic orientation most often takes place in echoic environments. The mammalian auditory system shows a variety of specializations to suppress misleading spatial information mediated by echoes. Psychophysically these specializations are summarized as the precedence effect. This study investigates how echolocating bats deal with multiple reflections of their sonar emissions from different spatial positions. In a two-alternative, forced choice paradigm, a study was made of the extent to which the echolocating bats Megaderma lyra and Phyllostomus discolor spontaneously suppress the spatial information of a second reflection of their sonar emission. The delay between the first and the second reflection ranged between 0 and 12.8 ms. In general, M. lyra (five individuals) and P. discolor (two individuals) did not suppress the spatial information of the second reflection of their sonar emission, whatever the delay. Only one M. lyra showed significant suppression for delays between 0.8 and 3.2 ms. However, this suppression could not be confirmed in an exact repetition of the experiment. The current data indicate that although bats may be able to suppress the spatial information of a second reflection, this is not their default mode of auditory processing. The reason for this exceptional absence of spatial echo suppression may lie in the shorter time constants of cochlear processing in the ultrasonic frequency range and the strong influence of cognitive components associated with the ;precedence effect'.

  18. VizieR Online Data Catalog: RR Lyrae variables in ESO294-G010 and ESO410-G005 (Yang+, 2014)

    NASA Astrophysics Data System (ADS)

    Yang, S.-C.; Wagner-Kaiser, R.; Sarajedini, A.; Kim, S. C.; Kyeong, J.

    2016-08-01

    The science images of ESO294-G010 and ESO410-G005 used in this study were taken with the Advanced Camera for Surveys Wide Field Channel (ACS/WFC) on board Hubble Space Telescope (HST) as a part of GO-10503 (PI: Da Costa). ESO294-G010 (R.A.=00:26:33.40 (J2000), Decl.=-41:51:19.0 (J2000)) was observed on the HJD (+2453000) range 859.27358-861.13659 with the F606W filter, and on the HJD (+2453000) range 859.40613-861.00342 with the F814W filter. ESO410-G005 (R.A.=00:15:31.40 (J2000), Decl.=-32:10:47.0 (J2000)) was observed on the HJD (+2453000) range 861.40425-863.21702 with the F606W filter, and on the HJD (+2453000) range 861.53711-866.08158 with the filter F814W. The central regions of each galaxy were placed on one of WFC chips so that the imaging covers almost the entire visual extent of the targets. ESO294-G010 was imaged 12 times in the F606W and 24 times in the F814W filter with an exposure time of 1160s during the observing baseline of ~1.86days. The same number of exposures were obtained for the observations of ESO410-G005 with an exposure time of 1120s over the observing baseline of 4.55days. The basic properties of each of these RRL candidates are summarized in Tables 2 and 3. We have also uncovered a significant number of Luminous Variable (LV) candidates in both transition-type dwarf galaxies (22 in ESO294-G010; 19 in ESO410-G005). Their photometric and pulsation properties are summarized in Table4. (4 data files).

  19. 2. Historic American Buildings Survey Southern Pacific RR Coll. About ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. Historic American Buildings Survey Southern Pacific RR Coll. About 1869 Oakland Point Pier - Used by First Central Pacific Train to Enter Oakland -- November 8, 1869 - Southern Pacific Mole & Pier, Seventh Street, Oakland, Alameda County, CA

  20. 2. August, 1972. GV SHOWING RR TUNNEL AND ALSO FLUE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. August, 1972. GV SHOWING RR TUNNEL AND ALSO FLUE FROM S. - International Smelting & Refining Company, Tooele Smelter, Reverberatory, Converter & Casting Building, State Route 178, Tooele, Tooele County, UT

  1. The Complex QT/RR Relationship in Mice

    PubMed Central

    Roussel, Julien; Champeroux, Pascal; Roy, Jérôme; Richard, Sylvain; Fauconnier, Jérémy; Le Guennec, Jean-Yves; Thireau, Jérôme

    2016-01-01

    The QT interval reflects the time between the depolarization of ventricles until their repolarization and is usually used as a predictive marker for the occurrence of arrhythmias. This parameter varies with the heart rate, expressed as the RR interval (time between two successive ventricular depolarizations). To calculate the QT independently of the RR, correction formulae are currently used. In mice, the QT-RR relationship as such has never been studied in conscious animals, and correction formulas are mainly empirical. In the present paper we studied how QT varies when the RR changes physiologically (comparison of nocturnal and diurnal periods) or after dosing mice with tachycardic agents (norepinephrine or nitroprusside). Our results show that there is significant variability of QT and RR in a given condition, resulting in the need to average at least 200 consecutive complexes to accurately compare the QT. Even following this method, no obvious shortening of the QT was observed with increased heart rate, regardless of whether or not this change occurs abruptly. In conclusion, the relationship between QT and RR in mice is weak, which renders the use of correction formulae inappropriate and misleading in this species. PMID:27138175

  2. The BUSS spectrum of Beta Lyrae. [Balloon-borne Ultraviolet Stellar Spectrograph

    NASA Technical Reports Server (NTRS)

    Hack, M.; Sahade, J.; De Jager, C.; Kondo, Y.

    1983-01-01

    The spectrum of Beta Lyrae from about 1975 to 3010 A taken with the Balloon-borne ultraviolet Stellar Spectrograph experiment in May 1976 at phase 0.61 P is analyzed. Results show the presence of N II semi-forbidden emission and provide evidence for about the same location, in the outer envelope of the system, of the layers responsible for the resonance Mg II doublet emissions and for the "narrow" H-alpha emission. In addition, three sets of absorption lines, P Cygni profiles of Fe III and broad Beals Type III emissions of Mg II, are found to be present.

  3. Proba2/Lyra: six years of EUV solar irradiance observation, from short to long timescales

    NASA Astrophysics Data System (ADS)

    Dominique, Marie; Dammasch, Ingolf; Wauters, Laurence; Katsiyannis, Athanassios

    2016-07-01

    With important questions such as the climate changes and the role of the Sun debated by the scientific community, it appears crucial to measure the evolution of the solar spectral irradiance. This is especially the case in the soft X-ray to UV range, which shows the highest variability and impacts the Earth's ionosphere on both long (background emission evolution) and short (e.g. flares) timescales. LYRA, the Large Yield Radiometer on-board PROBA2 has been observing the Sun for more than six years, making observations in four broadband channels in the EUV-to-MUV range, accumulating quasi-uninterrupted time series. However, maintaining instruments capable of high-quality measurements over years in the harsh space environment is an every-day challenge. We will provide an up-to-date overview of the instrument state and of its data products. We will then present how the LYRA data have been used to analyze the solar impact on the Earth upper atmosphere, addressing successively the effects on the long and short timescales.

  4. The effect of preceding sonar emission on temporal integration in the bat, Megaderma lyra.

    PubMed

    Weissenbacher, Petra; Wiegrebe, Lutz; Kössl, Manfred

    2002-03-01

    The present study investigated whether and to which extent temporal integration in bats is influenced by echolocation behavior. One way to quantify temporal integration is to measure the detection threshold for a pair of short tone pips as a function of the temporal separation between the pips. To asses the effect of preceding sonar emission on temporal integration in the bat, Megaderma lyra, the detection thresholds of identical subjects were measured in a passive as well as in an active paradigm. In the passive paradigm, the presentation of the pip pairs was independent of the bats' sonar emissions; in the active paradigm, the presentation was triggered by the bats' sonar emissions. In both cases, the bats showed a very short integration time in the range of 100-200 micros. Moreover, the comparison of the active and passive results within each bat revealed no systematic differences in the two measuring paradigms. These results indicate that temporal integration is not influenced by echolocation. Simulations with a computer model of cochlear filtering based on measurements of M. lyra cochlear tuning suggest that the perceptual temporal integration is dominated by the integration of the cochlear filters.

  5. "Lyra" Space Stellar Survey and Establishing a Large Grid of Photometric Standards

    NASA Astrophysics Data System (ADS)

    Mironov, A.; Zakharov, A.; Prokhorov, M.

    2016-05-01

    The "Lyra" space experiment is currently being prepared in Russia. Its main goal is to perform high precision 10-color photometry for all V<16 mag stars. Observations will be made using a 500-mm diameter 3-m focal length Ritchey-Chretien telescope with an afocal lens corrector mounted on the Russian segment of the International Space Station (ISS) and equipped with CCDs operated in the time delay and integration (drift, TDI) mode. One of the most important tasks of the "Lyra" mission is to create a dense all-sky grid of high-precision photometric standards. The total number of standards should be on the order of several million, and to achieve this goal, more than 300 million stars will be measured in the course of the mission. The photometric system must include standards in all ranges of magnitudes from the brightest stars down to 16th magnitude. Small random error will be achieved by providing sufficiently strong signal in all passbands and using highly accurate and stable detecting equipment. The random error of measured magnitudes is expected to be 0m.001–0m.003 and about 0m.01 for stars brighter than 14th magnitude and fainter stars, respectively. The system must be free from systematic errors, which are to be minimized by careful ground -based calibration and by maintaining this calibration throughout the mission.

  6. Ultraviolet light curves of beta Lyrae: Comparison of OAO A-2, IUE, and Voyager Observations

    NASA Technical Reports Server (NTRS)

    Kondo, Yoji; Mccluskey, George E.; Silvis, Jeffery M. S.; Polidan, Ronald S.; Mccluskey, Carolina P. S.; Eaton, Joel A.

    1994-01-01

    The six-band ultraviolet light curves of beta Lyrae obtained with the Orbiting Astronomical Observatory (OAO) A-2 in 1970 exhibited a very unusual behavior. The secondary minimum deepened at shorter wavelength, indicating that one was not observing light variations caused primarily by the eclipses of two stars having a roughly Planckian energy distribution. It was then suggested that the light variations were caused by a viewing angle effect of an optically thick, ellipsoidal circumbinary gas cloud. Since 1978 beta Lyrae has been observed with the International Ultraviolet Explorer (IUE) satellite. We have constructed ultraviolet light curves from the IUE archival data for comparison with the OAO A-2 results. We find that they are in substantial agreement with each other. The Voyager ultraviolet spectrometer was also used to observe this binary during a period covered by IUE observations. The Voyager results agree with those of the two other satellite observatories at wavelengths longer than about 1350 A. However, in the wavelength region shorter than the Lyman-alpha line at 1216 A, the light curves at 1085 and 965 A show virtually no light variation except an apparent flaring near phase 0.7, which is also in evidence at longer wavelengths. We suggest that the optically thick circumbinary gas cloud, which envelops the two stars completely, assumes a roughly spherical shape when observed at these shorter wavelengths.

  7. Analysis of the IUE spectra of the strongly interacting binary beta Lyrae

    NASA Technical Reports Server (NTRS)

    Mccluskey, George E., Jr.

    1993-01-01

    The six-band ultraviolet light curves of beta Lyrae obtained with the Orbiting Astronomical Observatory A-2 in 1970 exhibited a very unusual behavior. The secondary minimum deepened at shorter wavelength, indicating that one was not observing light variations caused primarily by the eclipses of two stars having a roughly Planckian energy distribution. It was then suggested that the light variations were caused by a viewing angle effect of an optically-thick, ellipsoidal circumbinary gas cloud. Since 1978 beta Lyrae has been observed with the International Ultraviolet Explorer (IUE) satellite. We have constructed ultraviolet light curves from the IUE archival data for comparison with the OAO-A2 results. We find that they are in substantial agreement with each other. The Voyager ultraviolet spectrometer was also used to observe this binary during a period covered by IUE observations. The Voyager results agree with those of the two other satellite observatories at wavelengths longer than about 1350 A. However, in the wavelength region shorter than the Lyman-alpha line at 1216 A, the light curves at 1085 A and 965 A show virtually no light variation except an apparent flaring near phase 0.7, which is also in evidence at longer wavelengths. We suggest that the optically-thick circumbinary gas cloud, which envelops the two stars completely, assumes a roughly spherical shape when observed at these shorter wavelengths.

  8. Statistical analysis of QT/RR hysteresis in healthy horses.

    PubMed

    Kozelek, Petr; Holcik, Jiri; Sedlinska, Marketa

    2007-01-01

    The paper describes experiments and their results that offered an insight to relationship between RR and QT intervals in equine ECG signals recorded under various conditions. In contrast to human heart in a great number of cases the QT intervals prolonged with a heart rate acceleration. Peak-to-peak differences between maximum and minimum RR intervals during the excitation response in non-standard responses were twice as smaller as in standard responses and the lengths of QT intervals were significantly longer in the non-standard records. This fact means that the electrical processes in equine heart ventricles must be controlled by different mechanisms than in human heart.

  9. 13. New York Connecting RR: Hell Gate Bridge. Queens, Queens ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. New York Connecting RR: Hell Gate Bridge. Queens, Queens Co., NY. Sec. 4207, MP 7.29. (See HAER No. NY-88 for further documentation on this site). - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York County, NY

  10. 12. New York Connecting RR: Hell Gate Bridge. Queens, Queens ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. New York Connecting RR: Hell Gate Bridge. Queens, Queens Co., NY. Sec. 4207, MP 7.29. (See HAER No. NY-88 for further documentation on this site). - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York County, NY

  11. 11. New York Connecting RR: Hell Gate Bridge. Queens, Queens ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. New York Connecting RR: Hell Gate Bridge. Queens, Queens Co., NY. Sec. 4207, MP 7.29. (See HAER No. NY-88 for further documentation on this site). - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York County, NY

  12. 10. New York Connecting RR viaduct approaching Hell Gate Bridge ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. New York Connecting RR viaduct approaching Hell Gate Bridge from S. Queens, Queens Co., NY. Sec. 4207, MP 7.29. - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York County, NY

  13. 21. Providence & Worchester RR: Freight house. Providence, Providence Co., ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. Providence & Worchester RR: Freight house. Providence, Providence Co., RI. Sec. 4119, mp 185.66 (See HAER no. RI-3 for further documentation on this site.) - Northeast Railroad Corridor, Amtrak route between CT & MA state lines, Providence, Providence County, RI

  14. 4. General view looking NW along Richmond Branch Reading RR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. General view looking NW along Richmond Branch Reading RR tracks, showing Building 16 on left, stack associated with Building 3 and Building 22 on right. Building on far right is not part of the Dobson Mills complex (camera side of Scotts Lane). - John & James Dobson Carpet Mill (West Parcel), 4041-4055 Ridge Avenue, Philadelphia, Philadelphia County, PA

  15. 5. General view from Richmond Branch Reading RR bridge over ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. General view from Richmond Branch Reading RR bridge over Scotts Lane. Building 22 left foreground, showing portion of profile of Building 22A north elevation on south elevation of Building 22. View looking NE. - John & James Dobson Carpet Mill (West Parcel), 4041-4055 Ridge Avenue, Philadelphia, Philadelphia County, PA

  16. 3. General view from Richmond Branch Reading RR bridge over ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. General view from Richmond Branch Reading RR bridge over Ridge Avenue, looking down Ridge Avenue showing Building 7, entrance to complex, Building 8 and finally Building 10. Building 11, tallest building in center, predominates. View looking NNW. - John & James Dobson Carpet Mill (West Parcel), 4041-4055 Ridge Avenue, Philadelphia, Philadelphia County, PA

  17. 2. General view from Richmond Branch Reading RR across Ridge ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. General view from Richmond Branch Reading RR across Ridge Avenue from Dobson Mills complex, showing entrance (between Buildings 8 on left and 7 on right), looking NE. Building 13/14 clearly visible in background to left. - John & James Dobson Carpet Mill (West Parcel), 4041-4055 Ridge Avenue, Philadelphia, Philadelphia County, PA

  18. 88. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    88. New York, New Haven & Hartford RR: East New Haven Shops Roundhouse. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  19. 84. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    84. New York, New Haven & Hartford RR: East New Haven Shops & Yards. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  20. 81. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    81. New York, New Haven & Hartford RR: East New Haven Shops & Yards. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  1. 85. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    85. New York, New Haven & Hartford RR: East New Haven Shops Roundhouse. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  2. 87. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    87. New York, New Haven & Hartford RR: East New Haven Shops Roundhouse. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  3. 61. New York, New Haven & Hartford RR: New Haven ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    61. New York, New Haven & Hartford RR: New Haven Station. New Haven, New Haven Co., CT. Sec. 9108, MP 72.00. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  4. 82. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    82. New York, New Haven & Hartford RR: East New Haven Shops & Yards. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  5. 80. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    80. New York, New Haven & Hartford RR: East New Haven Shops & Yards. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  6. 79. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    79. New York, New Haven & Hartford RR: East New Haven Shops with Roundhouse in foreground. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  7. 83. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    83. New York, New Haven & Hartford RR: East New Haven Shops & Yards. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  8. 86. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    86. New York, New Haven & Hartford RR: East New Haven Shops Roundhouse. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  9. A study of the P-Cygni lines in the ultraviolet spectrum of Beta Lyrae

    NASA Technical Reports Server (NTRS)

    Mazzali, Paolo A.

    1986-01-01

    The properties of the mass loss from the nondegenerate interacting binary system of beta Lyrae are investigated by analyzing the P-Cygni line profiles in the UV spectrum and considering these to be emitted in the wind outflow from the B8II primary component. Observed UV lines obtained by IUE are compared with theoretical models obtained using Sobolev's approximation. The models give satisfactory fittings. Simultaneous fitting of the resonance lines of Al II (1670 A) and Al III (1863 A) show that if the lines are emitted in the same region of the outflowing shell, as the line widths indicate, the electron temperature in the region is 23,500 K, and the mass loss is 2 times 10 to the minus 7th power solar masses/yr.

  10. An elementary theory of eclipsing depths of the light curve and its application to Beta Lyrae

    NASA Technical Reports Server (NTRS)

    Huang, S.-S.; Brown, D. A.

    1976-01-01

    An elementary theory of the ratio of depths of secondary and primary eclipses of a light curve has been proposed for studying the nature of component stars. It has been applied to light curves of Beta Lyrae in the visual, blue, and far-ultraviolet regions with the purpose of investigating the energy sources for the luminosity of the disk surrounding the secondary component and determining the dominant radiative process in the disk. No trace of the spectrum of primary radiation has been found in the disk. Therefore, it is suggested that LTE is the main radiative process in the disk, which radiates at a temperature of approximately 12,000 K in the portion that undergoes eclipse. A small source corresponding to 14,500 K has also been tentatively detected and may represent a hot spot caused by hydrodynamic flow of matter from the primary component to the disk.

  11. Evidence for a temperature rise in the outer layers of alpha Lyrae, from Copernicus observations of Lyman-alpha

    NASA Technical Reports Server (NTRS)

    Praderie, F.; Simonneau, E.; Snow, T. P., Jr.

    1975-01-01

    Copernicus satellite observations of the Ly-alpha profiles in alpha Lyrae (Vega) are used to determine whether classical radiative-equilibrium LTE model atmospheres can fit the thermal structure in the outer layers of that star. Two plane-parallel LTE model photospheres of alpha Lyrae are considered: a line-blanketed radiative-equilibrium model with an effective temperature of 9650 K and log g of 4.05, and the same model with a temperature of 9500 K and log g of 4.0. The profiles of the Ly-alpha wings are computed, and it is found that classical LTE models are unable to predict either the observed violet wing or the red wing longwards of 1239 A, regardless of the line source function. It is concluded that the electron temperature must increase outwards over the surface value reached in radiative equilibrium.

  12. Echolocation behaviour of Megaderma lyra during typical orientation situations and while hunting aerial prey: a field study.

    PubMed

    Schmidt, Sabine; Yapa, Wipula; Grunwald, Jan-Eric

    2011-05-01

    Bats modify the structure and emission pattern of their calls to cope with the functional constraints of a given echolocation situation. As a consequence, the flexibility in sonar call use affects the potential niche use of a species. The present paper addresses call use in Megaderma lyra, a species with a short, broadband multiharmonic basic call, in typical orientation situations, when emerging from and re-entering a day roost, in cruising flight and when passing through vegetation, and during the pursuit of tethered, flying insects. While call duration and emission rate were adapted to the four orientation situations, call spectral composition was similar in these situations, except that bats emitted calls containing more harmonics when re-entering the roost. These moderate call modifications may be accounted for by the observation that M. lyra stayed close to landscape elements even in open habitats. Although M. lyra is a typical gleaner, all tested bats approached flying insects, guided by sonar calls of significantly decreasing duration and pulse interval, and of increasing sweep rate. Before capture, peak frequency was lowered from call to call. The spontaneous approaches towards flying insects with systematic changes in call pattern suggest regular aerial hunting in this species.

  13. Eclipsing and density effects on the spectral behavior of Beta Lyrae binary system in the UV

    NASA Astrophysics Data System (ADS)

    Sanad, M. R.

    2010-01-01

    We analyze both long and short high resolution ultraviolet spectrum of Beta Lyrae eclipsing binary system observed with the International Ultraviolet Explorer (IUE) between 1980 and 1989. The main spectral features are P Cygni profiles originating from different environments of Beta Lyrae. A set of 23 Mg II k&h spectral lines at 2800 Å, originating from the extended envelope [Hack, M., 1980. IAUS, 88, 271H], have been identified and measured to determine their fluxes and widths. We found that there is spectral variability for these physical parameters with phase, similar to that found for the light curve [Kondo, Y., McCluskey, G.E., Jeffery, M.M.S., Ronald, S.P., Carolina, P.S. McCluskey, Joel, A.E., 1994. ApJ, 421, 787], which we attribute to the eclipse effects [Ak, H., Chadima, P., Harmanec, P., Demircan, O., Yang, S., Koubský, P., Škoda, P., Šlechta, M., Wolf, M., Božić, H., 2007. A&A, 463, 233], in addition to the changes of density and temperature of the region from which these lines are coming, as a result of the variability of mass loss from the primary star to the secondary [Hoffman, J.L., Nordsieck, K.H., Fox, G.K., 1998. AJ, 115, 1576; Linnell, A.P., Hubeny, I., Harmanec, P., 1998. ApJ, 509, 379]. Also we present a study of Fe II spectral line at 2600 Å, originating from the atmosphere of the primary star [Hack, M., 1980. IAUS, 88, 271H]. We found spectral variability of line fluxes and line widths with phase similar to that found for Mg II k&h lines. Finally we present a study of Si IV spectral line at 1394 Å, originating from the extended envelope [Hack, M., 1980. IAUS, 88, 271H]. A set of 52 Si IV spectral line at 1394 Å have been identified and measured to determine their fluxes and widths. Also we found spectral variability of these physical parameters with phase similar to that found for Mg II k&h and Fe II spectral lines.

  14. QT/RR curvatures in healthy subjects: sex differences and covariates.

    PubMed

    Malik, Marek; Hnatkova, Katerina; Kowalski, Donna; Keirns, James J; van Gelderen, E Marcel

    2013-12-01

    Data of a large clinical study were used to investigate how much are the QT/RR patterns in healthy subjects curved and whether these curvatures differ between women and men. Daytime drug-free 12-lead Holter recordings were repeated 4 times in each of 176 female healthy subjects and 176 male healthy subjects aged 32.7 ± 9.1 yr. In each of the subjects, up to 1,440 carefully verified QT interval measurements were obtained with QT/RR hysteresis-corrected RR intervals. Individual subject data were used to fit the following regression equation: QT = χ + (δ/γ)(1 - RR(γ)) + ε, where QT and RR are QT and RR measurements (in s), χ is regression intercept, δ is the QT/RR slope, γ is the QT/RR curvature and provides the lowest regression residual, and ε represents normally distributed zero-centered errors. The bootstrap technique showed the intrasubject reproducibility of QT/RR slopes and curvatures. In women and men, QT/RR curvatures were 0.544 ± 0.661 and 0.797 ± 0.706, respectively (P = 0.0006). The corresponding QT/RR slopes were 0.158 ± 0.030 and 0.139 ± 0.023, respectively (P < 0.0001). QT/RR curvatures were related to QT/RR slopes but not to individually corrected mean QTc intervals or individual QT/RR hysteresis profiles. The individual heart rate correction formula derived from the curvilinear regression provided a significantly lower intrasubject variability of QTc interval than individual optimisation of linear or log-linear QT/RR heart rate corrections. The QT/RR curvature can be reliable measured and expressed numerically. The corresponding heart rate correction formula provides more compact data than the previously proposed approaches. There are substantial sex differences in QT/RR patterns. Women have a QT/RR pattern that is not only steeper than men but also more curved. PMID:24163079

  15. TZ Lyrae: an Algol-type Eclipsing Binary with Mass Transfer

    NASA Astrophysics Data System (ADS)

    Yang, Yuan-Gui; Yin, Xin-Guo

    2007-04-01

    We present a detailed investigation of the Algol-type binary TZ Lyrae, based on 55 light minimum timings spanning 90 years. It is found that the orbital period shows a long-term increase with a cyclic variation superimposed. The rate of the secular increase is dP/dt=+7.18× 10^{-8} d yr^{-1}, indicating that a mass transfer from the less massive component to the more massive one at a rate of dm=+2.21×10^{-8} M_⊙ yr^{-1}. The cyclic component, with a period of P_{3}=45.5 yr and an amplitude of A=0.0040°, may be interpreted as either the light-time effect in the presence of a third body or magnetic activity cycles in the components. Using the latest version Wilson-Devinney code, a revised photometric solution was deduced from B and V observations. The results show that TZ Lyr is an Algol-type eclipsing binary with a mass ratio of q=0.297(±0.003). The semidetached configuration with a lobe-filling secondary suggests a mass transfer from the secondary to the primary, which is in agreement with the long-term period increase of the binary system.

  16. Solar-Blind Diamond Detectors for Lyra, the Solar VUV Radiometer on Board Proba II

    NASA Astrophysics Data System (ADS)

    Benmoussa, A.; Hochedez, J.-F.; Schmutz, W. K.; Schühle, U.; Nesládek, M.; Stockman, Y.; Kroth, U.; Richter, M.; Theissen, A.; Remes, Z.; Haenen, K.; Mortet, V.; Koller, S.; Halain, J. P.; Petersen, R.; Dominique, M.; D'Olieslaeger, M.

    2003-12-01

    Fabrication, packaging and experimental results on the calibration of metal-semiconductor-metal (MSM) photodetectors made on diamond are reported. LYRA (Lyman-α RAdiometer onboard PROBA-2) will use diamond detectors for the first time in space for a solar physics instrument. A set of measurement campaigns was designed to obtain the XUV-to-VIS responsivity of the devices and other characterizations. The measurements of responsivity in EUV and VUV spectral ranges (40 240 nm) have been carried out by the Physkalisch-Technische Bundesanstalt (PTB) in Germany at the electron storage ring BESSY II. The longer wavelength range from 210 to 1127 nm was measured with monochromatic light by using a Xe-lamp at IMO-IMOMEC. The diamond detectors exhibit a photoresponse which lie in the 35 65 mA/W range at 200 nm (corresponding to an external quantum efficiency of 20 40%) and indicate a visible rejection ratio (200 500 nm) higher than four orders of magnitude.

  17. Quark and strange quark matter solutions for higher dimensional FRW universe in Lyra geometry

    NASA Astrophysics Data System (ADS)

    Aygün, Sezgin; Caglar, Halife; Taşer, Dogukan; Aktaş, Can

    2015-01-01

    In this study, we have investigated the higher dimensional flat Friedmann-Robertson-Walker (FRW) universe for a cloud of string with perfect fluid attached quark and strange quark matter (SQM) in Lyra geometry. Generalized ( n + 2) dimensional flat FRW universe solutions have been achieved with the aid of equation of states (EOS) and deceleration parameter ( q). From the field equations, we have obtained that the cloud of string with perfect fluid does not survive. Since the string tension density vanishes ( λ = 0) for this model, as a result, the cloud of string with perfect-fluid-attached quark and strange quark matter energy-momentum tensor is automatically transformed into a perfect-fluid-attached quark and strange quark matter energy-momentum tensor. Also, our solutions agree with Halford's study. β 2 behaves like a cosmological constant. When t → ∞ the pressure of quark matter and the density go to zero, then, the quark matter transforms into another matter with time. Also our quark matter solutions are in agreement with the present idea.

  18. [Heart rate variability study based on a novel RdR RR Intervals Scatter Plot].

    PubMed

    Lu, Hongwei; Lu, Xiuyun; Wang, Chunfang; Hua, Youyuan; Tian, Jiajia; Liu, Shihai

    2014-08-01

    On the basis of Poincare scatter plot and first order difference scatter plot, a novel heart rate variability (HRV) analysis method based on scatter plots of RR intervals and first order difference of RR intervals (namely, RdR) was proposed. The abscissa of the RdR scatter plot, the x-axis, is RR intervals and the ordinate, y-axis, is the difference between successive RR intervals. The RdR scatter plot includes the information of RR intervals and the difference between successive RR intervals, which captures more HRV information. By RdR scatter plot analysis of some records of MIT-BIH arrhythmias database, we found that the scatter plot of uncoupled premature ventricular contraction (PVC), coupled ventricular bigeminy and ventricular trigeminy PVC had specific graphic characteristics. The RdR scatter plot method has higher detecting performance than the Poincare scatter plot method, and simpler and more intuitive than the first order difference method.

  19. Ventricular Cycle Length Characteristics Estimative of Prolonged RR Interval during Atrial Fibrillation

    PubMed Central

    CIACCIO, EDWARD J.; BIVIANO, ANGELO B.; GAMBHIR, ALOK; EINSTEIN, ANDREW J.; GARAN, HASAN

    2014-01-01

    Background When atrial fibrillation (AF) is incessant, imaging during a prolonged ventricular RR interval may improve image quality. It was hypothesized that long RR intervals could be predicted from preceding RR values. Methods From the PhysioNet database, electrocardiogram RR intervals were obtained from 74 persistent AF patients. An RR interval lengthened by at least 250 ms beyond the immediately preceding RR interval (termed T0 and T1, respectively) was considered prolonged. A two-parameter scatterplot was used to predict the occurrence of a prolonged interval T0. The scatterplot parameters were: (1) RR variability (RRv) estimated as the average second derivative from 10 previous pairs of RR differences, T13–T2, and (2) Tm–T1, the difference between Tm, the mean from T13 to T2, and T1. For each patient, scatterplots were constructed using preliminary data from the first hour. The ranges of parameters 1 and 2 were adjusted to maximize the proportion of prolonged RR intervals within range. These constraints were used for prediction of prolonged RR in test data collected during the second hour. Results The mean prolonged event was 1.0 seconds in duration. Actual prolonged events were identified with a mean positive predictive value (PPV) of 80% in the test set. PPV was >80% in 36 of 74 patients. An average of 10.8 prolonged RR intervals per 60 minutes was correctly identified. Conclusions A method was developed to predict prolonged RR intervals using two parameters and prior statistical sampling for each patient. This or similar methodology may help improve cardiac imaging in many longstanding persistent AF patients. PMID:23998759

  20. RR Tel: Getting Under the Flux Limit: An Observation with FUSE

    NASA Technical Reports Server (NTRS)

    Sonnenborn, George (Technical Monitor); Kenyon, Scott J.

    2004-01-01

    The goal of this program is to acquire a FUSE spectrum of the symbiotic binary RR Tel. With these data, we plan to derive improved constraints on the hot component, the nebula, and perhaps the red giant wind. Based on results from AG Dra, we should also be able to use some line detections to improve atomic parameters for high ionization emission lines. This results would benefit the general FUSE community. As of this writing, the FUSE observation of RR Tel has not been made. Because RR Tel is a very bright UV source, the FUSE team is assessing the likelihood that RR Tel will have an adverse affect on the instrument.

  1. Thermal analysis of the FSP-1RR irradiation test

    SciTech Connect

    Webb, R.H.; Lyon, W.F. III

    1992-10-14

    The thermal analysis of four unirradiated fuel pins to be tested in the FSP-1RR fuels irradiation experiment was completed. This test is a follow-on experiment in the series of fuel pin irradiation tests conducted by the SP-100 Program in the Fast Flux Test Facility. One of the pins contains several meltwire temperature monitors within the fuel and the Li annulus. A post-irradiation examination will verify the accuracy of the pre-irradiation thermal analysis. The purpose of the pre-irradiation analysis was to determine the appropriate insulating gap gas compositions required to provide the design goal cladding operating temperatures and to ensure that the meltwire temperature ranges in the temperature monitored pin bracket peak irradiation temperatures. This paper discusses the methodology and summarizes the results of the analysis.

  2. Photometric study of the eclipsing binary RR Leporis

    NASA Astrophysics Data System (ADS)

    Vyas, M. L.; Abhyankar, K. D.

    1989-11-01

    The eclipsing binary RR Leporis has been observed on 42 nights during 1982-1987 in standard U, B and V passbands. The complete light curves and photometric solutions for this binary system are presented. The preliminary elements derived by Russell-Merrill method were used as inputs in Wilson-Devinney's Differential Corrections Program. All the three light curves in UBV were treated simultaneously. Two different Mode 5 solutions, in which the secondary fills its roche lobe, fitted the light curves equally well. On comparing these photometric elements with those given by Samec et al. (1988), it was found that the solution is indeterminate because i and q are strongly correlated. In the absence of any accurate spectroscopic data, it is premature to derive absolute dimensions of the system. The most likely parameters are given.

  3. Mapping the outer bulge with RRab stars from the VVV Survey

    NASA Astrophysics Data System (ADS)

    Gran, F.; Minniti, D.; Saito, R. K.; Zoccali, M.; Gonzalez, O. A.; Navarrete, C.; Catelan, M.; Contreras Ramos, R.; Elorrieta, F.; Eyheramendy, S.; Jordán, A.

    2016-07-01

    Context. The VISTA Variables in the Vía Láctea (VVV) is a near-IR time-domain survey of the Galactic bulge and southern plane. One of the main goals of this survey is to reveal the 3D structure of the Milky Way through their variable stars. In particular, enormous numbers of RR Lyrae stars have been discovered in the inner regions of the bulge (-8° ≲ b ≲ -1°) by optical surveys such as OGLE and MACHO, but leaving an unexplored window of more than ~47 sq deg (-10.0° ≲ ℓ ≲ + 10.7° and - 10.3° ≲ b ≲ -8.0°) observed by the VVV Survey. Aims: Our goal is to characterize the RR Lyrae stars in the outer bulge in terms of their periods, amplitudes, Fourier coefficients, and distances in order to evaluate the 3D structure of the bulge in this area. The distance distribution of RR Lyrae stars will be compared to that of red clump stars, which is known to trace a X-shaped structure, in order to determine whether these two different stellar populations share the same Galactic distribution. Methods: A search for RR Lyrae stars was performed in more than ~47 sq deg at low Galactic latitudes (-10.3° ≲ b ≲ -8.0°). In the procedure the χ2 value and analysis of variance (AoV) statistic methods were used to determine the variability and periodic features of the light curves, respectively. To prevent misclassifications, the analysis was performed only on the fundamental mode RR Lyrae stars (RRab) owing to similarities found in the near-IR light curve shapes of contact eclipsing binaries (W UMa) and first overtone RR Lyrae stars (RRc). On the other hand, the red clump stars of the same analyzed tiles were selected, and cuts in the color-magnitude diagram were applied and the maximum distance restricted to ~20 kpc in order to construct a similar catalog in terms of distances and covered area compared to the RR Lyrae stars. Results: We report the detection of more than 1000 RR Lyrae ab-type stars in the VVV Survey located in the outskirts of the Galactic bulge

  4. Homogeneous Photometry VI: Variable Stars in the Leo I Dwarf Spheroidal Galaxy

    NASA Astrophysics Data System (ADS)

    Stetson, Peter B.; Fiorentino, Giuliana; Bono, Giuseppe; Bernard, Edouard J.; Monelli, Matteo; Iannicola, Giacinto; Gallart, Carme; Ferraro, Ivan

    2014-07-01

    From archival ground-based images of the Leo I dwarf spheroidal galaxy, we have identified and characterized the pulsation properties of 164 candidate RR Lyrae variables and 55 candidate anomalous and/or short-period Cepheids. We have also identified 19 candidate long-period variable stars and 13 other candidate variables whose physical nature is unclear, but due to the limitations of our observational material we are unable to estimate reliable periods for them. On the basis of its RR Lyrae star population, Leo I is confirmed to be an Oosterhoff-intermediate type galaxy, like several other dwarf spheroidals. From the RR Lyrae stars we have derived a range of possible distance moduli for Leo I : 22.06 ± 0.08 lsim μ0 lsim 22.25 ± 0.07 mag depending on the metallicity assumed for the old population ([Fe/H] from -1.43 to -2.15). This is in agreement with previous independent estimates. We show that in their pulsation properties, the RR Lyrae stars—representing the oldest stellar population in the galaxy—are not significantly different from those of five other nearby, isolated dwarf spheroidal galaxies. A similar result is obtained when comparing them to RR Lyrae stars in recently discovered ultra-faint dwarf galaxies. We are able to compare the period distributions and period-amplitude relations for a statistically significant sample of ab-type RR Lyrae stars in dwarf galaxies (~1300 stars) with those in the Galactic halo field (~14,000 stars) and globular clusters (~1000 stars). Field RRLs show a significant change in their period distribution when moving from the inner (dG lsim 14 kpc) to the outer (dG gsim 14 kpc) halo regions. This suggests that the halo formed from (at least) two dissimilar progenitors or types of progenitor. Considered together, the RR Lyrae stars in classical dwarf spheroidal and ultra-faint dwarf galaxies—as observed today—do not appear to follow the well defined pulsation properties shown by those in either the inner or the outer

  5. 28. RAILROAD, RR. BRIDGE MISSISSIPPI, CLAY CO. WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    28. RAILROAD, RR. BRIDGE MISSISSIPPI, CLAY CO. WAVERLY 1.5 mi. S of MS. 50 Detail: Turn machinery. DWG S-3-325. Contr # 7236. upper right quarter of sheet: plan & longitudinal elevation of turn table.. July 1914. Credit: Columbus and Greenville RR, Columbus, Ms. Sarcone Photocopy, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  6. 31. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    31. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Detail: Turn machinery. DWG S-3-325. Contr. #7236. Upper left quarter of sheet: plan and longitudinal elevation of Wedges. July 1914. Credit: Columbus and Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. Sep 1978 - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  7. 30. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    30. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Detail: Turn machinery. DWG S-3-325. Contr. #7236. Lower right quarter of sheet: Lateral elevation of turn table. July 1914. Credit: Columbus and Greenville RR, Columbus, MS. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  8. 29. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5. mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5. mi. S of MS. 50 Detail: Turn machinery. DWG S-3-325. Contr. #7236. Lower right quarter of sheet: Lateral elevation of turn table. July 1914. Credit: Columbus and Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  9. 21. RAILROAD, RR. BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. RAILROAD, RR. BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of Ms. 50 Proposed 218-foot turn span, design #2339 of Virginia Bridge and Iron Co., Roanoke, Va. 13 May 1914. Act. size: 16x11 in. Credit: Columbus & Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  10. 27. RAILROAD, RR. BRIDGE MISSISSIPPI, CLAY CO. WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    27. RAILROAD, RR. BRIDGE MISSISSIPPI, CLAY CO. WAVERLY 1.5 mi. S of MS. 50 Stress Sheet of 1888 Bridge: Conroy & Sinks, Consulting Engineers, Chicago. July 21, 1910. DWG #978. Act. size around border: 18x11 in. Credit: Columbus and Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  11. 19. BLUEPRINT, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. BLUEPRINT, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of Ms. 50 Map of Tombigbee River at Waverly, 'Proposed Crossing.' 12 May 1888. Credt: Columbus & Greenville, RR, Columbus, Ms. DWG S-3-343. Sarcone Photography, ColumbuS, Ms. Sept 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  12. 22. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Proposed 218-foot turn span, submitted by the Wisconsin Bridge & Iron Co., Milwaukee, Wisconsin 8 May 1914. Act size: approx. 23x34 in. Credit: Columbus & Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, MS. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  13. Evidence for an analytic perception of multiharmonic sounds in the bat, Megaderma lyra, and its possible role for echo spectral analysis.

    PubMed

    Krumbholz, K; Schmidt, S

    2001-04-01

    For echolocation, the gleaning bat Megaderma lyra relies on short and broadband calls consisting of multiple harmonic components, each of which is downward frequency modulated. The harmonic components in M. lyra's calls have a relatively small frequency excursion and do not overlap spectrally. Broadband calls of other bat species, on the other hand, often consist of only a few harmonics which are modulated over broad and sometimes overlapping frequency ranges. A call consisting of narrow and nonoverlapping harmonic components may provide a less complete representation of target structure than a call which consists of broadly modulated components. However, a multiharmonic call may help the bats to perceive local spectral changes in the echo from shifts in the peak frequencies of single harmonics, and thereby to extract additional information about the target. To assess this hypothesis, the accuracy with which M. lyra can analyze frequency shifts of single partials in multiharmonic complex tones was investigated. A two-alternative, forced-choice behavioral task was used to measure M. lyra's frequency discrimination threshold for the third partial in complex tones whose spectral composition resembled that of the bat's sonar calls. The discrimination threshold for the third partial in a 21.5-kHz harmonic tone amounted to about 2% and was similar to the bat's pure-tone discrimination threshold at 64.5 kHz. Discrimination performance was essentially unaffected by random frequency changes of the other partials and by reducing stimulus duration from 50.5 to 1.5 ms. Both findings are in accordance with predictions made on the basis of the shape of M. Ivra's cochlear filters. The comparison between the observed frequency discrimination performance and a computational estimate of the expected frequency shift in the third harmonic of an echo reflected by a simple, two-front target showed that M. lyra's frequency resolution is sufficient for analyzing the target

  14. The Hercules-Lyra association revisited. New age estimation and multiplicity study

    NASA Astrophysics Data System (ADS)

    Eisenbeiss, T.; Ammler-von Eiff, M.; Roell, T.; Mugrauer, M.; Adam, Ch.; Neuhäuser, R.; Schmidt, T. O. B.; Bedalov, A.

    2013-08-01

    Context. The Hercules-Lyra association, a purported nearby young moving group, contains a few tens of zero age main sequence stars of spectral types F to M. The existence and the properties of the Her-Lyr association are controversial and have been discussed in the literature. Aims: The present work reassesses the properties and the member list of the Her-Lyr association based on kinematics and age indicators. Many objects form multiple systems or have low-mass companions and so we need to properly account for multiplicity. Methods: We use our own new imaging observations and archival data to identify multiple systems. The colors and magnitudes of kinematic candidates are compared to isochrones. We derive further information on the age based on Li depletion, rotation, and coronal and chromospheric activity. A set of canonical members is identified to infer mean properties. Membership criteria are derived from the mean properties and used to discard non-members. Results: The candidates selected from the literature belong to 35 stellar systems, 42.9% of which are multiple. Four multiple systems (V538 Aur, DX Leo, V382 Ser, and HH Leo) are confirmed in this work by common proper motion. An orbital solution is presented for the binary system which forms a hierarchical triple with HH Leo. Indeed, a group of candidates displays signatures of youth. Seven canonical members are identified The distribution of Li equivalent widths of canonical Her-Lyr members is spread widely and is similar to that of the Pleiades and the UMa group. Gyrochronology gives an age of 257 ± 46 Myr which is roughly in between the ages of the Pleiades and the Ursa Major group. The measures of chromospheric and coronal activity support the young age. Four membership criteria are presented based on kinematics, lithium equivalent width, chromospheric activity, and gyrochronological age. In total, eleven stars are identified as certain members including co-moving objects plus additional 23 possible

  15. Important influence of respiration on human R-R interval power spectra is largely ignored.

    PubMed

    Brown, T E; Beightol, L A; Koh, J; Eckberg, D L

    1993-11-01

    Frequency-domain analyses of R-R intervals are used widely to estimate levels of autonomic neural traffic to the human heart. Because respiration modulates autonomic activity, we determined for nine healthy subjects the influence of breathing frequency and tidal volume on R-R interval power spectra (fast-Fourier transform method). We also surveyed published literature to determine current practices in this burgeoning field of scientific inquiry. Supine subjects breathed at rates of 6, 7.5, 10, 15, 17.1, 20, and 24 breaths/min and with nominal tidal volumes of 1,000 and 1,500 ml. R-R interval power at respiratory and low (0.06-0.14 Hz) frequencies declined significantly as breathing frequency increased. R-R interval power at respiratory frequencies was significantly greater at a tidal volume of 1,500 than 1,000 ml. Neither breathing frequency nor tidal volume influenced average R-R intervals significantly. Our review of studies reporting human R-R interval power spectra showed that 51% of the studies controlled respiratory rate, 11% controlled tidal volume, and 11% controlled both respiratory rate and tidal volume. The major implications of our analyses are that breathing parameters strongly influence low-frequency as well as respiratory frequency R-R interval power spectra and that this influence is largely ignored in published research.

  16. Important influence of respiration on human R-R interval power spectra is largely ignored

    NASA Technical Reports Server (NTRS)

    Brown, T. E.; Beightol, L. A.; Koh, J.; Eckberg, D. L.

    1993-01-01

    Frequency-domain analyses of R-R intervals are used widely to estimate levels of autonomic neural traffic to the human heart. Because respiration modulates autonomic activity, we determined for nine healthy subjects the influence of breathing frequency and tidal volume on R-R interval power spectra (fast-Fourier transform method). We also surveyed published literature to determine current practices in this burgeoning field of scientific inquiry. Supine subjects breathed at rates of 6, 7.5, 10, 15, 17.1, 20, and 24 breaths/min and with nominal tidal volumes of 1,000 and 1,500 ml. R-R interval power at respiratory and low (0.06-0.14 Hz) frequencies declined significantly as breathing frequency increased. R-R interval power at respiratory frequencies was significantly greater at a tidal volume of 1,500 than 1,000 ml. Neither breathing frequency nor tidal volume influenced average R-R intervals significantly. Our review of studies reporting human R-R interval power spectra showed that 51% of the studies controlled respiratory rate, 11% controlled tidal volume, and 11% controlled both respiratory rate and tidal volume. The major implications of our analyses are that breathing parameters strongly influence low-frequency as well as respiratory frequency R-R interval power spectra and that this influence is largely ignored in published research.

  17. A Cosmological Model of the Early Universe Based on ECG with Variable Λ-Term in Lyra Geometry

    NASA Astrophysics Data System (ADS)

    Saadat, H.

    2016-05-01

    In this paper, we study interacting extended Chaplygin gas as dark matter and quintessence scalar field as dark energy with an effective Λ-term in Lyra manifold. As we know Chaplygin gas behaves as dark matter at the early universe while cosmological constant at the late time. Modified field equations are given and motivation of the phenomenological models discussed in details. Four different models based on the interaction term are investigated in this work. Then, we consider other models where Extended Chaplygin gas and quintessence field play role of dark matter and dark energy respectively with two different forms of interaction between the extended Chaplygin gas and quintessence scalar field for both constant and varying Λ. Concerning to the mathematical hardness of the problems we discuss results numerically and graphically. Obtained results give us hope that proposed models can work as good models for the early universe with later stage of evolution containing accelerated expansion.

  18. Yet Another Spectro-Interferometric Study of The Gas Distribution in The Enigmatic Semi-Detached Binary β Lyrae

    NASA Astrophysics Data System (ADS)

    Nemravová, J.; Mourard, D.; Harmanec, P.; Meilland, A.

    2015-12-01

    The majority of close binaries undergo episodes of mass transfer between their components, which completely change their further evolution. Simulations and observations agree that the mass transfer has two phases: i) short and rapid one, and ii) long and slow one. The bulk of the mass is likely exchanged during the rapid phase, but due to its shortness, systems undergoing this phase are rare, but they hold the key to understanding of the process. One system that is either undergoing the rapid mass transfer phase or is in a transient phase between the two phases is β Lyrae. Our goal is to map the distribution of circumstellar gas in the system. To achieve it, a series of spectro-interferometric observations acquired with the optical instrument VEGA/CHARA are investigated. Here we present our tools and preliminary results of our analysis.

  19. Molecular cloning and expression analysis of RrNHX1 and RrVHA-c genes related to salt tolerance in wild Rosa rugosa.

    PubMed

    Feng, Liguo; Ding, Han; Wang, Jia; Wang, Meng; Xia, Wei; Zang, Shu; Sheng, Lixia

    2015-07-01

    Salt stress is one important factor influencing the growth and development of plants, and salt tolerance of plants is a result of combined action of multiple genes and mechanisms. Rosa rugosa is not only an important ornamental plant, but also the natural aromatic plant of high value. Wild R. rugosa which is naturally distributed on the coast and islands of China has a good salt tolerance due to the special living environment. Here, the vacuolar Na(+)/H(+) reverse transporter gene (NHX1) and the vacuolar H(+)-ATPase subunit C gene (VHA-c) closely related to plant salt tolerance were isolated from wild R. rugosa, and the expression patterns in R. rugosa leaves of the two genes under NaCl stress were determined by real-time quantitative fluorescence PCR. The results showed that the RrNHX1 protein is a constitutive Na(+)/H(+) reverse transporter, the expression of the RrNHX1 gene first increased and then decreased with the increasing salt concentration, and had a time-controlled effect. The RrVHA-c gene is suggestive of the housekeeping feature, its expression pattern showed a similar variation trend with the RrNHX1 gene under the stress of different concentrations of NaCl, and its temporal expression level under 200 mM NaCl stress presented bimodal change. These findings indicated that RrNHX1 and RrVHA-c genes are closely associated with the salt tolerance trait of wild R. rugosa. PMID:26150747

  20. Altered relationship between R-R interval and R-R interval variability in endurance athletes with overtraining syndrome.

    PubMed

    Kiviniemi, A M; Tulppo, M P; Hautala, A J; Vanninen, E; Uusitalo, A L T

    2014-04-01

    Autonomic dysfunction decreases within-subject correlation between R-R interval length (RRi) and vagally mediated RRi variability in cardiac disease. We tested the hypothesis that overtraining syndrome (OTS) may also weaken this relationship. Nine OTS and 10 control endurance athletes underwent 24-h electrocardiogram monitoring, which was repeated in eight OTS and nine control athletes after 6 months, when two OTS athletes still had symptoms of OTS. The power of high-frequency (HF) oscillations of RRi was analyzed in 5-min epochs over the whole recording. Quadratic regression was performed between 5-min values of RRi and log-transformed (ln) HF to obtain R(2) for each recording. The relationship between RRi and HFln was higher in the OTS athletes than controls [R(2): 0.87 (90% confidence interval, CI: 0.84-0.89) vs 0.78 (90% CI: 0.72-0.84); P = 0.034; effect size = 1.22]. Large decrease in R(2) was observed in six recovered OTS athletes after 6 months follow-up [ΔR(2): -0.12 (90% CI: -0.25-0.01); P = 0.11; effect size = 1.44] with no changes in the controls. Mean values of RRi and its variability did not differ between the groups. The within-subject correlation between RRi and vagally mediated RRi variability was stronger in endurance athletes with OTS compared with controls. The present findings may improve the detection of OTS and recovery from OTS in endurance athletes.

  1. Photocopy of floor plan of the C.B. & Q. R.R ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photocopy of floor plan of the C.B. & Q. R.R roundhouse and locomotive shops. June 1980. - Chicago, Burlington & Quincy Railroad, Roundhouse & Shops, Broadway & Spring Streets, Aurora, Kane County, IL

  2. Chicago, Burlington, & Quincy R.R car works aurora, ILL. Photocopy ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Chicago, Burlington, & Quincy R.R car works aurora, ILL. Photocopy of an undated lithograph based on an ambrotype by D.C. Pratt, C. 1857 - Chicago, Burlington & Quincy Railroad, Roundhouse & Shops, Broadway & Spring Streets, Aurora, Kane County, IL

  3. Microcystin-RR exposure results in growth impairment by disrupting thyroid endocrine in zebrafish larvae.

    PubMed

    Xie, Liqiang; Yan, Wei; Li, Jing; Yu, Liqin; Wang, Jianghua; Li, Guangyu; Chen, Nan; Steinman, Alan D

    2015-07-01

    Recent studies have shown that cyanobacteria-derived microcystins (MCs) have the potential to disrupt endocrine systems. However, the effects of microcystin-RR (MC-RR) and their underlying mechanisms are poorly resolved in fish. In this study, MC-RR exposure through submersion caused serious developmental toxicity, such as growth delay and depressed heart rates in zebrafish larvae. We also detected decreased levels of thyroid hormones (THs), suggesting that MC-RR-triggered thyroid endocrine disruption might contribute to the growth impairment observed in developing zebrafish. To further our understanding of mechanisms of MC-RR-induced endocrine toxicity, quantitative real-time PCR (QPCR) analysis was performed on hypothalamic-pituitary-thyroid (HPT) axis related genes, i.e., corticotropin-releasing factor (CRF), thyroid-stimulating hormone (TSH), sodium/iodide symporter (NIS), thyroglobulin (TG), thyroid receptors (TRα and TRβ) and iodothyronine deiodinases (Dio1 and Dio2), of developing zebrafish embryos exposed to 0, 0.3, 1.0 or 3.0mgL(-1) MC-RR until 96h post-fertilization. Our results showed that transcription pattern of HPT axis related genes were greatly changed by MC-RR exposure, except TG gene. Furthermore, western blot was used to validate the results of gene expression. The results showed protein synthesis of TG was not affected, while that of NIS was significantly up-regulated, which are in accordance with gene expression. The overall results indicated that exposure to MC-RR can induce developmental toxicity, which might be associated with thyroid endocrine disruption in developing zebrafish larvae. PMID:25897773

  4. 23. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Southern R'wy Co. in Ms. Repairs to Tombigbee River Bridge' gears and turn machinery. DWG # S. 30303. Scale: 1-1/2' = l'. July 21, 1913. Credit: Columbus & Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  5. 26. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Proposed 218-foot deck, plate-girder turn span, submitted by the Wisconsin Bridge and Iron Co., Milwaukee, Wisc. May 15 1914. Act size: approx. 23x34 in. Credit: columbus and Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  6. 25. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    25. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Proposed 218-foot turn span, submitted by the American Bridge Co., Pittsburg, Pa., 15 May 1914. Inquiry # P-19242. Act. size: approx: 23x24 in. Credit: Columbus and Greenville RR, columbus, MS. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  7. 24. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Southern R'wy; Co., in Ms. Present and proposed draw bridge over Tombigbee River.' Elevations and Plan, with falsework. Wisconsin Bridge and Iron Co., Milwaukee, Wisc., DWG #S. 3-303. Last Revision, Jan. 11 1915. Act. size: 23x34 in. Credit: Columbus and Greenville Rr, Columbus, Ms. Sarcone Photography, Columbus, MS. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  8. Mechanism of blood pressure and R-R variability: insights from ganglion blockade in humans

    NASA Technical Reports Server (NTRS)

    Zhang, Rong; Iwasaki, Kenichi; Zuckerman, Julie H.; Behbehani, Khosrow; Crandall, Craig G.; Levine, Benjamin D.; Blomqvist, C. G. (Principal Investigator)

    2002-01-01

    Spontaneous blood pressure (BP) and R-R variability are used frequently as 'windows' into cardiovascular control mechanisms. However, the origin of these rhythmic fluctuations is not completely understood. In this study, with ganglion blockade, we evaluated the role of autonomic neural activity versus other 'non-neural' factors in the origin of BP and R-R variability in humans. Beat-to-beat BP, R-R interval and respiratory excursions were recorded in ten healthy subjects (aged 30 +/- 6 years) before and after ganglion blockade with trimethaphan. The spectral power of these variables was calculated in the very low (0.0078-0.05 Hz), low (0.05-0.15 Hz) and high (0.15-0.35 Hz) frequency ranges. The relationship between systolic BP and R-R variability was examined by cross-spectral analysis. After blockade, R-R variability was virtually abolished at all frequencies; however, respiration and high frequency BP variability remained unchanged. Very low and low frequency BP variability was reduced substantially by 84 and 69 %, respectively, but still persisted. Transfer function gain between systolic BP and R-R interval variability decreased by 92 and 88 % at low and high frequencies, respectively, while the phase changed from negative to positive values at the high frequencies. These data suggest that under supine resting conditions with spontaneous breathing: (1) R-R variability at all measured frequencies is predominantly controlled by autonomic neural activity; (2) BP variability at high frequencies (> 0.15 Hz) is mediated largely, if not exclusively, by mechanical effects of respiration on intrathoracic pressure and/or cardiac filling; (3) BP variability at very low and low frequencies (< 0.15 Hz) is probably mediated by both sympathetic nerve activity and intrinsic vasomotor rhythmicity; and (4) the dynamic relationship between BP and R-R variability as quantified by transfer function analysis is determined predominantly by autonomic neural activity rather than other

  9. Microcystin-RR exposure results in growth impairment by disrupting thyroid endocrine in zebrafish larvae.

    PubMed

    Xie, Liqiang; Yan, Wei; Li, Jing; Yu, Liqin; Wang, Jianghua; Li, Guangyu; Chen, Nan; Steinman, Alan D

    2015-07-01

    Recent studies have shown that cyanobacteria-derived microcystins (MCs) have the potential to disrupt endocrine systems. However, the effects of microcystin-RR (MC-RR) and their underlying mechanisms are poorly resolved in fish. In this study, MC-RR exposure through submersion caused serious developmental toxicity, such as growth delay and depressed heart rates in zebrafish larvae. We also detected decreased levels of thyroid hormones (THs), suggesting that MC-RR-triggered thyroid endocrine disruption might contribute to the growth impairment observed in developing zebrafish. To further our understanding of mechanisms of MC-RR-induced endocrine toxicity, quantitative real-time PCR (QPCR) analysis was performed on hypothalamic-pituitary-thyroid (HPT) axis related genes, i.e., corticotropin-releasing factor (CRF), thyroid-stimulating hormone (TSH), sodium/iodide symporter (NIS), thyroglobulin (TG), thyroid receptors (TRα and TRβ) and iodothyronine deiodinases (Dio1 and Dio2), of developing zebrafish embryos exposed to 0, 0.3, 1.0 or 3.0mgL(-1) MC-RR until 96h post-fertilization. Our results showed that transcription pattern of HPT axis related genes were greatly changed by MC-RR exposure, except TG gene. Furthermore, western blot was used to validate the results of gene expression. The results showed protein synthesis of TG was not affected, while that of NIS was significantly up-regulated, which are in accordance with gene expression. The overall results indicated that exposure to MC-RR can induce developmental toxicity, which might be associated with thyroid endocrine disruption in developing zebrafish larvae.

  10. Removal of microcystin-LR and microcystin-RR by graphene oxide: adsorption and kinetic experiments.

    PubMed

    Pavagadhi, Shruti; Tang, Ai Ling Lena; Sathishkumar, Muthuswamy; Loh, Kian Ping; Balasubramanian, Rajasekhar

    2013-09-01

    Graphene oxide (GO) was employed in the present study for removal of two commonly occurring algal toxins, microcystin-LR (MC-LR) and microcystin-RR (MC-RR), from water. The adsorption performance of GO was compared to that of commercially available activated carbon. Further, adsorption experiments were conducted in the presence of other environmental pollutants to understand the matrix effects of contaminated water on the selective adsorption of MC-LR and MC-RR onto GO. The environmental pollutants addressed in this study included different anions (nitrate NO3-, nitrite NO2-, sulphate SO4(2-), chloride (Cl(-)), phosphate PO4(3-) and fluoride (F(-))) and cations (sodium (Na(+)), potassium (K(+)), magnesium (Mg(2+)) and calcium (Ca(2+))). GO showed very a high adsorption capacity of 1700 μg/g for removal of MC-LR and 1878 μg/g for MC-RR while the maximum adsorption capacity obtained with the commercial activated carbon was 1481.7 μg/g and 1034.1 μg/g for MC-LR and MC-RR, respectively. The sorption kinetic experiments revealed that more than 90% removal of both MC-LR/RR was achieved within 5 min for all the doses studied (500, 700 and 900 μg/L). GO could be reused as an adsorbent following ten cycles of adsorption/desorption with no significant loss in its adsorption capacity.

  11. Development and validation of a liquid chromatography-tandem mass spectrometry assay for the simultaneous quantitation of microcystin-RR and its metabolites in fish liver.

    PubMed

    Wu, Laiyan; Xie, Ping; Chen, Jun; Zhang, Dawen; Liang, Gaodao

    2010-02-26

    A novel method for identification and quantification of microcystin-RR (MC-RR) and its metabolites (MC-RR-GSH and MC-RR-Cys) in the fish liver was developed and validated. These analytes were simultaneously extracted from fish liver using water containing EDTA with 5% acetic acid, followed by a mixed-mode cation-exchange SPE (Oasis MCX) and subsequently determined by liquid chromatography-electrospray ionization ion trap mass spectrometry (LC-ESI-ITMS). Extraction parameters including volume and pH of eluting solvents, were optimized. Best recoveries were obtained by using 10 mL of 15% ammonia solution in methanol. The mean recoveries at three concentrations (0.2, 1.0, and 5.0 microg g(-1) dry weight [DW]) for MC-RR, MC-RR-GSH and MC-RR-Cys were 93.6-99%, 68.1-73.6% and 90.0-95.2%, respectively. Method detection limit (MDL) were 4, 7 and 5 ng g(-1) DW for MC-RR, MC-RR-GSH and MC-RR-Cys, respectively. Limits of quantification (LOQs) for MC-RR, MC-RR-GSH and MC-RR-Cys were calculated to be 10, 18 and 13 ng g(-1) DW, respectively. Finally, this method was successfully applied to the identification and quantification of MC-RR, MC-RR-GSH and MC-RR-Cys in the liver of bighead carp with acute exposure of MCs. PMID:20060532

  12. Semiautomatic validation of RR time series in an ECG stress test database

    NASA Astrophysics Data System (ADS)

    Armijos, Jairo; García, David; Astudillo, Darwin; Palacio-Baus, Kenneth; Medina, Rubén.; Wong, Sara

    2015-12-01

    This paper reports an automatic method for characterizing the quality of the RR-time series in the stress test database known as DICARDIA. The proposed methodology is simple and consists in subdividing the RR time series in a set of windows for estimating the quantity of artifacts based on a threshold value that depends on the standard deviation of RR-time series for each recorded lead. In a first stage, a manual annotation was performed considering four quality classes for the RR-time series (Reference lead, Good Lead, Low Quality Lead and Useless Lead). Automatic annotation was then performed varying the number of windows and threshold value for the standard deviation of the RR-time series. The metric used for evaluating the quality of the annotation was the Matching Ratio. The best results were obtained using a higher number of windows and considering only three classes (Good Lead, Low Quality Lead and Useless). The proposed methodology allows the utilization of the online available DICARDIA Stress Test database for different types of research.

  13. Degradation of microcystin-RR using boron-doped diamond electrode.

    PubMed

    Zhang, Chunyong; Fu, Degang; Gu, Zhongze

    2009-12-30

    Microcystins (MCs), produced by blue-green algae, are one of the most common naturally occurring toxins found in natural environment. The presence of MCs in drinking water sources poses a great threat to people's health. In this study, the degradation behavior of microcystin-RR on boron-doped diamond (BDD) electrode was investigated under galvanostatic conditions. Such parameters as reaction time, supporting electrolyte and applied current density were varied in order to determine their effects on this oxidation process. The experimental results revealed the suitability of electrochemical processes employing BDD electrode for removing MC-RR from the solution. However, the efficient removal of MC-RR only occurred in the presence of sodium chloride that acted as redox mediators and the reaction was mainly affected by the chloride concentration (c(NaCl)) and applied current density (I(appl)). Full and quick removal of 0.50 microg/ml MC-RR in solution was achieved when the operating conditions of c(NaCl) and I(appl) were 20mM and 46.3 mA/cm(2), or 35 mM and 18.2 mA/cm(2) respectively. The kinetics for MC-RR degradation followed a pesudo-first order reaction in most cases, indicating the process was under mass transfer control. As a result of its excellent performance, the BDD technology could be considered as a promising alternative to promote the degradation of MC-RR than chlorination in drinking water supplies.

  14. A study of the continuum flux and the line structure in the IUE spectrum of Beta Lyrae

    NASA Technical Reports Server (NTRS)

    Aydin, C.; Engin, S.; Brandi, E.; Ferrer, O. E.; Hack, M.

    1988-01-01

    A study of the available archival IUE images of Beta Lyrae has led to the following results: (1) for lambda in the range of 1250 - 1500 A, the eclipse depth at second conjunction is slightly larger than the eclipse depth at primary conjunction; they are equal at about 1670 A; (2) the profiles of the resonance lines of SiIV (and the same seems to be true for NV and CIV) can be described as composite, formed by the superposition of a stationary P Cygni profile that suggests a velocity of approach of -170 km/s and a broad, less strong, emission that seems to yield a velocity distribution in antiphase with the velocity curve of the B8 II component of the system; and (3) the emission lines of the intercombination doublet of semiforbidden N II at about 2140 A suggest a velocity of about -130 km/s. The interpretation of the latter composite profile appears similar to the one suggested by Sahade (1966) to describe H-alpha and He I 5876 and He I 6678, and by Batten and Sahade (1973) to describe H-alpha.

  15. The Outer Galactic Halo As Probed By RR Lyr Stars From the Palomar Transient Facility + Keck

    NASA Astrophysics Data System (ADS)

    Cohen, Judith; Sesar, Branimir; Banholzer, Sophianna

    2016-08-01

    We present initial results from our study of the outer halo of the Milky Way using a large sample of RR Lyr(ab) variables datamined from the archives of the Palomar Transient Facility. Of the 464 RR Lyr in our sample with distances exceeding 50 kpc, 62 have been observed spectroscopically at the Keck Observatory. vr and σ(vr ) are given as a function of distance between 50 and 110 kpc, and a very preliminary rather low total mass for the Milky Way out to 110 kpc of ~7+/-1.5×1011 M ⊙ is derived from our data.

  16. Mechanism of blood pressure and R-R variability: insights from ganglion blockade in humans

    PubMed Central

    Zhang, Rong; Iwasaki, Kenichi; Zuckerman, Julie H; Behbehani, Khosrow; Crandall, Craig G; Levine, Benjamin D

    2002-01-01

    Spontaneous blood pressure (BP) and R-R variability are used frequently as ‘windows’ into cardiovascular control mechanisms. However, the origin of these rhythmic fluctuations is not completely understood. In this study, with ganglion blockade, we evaluated the role of autonomic neural activity versus other ‘non-neural’ factors in the origin of BP and R-R variability in humans. Beat-to-beat BP, R-R interval and respiratory excursions were recorded in ten healthy subjects (aged 30 ± 6 years) before and after ganglion blockade with trimethaphan. The spectral power of these variables was calculated in the very low (0.0078-0.05 Hz), low (0.05-0.15 Hz) and high (0.15-0.35 Hz) frequency ranges. The relationship between systolic BP and R-R variability was examined by cross-spectral analysis. After blockade, R-R variability was virtually abolished at all frequencies; however, respiration and high frequency BP variability remained unchanged. Very low and low frequency BP variability was reduced substantially by 84 and 69 %, respectively, but still persisted. Transfer function gain between systolic BP and R-R interval variability decreased by 92 and 88 % at low and high frequencies, respectively, while the phase changed from negative to positive values at the high frequencies. These data suggest that under supine resting conditions with spontaneous breathing: (1) R-R variability at all measured frequencies is predominantly controlled by autonomic neural activity; (2) BP variability at high frequencies (> 0.15 Hz) is mediated largely, if not exclusively, by mechanical effects of respiration on intrathoracic pressure and/or cardiac filling; (3) BP variability at very low and low frequencies (< 0.15 Hz) is probably mediated by both sympathetic nerve activity and intrinsic vasomotor rhythmicity; and (4) the dynamic relationship between BP and R-R variability as quantified by transfer function analysis is determined predominantly by autonomic neural activity rather than

  17. Mechanisms underlying very-low-frequency RR-interval oscillations in humans

    NASA Technical Reports Server (NTRS)

    Taylor, J. A.; Carr, D. L.; Myers, C. W.; Eckberg, D. L.

    1998-01-01

    BACKGROUND: Survival of post-myocardial infarction patients is related inversely to their levels of very-low-frequency (0.003 to 0.03 Hz) RR-interval variability. The physiological basis for such oscillations is unclear. In our study, we used blocking drugs to evaluate potential contributions of sympathetic and vagal mechanisms and the renin-angiotensin-aldosterone system to very-low-frequency RR-interval variability in 10 young healthy subjects. METHODS AND RESULTS: We recorded RR intervals and arterial pressures during three separate sessions, with the patient in supine and 40 degree upright tilt positions, during 20-minute frequency (0.25 Hz) and tidal volume-controlled breathing after intravenous injections: saline (control), atenolol (0.2 mg/kg, beta-adrenergic blockade), atropine sulfate (0.04 mg/kg, parasympathetic blockade), atenolol and atropine (complete autonomic blockade), and enalaprilat (0.02 mg/kg, ACE blockade). We integrated fast Fourier transform RR-interval spectral power at very low (0.003 to 0.03 Hz), low (0.05 to 0. 15 Hz), and respiratory (0.2 to 0.3 Hz) frequencies. Beta-adrenergic blockade had no significant effect on very-low- or low-frequency RR-interval power but increased respiratory frequency power 2-fold. ACE blockade had no significant effect on low or respiratory frequency RR-interval power but modestly (approximately 21%) increased very-low-frequency power in the supine (but not upright tilt) position (P<0.05). The most profound effects were exerted by parasympathetic blockade: Atropine, given alone or with atenolol, abolished nearly all RR-interval variability and decreased very-low-frequency variability by 92%. CONCLUSIONS: Although very-low-frequency heart period rhythms are influenced by the renin-angiotensin-aldosterone system, as low and respiratory frequency RR-interval rhythms, they depend primarily on the presence of parasympathetic outflow. Therefore the prognostic value of very-low-frequency heart period oscillations may

  18. Prediction of left ventricular peak ejection velocity by preceding and prepreceding RR intervals in atrial fibrillation: a new method to adjust the influence between two intervals.

    PubMed Central

    Ko, Hong Sook; Lee, Kwang Je; Kim, Sang Wook; Kim, Tae Ho; Kim, Chee Jeong; Ryu, Wang Seong

    2002-01-01

    In atrial fibrillation, cardiac performance is dependent on both preceding RR (RR-1) and prepreceding RR (RR-2) intervals. However, relative contributions were not well defined. Left ventricular outflow peak ejection velocity (Vpe) was measured by echocardiography from 21 patients. The relation between RR-1 and Vpe could be divided into two zones; steep slope in short RR-1 intervals (< or =0.5 sec) and plateau in long RR-1 intervals (> 0.5 sec). RR-2 had a weak negative association with Vpe. The mean squared correlation coefficient (r2) between RR-2 and Vpe was 0.15 +/-0.13 and improved to 0.29+/-0.21 (p<0.001), when coordinates with RR-1 < or =0.5 sec were excluded. The RR-1 was positively associated with Vpe. The mean r2 between RR-1 and Vpe was 0.52+/-0.17 and improved to 0.72+/-0.11 (p<0.001), when adjusted by RR-2. Simple linear regression analysis showed that mean RR interval, age, fractional shortening (FS), and mean peak velocity were negatively correlated with modified r2 between RR-2 and Vpe. Multiple stepwise regression analysis revealed that mean RR interval (r2=0.32) and FS (r2=0.16) were significant. In summary, simple modification could improve the relationship of both RR-1 and RR-2 with cardiac performance. RR-2 might play a more role in cardiac performance than previously expected, and when cardiac function was impaired. PMID:12482995

  19. 76 FR 64283 - Airworthiness Directives; Rolls-Royce plc (RR) Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-18

    ... proposed AD. Discussion On August 25, 2008, we issued AD 2008-18-08, Amendment 39-15665 (73 FR 52201... Was Issued Since we issued AD 2008-18-08, (73 FR 52201, September 9, 2008), RR reports that they have... and Procedures (44 FR 11034, February 26, 1979), (3) Will not affect intrastate aviation in...

  20. Toxicological Review of Cyanobacterial Toxins: Microcystins Lr, Rr, Yr and La (External Review Draft)

    EPA Science Inventory

    The National Center for Environmental Assessment has prepared the Toxicological Reviews of Cyanobacterial Toxins: Anatoxin-a, Cylindrospermopsin and Microcystins (LR, RR, YR and LA) as a series of dose-response assessments to support the health assessment of unregulated contamina...

  1. 77 FR 27085 - R.R. Donnelley, Inc., Bloomsburg, PA; Notice of Negative Determination on Reconsideration

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-08

    ... Employment and Training Administration R.R. Donnelley, Inc., Bloomsburg, PA; Notice of Negative Determination... Register on February 21, 2012 (77 FR 9972). The workers are engaged in employment related to the production.... The initial investigation resulted in a negative determination based on the findings that the...

  2. Stability of UV exposed RR-P3BT films by spectroscopic ellipsometry

    SciTech Connect

    Diware, Mangesh S.; Byun, J. S.; Hwang, S. Y.; Kim, T. J.; Kim, Y. D.

    2013-02-05

    Stability of regioregular poly(3-butylthiophene) (RR-P3BT) films under irradiation of ultra-violet (UV) light has been studied by spectroscopic ellipsometry at room temperature. Consistent decrease in dielectric function with UV exposure time showed the degree of degradation of polymer. This work suggests that, protective methods are mandatory to use this kind of material in optical devices.

  3. Photometric study of two β Lyr-type binaries: DD Aqr and RR Lep

    NASA Astrophysics Data System (ADS)

    Erdem, A.; Öztürk, O.

    2016-10-01

    This paper presents detailed analysis of photometric observations of two eclipsing binary systems, DD Aqr and RR Lep. The V light curve of the neglected binary star DD Aqr from the All Sky Automated Survey was solved for the first time. The 1982-1987 UBV light curves of RR Lep from Vyas and Abhyankar (1989) were re-analysed. The final solutions give these two β Lyr-type binary stars as having near contact configurations in which the secondary components almost fill their Roche limiting lobes. Using O-C residuals formed by the updated minima times, orbital period changes of the systems were analysed. The O-C diagram of DD Aqr displays a cyclic variation, while that of RR Lep shows a quasi-sinusoidal variation superimposed on a downward parabolic form. The parabolic variation, which suggests a secular orbital period decrease in RR Lep, was interpreted in terms of the combined effect of mass transfer and loss. The cyclic O-C variations were interpreted in terms of the light travel time effect due to unseen components in these two systems. The absolute parameters of the components of the systems were estimated, and their present evolutionary status is also discussed.

  4. "D.L.&W. R.R. Profile for New Tunnel Through Bergen Hill" Plan ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    "D.L.&W. R.R. Profile for New Tunnel Through Bergen Hill" Plan Sheet. December 1, 1905. On file at New Jersey Transit Corporation Headquarters, Newark, New Jersey - Delaware, Lackawanna & Western Railroad, South Bergen Tunnel, Jersey City, Hudson County, NJ

  5. 16. The Baltimore & Ohio R.R System, Division BaltimoreEast, Bridge ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. The Baltimore & Ohio R.R System, Division Baltimore-East, Bridge No 13-A, Branch Philadelphia. Baltimore: Office of Engineer of Bridges, 1945. Copy of drawing located at the Baltimore County Department of Public Works, Towson, Maryland. - Allender Road Bridge, Spanning CSX Transportation railroad tracks at Allender Road, White Marsh, Baltimore County, MD

  6. 15. 'Southern Pacific R.R., One 236'0' Bet. End Pins S. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. 'Southern Pacific R.R., One 236'-0' Bet. End Pins S. Tr. Thro'. Draw Bridge over Sacramento River at Tehama, The Phoenix Bridge Co., Phoenixville, Pa., Jan'y 19th 98, Dwg. 585.' - Southern Pacific Railroad Shasta Route, Bridge No. 210.52, Milepost 210.52, Tehama, Tehama County, CA

  7. Stability of UV exposed RR-P3BT films by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Diware, Mangesh S.; Byun, J. S.; Hwang, S. Y.; Kim, T. J.; Kim, Y. D.

    2013-02-01

    Stability of regioregular poly(3-butylthiophene) (RR-P3BT) films under irradiation of ultra-violet (UV) light has been studied by spectroscopic ellipsometry at room temperature. Consistent decrease in dielectric function with UV exposure time showed the degree of degradation of polymer. This work suggests that, protective methods are mandatory to use this kind of material in optical devices.

  8. Fundamental relations between short-term RR interval and arterial pressure oscillations in humans

    NASA Technical Reports Server (NTRS)

    Taylor, J. A.; Eckberg, D. L.

    1996-01-01

    BACKGROUND: One of the principal explanations for respiratory sinus arrhythmia is that it reflects arterial baroreflex buffering of respiration-induced arterial pressure fluctuations. If this explanation is correct, then elimination of RR interval fluctuations should increase respiratory arterial pressure fluctuations. METHODS AND RESULTS: We measured RR interval and arterial pressure fluctuations during normal sinus rhythm and fixed-rate atrial pacing at 17.2+/-1.8 (SEM) beats per minute greater than the sinus rate in 16 healthy men and 4 healthy women, 20 to 34 years of age. Measurements were made during controlled-frequency breathing (15 breaths per minute or 0.25 Hz) with subjects in the supine and 40 degree head-up tilt positions. We characterized RR interval and arterial pressure variabilities in low-frequency (0.05 to 0.15 Hz) and respiratory-frequency (0.20 to 0.30 Hz) ranges with fast Fourier transform power spectra and used cross-spectral analysis to determine the phase relation between the two signals. As expected, cardiac pacing eliminated beat-to-beat RR interval variability. Against expectations, however, cardiac pacing in the supine position significantly reduced arterial pressure oscillations in the respiratory frequency (systolic, 6.8+/-1.8 to 2.9 +/-0.6 mm Hg2/Hz, P=.017). In contrast, cardiac pacing in the 40 degree tilt position increased arterial pressure variability (systolic, 8.0+/-1.8 to 10.8 +/-2.6, P=.027). Cross-spectral analysis showed that 40 degree tilt shifted the phase relation between systolic pressure and RR interval at the respiratory frequency from positive to negative (9 +/-7 degrees versus -17+/-11 degrees, P=.04); that is, in the supine position, RR interval changes appeared to lead arterial pressure changes, and in the upright position, RR interval changes appeared to follow arterial pressure changes. CONCLUSIONS: These results demonstrate that respiratory sinus arrhythmia can actually contribute to respiratory arterial

  9. RB virus: a strain of Friend virus that produces a 'Friend virus-like' disease in Fv-2rr mice.

    PubMed

    Geib, R W; Seaward, M B; Stevens, M L; Cho, C L; Majumdar, M

    1989-10-01

    RB virus is a newly derived strain of Friend virus that was adapted to produce a 'Friend-like' disease in mice that are genetically resistant to wild-type Friend virus. RB virus was produced by passing high titers of the wild-type Friend virus (Lilly-Steeves polycythemia-producing strain) through adult Fv-2rr mice. Titration of the defective spleen focus-forming virus indicated RB virus infected similar numbers of Fv-2ss or Fv-2rr target cells. Analysis of the spleens from mice infected with RB virus indicated that RB induced the early stage of Friend disease (erythroid proliferation) in both Fv-2rr and Fv-2ss mice. Fv-2ss mice infected with RB virus developed the classical Friend disease within 3 weeks. In contrast, the percentage of Fv-2rr mice developing the 'Friend-like' disease after infection with RB virus never exceeded 60%. The latency period of RBV in Fv-2rr mice was strain dependent. D2.R16 (Fv-2rr) developed the syndrome more rapidly than C57BL/6 (Fv-2rr). RB virus retained the capacity to transform erythroprogenitor cells from both Fv-2ss and Fv-2rr animals. Cells infected with RB virus consistently produced a modified SFFV envelope protein, gp48.

  10. The Use of TaBoRR as a Heavy Oil Upgrader

    SciTech Connect

    Lee Brecher; Charles Mones

    2009-02-05

    Preliminary testing has shown that Western Research Institute's (WRI) Tank Bottom Recovery and Remediation (TaBoRR{reg_sign}) technology shows promise for heavy oil upgrading. Approximately 70 to 75 wt% of a Canadian Cold Lake bitumen feed was converted to a partially upgraded overhead product that could be transported directly by pipeline or blended with the parent bitumen to produce transportable crude. TaBoRR{reg_sign} was originally developed to remediate tank bottom wastes by producing a distillate product and solid waste. TaBoRR{reg_sign}'s processing steps include breaking a water-oil emulsion, recovering a light hydrocarbon fraction by distillation in a stripper unit, and pyrolyzing the residua reducing it to additional overhead and a benign coke for disposal. Cold Lake bitumen was tested in WRI's bench-scale equipment to evaluate the potential use of TaBoRR{reg_sign} technology for heavy oil upgrading to produce a stable, partially (or fully) upgraded product that will allow diluent-reduced or diluent-free transportation of bitumen or ultra-heavy crudes to market. Runs were conducted at temperatures of low, intermediate and high severity in the stripper to produce stripper overhead and bottoms. The bottoms from each of these runs were processed further in a 6-inch screw pyrolyzer to produce pyrolyzer overhead for blending with the corresponding stripper overheads. Proceeding in this fashion yielded three partially upgraded crudes. The products from TaBoRR{reg_sign} processing, the parent bitumen, and bitumen blends were subjected to stability and compatibility testing at the National Centre for Upgrading Technology (NCUT). Chemical analyses of the overhead product blends have met pipeline specifications for viscosity and density; however the bromine number does not, which might indicate the need for mild hydrotreating. Storage stability tests showed the blends to be stable. The blends were also soluble and compatible with most other Alberta crudes.

  11. 3D τ RR -minimization in AdS4 gauged supergravity

    NASA Astrophysics Data System (ADS)

    Amariti, Antonio; Gnecchi, Alessandra

    2016-07-01

    In this paper we propose the identification in AdS4 N = 2 gauged supergravity of the coefficient τRR of 3D N = 2 SCFTs. We constrain the structure of this function in supergravity by combining the results from unitarity, holography and localization. We show that our conjectured function is minimized by the exact R-charge, corresponding to a gravitational attractor for the scalars of special geometry. We identify this mechanism with the supergravity dual of τ RR -minimization. We check this proposal in ABJM model, comparing with expectations from localization and AdS/CFT duality. We comment also on possible relations with black hole microstates counting, recently obtained from application of localization techniques.

  12. Exploring the use of fuzzy logic models to describe the relation between SBP and RR values.

    PubMed

    Gouveia, Sónia; Brás, Susana

    2012-01-01

    In this work, fuzzy logic based models are used to describe the relation between systolic blood pressure (SBP) and tachogram (RR) values as a function of the SBP level. The applicability of these methods is tested using real data in Lying (L) and Standing (S) conditions and generated surrogate data. The results indicate that fuzzy models exhibit a similar performance in both conditions, and their performance is significantly higher with real data than with surrogate data. These results point out the potential of a fuzzy logic approach to model properly the relation between SBP and RR values. As a future work, it remains to assess the clinical impact of these findings and inherent repercussion on the estimation of time domain baroreflex sensitivity indices.

  13. Evaluation of repolarization dynamics using the QT-RR regression line slope and intercept relationship during 24-h Holter ECG.

    PubMed

    Fujiki, Akira; Yoshioka, Ryozo; Sakabe, Masao

    2015-03-01

    QT-RR linear regression consists of two parameters, slope and intercept, and the aim of this study was to evaluate repolarization dynamics using the QT-RR linear regression slope and intercept relationship during 24-h Holter ECG. This study included 466 healthy subjects (54.6 ± 14.6 years; 200 men and 266 women) and 17 patients with ventricular arrhythmias, consisted of 10 patients with idiopathic ventricular fibrillation (IVF) and 7 patients with torsades de pointes (TDP). QT and RR intervals were measured from ECG waves based on a 15-s averaged ECG during 24-h Holter recording using an automatic QT analyzing system. The QT interval dependence on the RR interval was analyzed using a linear regression line for each subject ([QT] = A[RR] + B; where A is the slope and B is the y-intercept). The slope of the QT-RR regression line in healthy subjects was significantly greater in women than in men (0.185 ± 0.036 vs. 0.161 ± 0.033, p < 0.001) and the intercept was significantly smaller in women than in men (0.229 ± 0.028 vs. 0.240 ± 0.027, p < 0.001). A scatter diagram of the QT-RR regression line slope and intercept among healthy subjects demonstrated a statistically significant negative correlation (B = -0.62A + 0.34, r = -0.79). Distribution of both scatter diagrams of the slope and the intercept of the QT-RR regression line in patients with IVF and TDP was different from healthy subjects (left corner for IVF and upward shift for TDP). The slope and intercept relationship of the QT-RR linear regression line based on 24-h Holter ECG may become a simple useful marker for abnormality of ventricular repolarization dynamics.

  14. The RR1 gene of herpes simplex virus type 1 is uniquely trans activated by ICP0 during infection.

    PubMed Central

    Desai, P; Ramakrishnan, R; Lin, Z W; Osak, B; Glorioso, J C; Levine, M

    1993-01-01

    As has been demonstrated for herpes simplex virus type 2, we show in this report that the herpes simplex virus type 1 ribonucleotide reductase large subunit (RR1) gene is trans activated in transient transfection assays by VP16 and ICP0 but not by ICP4. Deletion analysis demonstrated that responsiveness to induction to VP16 resides in an octamer/TAATGARAT sequence of the RR1 promoter and that the TATA box alone is sufficient to provide induction by ICP0. The induction of the RR1 gene by ICP0 but not by ICP4 suggested that it might be possible to identify the cis-acting element(s) responsive to ICP4 in an ICP4-inducible promoter. To this end, a series of chimeric promoters containing various portions of the regulatory sequences of the RR1 promoter and thymidine kinase (TK) promoter were constructed. The TK promoter is trans activated by both ICP0 and ICP4 in transient transfection assays and by ICP4 in infection. The data show that replacing the RR1 TATA region with the TK TATA region permits ICP4 inducibility even if the rest of the RR1 promoter elements remain intact. To test whether the RR1 gene is induced by ICP0 during infection, four mutant viruses were constructed. (i) TAATGARAT+ has the wild-type RR1 promoter driving chloramphenicol acetyltransferase (CAT) and the RR2 promoter driving the lacZ gene. The RR2 gene codes for the small subunit of the ribonucleotide reductase and is expressed as a beta gene. (ii) TAATGARAT- has a triple-base change in the octamer/TAATGARAT element which renders it unresponsive to VP16 trans activation, eliminating that portion of the activation of the RR1 gene. (iii) TAATGARAT- delta alpha 0 has a deletion of the alpha 0 gene. (iv) TAATGARAT- delta alpha 4 has a deletion of the alpha 4 gene. Infections were carried out in Vero cells at a multiplicity of infection of 10 per cell; cells were assayed for CAT and beta-galactosidase (beta-Gal) activities and for virus yields. The first two infections gave strong CAT and beta

  15. Alignment of R-R interval signals using the circadian heart rate rhythm.

    PubMed

    Gayraud, Nathalie T H; Manis, George

    2015-01-01

    R-R interval signals that come from different subjects are regularly aligned and averaged according to the horological starting time of the recordings. We argue that the horological time is a faulty alignment criterion and provide evidence in the form of a new alignment method. Our main motivation is that the human heart rate (HR) rhythm follows a circadian cycle, whose pattern can vary among different classes of people. We propose two novel alignment algorithms that consider the HR circadian rhythm, the Puzzle Piece Alignment Algorithm (PPA) and the Event Based Alignment Algorithm (EBA). First, we convert the R-R interval signal into a series of time windows and compute the mean HR per window. Then our algorithms search for matching circadian patterns to align the signals. We conduct experiments using R-R interval signals extracted from two databases in the Physionet Data Bank. Both algorithms are able to align the signals with respect to the circadian rhythmicity of HR. Furthermore, our findings confirm the presence of more than one pattern in the circadian HR rhythm. We suggest an automatic classification of signals according to the three most prominent patterns. PMID:26737009

  16. Contributions of tidal lung inflation to human R-R interval and arterial pressure fluctuations.

    PubMed

    Koh, J; Brown, T E; Beightol, L A; Eckberg, D L

    1998-01-19

    We studied the effects of mechanical lung inflation on respiratory frequency R-R interval and arterial pressure fluctuations in nine healthy young adults undergoing elective orthopedic surgery. We conducted this research to define the contribution of pulmonary and thoracic stretch receptor input to respiratory sinus arrhythmia. We compared fast Fourier transform spectral power during three modes of ventilation: (1) spontaneous, frequency-controlled (0.25 Hz) breathing, (2) intermittent positive pressure ventilation (0.25 Hz, with a tidal volume of 8 ml/kg) and (3) high frequency jet ventilation (5.0 Hz, 2.5 kg/cm2), after sedation and vecuronium paralysis. Mean R-R intervals, arterial pressures and arterial blood gas levels were comparable during all three breathing conditions. Respiratory frequency systolic pressure spectral power was comparable during spontaneous breathing and conventional mechanical ventilation, but was significantly reduced during high frequency jet ventilation (P < 0.05). Respiratory frequency R-R interval spectral power (used as an index of respiratory sinus arrhythmia) declined dramatically with sedation and muscle paralysis (P < 0.05), but was greater during conventional mechanical, than high frequency jet ventilation (P < 0.05). These results suggest that although phasic inputs from pulmonary and thoracic stretch receptors make a statistically significant contribution to respiratory sinus arrhythmia, that contribution is small.

  17. Contributions of tidal lung inflation to human R-R interval and arterial pressure fluctuations

    NASA Technical Reports Server (NTRS)

    Koh, J.; Brown, T. E.; Beightol, L. A.; Eckberg, D. L.

    1998-01-01

    We studied the effects of mechanical lung inflation on respiratory frequency R-R interval and arterial pressure fluctuations in nine healthy young adults undergoing elective orthopedic surgery. We conducted this research to define the contribution of pulmonary and thoracic stretch receptor input to respiratory sinus arrhythmia. We compared fast Fourier transform spectral power during three modes of ventilation: (1) spontaneous, frequency-controlled (0.25 Hz) breathing, (2) intermittent positive pressure ventilation (0.25 Hz, with a tidal volume of 8 ml/kg) and (3) high frequency jet ventilation (5.0 Hz, 2.5 kg/cm2), after sedation and vecuronium paralysis. Mean R-R intervals, arterial pressures and arterial blood gas levels were comparable during all three breathing conditions. Respiratory frequency systolic pressure spectral power was comparable during spontaneous breathing and conventional mechanical ventilation, but was significantly reduced during high frequency jet ventilation (P < 0.05). Respiratory frequency R-R interval spectral power (used as an index of respiratory sinus arrhythmia) declined dramatically with sedation and muscle paralysis (P < 0.05), but was greater during conventional mechanical, than high frequency jet ventilation (P < 0.05). These results suggest that although phasic inputs from pulmonary and thoracic stretch receptors make a statistically significant contribution to respiratory sinus arrhythmia, that contribution is small.

  18. Alignment of R-R interval signals using the circadian heart rate rhythm.

    PubMed

    Gayraud, Nathalie T H; Manis, George

    2015-01-01

    R-R interval signals that come from different subjects are regularly aligned and averaged according to the horological starting time of the recordings. We argue that the horological time is a faulty alignment criterion and provide evidence in the form of a new alignment method. Our main motivation is that the human heart rate (HR) rhythm follows a circadian cycle, whose pattern can vary among different classes of people. We propose two novel alignment algorithms that consider the HR circadian rhythm, the Puzzle Piece Alignment Algorithm (PPA) and the Event Based Alignment Algorithm (EBA). First, we convert the R-R interval signal into a series of time windows and compute the mean HR per window. Then our algorithms search for matching circadian patterns to align the signals. We conduct experiments using R-R interval signals extracted from two databases in the Physionet Data Bank. Both algorithms are able to align the signals with respect to the circadian rhythmicity of HR. Furthermore, our findings confirm the presence of more than one pattern in the circadian HR rhythm. We suggest an automatic classification of signals according to the three most prominent patterns.

  19. Biodegradation of microcystin-LR and-RR by a novel microcystin-degrading bacterium isolated from Lake Taihu.

    PubMed

    Yang, Fei; Zhou, Yuanlong; Sun, Rongli; Wei, Haiyan; Li, Yunhui; Yin, Lihong; Pu, Yuepu

    2014-06-01

    Microcystin-LR (MC-LR) and microcystin-RR (MC-RR) are the two most common microcystins (MCs) present in fresh water posing a direct threat to public health because of their hepatotoxicity. A novel MC-degrading bacterium designated MC-LTH1 capable of degrading MC-LR and -RR was isolated, and the degradation rates and mechanisms of MC-LR and -RR for this bacterium were investigated. The bacterium was identified as Bordetella sp. and shown to possess a homologous mlrA gene responsible for degrading MCs. To the best of our knowledge, this is the first report of mlrA gene detection in Bordetella species. MC-LR and -RR were completely degraded separately at rates of 0.31 mg/(L h) and 0.17 mg/(L h). However, the degradation rates of MC-LR and -RR decreased surprisingly to 0.27 mg/(L h) and 0.12 mg/(L h), respectively, when both of them were simultaneously present. Degradation products were identified by high performance liquid chromatography coupled with time-of-flight mass spectrometry. Adda (m/z 332.2215, C20H29NO3) commonly known as a final product of MC degradation by isolated bacteria was detected as an intermediate in this study. Linearized MC-LR (m/z 1013.5638, C49H76N10O13), linearized MC-RR (m/z 1056.4970, C49H77N13O13), and tetrapeptide (m/z 615.3394, C32H46N4O8) were also detected as intermediates. These results indicate that the bacterial strain MC-LTH1 is quite efficient for the detoxification of MC-LR and MC-RR, and possesses significant bioremediation potential.

  20. [PAIN MANAGEMENT IN PATIENTS OF RAPID RECOVERY (RR) PROGRAM IN TOTAL KNEE ARTHROPLASTY (TKA)].

    PubMed

    Marina Fernández, Rosa; Ginés Mateos, Gracia; Arco Pérez, Ma Carmen; Nuevo Gayoso, Montse; Faura Vendrell, Teresa

    2015-06-01

    Total knee arthroplasty (TKA) is a surgery consisting on the artificial joint replacement, due to a traumatic injury or a degenerative process or arthrosis. This surgery causes an important pain to patients, and sometimes affects negatively on their recovery. The choice of the prostheses will depend on the anatomical features of the patient and the surgeon criterion. The concept of a "rapid recovery surgery" was introduced in 1997 by Khelet and meant the beginning of the Fast Track model or the Rapid Recovery (RR) linked to an accelerated rehabilitation, an early discharge and the optimization of all the aspects of pre, intra and post-operative patient experience. Fast recovery is a surgical process which aims to achieve maximum autonomy of the patient through education, pain control and early mobilization. The key of the rapid recovery is to get the involvement of the patient thanks to the empowerment, which means a preoperative patient education that will help to reduce anxiety and it will make easier to engage in their own recovery. Furthermore the patient will take part of an effective post-operative physical therapy, using all the necessary tools to increase their ability to manage their own health problems. The empowerment of these patients is part of the Nursing Model in the Hospital Clinic de Barcelona (HCB), adopted by the Nursing Management in December of 2012. In Catalonia, until the start of the RR surgery, 14,132 interventions in 2008 where done by TKA conventional surgery, needing subsequent conventional hospitalization. This article describes the care and outcomes of nurse interventions, defined in the RR of TKA clinical way, which is focused on the pain's minimization and the impact on patients' mobilization. It was performed in a monographic unit from a tertiary-level hospital in Barcelona in 2013.

  1. Automatic identification of fetal breathing movements in fetal RR interval time series.

    PubMed

    Van Leeuwen, Peter; Voss, Anna; Cysarz, Dirk; Edelhäuser, Friedrich; Grönemeyer, Dietrich

    2012-03-01

    Fetal breathing movements are associated with respiratory sinus arrhythmia (RSA). We present an algorithm which processes RR interval time series in the time and frequency domain, identifying spectral peaks with characteristics consistent with fetal RSA. Tested on 50 data sets from the second and third trimester, the algorithm had a sensitivity of 96.1%, false positive rate 35.7%, false negative rate 3.9%. The characteristics of automatically and visually identified episodes were very similar and corresponded the expected changes over gestation. The method is suited for easy and reliable identification of fetal breathing movements.

  2. NF-κB plays a key role in microcystin-RR-induced HeLa cell proliferation and apoptosis.

    PubMed

    Chen, Liang; Zhang, Xin; Chen, Jun; Zhang, Xuezhen; Fan, Huihui; Li, Shangchun; Xie, Ping

    2014-09-01

    Microcystins (MCs) are well-known cyanobacterial toxins produced in eutrophic waters and can act as potential carcinogens and have caused serious risk to human health. However, pleiotropic even paradoxical actions of cells exposure to MCs have been reported, and the mechanisms of MC-induced tumorigenesis and apoptosis are still unknown. In this study, we performed the first comprehensive in vitro investigation on carcinogenesis associated with nuclear factor kappa B (NF-κB) and its downstream genes in HeLa cells (Human cervix adenocarcinoma cell line from epithelial cells) exposure to MC-RR. HeLa cells were treated with 0, 20, 40, 60, and 80 µg/mL MC-RR for 4, 8, 12, and 24 h. HeLa cells presented dualistic responses to different doses of MCs. CCK8 assay showed that MC-RR exposure evidently enhanced cell viability of HeLa cells at lower MCs doses. Cell cycle and apoptosis analysis revealed that lower MCs doses promoted G1/S transition and cell proliferation while higher doses of MCs induced apoptosis, with a dose-dependent manner. Electrophoretic mobility shift assay (EMSA) revealed that MC-RR could increase/decrease NF-κB activity at lower/higher MC-RR doses, respectively. Furthermore, the expression of NF-κB downstream target genes including c-FLIP, cyclinD1, c-myc, and c-IAP2 showed the same variation trend as NF-κB activity both at mRNA and protein levels, which were induced by lower doses of MC-RR and suppressed by higher doses. Our data verified for the first time that NF-κB pathway may mediate MC-induced cell proliferation and apoptosis and provided a better understanding of the molecular mechanism for potential carcinogenicity of MC-RR.

  3. XMM-Newton observations of RR Telescopii: evidence for wind signatures and shocked gas emission

    NASA Astrophysics Data System (ADS)

    González-Riestra, R.; Selvelli, P.; Cassatella, A.

    2013-08-01

    RR Telescopii is the prototype of the symbiotic novae class. Since its outburst in 1944, it has been slowly fading, and its emission-line spectrum has evolved significantly. In this paper we discuss XMM-Newton observations of RR Tel taken in April 2009. These are the first X-ray high-resolution spectra of this system, and they provide important information about the physical conditions of the emitting gas. We have estimated the temperature and the luminosity of the hot star to be 154 kK and 5000 L⊙, respectively, from the comparison of model atmospheres with the X-ray spectra. Normalisation of the models with the far ultraviolet flux leads to similar values. Both the shape of the low-resolution X-ray spectrum and the spectral diagnostics that make use of the emission lines present in the RGS spectrum indicate the existence of collisionally ionised gas. At least two components are present, with temperatures of ≈0.6 and 1.7 MK. The existence of a wind from the hot star is unequivocally confirmed by HST-STIS observations taken in 2000, which showed displaced absorption components for the N V 1240 Å and C IV 1550 Å doublets. These components have terminal velocities of the order of 400 km s-1, which is consistent with the temperature of the gas detected in X-rays.

  4. [Measurement of coefficient of variation of R-R interval in ECG for patients with impotence].

    PubMed

    Takasaki, N; Kotani, T; Miyazaki, S; Saitou, S

    1989-08-01

    The coefficient of variation (CV = SD/mean x 100) of the R-R interval in electrocardiogram (ECG) was measured as an indication of parasympathetic nerve function in patients with impotence. Of 762 patients 104 (13.6%) had a CV value lower than 2.0. The factors which led to the low CV value were evident in 50 patients (48%), i.e. diabetes mellitus in 26, side effects by antiulcer, antidepressant or antihypertensive agent in 16, renal failure in 1, alcoholism in 2 and age over 70 years old in 4. The possible factors of the low CV value, such as neurogenic, thyroid, cardiovascular and endocrine disorders were found in 12 patients (11.5%). In the remaining 42 patients (40.4%), CV value was decreased by unknown factors. Measurement of CV of R-R interval in ECG was safe and useful as a screening test for patients with impotence to detect the dysfunction of the parasympathetic nerve system.

  5. Optimization of Exopolysaccharide Production by Lactobacillus delbrueckii subsp. bulgaricus RR Grown in a Semidefined Medium

    PubMed Central

    Kimmel, Stacy A.; Roberts, Robert F.; Ziegler, Gregory R.

    1998-01-01

    The optimal fermentation temperature, pH, and Bacto-casitone (Difco Laboratories, Detroit, Mich.) concentration for production of exopolysaccharide by Lactobacillus delbrueckii subsp. bulgaricus RR in a semidefined medium were determined by using response surface methods. The design consisted of 20 experiments, 15 unique combinations, and five replications. All fermentations were conducted in a fermentor with a 2.5-liter working volume and were terminated when 90% of the glucose in the medium had been consumed. The population of L. delbrueckii subsp. bulgaricus RR and exopolysaccharide content were measured at the end of each fermentation. The optimum temperature, pH, and Bacto-casitone concentration for exopolysaccharide production were 38°C, 5, and 30 g/liter, respectively, with a predicted yield of 295 mg of exopolysaccharide/liter. The actual yield under these conditions was 354 mg of exopolysaccharide/liter, which was within the 95% confidence interval (217 to 374 mg of exopolysaccharide/liter). An additional experiment conducted under optimum conditions showed that exopolysaccharide production was growth associated, with a specific production at the endpoint of 101.4 mg/g of dry cells. Finally, to obtain material for further characterization, a 100-liter fermentation was conducted under optimum conditions. Twenty-nine grams of exopolysaccharide was isolated from centrifuged, ultrafiltered fermentation broth by ethanol precipitation. PMID:9464404

  6. A preprocessing tool for removing artifact from cardiac RR interval recordings using three-dimensional spatial distribution mapping.

    PubMed

    Stapelberg, Nicolas J C; Neumann, David L; Shum, David H K; McConnell, Harry; Hamilton-Craig, Ian

    2016-04-01

    Artifact is common in cardiac RR interval data that is recorded for heart rate variability (HRV) analysis. A novel algorithm for artifact detection and interpolation in RR interval data is described. It is based on spatial distribution mapping of RR interval magnitude and relationships to adjacent values in three dimensions. The characteristics of normal physiological RR intervals and artifact intervals were established using 24-h recordings from 20 technician-assessed human cardiac recordings. The algorithm was incorporated into a preprocessing tool and validated using 30 artificial RR (ARR) interval data files, to which known quantities of artifact (0.5%, 1%, 2%, 3%, 5%, 7%, 10%) were added. The impact of preprocessing ARR files with 1% added artifact was also assessed using 10 time domain and frequency domain HRV metrics. The preprocessing tool was also used to preprocess 69 24-h human cardiac recordings. The tool was able to remove artifact from technician-assessed human cardiac recordings (sensitivity 0.84, SD = 0.09, specificity of 1.00, SD = 0.01) and artificial data files. The removal of artifact had a low impact on time domain and frequency domain HRV metrics (ranging from 0% to 2.5% change in values). This novel preprocessing tool can be used with human 24-h cardiac recordings to remove artifact while minimally affecting physiological data and therefore having a low impact on HRV measures of that data.

  7. Relationship between the Initial Systolic Time Interval and RR-interval during an exercise stimulus measured with Impedance Cardiography

    NASA Astrophysics Data System (ADS)

    Hoekstra, Femke; Habers, Esther; Janssen, Thomas W. J.; Verdaasdonk, Rudolf M.; Meijer, Jan H.

    2010-04-01

    The Initial Systolic Time Interval (ISTI), obtained from the electrocardiogram and impedance cardiogram, is considered to be a measure for the time delay between the electrical and mechanical activity of the heart and reflects an active period of the heart cycle. The relationship between ISTI and the total heart cycle (RR-interval) was studied in three groups of young, healthy volunteers: low, moderately and highly trained subjects. The three groups were exposed to an exercise stimulus on a cycle ergometer with an increasing work load to increase the heart rate. ISTI was decreased with decreasing RR-interval. However, the relative proportion of ISTI, ISTI/RR, was found to increase with decreasing RR-interval. This relationship was found to be inversely proportional. The rate of this increase in ISTI/RR was significantly higher in highly trained subjects. Also, over the whole range of heart rates ISTI was longer in these subjects. It is concluded that ISTI can be used to evaluate cardiac performance during physical exercise non-invasively and in an extramural setting.

  8. Controlled Pd(0)/t Bu3P Catalyzed Suzuki Cross-Coupling Polymerization of AB-Type Monomers with ArPd(t Bu3P)X or Pd2(dba)3/t Bu3P/ArX as the Initiator

    DOE PAGES

    Zhang, Honghai; Xing, Chun-Hui; Hu, Qiao-Sheng; Hong, Kunlun

    2015-02-05

    The synthesis of well-defined and functionalized conjugated polymers, which are essential in the development of efficient organic electronics, through Suzuki cross-coupling polymerizations has been a challenging task. We developed controlled Pd(0)/t-Bu3P-catalyzed Suzuki cross-coupling polymerizations of AB-type monomers via the chain-growth mechanism with a series of in situ generated ArPd(t-Bu3P)X (X = I, Br, Cl) complexes as initiators. Among them, the combinations of Pd2(dba)3/t-Bu3P/p-BrC6H4I, Pd2(dba)3/t-Bu3P/p-BrC6H4CH2OH and Pd2(dba)3/t-Bu3P/p-PhCOC6H4Br were identified as highly robust initiator systems, resulting in polymers with predictable molecular weight and narrow polydispersity (PDI~1.13-1.20). In addition, Pd2(dba)3/t-Bu3P/p-BrC6H4CH2OH and Pd2(dba)3/t-Bu3P/p-PhCOC6H4Br initiator systems afforded functional polymers with >95% fidelity. Our results pavedmore » the road to access well-defined conjugated polymers, including conjugated polymers with complex polymer architectures such as block copolymers and branch copolymers.« less

  9. Controlled Pd(0)/t Bu3P Catalyzed Suzuki Cross-Coupling Polymerization of AB-Type Monomers with ArPd(t Bu3P)X or Pd2(dba)3/t Bu3P/ArX as the Initiator

    SciTech Connect

    Zhang, Honghai; Xing, Chun-Hui; Hu, Qiao-Sheng; Hong, Kunlun

    2015-02-05

    The synthesis of well-defined and functionalized conjugated polymers, which are essential in the development of efficient organic electronics, through Suzuki cross-coupling polymerizations has been a challenging task. We developed controlled Pd(0)/t-Bu3P-catalyzed Suzuki cross-coupling polymerizations of AB-type monomers via the chain-growth mechanism with a series of in situ generated ArPd(t-Bu3P)X (X = I, Br, Cl) complexes as initiators. Among them, the combinations of Pd2(dba)3/t-Bu3P/p-BrC6H4I, Pd2(dba)3/t-Bu3P/p-BrC6H4CH2OH and Pd2(dba)3/t-Bu3P/p-PhCOC6H4Br were identified as highly robust initiator systems, resulting in polymers with predictable molecular weight and narrow polydispersity (PDI~1.13-1.20). In addition, Pd2(dba)3/t-Bu3P/p-BrC6H4CH2OH and Pd2(dba)3/t-Bu3P/p-PhCOC6H4Br initiator systems afforded functional polymers with >95% fidelity. Our results paved the road to access well-defined conjugated polymers, including conjugated polymers with complex polymer architectures such as block copolymers and branch copolymers.

  10. Tribolium castaneum RR-1 Cuticular Protein TcCPR4 Is Required for Formation of Pore Canals in Rigid Cuticle

    PubMed Central

    Noh, Mi Young; Muthukrishnan, Subbaratnam; Kramer, Karl J.; Arakane, Yasuyuki

    2015-01-01

    Insect cuticle is composed mainly of structural proteins and the polysaccharide chitin. The CPR family is the largest family of cuticle proteins (CPs), which can be further divided into three subgroups based on the presence of one of the three presumptive chitin-binding sequence motifs denoted as Rebers-Riddiford (R&R) consensus sequence motifs RR-1, RR-2 and RR-3. The TcCPR27 protein containing the RR-2 motif is one of the most abundant CPs present both in the horizontal laminae and in vertical pore canals in the procuticle of rigid cuticle found in the elytron of the red flour beetle, Tribolium castaneum. Depletion of TcCPR27 by RNA interference (RNAi) causes both unorganized laminae and pore canals, resulting in malformation and weakening of the elytron. In this study, we investigated the function(s) of another CP, TcCPR4, which contains the RR-1 motif and is easily extractable from elytra after RNAi to deplete the level of TcCPR27. Transcript levels of the TcCPR4 gene are dramatically increased in 3 d-old pupae when adult cuticle synthesis begins. Immunohistochemical studies revealed that TcCPR4 protein is present in the rigid cuticles of the dorsal elytron, ventral abdomen and leg but not in the flexible cuticles of the hindwing and dorsal abdomen of adult T. castaneum. Immunogold labeling and transmission electron microscopic analyses revealed that TcCPR4 is predominantly localized in pore canals and regions around the apical plasma membrane protrusions into the procuticle of rigid adult cuticles. RNAi for TcCPR4 resulted in an abnormal shape of the pore canals with amorphous pore canal fibers (PCFs) in their lumen. These results support the hypothesis that TcCPR4 is required for achieving proper morphology of the vertical pore canals and PCFs that contribute to the assembly of a cuticle that is both lightweight and rigid. PMID:25664770

  11. Oscillations in the evaluation of fractal dimension of RR intervals time series.

    PubMed

    Muñoz Diosdado, A; Gálvez Coyt, G; Pérez Uribe, B M

    2010-01-01

    Previously, we have reported the presence of oscillations in the graphs we have used to evaluate the Higuchi's fractal dimension in RR intervals time series of congestive heart failure (CHF) patients in the sleep phase but these oscillations hardly appear in all the six hours of the awake phase. In this paper we report the same analysis for heart rate time series for different groups of healthy subjects; we are looking for the presence of this kind of oscillations in other situations. We analyzed all the time series in the Exaggerated Heart Rate Oscillations database of Physionet during two meditation techniques: volunteers with spontaneous breathing, subjects in meditation, volunteers in a metronomic breathing group and elite athletes. We have found oscillations in the graphs of the Higuchi's fractal dimension in the heart rate time series of subjects in meditation and metronomic breathing and this fact coincides with previous reported results.

  12. New Line Identifications in the Optical Spectrum of the Slow Nova RR Telescopii

    NASA Astrophysics Data System (ADS)

    McKenna, F. C.; Keenan, F. P.; Hambly, N. C.; Allende, C.; Aller, L. H.; Feibelman, W. A.

    1996-07-01

    The symbiotic nova RR~Telescopii has been observed with the 1.5m telescope of the Cerro Tololo Inter-American Observatory (CTIO), using the 1.5m Bench-Mounted Echelle Spectrograph (BME) in conjunction with a Tek CCD. It displays a rich emission line spectrum, ranging in excitation from O I to [Ni VIII]. The result is a list of 483 measured lines, with their suggested identifications, covering a range from 3430 A to 9320 A. Of these, only nine are unidentified, and 70 lines are catalogued that were not given in the original line list of Thackeray. We have also obtained absolute line intensities, which have been derived by comparing the high-resolution data with a flux calibrated low-resolution spectrum taken with the Cassegrain Spectrograph on the 1.0m at the CTIO.

  13. 7-Desmethyl-microcystin-RR, a hepatotoxin from a waterbloom of Microcystis aeruginosa.

    PubMed

    Martin, C; Weckesser, J; Ino, T; König, W A; Skulberg, O M

    1992-01-01

    A peptide toxin was isolated from a waterbloom of Microcystis aeruginosa from Lake Frøylandsvatn in Norway. The isolation procedure included liquid and solid phase extraction and reversed phase high performance liquid chromatography. Amino acid analysis yielded D-glutamic acid, D-erythro-beta-methylaspartic acid and D-alanine in equimolar and L-arginine in twofold molar ratios. The presence of dehydroalanine was confirmed by hydrogenation and subsequent amino acid analysis with combined gas liquid chromatography/mass spectrometry. Investigation of the toxin with fast atom bombardment mass spectrometry showed a nominal relative molecular mass of 1023. 3-Amino-9-methoxy-2,6,8-trimethyl-10-phenyl- 4,6-decadienoic acid (Adda) was identified by 1H NMR and 1H, 1H COSY spectroscopy. The structure of the toxin was elucidated as 7-desmethyl-microcystin-RR.

  14. Effects of particle characteristics on performance of RR5K PETN

    SciTech Connect

    Rogers, J.W. Jr.; Duncan, A.A.

    1982-06-01

    A particle characterization of production lots of RR5K PETN has been completed. Prediction models were derived which identify those particle characteristics which influence sensitivity and performance. Those factors which have a positive influence on threshold burst current were also found to have a positive influence on transit time. The models may be useful in screening new lots of PETN prior to test firing. In general, large distributions of shapes and sizes, with the larger particles being needle-like or elongated, lead to low threshold burst currents and short transit times. The threshold burst current was also found to be inversely proportional to the temperature at which the units were test fired.

  15. Using complexity metrics with R-R intervals and BPM heart rate measures

    PubMed Central

    Wallot, Sebastian; Fusaroli, Riccardo; Tylén, Kristian; Jegindø, Else-Marie

    2013-01-01

    Lately, growing attention in the health sciences has been paid to the dynamics of heart rate as indicator of impending failures and for prognoses. Likewise, in social and cognitive sciences, heart rate is increasingly employed as a measure of arousal, emotional engagement and as a marker of interpersonal coordination. However, there is no consensus about which measurements and analytical tools are most appropriate in mapping the temporal dynamics of heart rate and quite different metrics are reported in the literature. As complexity metrics of heart rate variability depend critically on variability of the data, different choices regarding the kind of measures can have a substantial impact on the results. In this article we compare linear and non-linear statistics on two prominent types of heart beat data, beat-to-beat intervals (R-R interval) and beats-per-min (BPM). As a proof-of-concept, we employ a simple rest-exercise-rest task and show that non-linear statistics—fractal (DFA) and recurrence (RQA) analyses—reveal information about heart beat activity above and beyond the simple level of heart rate. Non-linear statistics unveil sustained post-exercise effects on heart rate dynamics, but their power to do so critically depends on the type data that is employed: While R-R intervals are very susceptible to non-linear analyses, the success of non-linear methods for BPM data critically depends on their construction. Generally, “oversampled” BPM time-series can be recommended as they retain most of the information about non-linear aspects of heart beat dynamics. PMID:23964244

  16. Transgenic Overexpression of Aryl Hydrocarbon Receptor Repressor (AhRR) and AhR-Mediated Induction of CYP1A1, Cytokines, and Acute Toxicity

    PubMed Central

    Vogel, Christoph F.A.; Chang, W.L. William; Kado, Sarah; McCulloh, Kelly; Vogel, Helena; Wu, Dalei; Haarmann-Stemmann, Thomas; Yang, GuoXiang; Leung, Patrick S.C.; Matsumura, Fumio; Gershwin, M. Eric

    2016-01-01

    Background: The aryl hydrocarbon receptor repressor (AhRR) is known to repress aryl hydrocarbon receptor (AhR) signaling, but very little is known regarding the role of the AhRR in vivo. Objective: This study tested the role of AhRR in vivo in AhRR overexpressing mice on molecular and toxic end points mediated through a prototypical AhR ligand. Methods: We generated AhRR-transgenic mice (AhRR Tg) based on the genetic background of C57BL/6J wild type (wt) mice. We tested the effect of the prototypical AhR ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the expression of cytochrome P450 (CYP)1A1 and cytokines in various tissues of mice. We next analyzed the infiltration of immune cells in adipose tissue of mice after treatment with TCDD using flow cytometry. Results: AhRR Tg mice express significantly higher levels of AhRR compared to wt mice. Activation of AhR by TCDD caused a significant increase of the inflammatory cytokines Interleukin (IL)-1β, IL-6 and IL-10, and CXCL chemokines in white epididymal adipose tissue from both wt and AhRR Tg mice. However, the expression of IL-1β, CXCL2 and CXCL3 were significantly lower in AhRR Tg versus wt mice following TCDD treatment. Exposure to TCDD caused a rapid accumulation of neutrophils and macrophages in white adipose tissue of wt and AhRR Tg mice. Furthermore we found that male AhRR Tg mice were protected from high-dose TCDD-induced lethality associated with a reduced inflammatory response and liver damage as indicated by lower levels of TCDD-induced alanine aminotransferase and hepatic triglycerides. Females from both wt and AhRR Tg mice were less sensitive than male mice to acute toxicity induced by TCDD. Conclusion: In conclusion, the current study identifies AhRR as a previously uncharacterized regulator of specific inflammatory cytokines, which may protect from acute toxicity induced by TCDD. Citation: Vogel CF, Chang WL, Kado S, McCulloh K, Vogel H, Wu D, Haarmann-Stemmann T, Yang GX, Leung PS, Matsumura F

  17. 76 FR 68663 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-Trent 800 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-07

    ... published in the Federal Register on August 3, 2010 (75 FR 45560). That NPRM would have revised the TLM of... the previous NPRM (75 FR 45560, August 3, 2010), RR requested that we supersede existing AD 2003-16-18, Amendment 39-13271 (68 FR 49344, August 18, 2003). That AD currently requires a life limit for...

  18. 76 FR 40217 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-524 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-08

    ... Register published on April 11, 2000 (65 FR 19477-78). Authority for This Rulemaking Title 49 of the United... Procedures (44 FR 11034, February 26, 1979); and 3. Will not have a significant economic impact, positive or...; AD 2011-13-01] RIN 2120-AA64 Airworthiness Directives; Rolls-Royce plc (RR) RB211-524 Series...

  19. Microcystin-RR uptake and its effects on the growth of submerged macrophyte Vallisneria natans (lour.) hara.

    PubMed

    Yin, Liyan; Huang, Jiaquan; Li, Dunhai; Liu, Yongding

    2005-06-01

    Microcystins are hepatotoxins produced by many species of several cyanobacterial genera. Their toxic effects on animals and some terrestrial higher plants have been well studied, but their potential effects on the development of aquatic plant seedlings are not well known, and their uptake by aquatic plants is seldom reported. In our research the seeds and seedlings of the submerged macrophyte Vallisneria natans were exposed to different concentrations of microcystin-RR, which was purified with high-performance liquid chromatography (HPLC). The results indicated that microcystin-RR could accumulate differentially in the roots and leaves of V. natans seedlings. Toxin accumulation in the roots and leaves was time- and dose-dependent, with higher uptake detected in the roots. Growth and development detection revealed that V. natans was relatively insensitive to microcystin-RR at concentrations ranging from 0.0001 to 0.01 mg/L. However, when the toxin concentration was more than 0.01 mg/L, both the fresh weight and the longest leaf length of seedlings were significantly reduced after a 30-day treatment. The root and leaf numbers were significantly decreased when 10 mg/L of toxin was used. These results suggest that microcystin-RR can be taken up by V. natans, which subsequently will retard its development. PMID:15892062

  20. "D.L.&W. R.R. New Bergen Tunnel...Details of Shaft..." Plan Sheet. October ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    "D.L.&W. R.R. New Bergen Tunnel...Details of Shaft..." Plan Sheet. October 30, 1908. On file at New Jersey Transit Corporation Headquarters, Newark, New Jersey - Delaware, Lackawanna & Western Railroad, South Bergen Tunnel, Jersey City, Hudson County, NJ

  1. "D.L.&W. R.R. New Bergen Tunnel...Detail of Portal Masonry..." Plan Sheet. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    "D.L.&W. R.R. New Bergen Tunnel...Detail of Portal Masonry..." Plan Sheet. Revised December 22, 1906. On file at New Jersey Transit Corporation Headquarters, Newark, New Jersey - Delaware, Lackawanna & Western Railroad, South Bergen Tunnel, Jersey City, Hudson County, NJ

  2. "D.L.&W. R.R. New Bergen Tunnel...Detail of Open Cut Masonry..." Plan ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    "D.L.&W. R.R. New Bergen Tunnel...Detail of Open Cut Masonry..." Plan Sheet. Revised December 22, 1906. On file at New Jersey Transit Corporation Headquarters, Newark, New Jersey - Delaware, Lackawanna & Western Railroad, South Bergen Tunnel, Jersey City, Hudson County, NJ

  3. 76 FR 65997 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-535 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-25

    ... & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803. For information on the availability of this material at the FAA, call 781-238-7125. Examining the AD Docket You may examine the AD... (76 FR 30529, May 26, 2011), for all RR RB211-535E4-37, -535E4-B-37, -535E4-B- 75, and...

  4. Ectoparasite Raymondia lobulata infestation in relation to the reproductive cycle of its host--the greater false vampire bat Megaderma lyra.

    PubMed

    Sundari, Arasamuthu Arul; Bogdanowicz, Wieslaw; Varman, Durairaj Ragu; Marimuthu, Ganapathy; Rajan, Koilmani Emmanuvel

    2012-02-01

    To study variation of infestations by the bat fly Raymondia lobulata (Diptera: Streblidae) on the greater false vampire bat Megaderma lyra (Chiroptera: Megadermatidae), we captured individual bats at their day roost in the south of India and recorded their rate of infestation continuously for a year. All examined bats (n = 72 individuals, 202 captures) were infested with parasites (n = 3,008). However, the recorded intensity of infestation (range 1-33) was gender-related and statistically higher in females than in males (F(1, 200) = 304.45, P < 0.001). Furthermore, pregnant and lactating females had greater parasite loads than non-reproductive females and males (F(1, 63) = 23.34, P < 0.001 and F(1, 37) = 78.07, P < 0.001, respectively). No significant differences were observed between males either during mating and non-mating periods or breeding and non-breeding seasons. Analysis of the relationship between parasite infestation and the reproductive status of bats revealed that pregnant and lactating females with pups were more vulnerable hosts for parasites. Our results also suggest a well-developed coevolutionary strategy for synchronized reproduction within the host-parasite relationship and add to our understanding of how host sex and reproductive status shape the dynamics of parasitism.

  5. Carbonic anhydrase-related protein XI: structure of the gene in the greater false vampire bat (Megaderma lyra) compared with human and domestic pig.

    PubMed

    Porter, Calvin A; Hewett-Emmett, David; Tashian, Richard E

    2013-06-01

    Carbonic anhydrase-related protein XI (CA-RP XI) is a member of the α-carbonic anhydrase family (encoded by the gene CA-11), which has lost features of the active site required for enzymatic activity. Using PCR, we amplified CA-11 from genomic DNA of the bat Megaderma lyra. To elucidate the gene structure, we sequenced PCR products and compared their sequences with genomic and mRNA sequences known from human and domestic pig. We identified and sequenced eight introns in the bat CA-11. Five introns (introns 3-7) are located in identical or similar positions in other members of the vertebrate α-carbonic anhydrase gene family. Two 5' introns and one 3' intron are located in the regions of little or no sequence similarity with other members of the gene family. The low sequence similarity and additional introns suggest a separate evolutionary origin for the 5' and 3' portions of the CA-RP XI gene.

  6. Ectoparasite Raymondia lobulata infestation in relation to the reproductive cycle of its host--the greater false vampire bat Megaderma lyra.

    PubMed

    Sundari, Arasamuthu Arul; Bogdanowicz, Wieslaw; Varman, Durairaj Ragu; Marimuthu, Ganapathy; Rajan, Koilmani Emmanuvel

    2012-02-01

    To study variation of infestations by the bat fly Raymondia lobulata (Diptera: Streblidae) on the greater false vampire bat Megaderma lyra (Chiroptera: Megadermatidae), we captured individual bats at their day roost in the south of India and recorded their rate of infestation continuously for a year. All examined bats (n = 72 individuals, 202 captures) were infested with parasites (n = 3,008). However, the recorded intensity of infestation (range 1-33) was gender-related and statistically higher in females than in males (F(1, 200) = 304.45, P < 0.001). Furthermore, pregnant and lactating females had greater parasite loads than non-reproductive females and males (F(1, 63) = 23.34, P < 0.001 and F(1, 37) = 78.07, P < 0.001, respectively). No significant differences were observed between males either during mating and non-mating periods or breeding and non-breeding seasons. Analysis of the relationship between parasite infestation and the reproductive status of bats revealed that pregnant and lactating females with pups were more vulnerable hosts for parasites. Our results also suggest a well-developed coevolutionary strategy for synchronized reproduction within the host-parasite relationship and add to our understanding of how host sex and reproductive status shape the dynamics of parasitism. PMID:21923461

  7. Carbonic anhydrase-related protein XI: structure of the gene in the greater false vampire bat (Megaderma lyra) compared with human and domestic pig.

    PubMed

    Porter, Calvin A; Hewett-Emmett, David; Tashian, Richard E

    2013-06-01

    Carbonic anhydrase-related protein XI (CA-RP XI) is a member of the α-carbonic anhydrase family (encoded by the gene CA-11), which has lost features of the active site required for enzymatic activity. Using PCR, we amplified CA-11 from genomic DNA of the bat Megaderma lyra. To elucidate the gene structure, we sequenced PCR products and compared their sequences with genomic and mRNA sequences known from human and domestic pig. We identified and sequenced eight introns in the bat CA-11. Five introns (introns 3-7) are located in identical or similar positions in other members of the vertebrate α-carbonic anhydrase gene family. Two 5' introns and one 3' intron are located in the regions of little or no sequence similarity with other members of the gene family. The low sequence similarity and additional introns suggest a separate evolutionary origin for the 5' and 3' portions of the CA-RP XI gene. PMID:23417223

  8. The role of echolocation in the hunting of terrestrial prey--new evidence for an underestimated strategy in the gleaning bat, Megaderma lyra.

    PubMed

    Schmidt, S; Hanke, S; Pillat, J

    2000-10-01

    The observation that gleaning bats detect prey by its noises, together with difficulties in recording their faint sonar calls, have led some authors to conclude that gleaning bats may not use echolocation in certain hunting situations. In particular, it is conjectured that echolocation plays no role in the classification and tracking of prey. In the present study, we show that the gleaning bat, Megaderma lyra, is able to find silent and motionless prey on the ground. The significance of sonar for catching a variety of terrestrial prey is established in a standardized situation. Sonar calls were found to be emitted during all stages, i.e. approach, hovering above the prey, and return to the roost, of every hunting flight. The harmonic pattern of the calls differed significantly between these stages, calls with three or more prominent components prevailing during hovering. Bats identified prey and rejected dummies while hovering above them. During this stage, increased call rates and reduced call durations were found. Echolocation activity during, and the duration of, the hovering phase depended on prey type, in particular on prey movement. The prey-dependent shifts in sonar activity, the broadband call structure with an emphasis on higher harmonics, and a systematic shift of the calls' peak frequencies during hovering, are discussed as adaptations to identifying prey by sonar.

  9. Grain boundary engineering of powder-processed Ni-base superalloy RR1000

    NASA Astrophysics Data System (ADS)

    Detrois, Martin

    Grain boundary engineering (GBE) has been used to improve the properties of various polycrystalline materials by optimization of their grain boundary network. Traditional processing routes for GBE often require multiple iterations of cold work followed by short annealing cycles where each iteration imparts a modest increase in the fraction of special grain boundaries. Multiple iterations are then required to achieve sufficiently high fractions (>50%) that result in the improved properties. Thus, this GBE approach is not suitable for the fabrication of large, complex-shaped structures and leads to added manufacturing lead time and cost. In this investigation, the Ni-base superalloy RR1000 used as turbine discs in gas turbine engines manufactured by Rolls-Royce, was considered for GBE using alternative processing routes more suitable to the forging of Ni-base superalloy components. A preliminary study of the effects of hot deformation parameters closer to typical industrial processing revealed that the length fraction of Sigma3 boundaries increased from 35% to 52% following a single deformation/anneal cycle. Deformation parameters that resulted in strain accommodation via superplastic flow did not enhance the formation of Sigma3 boundaries upon annealing. Whereas deformation parameters that resulted in a dominant dislocation-based plasticity flow mechanism promoted the formation of annealing twins. Using misorientation maps and by estimating the stored strain energy from deformation, equations for the length fraction and density of Sigma3 boundaries were generated for high-temperature GBE of RR1000. The grain boundary characters obtained via high-temperature deformation, however, are less ideal than those resulting from traditional cold rolling. The underlying mechanisms responsible for the formation of Sigma3n boundaries during high-temperature GBE were further investigated. A larger starting grain size prior to deformation was found to be unfavorable to the

  10. [Primary Study on Predicting the Termination of Paroxysmal Atrial Fibrillation Based on a Novel RdR RR Intervals Scatter Plot].

    PubMed

    Lu, Hongwei; Zhang, Chenxi; Sun, Ying; Hao, Zhidong; Wang, Chunfang; Tian, Jiajia

    2015-08-01

    Predicting the termination of paroxysmal atrial fibrillation (AF) may provide a signal to decide whether there is a need to intervene the AF timely. We proposed a novel RdR RR intervals scatter plot in our study. The abscissa of the RdR scatter plot was set to RR intervals and the ordinate was set as the difference between successive RR intervals. The RdR scatter plot includes information of RR intervals and difference between successive RR intervals, which captures more heart rate variability (HRV) information. By RdR scatter plot analysis of one minute RR intervals for 50 segments with non-terminating AF and immediately terminating AF, it was found that the points in RdR scatter plot of non-terminating AF were more decentralized than the ones of immediately terminating AF. By dividing the RdR scatter plot into uniform grids and counting the number of non-empty grids, non-terminating AF and immediately terminating AF segments were differentiated. By utilizing 49 RR intervals, for 20 segments of learning set, 17 segments were correctly detected, and for 30 segments of test set, 20 segments were detected. While utilizing 66 RR intervals, for 18 segments of learning set, 16 segments were correctly detected, and for 28 segments of test set, 20 segments were detected. The results demonstrated that during the last one minute before the termination of paroxysmal AF, the variance of the RR intervals and the difference of the neighboring two RR intervals became smaller. The termination of paroxysmal AF could be successfully predicted by utilizing the RdR scatter plot, while the predicting accuracy should be further improved.

  11. Coefficient of variation of R-R intervals in severe brain damage.

    PubMed

    Nezu, A; Kimura, S; Kobayashi, T; Osaka, H; Uehara, S

    1996-01-01

    The coefficient of variation of R-R intervals (CVRR) was studied in 18 children having severe brain damage with a mean +/- standard deviation (s.d.) age of 8.4 +/- 5.9 years, who were divided into ten patients complicated with respiratory insufficiency (RI group) and eight patients with severe athetotic cerebral palsy (SA group). CVRR was obtained in the resting supine position, and was compared with that in 22 neurologically normal controls. CVRR in the RI group (mean +/- S.D., 2.19 +/- 1.28%) was significantly lower than that in controls (5.56 +/- 1.53%), while CVRR in the SA group (11.30 +/- 3.91%) was significantly higher than that in controls (both P < 0.01, ANOVA). In particular, the four patients with brain death showed extremely low CVRR of 1.00-1.29%. Since CVRR was 4.09% in the patient aged 4 years with birth injury of the upper cervical spinal cord causing absence of spontaneous respiration, the extremely low CVRR in patients with brain death may be directly related to brainstem dysfunction. The cause of the high CVRR in the SA group was not determined. Thus, CVRR may be useful for quantitative evaluation of severe neurological disorder.

  12. [Changes in autonomic nerve function during the normal menstrual cycle measured by the coefficient of variation of R-R intervals].

    PubMed

    Kondo, M; Hirano, T; Okamura, Y

    1989-05-01

    The purpose of this study was to determine if there is a change in autonomic nerve function during the menstrual cycle. The subjects were 20 females (average age 26.1 years +/- 4.6) with a normal menstrual cycle. The coefficient of variation of R-R intervals (CV R.R) was measured to investigate autonomic function in the menstrual, follicular, ovulatory, luteal, and premenstrual phases. Average CV R-R for all phases was 5.2 +/- 1.9%. And the CV R-R tended to be lower in those in their 30s than in those in their 20s. And no noticeable difference was seen in the CV R-R among the 5 phases of the menstrual cycle. On the other hand, the CV R-R of 11 females with premenstrual syndrome was low in the ovulatory, luteal and premenstrual phases. These results, which provide basic data for clinical use, suggest the following. (1) The age of subjects should be taken into consideration. (2) Changes in the CV R-R during the menstrual cycle are negligible. (3) However, in those showing symptoms associated with the menstrual cycle such as premenstrual syndrome, changes during the menstrual cycle should be taken into account. At the same time psychological changes in the subjects were evaluated by the following tests: Cornell Medical Index, Taylor's manifest anxiety scale, and Zung's self-rating depression scale. The results of these tests did not vary significantly during the menstrual cycle.

  13. Organ-dependent response in antioxidants, myoglobin and neuroglobin in goldfish (Carassius auratus) exposed to MC-RR under varying oxygen level.

    PubMed

    Okogwu, Okechukwu Idumah; Xie, Ping; Zhao, Yanyan; Fan, Huihui

    2014-10-01

    Cyanobacterial bloom, a common phenomenon nowadays often results in the depletion of dissolved oxygen (hypoxia) and releases microcystin-RR (MC-RR) in the water. Information on the combined effects of MC-RR and hypoxia on the goldfish is lacking, therefore, this study is aimed at evaluating the effect of two doses of MC-RR on the antioxidants and globin mRNA of goldfish under normoxia, hypoxia and reoxygenation. The result showed that MC-RR at both doses (50 and 200 μg kg(-1) body weight) significantly (p<0.05) induced superoxide dismutase activities in the liver and kidney but catalase activities and total antioxidant capacity were low in these organs during hypoxia and reoxygenation compared to normoxia and control. Myoglobin and neuroglobin mRNAs in MC-RR group were significantly induced in the brain only and are believed to protect the brain from oxidative damage. However, other organs were unprotected and extensive damage was observed in the liver cells. Our results clearly demonstrated that MC-RR and hypoxia-reoxygenation transitions were synergistically harmful to the goldfish and could impair its adaptation to hypoxia, especially during reoxygenation.

  14. Indirect IUE observation of O VI from photoexcited fluorescence lines of Fe II, present in the spectrum of RR Telescopii

    NASA Technical Reports Server (NTRS)

    Johansson, Sveneric

    1988-01-01

    A new, highly excited level of Fe II at 13.7 eV has been established by means of six lines in the laboratory spectrum below 2000 A. Confirming transitions appear in the infrared region. Four of the ultraviolet lines coincide with previously unidentified lines in the IUE spectrum of RR Tel reported by Penston et al. in 1983. One of the remaining UV lines coincides with the resonance line of O VI at 1032 A, outside the range of the IUE. This suggests that the new FE II level is selectively photoexcited by O VI in RR Tel, resulting in the strong fluorescence lines observed. This case of a Bowen mechanism provides an indirect observation of O VI, important for diagnostics of, e.g., symbiotic stars.

  15. RcRR1, a Rosa canina type-A response regulator gene, is involved in cytokinin-modulated rhizoid organogenesis.

    PubMed

    Gao, Bin; Fan, Lusheng; Li, Xingxing; Yang, Huifang; Liu, Fengluan; Wang, Ling; Xi, Lin; Ma, Nan; Zhao, Liangjun

    2013-01-01

    In vitro, a new protocol of plant regeneration in rose was achieved via protocorm-like bodies (PLBs) induced from the root-like organs named rhizoids that developed from leaf explants. The development of rhizoids is a critical stage for efficient regeneration, which is triggered by exogenous auxin. However, the role of cytokinin in the control of organogenesis in rose is as yet uncharacterized. The aim of this study was to elucidate the molecular mechanism of cytokinin-modulated rhizoid formation in Rosa canina. Here, we found that cytokinin is a key regulator in the formation of rhizoids. Treatment with cytokinin reduced callus activity and significantly inhibited rhizoid formation in Rosa canina. We further isolated the full-length cDNA of a type-A response regulator gene of cytokinin signaling, RcRR1, from which the deduced amino acid sequence contained the conserved DDK motif. Gene expression analysis revealed that RcRR1 was differentially expressed during rhizoid formation and its expression level was rapidly up-regulated by cytokinin. In addition, the functionality of RcRR1 was tested in Arabidopsis. RcRR1 was found to be localized to the nucleus in GFP-RcRR1 transgenic plants and overexpression of RcRR1 resulted in increased primary root length and lateral root density. More importantly, RcRR1 overexpression transgenic plants also showed reduced sensitivity to cytokinin during root growth; auxin distribution and the expression of auxin efflux carriers PIN genes were altered in RcRR1 overexpression plants. Taken together, these results demonstrate that RcRR1 is a functional type-A response regulator which is involved in cytokinin-regulated rhizoid formation in Rosa canina.

  16. RcRR1, a Rosa canina type-A response regulator gene, is involved in cytokinin-modulated rhizoid organogenesis.

    PubMed

    Gao, Bin; Fan, Lusheng; Li, Xingxing; Yang, Huifang; Liu, Fengluan; Wang, Ling; Xi, Lin; Ma, Nan; Zhao, Liangjun

    2013-01-01

    In vitro, a new protocol of plant regeneration in rose was achieved via protocorm-like bodies (PLBs) induced from the root-like organs named rhizoids that developed from leaf explants. The development of rhizoids is a critical stage for efficient regeneration, which is triggered by exogenous auxin. However, the role of cytokinin in the control of organogenesis in rose is as yet uncharacterized. The aim of this study was to elucidate the molecular mechanism of cytokinin-modulated rhizoid formation in Rosa canina. Here, we found that cytokinin is a key regulator in the formation of rhizoids. Treatment with cytokinin reduced callus activity and significantly inhibited rhizoid formation in Rosa canina. We further isolated the full-length cDNA of a type-A response regulator gene of cytokinin signaling, RcRR1, from which the deduced amino acid sequence contained the conserved DDK motif. Gene expression analysis revealed that RcRR1 was differentially expressed during rhizoid formation and its expression level was rapidly up-regulated by cytokinin. In addition, the functionality of RcRR1 was tested in Arabidopsis. RcRR1 was found to be localized to the nucleus in GFP-RcRR1 transgenic plants and overexpression of RcRR1 resulted in increased primary root length and lateral root density. More importantly, RcRR1 overexpression transgenic plants also showed reduced sensitivity to cytokinin during root growth; auxin distribution and the expression of auxin efflux carriers PIN genes were altered in RcRR1 overexpression plants. Taken together, these results demonstrate that RcRR1 is a functional type-A response regulator which is involved in cytokinin-regulated rhizoid formation in Rosa canina. PMID:24009713

  17. Photocatalytic degradation efficiency and mechanism of microcystin-RR by mesoporous Bi₂WO₆ under near ultraviolet light.

    PubMed

    Chen, Peng; Zhu, Lingyan; Fang, Shuhong; Wang, Chunying; Shan, Guoqiang

    2012-02-21

    Microcystin-RR (MC-RR) is one of the most common cyanotoxin microcystins in fresh water and is of great concern due to its potential hepatotoxicity. In the present study, Bi(2)WO(6) was synthesized with a hydrothermal method by varying the pH of the reaction solution in the range of 1-11. The surface area of the catalysts decreased, but the crystallinity and crystal size increased with the pH. The adsorption and degradation capacities of the catalysts decreased with increasing the preparation solution pH. The Bi(2)WO(6) prepared at pH 1 (Bi(2)WO(6)-pH1) displayed the highest adsorption and degradation capacity to MC-RR even though it consisted of randomly aggregated particles. Nearly 100% of MC-RR at 10 mg L(-1) was removed after 30 min of irradiation of near-ultraviolet light (300-400 nm) in a solution with Bi(2)WO(6) concentration of 0.2 g L(-1). The photodegradation efficiency of Bi(2)WO(6)-pH1 was greater in acid medium than in basic solutions. Several intermediate products were observed and identified by liquid chromatography/mass spectrometry/mass spectrometry, and a unique photodegradation pathway was proposed. It was assumed that a photo-Kolbe process happened at the site carboxyl acid group of the d-Glu residue by the photogenerated holes, producing a hydroperoxyl product at m/z 513.8. This intermediate could be further decomposed to an alcohol product at m/z 505.8 and a ketone product at m/z 504.8. The aromatic ring and diene bond of the Adda chain could also be attacked by the holes and form phenol and diol products. PMID:22250846

  18. Training-related changes in the R-R interval at the onset of passive movements in humans.

    PubMed

    Vianna, L C; Ricardo, D R; Araújo, C G S

    2008-09-01

    The aim of the present study was to determine whether training-related alterations in muscle mechanoreflex activation affect cardiac vagal withdrawal at the onset of exercise. Eighteen male volunteers divided into 9 controls (26 +/- 1.9 years) and 9 racket players (25 +/- 1.9 years) performed 10 s of voluntary and passive movement characterized by the wrist flexion of their dominant and non-dominant limbs. The respiratory cycle was divided into four phases and the phase 4 R-R interval was measured before and immediately following the initiation of either voluntary or passive movement. At the onset of voluntary exercise, the decrease in R-R interval was similar between dominant and non-dominant forearms in both controls (166 +/- 20 vs 180 +/- 34 ms, respectively; P > 0.05) and racket players (202 +/- 29 vs 201 +/- 31 ms, respectively; P > 0.05). Following passive movement, the non-dominant forearm of racket players elicited greater changes than the dominant forearm (129 +/- 30 vs 77 +/- 17 ms; P < 0.05), as well as both the dominant (54 +/- 20 ms; P < 0.05) and non-dominant (59 +/- 14 ms; P < 0.05) forearms of control subjects. In contrast, changes in R-R interval elicited by the racket players' dominant forearm were similar to that observed in the control group, indicating that changes in R-R interval at the onset of passive exercise were not attenuated in the dominant forearm of racket players. In summary, cardiac vagal withdrawal induced by muscle mechanoreflex stimulation is well-maintained, despite long-term exposure to training.

  19. Auditory pre-experience modulates classification of affect intensity: evidence for the evaluation of call salience by a non-human mammal, the bat Megaderma lyra

    PubMed Central

    2013-01-01

    Introduction Immediate responses towards emotional utterances in humans are determined by the acoustic structure and perceived relevance, i.e. salience, of the stimuli, and are controlled via a central feedback taking into account acoustic pre-experience. The present study explores whether the evaluation of stimulus salience in the acoustic communication of emotions is specifically human or has precursors in mammals. We created different pre-experiences by habituating bats (Megaderma lyra) to stimuli based on aggression, and response, calls from high or low intensity level agonistic interactions, respectively. Then we presented a test stimulus of opposite affect intensity of the same call type. We compared the modulation of response behaviour by affect intensity between the reciprocal experiments. Results For aggression call stimuli, the bats responded to the dishabituation stimuli independent of affect intensity, emphasising the attention-grabbing function of this call type. For response call stimuli, the bats responded to a high affect intensity test stimulus after experiencing stimuli of low affect intensity, but transferred habituation to a low affect intensity test stimulus after experiencing stimuli of high affect intensity. This transfer of habituation was not due to over-habituation as the bats responded to a frequency-shifted control stimulus. A direct comparison confirmed the asymmetric response behaviour in the reciprocal experiments. Conclusions Thus, the present study provides not only evidence for a discrimination of affect intensity, but also for an evaluation of stimulus salience, suggesting that basic assessment mechanisms involved in the perception of emotion are an ancestral trait in mammals. PMID:24341839

  20. MONITORING H{alpha} EMISSION AND CONTINUUM OF UXORs: RR Tauri

    SciTech Connect

    Bedell, Megan; Villaume, Alexa; Weiss, Lauren; Sliski, David; Strelnitski, Vladimir; Walker, Gary; Williams, Jedediyah; Henden, Arne; Krajci, Tom

    2011-11-15

    The Maria Mitchell Observatory, in collaboration with the Astrokolkhoz Observatory, started a program of photometric monitoring of UX Ori-type stars (UXORs) with narrowband interference filters (IFs; augmented with the traditional broadband filters) aimed at separating the H{alpha} emission variations from those of the continuum. We present the method of separation and the first results for RR Tau obtained in two seasons, each roughly 100 days long (2010 Winter-Spring and 2010 Fall-2011 Spring). We confirm the conclusion from previous studies that the H{alpha} emission in this star is less variable than the continuum. Although some correlation between the two is not excluded, the amplitude of H{alpha} variations is much smaller (factors of 3-5) than that of the continuum. These results are compatible with Grinin's model of UXORs, which postulates the presence of small obscuring circumstellar clouds as the cause of the continuum fading, as well as the presence of a circumstellar reflection/emission nebula, larger than the star and the obscuring clouds, which is responsible for H{alpha} emission and the effect of the 'color reversal' in deep minima. However, the results of both our broadband and narrowband photometry indicate that the obscuration model may be insufficient to explain all of the observations. Disk accretion, the presence of stellar or (proto) planetary companion(s), as well as the intrinsic variations of the star, may contribute to the observed light variations. We argue, in particular, that the H{alpha} emission may be more closely correlated with the intrinsic variations of the star than with the much stronger observed variations caused by the cloud obscuration. If this hypothesis is correct, the close monitoring of H{alpha} emission with IFs, accessible to small-size telescopes, may become an important tool in studying the physical nature of the UXORs' central stars.

  1. Homofermentative Production of d- or l-Lactate in Metabolically Engineered Escherichia coli RR1

    PubMed Central

    Chang, Dong-Eun; Jung, Heung-Chae; Rhee, Joon-Shick; Pan, Jae-Gu

    1999-01-01

    We investigated metabolic engineering of fermentation pathways in Escherichia coli for production of optically pure d- or l-lactate. Several pta mutant strains were examined, and a pta mutant of E. coli RR1 which was deficient in the phosphotransacetylase of the Pta-AckA pathway was found to metabolize glucose to d-lactate and to produce a small amount of succinate by-product under anaerobic conditions. An additional mutation in ppc made the mutant produce d-lactate like a homofermentative lactic acid bacterium. When the pta ppc double mutant was grown to higher biomass concentrations under aerobic conditions before it shifted to the anaerobic phase of d-lactate production, more than 62.2 g of d-lactate per liter was produced in 60 h, and the volumetric productivity was 1.04 g/liter/h. To examine whether the blocked acetate flux could be reoriented to a nonindigenous l-lactate pathway, an l-lactate dehydrogenase gene from Lactobacillus casei was introduced into a pta ldhA strain which lacked phosphotransacetylase and d-lactate dehydrogenase. This recombinant strain was able to metabolize glucose to l-lactate as the major fermentation product, and up to 45 g of l-lactate per liter was produced in 67 h. These results demonstrate that the central fermentation metabolism of E. coli can be reoriented to the production of d-lactate, an indigenous fermentation product, or to the production of l-lactate, a nonindigenous fermentation product. PMID:10103226

  2. An easy-to-use technique to characterize cardiodynamics from first-return maps on ΔRR-intervals

    NASA Astrophysics Data System (ADS)

    Fresnel, Emeline; Yacoub, Emad; Freitas, Ubiratan; Kerfourn, Adrien; Messager, Valérie; Mallet, Eric; Muir, Jean-François; Letellier, Christophe

    2015-08-01

    Heart rate variability analysis using 24-h Holter monitoring is frequently performed to assess the cardiovascular status of a patient. The present retrospective study is based on the beat-to-beat interval variations or ΔRR, which offer a better view of the underlying structures governing the cardiodynamics than the common RR-intervals. By investigating data for three groups of adults (with normal sinus rhythm, congestive heart failure, and atrial fibrillation, respectively), we showed that the first-return maps built on ΔRR can be classified according to three structures: (i) a moderate central disk, (ii) a reduced central disk with well-defined segments, and (iii) a large triangular shape. These three very different structures can be distinguished by computing a Shannon entropy based on a symbolic dynamics and an asymmetry coefficient, here introduced to quantify the balance between accelerations and decelerations in the cardiac rhythm. The probability P111111 of successive heart beats without large beat-to-beat fluctuations allows to assess the regularity of the cardiodynamics. A characteristic time scale, corresponding to the partition inducing the largest Shannon entropy, was also introduced to quantify the ability of the heart to modulate its rhythm: it was significantly different for the three structures of first-return maps. A blind validation was performed to validate the technique.

  3. Pyrazaboles of the type RR'B (/mu/-pz)/sub 2/BRR' and related studies

    SciTech Connect

    Das, M.K.; DeGraffenreid, A.L.; Edwards, K.D.; Komorowski, L.; Mariategui, J.F.; Miller, B.W.; Mojesky, M.T.; Niedenzu, K.

    1988-09-07

    Boron-bonded hydrogen or organylthio groups of pyrazaboles, R/sub 2/B(/mu/-pz/sup */)/sub 2/BR/sub 2/ (HPz/sup */ = pyrazole or C-substituted derivatives thereof), can be replaced by reaction with either (C/sub 2/H/sub 5/)/sub 2/O/center dot/BF/sub 3/ or CH/sub 3/OH/center dot/BF/sub 3/ to give the corresponding F/sub 2/B(/mu/-pz/sup */)/sub 2/BF/sub 2/ species. Attempts to replace boron-bonded hydrocarbon groups require much more forcing conditions and usually result in a complete breakdown of the molecule. However, under mild conditions the B-C bond is not attacked and (C/sub 6/H/sub 5/)FB(/mu/-pz)/sub 2/B(C/sub 6/H/sub 5/)F is readily obtained from the reaction of (C/sub 6/H/sub 5/)(C/sub 2/H/sub 5/S)B(/mu/-pz)/sub 2/B(C/sub 6/H/sub 5/)(SC/sub 2/H/sub 5/) with BF/sub 3/. 4,8-Dihalopyrazaboles, RXB(/mu/-ps)/sub 2/BRX, are also obtained from the reaction of dihaloboranes, RBX/sub 2/, with N-(trimethylsilyl)pyrazole, (CH/sub 3/)/sub 3/Si(pz); the halogen of the pyrazabole can be displaced readily be reaction with a Grignard reagent or an alcohol. The compound ((C/sub 2/H/sub 5/)/sub 2/N)(pz)B(/mu/-pz)/sub 2/B(N(C/sub 2/H/sub 5/)/sub 2/)(pz) was also prepared by the cited procedure. The diethylamino group of the latter species is easily displaced by reaction with pyrazole. Several additional pyrazaboles of the type RR'B(/mu/-pz)/sub 2/BBR' have been prepared. (C/sub 6/H/sub 5/)(pz)B(/mu/-pz)/sub 2/B(C/sub 6/H/sub 5/)(pz), which is accessible by various preparative routes, was separated into isomers that exhibit distinctly different /sup 1/H NMR spectra. The mass spectral fragmentations of such (cis and trans) isomers are significantly different with respect to their loss of the first fragments from the parent ions. 18 references, 2 tables.

  4. SCD-HeFT: Use of RR Interval Statistics for Long-term Risk Stratification for Arrhythmic Sudden Cardiac Death

    PubMed Central

    Au-yeung, Wan-tai M.; Reinhall, Per; Poole, Jeanne E.; Anderson, Jill; Johnson, George; Fletcher, Ross D.; Moore, Hans J.; Mark, Daniel B.; Lee, Kerry L.; Bardy, Gust H.

    2015-01-01

    Background In the SCD-HeFT a significant fraction of the congestive heart failure (CHF) patients ultimately did not die suddenly from arrhythmic causes. CHF patients will benefit from better tools to identify if ICD therapy is needed. Objective To identify predictor variables from baseline SCD-HeFT patients’ RR intervals that correlate to arrhythmic sudden cardiac death (SCD) and mortality and to design an ICD therapy screening test. Methods Ten predictor variables were extracted from pre-randomization Holter data from 475 patients enrolled in the SCD-HeFT ICD arm using novel and traditional heart rate variability methods. All variables were correlated to SCD using Mann Whitney-Wilcoxon test and receiver operating characteristic analysis. ICD therapy screening tests were designed by minimizing the cost of false classifications. Survival analysis, including log-rank test and Cox models, was also performed. Results α1 and α2 from detrended fluctuation analysis, the ratio of low to high frequency power, the number of PVCs per hour and heart rate turbulence slope are all statistically significant for predicting the occurrences of SCD (p<0.001) and survival (log-rank p<0.01). The most powerful multivariate predictor tool using the Cox Proportional Hazards was α2 with a hazard ratio of 0.0465 (95% CI: 0.00528 – 0.409, p<0.01). Conclusion Predictor variables from RR intervals correlate to the occurrences of SCD and distinguish survival among SCD-HeFT ICD patients. We believe SCD prediction models should incorporate Holter based RR interval analysis to refine ICD patient selection especially in removing patients who are unlikely to benefit from ICD therapy. PMID:26096609

  5. Interval ridge regression (iRR) as a fast and robust method for quantitative prediction and variable selection applied to edible oil adulteration.

    PubMed

    Jović, Ozren; Smrečki, Neven; Popović, Zora

    2016-04-01

    A novel quantitative prediction and variable selection method called interval ridge regression (iRR) is studied in this work. The method is performed on six data sets of FTIR, two data sets of UV-vis and one data set of DSC. The obtained results show that models built with ridge regression on optimal variables selected with iRR significantly outperfom models built with ridge regression on all variables in both calibration (6 out of 9 cases) and validation (2 out of 9 cases). In this study, iRR is also compared with interval partial least squares regression (iPLS). iRR outperfomed iPLS in validation (insignificantly in 6 out of 9 cases and significantly in one out of 9 cases for p<0.05). Also, iRR can be a fast alternative to iPLS, especially in case of unknown degree of complexity of analyzed system, i.e. if upper limit of number of latent variables is not easily estimated for iPLS. Adulteration of hempseed (H) oil, a well known health beneficial nutrient, is studied in this work by mixing it with cheap and widely used oils such as soybean (So) oil, rapeseed (R) oil and sunflower (Su) oil. Binary mixture sets of hempseed oil with these three oils (HSo, HR and HSu) and a ternary mixture set of H oil, R oil and Su oil (HRSu) were considered. The obtained accuracy indicates that using iRR on FTIR and UV-vis data, each particular oil can be very successfully quantified (in all 8 cases RMSEP<1.2%). This means that FTIR-ATR coupled with iRR can very rapidly and effectively determine the level of adulteration in the adulterated hempseed oil (R(2)>0.99).

  6. Evaluation of techniques for estimating the power spectral density of RR-intervals under paced respiration conditions.

    PubMed

    Schaffer, Thorsten; Hensel, Bernhard; Weigand, Christian; Schüttler, Jürgen; Jeleazcov, Christian

    2014-10-01

    Heart rate variability (HRV) analysis is increasingly used in anaesthesia and intensive care monitoring of spontaneous breathing and mechanical ventilated patients. In the frequency domain, different estimation methods of the power spectral density (PSD) of RR-intervals lead to different results. Therefore, we investigated the PSD estimates of fast Fourier transform (FFT), autoregressive modeling (AR) and Lomb-Scargle periodogram (LSP) for 25 young healthy subjects subjected to metronomic breathing. The optimum method for determination of HRV spectral parameters under paced respiration was identified by evaluating the relative error (RE) and the root mean square relative error (RMSRE) for each breathing frequency (BF) and spectral estimation method. Additionally, the sympathovagal balance was investigated by calculating the low frequency/high frequency (LF/HF) ratio. Above 7 breaths per minute, all methods showed a significant increase in LF/HF ratio with increasing BF. On average, the RMSRE of FFT was lower than for LSP and AR. Therefore, under paced respiration conditions, estimating RR-interval PSD using FFT is recommend. PMID:23508826

  7. Poincaré plot analysis of autocorrelation function of RR intervals in patients with acute myocardial infarction.

    PubMed

    Chuang, Shin-Shin; Wu, Kung-Tai; Lin, Chen-Yang; Lee, Steven; Chen, Gau-Yang; Kuo, Cheng-Deng

    2014-08-01

    The Poincaré plot of RR intervals (RRI) is obtained by plotting RRIn+1 against RRIn. The Pearson correlation coefficient (ρRRI), slope (SRRI), Y-intercept (YRRI), standard deviation of instantaneous beat-to-beat RRI variability (SD1RR), and standard deviation of continuous long-term RRI variability (SD2RR) can be defined to characterize the plot. Similarly, the Poincaré plot of autocorrelation function (ACF) of RRI can be obtained by plotting ACFk+1 against ACFk. The corresponding Pearson correlation coefficient (ρACF), slope (SACF), Y-intercept (YACF), SD1ACF, and SD2ACF can be defined similarly to characterize the plot. By comparing the indices of Poincaré plots of RRI and ACF between patients with acute myocardial infarction (AMI) and patients with patent coronary artery (PCA), we found that the ρACF and SACF were significantly larger, whereas the RMSSDACF/SDACF and SD1ACF/SD2ACF were significantly smaller in AMI patients. The ρACF and SACF correlated significantly and negatively with normalized high-frequency power (nHFP), and significantly and positively with normalized very low-frequency power (nVLFP) of heart rate variability in both groups of patients. On the contrary, the RMSSDACF/SDACF and SD1ACF/SD2ACF correlated significantly and positively with nHFP, and significantly and negatively with nVLFP and low-/high-frequency power ratio (LHR) in both groups of patients. We concluded that the ρACF, SACF, RMSSDACF/SDACF, and SD1ACF/SD2ACF, among many other indices of ACF Poincaré plot, can be used to differentiate between patients with AMI and patients with PCA, and that the increase in ρACF and SACF and the decrease in RMSSDACF/SDACF and SD1ACF/SD2ACF suggest an increased sympathetic and decreased vagal modulations in both groups of patients.

  8. Quantification of the acute effect of a low dose of red wine by nonlinear measures of RR and QT interval series in healthy subjects.

    PubMed

    Platiša, Mirjana M; Gal, Vera; Nestorović, Zorica; Gojković-Bukarica, Ljiljana

    2014-10-01

    The measures of nonlinear properties of RR interval and QT interval time series are sensitive to physiologically- or pathologically-induced complexity/regularity changes, but were not used to estimate the effect of alcohol intake. We wanted to examine the potential of these measures to quantify the acute effect of a low dose of red wine in healthy subjects. In separate experiments, fourteen young volunteers drank 200ml of red wine and a control drink with equal concentration of ethanol. ECG in supine position was recorded 20min before and 60min after drink intake. RR interval and QT interval series were extracted from ECG and we calculated variability, scaling exponents (α1 and α2) and sample entropy (SampEn) for both series. Systolic and diastolic blood pressures (BP) were measured every 10min. The immediate effect of both the drinks was equal: HR, BP and QT variability exhibited a sudden increase and then a decrease. However, the prolonged effect of wine and the control drink was different. Wine decreased both BP (p<0.05) and reduced complexity of RR and QT series (increased scaling exponents and decreased SampEn). The control drink prolonged QT and RR intervals (p<0.05). These results point out that the nonlinear properties of RR and QT interval series could be used to differentiate the effect of wine and ethanol. Changes in RR and QT interval series induced by a low dose of red wine are more detectable by methods that quantify the structure of the series than by methods that quantify their variability.

  9. Fractal correlation properties of R-R interval dynamics and mortality in patients with depressed left ventricular function after an acute myocardial infarction

    NASA Technical Reports Server (NTRS)

    Huikuri, H. V.; Makikallio, T. H.; Peng, C. K.; Goldberger, A. L.; Hintze, U.; Moller, M.

    2000-01-01

    BACKGROUND: Preliminary data suggest that the analysis of R-R interval variability by fractal analysis methods may provide clinically useful information on patients with heart failure. The purpose of this study was to compare the prognostic power of new fractal and traditional measures of R-R interval variability as predictors of death after acute myocardial infarction. METHODS AND RESULTS: Time and frequency domain heart rate (HR) variability measures, along with short- and long-term correlation (fractal) properties of R-R intervals (exponents alpha(1) and alpha(2)) and power-law scaling of the power spectra (exponent beta), were assessed from 24-hour Holter recordings in 446 survivors of acute myocardial infarction with a depressed left ventricular function (ejection fraction R-R interval variability were significant univariate predictors of all-cause mortality. Reduced short-term scaling exponent alpha(1) was the most powerful R-R interval variability measure as a predictor of all-cause mortality (alpha(1) <0.75, relative risk 3.0, 95% confidence interval 2.5 to 4.2, P<0.001). It remained an independent predictor of death (P<0.001) after adjustment for other postinfarction risk markers, such as age, ejection fraction, NYHA class, and medication. Reduced alpha(1) predicted both arrhythmic death (P<0.001) and nonarrhythmic cardiac death (P<0.001). CONCLUSIONS: Analysis of the fractal characteristics of short-term R-R interval dynamics yields more powerful prognostic information than the traditional measures of HR variability among patients with depressed left ventricular function after an acute myocardial infarction.

  10. [Evaluation of the principles of distribution of electrocardiographic R-R intervals for elaboration of methods of automated diagnosis of cardiac rhythm disorders].

    PubMed

    Tsukerman, B M; Finkel'shteĭn, I E

    1987-07-01

    A statistical analysis of prolonged ECG records has been carried out in patients with various heart rhythm and conductivity disorders. The distribution of absolute R-R duration values and relationships between adjacent intervals have been examined. A two-step algorithm has been constructed that excludes anomalous and "suspicious" intervals from a sample of consecutively recorded R-R intervals, until only the intervals between contractions of veritably sinus origin remain in the sample. The algorithm has been developed into a programme for microcomputer Electronica NC-80. It operates reliably even in cases of complex combined rhythm and conductivity disorders.

  11. Robust algorithmic detection of the developed cardiac pathologies and emerging or transient abnormalities from short periods of RR data

    NASA Astrophysics Data System (ADS)

    Gavrishchaka, Valeriy V.; Senyukova, Olga

    2011-06-01

    Numerous research efforts and clinical testing have confirmed validity of heart rate variability (HRV) analysis as one of the cardiac diagnostics modalities. The majority of HRV analysis tools currently used in practice are based on linear indicators. Methods from nonlinear dynamics (NLD) provide more natural modeling framework for adaptive biological systems with multiple feedback loops. Compared to linear indicators, many NLD-based measures are much less sensitive to data artifacts and non-stationarity. However, majority of NLD measures require long time series for stable calculation. Similar restrictions also apply for linear indicators. Such requirements could drastically limit practical usability of HRV analysis in many applications, including express diagnostics, early indication of subtle directional changes during personalization of medical treatment, and robust detection of emerging or transient abnormalities. Recently we have illustrated that these challenges could be overcome by using classification framework based on boosting-like ensemble learning techniques that are capable of discovering robust meta-indicators from existing HRV measures and other incomplete empirical knowledge. In this paper we demonstrate universality of such meta-indicators and discuss operational details of their practical usage. Using such pathology examples as congestive heart failure (CHF) and arrhythmias, we show that classifiers trained on short RR segments (down to several minutes) could achieve reasonable classification accuracy (˜80-85% and higher). These indicators calculated from longer RR segments could be applicable for accurate diagnostics with classification accuracy approaching 100%. In addition, it is feasible to discover single "normal-abnormal" meta-classifier capable of detecting multiple abnormalities.

  12. 76 FR 20229 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-Trent 768-60 and Trent 772-60 Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-12

    ... (63 FR 49416, September 16, 1998). We must receive any comments on this AD by May 27, 2011. ADDRESSES... 39-10754 (63 FR 49416, September 16, 1998), for RR RB211-Trent 700 series turbofan engines. That AD... Policies and Procedures (44 FR 11034, February 26, 1979), (3) Will not affect intrastate aviation in...

  13. Genome sequence of Novosphingobium sp. strain Rr 2-17, a nopaline crown gall-associated bacterium isolated from Vitis vinifera L. grapevine.

    PubMed

    Gan, Han Ming; Chew, Teong Han; Hudson, André O; Savka, Michael A

    2012-09-01

    Novosphingobium sp. strain Rr 2-17 is an N-acyl homoserine lactone (AHL)-producing bacterium isolated from the crown gall tumor of a grapevine. To our knowledge, this is the first draft genome announcement of a plant-associated strain from the genus Novosphingobium. PMID:22933764

  14. AVHotRR version 2.0. Enhanced routine for near-real time monitoring of active volcanoes using IR satellite data.

    NASA Astrophysics Data System (ADS)

    Lombardo, Valerio

    2016-04-01

    The AVHotRR routine operates since 2006 to process satellite data for monitoring active volcanoes in the Mediterranean area. AVHotRR is a continually evolving program. It needs to adapt both to the availability of new incoming data and to the variability of volcanic phenomena. Though originally developed to work with Advanced Very High Resolution Radiometer (AVHRR) data, AVHotRR has been improved over the years to adapt to other sensors. Currently implemented version allows to integrate results from different dataset in order to better constrain the detection of volcanic hot-spots. In particular, the high temporal resolution of the SEVIRI instrument aboard MSG provides a key to reduce false positives in AVHRR and Moderate Resolution Imaging Spectroradiometer MODIS images. A new detection method based on the wavelet transform of SEVIRI data is proposed. Results from the application of AVHotRR to a dataset of AVHRR and SEVIRI images from Mt Etna, Italy, are presented and discussed to advantages and limitations of the algorithm.

  15. Effect of Dual Cathode Buffer Layer on the Charge Carrier Dynamics of rrP3HT:PCBM Based Bulk Heterojunction Solar Cell.

    PubMed

    Singh, Ashish; Dey, Anamika; Das, Dipjyoti; Iyer, Parameswar Krishnan

    2016-05-01

    In bulk heterojunction (BHJ) solar cells, the buffer layer plays a vital role in enhancing the power conversion efficiency (PCE) by improving the charge carrier dynamics. A comprehensive understanding of the contacts is especially essential in order to optimize the performance of organic solar cells (OSCs). Although there are several fundamental reports on this subject, a proper correlation of the physical processes with experimental evidence at the photoactive layer and contact materials is essential. In this work, we incorporated three different additional buffer layers, namely, tris(8-hydroxyquinolinato) aluminum (Alq3), bathophenanthroline (BPhen) or bathocuproine (BCP) with LiF/Al as conventional cathode contact in both rrP3HT:PC61BM and rrP3HT:PC71BM blend BHJ solar cells and their corresponding photovoltaic performances were systematically correlated with their energy level diagram. The device with dual cathode buffer layer having ITO/PEDOT:PSS/blend polymer/BCP/LiF/Al configuration showed the best device performance with PCE, η = 4.96%, Jsc = 13.53 mA/cm(2), Voc = 0.60 V and FF= 61% for rrP3HT:PC71BM and PCE, η = 4.5% with Jsc = 13.3 mA/cm(2), Voc = 0.59 V and FF = 59% for rrP3HT:PC61BM. This drastic improvement in PCE in both the device configurations are due to the combined effects of better hole-blocking capacity of BCP and low work function provided by LiF/Al with the blend polymer. These results successfully explain the role of dual cathode buffer layers and their contribution to the PCE improvement and overall device performance with rrP3HT:PCBM based BHJ solar cell. PMID:27075007

  16. Effect of Dual Cathode Buffer Layer on the Charge Carrier Dynamics of rrP3HT:PCBM Based Bulk Heterojunction Solar Cell.

    PubMed

    Singh, Ashish; Dey, Anamika; Das, Dipjyoti; Iyer, Parameswar Krishnan

    2016-05-01

    In bulk heterojunction (BHJ) solar cells, the buffer layer plays a vital role in enhancing the power conversion efficiency (PCE) by improving the charge carrier dynamics. A comprehensive understanding of the contacts is especially essential in order to optimize the performance of organic solar cells (OSCs). Although there are several fundamental reports on this subject, a proper correlation of the physical processes with experimental evidence at the photoactive layer and contact materials is essential. In this work, we incorporated three different additional buffer layers, namely, tris(8-hydroxyquinolinato) aluminum (Alq3), bathophenanthroline (BPhen) or bathocuproine (BCP) with LiF/Al as conventional cathode contact in both rrP3HT:PC61BM and rrP3HT:PC71BM blend BHJ solar cells and their corresponding photovoltaic performances were systematically correlated with their energy level diagram. The device with dual cathode buffer layer having ITO/PEDOT:PSS/blend polymer/BCP/LiF/Al configuration showed the best device performance with PCE, η = 4.96%, Jsc = 13.53 mA/cm(2), Voc = 0.60 V and FF= 61% for rrP3HT:PC71BM and PCE, η = 4.5% with Jsc = 13.3 mA/cm(2), Voc = 0.59 V and FF = 59% for rrP3HT:PC61BM. This drastic improvement in PCE in both the device configurations are due to the combined effects of better hole-blocking capacity of BCP and low work function provided by LiF/Al with the blend polymer. These results successfully explain the role of dual cathode buffer layers and their contribution to the PCE improvement and overall device performance with rrP3HT:PCBM based BHJ solar cell.

  17. FUSE and HST FUV Spectroscopic Analysis of the Old Novae V533 Her, DI Lac and RR Pic

    NASA Astrophysics Data System (ADS)

    Sion, Edward M.; Ruby, John J.; Godon, Patrick

    2016-01-01

    The old novae V533 Her (Nova Her 1963), DI Lac (Nova Lac 1910) and RR Pic (Nova Pic 1891) are in (or near) their quiescent stage following their nova explosions and continue to accrete at a high rate in the aftermath of their explosions. All three systems appear to be accreting at high rates long after their novae. They exhibit continua that are steeply rising into the FUV as well as absorption lines and emission lines of uncertain origin. All three have FUSE spectra which offer not only higher spectral resolution but also wavelength coverage extending down to the Lyman Limit. We have matched these FUSE spectra with existing archival HST STIS and IUE spectral coverage, and adopted the newly determined interstellar reddening corrections of Selvelli and Gilmozzi (2013). The dereddened FUV spectra have been modeled with our grids of optically thick accretion disks and hot white dwarf photospheres. We present the results of our modeling analysis and discuss implications for the poorly understood quiescent states of old novae including the role of irradiation in enhancing the rate of accretion far into quiescence.This work is supported by NASA grants NNX13AF11G and NNX13AF12G to Villanova University.

  18. Oxidation of MC-LR and -RR with chlorine and potassium permanganate: toxicity of the reaction products.

    PubMed

    Rodríguez, Eva M; Acero, Juan L; Spoof, Lisa; Meriluoto, Jussi

    2008-03-01

    Toxin-producing cyanobacteria are abundant in surface waters used as drinking water resources. Microcystins (MC) produced by certain cyanobacteria present acute and chronic toxicity, and their removal in drinking water treatment processes is of increasing concern. Previous studies have demonstrated that chlorine and potassium permanganate are feasible oxidants for the removal of MCs present in drinking water resources, although the oxidation might lead to toxic oxidation products. In this paper, the toxicity of the oxidation products of MC-LR and -RR has been studied using protein phosphatase 1 inhibition assay (PPIA). The HPLC and ELISA analyses correlated with the PPIA results for both toxins. The samples containing the oxidation products were fractionated by HPLC and the toxicity of the fractions was tested with PPIA. The results revealed that protein phosphatase 1 inhibition emerged only from intact MC, while the oxidation products were non-toxic. Similar results were obtained in experiments performed in natural waters: no reaction products or interactions exhibiting protein phosphatase 1 inhibition were detected.

  19. A new approach to detect congestive heart failure using Teager energy nonlinear scatter plot of R-R interval series.

    PubMed

    Kamath, Chandrakar

    2012-09-01

    A novel approach to distinguish congestive heart failure (CHF) subjects from healthy subjects is proposed. Heart rate variability (HRV) is impaired in CHF subjects. In this work hypothesizing that capturing moment to moment nonlinear dynamics of HRV will reveal cardiac patterning, we construct the nonlinear scatter plot for Teager energy of R-R interval series. The key feature of Teager energy is that it models the energy of the source that generated the signal rather than the energy of the signal itself. Hence, any deviations in the genesis of HRV, by complex interactions of hemodynamic, electrophysiological, and humoral variables, as well as by the autonomic and central nervous regulations, get manifested in the Teager energy function. Comparison of the Teager energy scatter plot with the second-order difference plot (SODP) for normal and CHF subjects reveals significant differences qualitatively and quantitatively. We introduce the concept of curvilinearity for central tendency measures of the plots and define a radial distance index that reveals the efficacy of the Teager energy scatter plot over SODP in separating CHF subjects from healthy subjects. The k-nearest neighbor classifier with RDI as feature showed almost 100% classification rate.

  20. Nonradial oscillations in classical pulsating stars. Predictions and discoveries

    NASA Astrophysics Data System (ADS)

    Dziembowski, W. A.

    2016-05-01

    After a brief historical introduction and recalling basic concepts of stellar oscillation theory, I focus my review on interpretation of secondary periodicities found in RR Lyrae stars and Cepheids as a manifestation of nonradial mode excitation.

  1. The Projects for Onboard Autonomy (PROBA2) Science Centre: Sun Watcher Using APS Detectors and Image Processing (SWAP) and Large-Yield Radiometer (LYRA) Science Operations and Data Products

    NASA Astrophysics Data System (ADS)

    Zender, J.; Berghmans, D.; Bloomfield, D. S.; Cabanas Parada, C.; Dammasch, I.; De Groof, A.; D'Huys, E.; Dominique, M.; Gallagher, P.; Giordanengo, B.; Higgins, P. A.; Hochedez, J.-F.; Yalim, M. S.; Nicula, B.; Pylyser, E.; Sanchez-Duarte, L.; Schwehm, G.; Seaton, D. B.; Stanger, A.; Stegen, K.; Willems, S.

    2013-08-01

    The PROBA2 Science Centre (P2SC) is a small-scale science operations centre supporting the Sun observation instruments onboard PROBA2: the EUV imager Sun Watcher using APS detectors and image Processing (SWAP) and Large-Yield Radiometer (LYRA). PROBA2 is one of ESA's small, low-cost Projects for Onboard Autonomy (PROBA) and part of ESA's In-Orbit Technology Demonstration Programme. The P2SC is hosted at the Royal Observatory of Belgium, co-located with both Principal Investigator teams. The P2SC tasks cover science planning, instrument commanding, instrument monitoring, data processing, support of outreach activities, and distribution of science data products. PROBA missions aim for a high degree of autonomy at mission and system level, including the science operations centre. The autonomy and flexibility of the P2SC is reached by a set of web-based interfaces allowing the operators as well as the instrument teams to monitor quasi-continuously the status of the operations, allowing a quick reaction to solar events. In addition, several new concepts are implemented at instrument, spacecraft, and ground-segment levels allowing a high degree of flexibility in the operations of the instruments. This article explains the key concepts of the P2SC, emphasising the automation and the flexibility achieved in the commanding as well as the data-processing chain.

  2. Biology and survival of extremely halophilic archaeon Haloarcula marismortui RR12 isolated from Mumbai salterns, India in response to salinity stress.

    PubMed

    Thombre, Rebecca S; Shinde, Vinaya D; Oke, Radhika S; Dhar, Sunil Kumar; Shouche, Yogesh S

    2016-01-01

    Haloarchaea are unique microorganism's resistant to environmental and osmotic stresses and thrive in their habitats despite extreme fluctuating salinities. In the present study, haloarchaea were isolated from hypersaline thalossohaline salterns of Bhandup, Mumbai, India and were identified as Haloferax prahovense, Haloferax alexandrines, Haloferax lucentense, Haloarcula tradensis, Haloarcula marismortui and Haloarcula argentinensis. The mechanism of adaptation to contrasting salinities (1.5 M and 4.5 M) was investigated in the extreme haloarchaeon, Hal. marismortui RR12. Hal. marismortui RR12 increased the intracellular sequestration of K(+) and Cl(-) ions in hypo salinity and hyper salinity respectively as detected by Energy-dispersive X-ray spectroscopy microanalysis (EDAX) and Inductively Coupled Plasma- atomic Emission Spectroscopy (ICP-AES) indicating the presence of 'salt-in' strategy of osmoadaptation. As a cellular response to salinity stress, it produced small heat shock like proteins (sHSP) identified using MALDI-TOF MS and increased the production of protective red carotenoid pigment. This is the first report on the study of the concomitant cellular, molecular and physiological mechanism adapted by Hal. marismortui RR12 when exposed to contrasting salinities in external environment. PMID:27231230

  3. The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. IX. RR Lyr Stars in the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Soszyński, I.; Udalski, A.; Szymański, M. K.; Kubiak, J.; Pietrzyński, G.; Wyrzykowski, Ł.; Ulaczyk, K.; Poleski, R.

    2010-09-01

    The ninth part of the OGLE-III Catalog of Variable Stars (OIII-CVS) comprises RR Lyr stars in the Small Magellanic Cloud (SMC). Our sample consists of 2475 variable stars, of which 1933 pulsate in the fundamental mode (RRab), 175 are the first overtone pulsators (RRc), 258 oscillate simultaneously in both modes (RRd) and 109 stars are suspected second-overtone pulsators (RRe). 30 objects are Galactic RR Lyr stars seen in the foreground of the SMC. We discuss some statistical features of the sample. Period distributions show distinct differences between SMC and LMC populations of RR Lyr variable stars, with the SMC stars having on average longer periods. The mean periods for RRab, RRc and RRe stars are 0.596, 0.366 and 0.293 days, respectively. The mean apparent magnitudes of RRab stars are equal to 19.70 mag in the V-band and 19.12 mag in the I-band. Spatial distribution of RRLyr stars shows that the halo of the SMC is roughly round in the sky, however the density map reveals two maxima near the center of the SMC. For each object the multi-epoch V- and I-band photometry collected over 8 or 13 years of observations and finding charts are available to the astronomical community from the OGLE Internet archive.

  4. Biology and survival of extremely halophilic archaeon Haloarcula marismortui RR12 isolated from Mumbai salterns, India in response to salinity stress

    PubMed Central

    Thombre, Rebecca S.; Shinde, Vinaya D.; Oke, Radhika S.; Dhar, Sunil Kumar; Shouche, Yogesh S.

    2016-01-01

    Haloarchaea are unique microorganism’s resistant to environmental and osmotic stresses and thrive in their habitats despite extreme fluctuating salinities. In the present study, haloarchaea were isolated from hypersaline thalossohaline salterns of Bhandup, Mumbai, India and were identified as Haloferax prahovense, Haloferax alexandrines, Haloferax lucentense, Haloarcula tradensis, Haloarcula marismortui and Haloarcula argentinensis. The mechanism of adaptation to contrasting salinities (1.5 M and 4.5 M) was investigated in the extreme haloarchaeon, Hal. marismortui RR12. Hal. marismortui RR12 increased the intracellular sequestration of K+ and Cl− ions in hypo salinity and hyper salinity respectively as detected by Energy-dispersive X-ray spectroscopy microanalysis (EDAX) and Inductively Coupled Plasma- atomic Emission Spectroscopy (ICP-AES) indicating the presence of ‘salt-in’ strategy of osmoadaptation. As a cellular response to salinity stress, it produced small heat shock like proteins (sHSP) identified using MALDI-TOF MS and increased the production of protective red carotenoid pigment. This is the first report on the study of the concomitant cellular, molecular and physiological mechanism adapted by Hal. marismortui RR12 when exposed to contrasting salinities in external environment. PMID:27231230

  5. Hypercoordinate ketone adducts of electrophilic η3-H2SiRR' ligands on ruthenium as key intermediates for efficient and robust catalytic hydrosilation.

    PubMed

    Lipke, Mark C; Tilley, T Don

    2014-11-19

    The electrophilic η(3)-H2SiRR' σ-complexes [PhBP(Ph)3]RuH(η(3)-H2SiRR') (RR' = MePh, 1a; Ph2, 1b; [PhBP(Ph)3](-) = [PhB(CH2PPh2)3](-)) are efficient catalysts (0.01-2.5 mol % loading) for the hydrosilation of ketones with PhMeSiH2, Ph2SiH2, or EtMe2SiH. An alkoxy complex [PhBP(Ph)3]Ru-OCHPh2 (4b) was observed (by (31)P{(1)H} NMR spectroscopy) as the catalyst resting state during hydrosilation of benzophenone with EtMe2SiH. A different catalyst resting state was observed for reactions using PhMeSiH2 or Ph2SiH2, and was identified as a silane σ-complex [PhBP(Ph)3]RuH[η(2)-H-SiRR'(OCHPh2)] (RR' = MePh, 5a; Ph2, 5b) using variable temperature multinuclear NMR spectroscopy (-80 to 20 °C). The hydrosilation of benzophenone with PhMeSiH2 and 1a was examined by (1)H NMR spectroscopy at -18 °C (in CD2Cl2), and this revealed that either 1a, 5a, or both 1a and 5a could be observed as resting states of the catalytic cycle, depending on the initial [PhMeSiH2]:[benzophenone] ratio. Kinetic studies revealed two possible expressions for the rate of product formation, depending on which catalyst resting state was present (rate = kobs[PhMeSiH2][5a] and rate = k'obs[benzophenone][1a]). Computational methods (DFT, b3pw91, 6-31G(d,p)/LANL2DZ) were used to determine a model catalytic cycle for the hydrosilation of acetone with PhMeSiH2. A key step in this mechanism involves coordination of acetone to the silicon center of 1a-DFT, which leads to insertion of the carbonyl group into an Si-H bond (that is part of a Ru-H-Si 3c-2e bond). This generates an intermediate analogous to 5a (5a-i-DFT), and the final product is displaced from 5a-i-DFT by an associative process involving PhMeSiH2. PMID:25347044

  6. Predicting the effect of D,L-sotalol on ventricular tachycardia inducibility from the RR variability response

    PubMed Central

    Brembilla-Perrot, B; Houriez, P; Claudon, O; Preiss, J; Beurrier, D

    1999-01-01

    AIM—To find a rapid way of identifying non-responders to D,L-sotalol in patients with ventricular tachycardia.
METHODS—Programmed ventricular stimulation and RR variability were studied in the control state and 10 days after treatment with 160 to 320 mg of D,L-sotalol in 36 consecutive patients with ventricular tachycardia.
RESULTS—In 14 patients (group I) D,L-sotalol suppressed ventricular tachycardia inducibility. In 22 patients (group II) sustained ventricular tachycardia remained inducible during D,L-sotalol treatment. The ventricular tachycardia rate was slowed in eight patients and unchanged or accelerated in 14. At baseline, heart rate variability was similar in both groups. During treatment with D,L-sotalol, variables reflecting parasympathetic activity (pNN50, rMSSD, and high frequency amplitude (HF)) increased in both groups: HF increased from (mean (SD)) 75 (68) to 146 (134) in group I (p < 0.05) and from 60 (49) to 125 (79) in group II (p < 0.05). Other variables were unchanged in group I. In group II, the variables associated with sympathetic activity (coefficient of variance (CV), ratio of low frequency amplitude (LF) to HF) decreased significantly: CV decreased from 13 (4) to 9 (2) (p < 0.001) and LF/HF from 4.74 (3.02) to 3.00 (2.02) (p < 0.05).
CONCLUSIONS—The β blocking effect of D,L-sotalol produced a significant improvement over control values in indices of parasympathetic tone in all treated patients. However, the heart rate variability indices related to sympathetic activity were decreased only in non-responders. This effect of D,L-sotalol on heart rate variability could help detect non-responders to the drug and avoid an electrophysiological study.


Keywords: sotalol; ventricular tachycardia; heart rate variability PMID:10455080

  7. The impact of varying autonomic states on the dynamic beat-to-beat QT-RR and QT-TQ interval relationships.

    PubMed

    Fossa, A A

    2008-08-01

    The beat-to-beat dynamicity of the QT-RR interval relationship is difficult to assess with the use of traditional correction factors (QTc) and changes in QTc do not accurately reflect or quantify arrhythmogenic risk. Further, the interpretation of arrhythmogenic risk is influenced by autonomic state. To visualize the QT-RR interval dynamics under varying conditions of autonomic state from impaired repolarization, we have developed a system to sequentially plot the beat-to-beat confluence of ECG data or 'clouds' obtained from conscious dogs and humans. To represent the non-uniformity of the clouds, a bootstrap sampling method that computes the mathematical centre of the uncorrected beat-to-beat QT value (QTbtb) and defines the upper and lower 95% confidence bounds is used. The same method can also be used to examine heterogeneity, hysteresis (both acceleration and deceleration) and restitution (beat-to-beat QT-TQ interval relationship). Impaired repolarization with the combination of E-4031 and L-768,673 (inhibitor of IKs current) increased heterogeneity of restitution at rest 55-91%; increased hysteresis during heart rate acceleration after isoproterenol challenge by approximately 40-60%; and dramatically diminished the minimum TQ boundary by 72% to only 28 ms. Impaired repolarization alters restitution during normal sinus rhythm and increases hysteresis/heterogeneity during heart rate acceleration following sympathetic stimulation. These findings are supported by similar clinical observations in LQT1 and LQT2 syndromes. Therefore, the assessment of the dynamic QT-RR and QT-TQ interval relationships through quantification of heterogeneity, hysteresis and restitution may allow a more accurate non-invasive evaluation of the conditions leading to cardiac arrhythmia.

  8. A survey of HK, HPt, and RR domains and their organization in two-component systems and phosphorelay proteins of organisms with fully sequenced genomes

    PubMed Central

    Salvado, Baldiri; Vilaprinyo, Ester; Sorribas, Albert

    2015-01-01

    Two Component Systems and Phosphorelays (TCS/PR) are environmental signal transduction cascades in prokaryotes and, less frequently, in eukaryotes. The internal domain organization of proteins and the topology of TCS/PR cascades play an important role in shaping the responses of the circuits. It is thus important to maintain updated censuses of TCS/PR proteins in order to identify the various topologies used by nature and enable a systematic study of the dynamics associated with those topologies. To create such a census, we analyzed the proteomes of 7,609 organisms from all domains of life with fully sequenced and annotated genomes. To begin, we survey each proteome searching for proteins containing domains that are associated with internal signal transmission within TCS/PR: Histidine Kinase (HK), Response Regulator (RR) and Histidine Phosphotranfer (HPt) domains, and analyze how these domains are arranged in the individual proteins. Then, we find all types of operon organization and calculate how much more likely are proteins that contain TCS/PR domains to be coded by neighboring genes than one would expect from the genome background of each organism. Finally, we analyze if the fusion of domains into single TCS/PR proteins is more frequently observed than one might expect from the background of each proteome. We find 50 alternative ways in which the HK, HPt, and RR domains are observed to organize into single proteins. In prokaryotes, TCS/PR coding genes tend to be clustered in operons. 90% of all proteins identified in this study contain just one of the three domains, while 8% of the remaining proteins combine one copy of an HK, a RR, and/or an HPt domain. In eukaryotes, 25% of all TCS/PR proteins have more than one domain. These results might have implications for how signals are internally transmitted within TCS/PR cascades. These implications could explain the selection of the various designs in alternative circumstances. PMID:26339559

  9. K2 variable catalogue - II. Machine learning classification of variable stars and eclipsing binaries in K2 fields 0-4

    NASA Astrophysics Data System (ADS)

    Armstrong, D. J.; Kirk, J.; Lam, K. W. F.; McCormac, J.; Osborn, H. P.; Spake, J.; Walker, S.; Brown, D. J. A.; Kristiansen, M. H.; Pollacco, D.; West, R.; Wheatley, P. J.

    2016-02-01

    We are entering an era of unprecedented quantities of data from current and planned survey telescopes. To maximize the potential of such surveys, automated data analysis techniques are required. Here we implement a new methodology for variable star classification, through the combination of Kohonen Self-Organizing Maps (SOMs, an unsupervised machine learning algorithm) and the more common Random Forest (RF) supervised machine learning technique. We apply this method to data from the K2 mission fields 0-4, finding 154 ab-type RR Lyraes (10 newly discovered), 377 δ Scuti pulsators, 133 γ Doradus pulsators, 183 detached eclipsing binaries, 290 semidetached or contact eclipsing binaries and 9399 other periodic (mostly spot-modulated) sources, once class significance cuts are taken into account. We present light-curve features for all K2 stellar targets, including their three strongest detected frequencies, which can be used to study stellar rotation periods where the observed variability arises from spot modulation. The resulting catalogue of variable stars, classes, and associated data features are made available online. We publish our SOM code in PYTHON as part of the open source PYMVPA package, which in combination with already available RF modules can be easily used to recreate the method.

  10. Standard operating procedures for collection of soil and sediment samples for the Sediment-bound Contaminant Resiliency and Response (SCoRR) strategy pilot study

    USGS Publications Warehouse

    Fisher, Shawn C.; Reilly, Timothy J.; Jones, Daniel K.; Benzel, William M.; Griffin, Dale W.; Loftin, Keith A.; Iwanowicz, Luke R.; Cohl, Jonathan A.

    2015-12-17

    An understanding of the effects on human and ecological health brought by major coastal storms or flooding events is typically limited because of a lack of regionally consistent baseline and trends data in locations proximal to potential contaminant sources and mitigation activities, sensitive ecosystems, and recreational facilities where exposures are probable. In an attempt to close this gap, the U.S. Geological Survey (USGS) has implemented the Sediment-bound Contaminant Resiliency and Response (SCoRR) strategy pilot study to collect regional sediment-quality data prior to and in response to future coastal storms. The standard operating procedure (SOP) detailed in this document serves as the sample-collection protocol for the SCoRR strategy by providing step-by-step instructions for site preparation, sample collection and processing, and shipping of soil and surficial sediment (for example, bed sediment, marsh sediment, or beach material). The objectives of the SCoRR strategy pilot study are (1) to create a baseline of soil-, sand-, marsh sediment-, and bed-sediment-quality data from sites located in the coastal counties from Maine to Virginia based on their potential risk of being contaminated in the event of a major coastal storm or flooding (defined as Resiliency mode); and (2) respond to major coastal storms and flooding by reoccupying select baseline sites and sampling within days of the event (defined as Response mode). For both modes, samples are collected in a consistent manner to minimize bias and maximize quality control by ensuring that all sampling personnel across the region collect, document, and process soil and sediment samples following the procedures outlined in this SOP. Samples are analyzed using four USGS-developed screening methods—inorganic geochemistry, organic geochemistry, pathogens, and biological assays—which are also outlined in this SOP. Because the SCoRR strategy employs a multi-metric approach for sample analyses, this

  11. Autonomic nervous system dysfunction in workers exposed to lead, zinc, and copper in relation to peripheral nerve conduction: a study of R-R interval variability

    SciTech Connect

    Murata, K.; Araki, S. )

    1991-01-01

    Quantitative assessment of the autonomic neurotoxicity due to lead was undertaken by measuring variability in the electrocardiographic R-R interval (CVRR) in 16 male workers exposed to lead, zinc, copper, and tin and in 16 unexposed control subjects. Two component coefficients of variation in the R-R interval, the C-CVRSA (respiratory sinus arrhythmia) and C-CVMWSA (Mayer wave related sinus arrhythmia), were examined; these indices are considered to reflect parasympathetic and sympathetic activities, respectively. Maximal motor and sensory conduction velocities (MCV and SCV) in the median nerve were also measured. In the 16 exposed workers, blood lead concentrations ranged from 16 to 60 (mean 34) micrograms/dl. The CVRR and C-CVRSA were found to be significantly reduced in the workers with elevated lead, zinc, and copper absorption as compared to unexposed control subjects; also, the MCV and SCV were significantly slowed. The C-CVMWSA was not significantly reduced, and was positively related to plasma zinc concentrations. No significant relationships were found between indicators of lead and copper absorption and these electrophysiological measurements. These data suggest that subclinical toxicity of lead occurs in the parasympathetic component of the autonomic nervous system as well as in the peripheral nerves. Zinc may antagonize the autonomic nervous dysfunction caused by lead.

  12. Appearance of Planktothrix rubescens Bloom with [D-Asp3, Mdha7]MC–RR in Gravel Pit Pond of a Shallow Lake-Dominated Area

    PubMed Central

    Vasas, Gábor; Farkas, Oszkár; Borics, Gábor; Felföldi, Tamás; Sramkó, Gábor; Batta, Gyula; Bácsi, István; Gonda, Sándor

    2013-01-01

    Blooms of toxic cyanobacteria are well-known phenomena in many regions of the world. Microcystin (MC), the most frequent cyanobacterial toxin, is produced by entirely different cyanobacteria, including unicellular, multicellular filamentous, heterocytic, and non-heterocytic bloom-forming species. Planktothrix is one of the most important MC-producing genera in temperate lakes. The reddish color of cyanobacterial blooms viewed in a gravel pit pond with the appearance of a dense 3 cm thick layer (biovolume: 28.4 mm3 L−1) was an unexpected observation in the shallow lake-dominated alluvial region of the Carpathian Basin. [d-Asp3, Mdha7]MC–RR was identified from the blooms sample by MALDI-TOF and NMR. Concentrations of [d-Asp3, Mdha7]MC–RR were measured by capillary electrophoresis to compare the microcystin content of the field samples and the isolated, laboratory-maintained P. rubescens strain. In analyzing the MC gene cluster of the isolated P. rubescens strain, a deletion in the spacer region between mcyE and mcyG and an insertion were located in the spacer region between mcyT and mcyD. The insertion elements were sequenced and partly identified. Although some invasive tropical cyanobacterial species have been given a great deal of attention in many recent studies, our results draw attention to the spread of the alpine organism P. rubescens as a MC-producing, bloom-forming species. PMID:24351711

  13. Convenient Relations for the Estimation of Bond Ionicity in A-B Type Compounds.

    ERIC Educational Resources Information Center

    Barbe, Jacques

    1983-01-01

    Bond character is directly conditioned by the peculiar capacity of bonded atoms to exchange electrons; such a capacity is clearly illustrated by electronegativity. The determination of bond character using the electronegativity difference between the bonded atoms is discussed and an equation focusing on relationships between bonds is provided. (JN)

  14. Variable Stars In the Unusual, Metal-Rich Globular Cluster

    NASA Technical Reports Server (NTRS)

    Pritzl, Barton J.; Smith, Horace A.; Catelan, Marcio; Sweigart, Allen V.; Oegerle, William R. (Technical Monitor)

    2002-01-01

    We have undertaken a search for variable stars in the metal-rich globular cluster NGC 6388 using time-series BV photometry. Twenty-eight new variables were found in this survey, increasing the total number of variables found near NGC 6388 to approx. 57. A significant number of the variables are RR Lyrae (approx. 14), most of which are probable cluster members. The periods of the fundamental mode RR Lyrae are shown to be unusually long compared to metal-rich field stars. The existence of these long period RRab stars suggests that the horizontal branch of NGC 6388 is unusually bright. This implies that the metallicity-luminosity relationship for RR Lyrae stars is not universal if the RR Lyrae in NGC 6388 are indeed metal-rich. We consider the alternative possibility that the stars in NGC 6388 may span a range in [Fe/H]. Four candidate Population II Cepheids were also found. If they are members of the cluster, NGC 6388 would be the most metal-rich globular cluster to contain Population II Cepheids. The mean V magnitude of the RR Lyrae is found to be 16.85 +/- 0.05 resulting in a distance of 9.0 to 10.3 kpc, for a range of assumed values of (M(sub V)) for RR Lyrae. We determine the reddening of the cluster to be E(B - V) = 0.40 +/- 0.03 mag, with differential reddening across the face of the cluster. We discuss the difficulty in determining the Oosterhoff classification of NGC 6388 and NGC 6441 due to the unusual nature of their RR Lyrae, and address evolutionary constraints on a recent suggestion that they are of Oosterhoff type II.

  15. A new method of assessing cardiac autonomic function and its comparison with spectral analysis and coefficient of variation of R-R interval.

    PubMed

    Toichi, M; Sugiura, T; Murai, T; Sengoku, A

    1997-01-12

    A new non-linear method of assessing cardiac autonomic function was examined in a pharmacological experiment in ten healthy volunteers. The R-R interval data obtained under a control condition and in autonomic blockade by atropine and by propranolol were analyzed by each of the new methods employing Lorenz plot, spectral analysis and the coefficient of variation. With our method we derived two measures, the cardiac vagal index and the cardiac sympathetic index, which indicate vagal and sympathetic function separately. These two indices were found to be more reliable than those obtained by the other two methods. We anticipate that the non-invasive assessment of short-term cardiac autonomic function will come to be performed more reliably and conveniently by this method.

  16. Association of decreased variation of R-R interval and elevated serum C-reactive protein level in a general population in Japan.

    PubMed

    Kon, Hisashi; Nagano, Masahide; Tanaka, Fumitaka; Satoh, Kenyu; Segawa, Toshie; Nakamura, Motoyuki

    2006-11-01

    Several studies have suggested that an increased high sensitivity C-reactive protein (hsCRP) level is a strong independent predictor of increased risk for atherosclerotic cardiovascular mortality and morbidity. Reduced heart rate variability (HRV) has also been reported to predict cardiovascular events such as sudden death and myocardial infarction in apparently healthy subjects. The aim of this cross-sectional study was to test the possible correlation between variation of the R-R interval as one of the markers of HRV and serum hsCRP levels in a general population in Japan. Resting, supine, 2-minute, beat-to-beat heart rate data were collected in 823 randomly selected participants enrolled in our cohort study. The coefficient of variation of the R-R interval (CVrr) was obtained as a parameter of HRV. To determine which factors predict the presence of low CVrr (below the 5 percentile) in this group, we performed a multivariate logistic regression analysis using cardiovascular risk factors and an elevated hsCRP level as independent variables. The lowest CVrr group showed significantly higher hsCRP levels compared to those of other quartiles (P < 0.01). After adjustment for confounding factors such as age, heart rate, obesity, hypercholesterolemia, and hypertension by multivariate logistic analysis, an elevated hsCRP level (OR = 3.11, 95%CI; 1.27-7.60: P < 0.02) was a significant independent predictor of low CVrr. The results of the present study indicate that an increased serum hsCRP level is significantly associated with reduced CVrr in this general population. It is conceivable that the parasympathetic nerve withdrawal and inflammation could interact with each other, resulting in the progression of atherosclerotic cardiovascular disease. PMID:17268121

  17. Ultrasonically Induced Degradation of Microcystin-LR and -RR: Identification of Products, Effect of pH, Formation and Destruction of Peroxides

    PubMed Central

    SONG, WEIHUA; DE LA CRUZ, ARMAH A.; REIN, KATHLEEN; O'SHEA, KEVIN E.

    2008-01-01

    Microcystins (MCs) are a family of toxic peptides produced by a number of cyanobacteria commonly found in lakes, water reservoirs, and recreational facilities. The increased eutrophication of freshwater supplies has led to an increase in the incidence of cyanobacterial harmful algal blooms and concerns over the public health implications of these toxins in the water supply. Conventional water treatment methods are ineffective at removing low concentrations of cyanotoxins, hence specialized treatment is usually recommended for treatment of contaminated water. In this study, the products of ultrasonically induced degradation of microcystin-LR (MC-LR) and microcystin-RR (MC-RR) were analyzed by LC–MS to elucidate the probable pathways of degradation of these toxins. Results indicate preliminary products of sonolysis of MCs are due to the hydroxyl radical attack on the benzene ring and diene of the Adda peptide residue and cleavage of the Mdha–Ala peptide bond. The effect of pH on the toxin degradation was evaluated since the pH of the solution changes upon ultrasonic irradiation and varies with the water quality of treatable waters. The initial rate of MC-LR degradation is greater at acidic pH and coincides with the change in hydrophobic character of MC-LR as a function of pH. Hydrogen and organic peroxides are formed during ultrasonic irradiation, but can be eliminated by adding Fe(II). The addition of Fe(II) also accelerates the degradation of MC-LR, presumably by promoting the formation of hydroxyl radicals via conversion of ultrasonically produced H2O2. These findings suggest that sonolysis can effectively degrade MCs in drinking water. PMID:16830565

  18. Ultrasonically induced degradation of microcystin-LR and -RR: identification of products, effect of pH, formation and destruction of peroxides.

    PubMed

    Song, Weihua; de la Cruz, Armah A; Rein, Kathleen; O'Shea, Kevin E

    2006-06-15

    Microcystins (MCs) are a family of toxic peptides produced by a number of cyanobacteria commonly found in lakes, water reservoirs, and recreational facilities. The increased eutrophication of freshwater supplies has led to an increase in the incidence of cyanobacterial harmful algal blooms and concerns over the public health implications of these toxins in the water supply. Conventional water treatment methods are ineffective at removing low concentrations of cyanotoxins, hence specialized treatment is usually recommended for treatment of contaminated water. In this study, the products of ultrasonically induced degradation of microcystin-LR (MC-LR) and microcystin-RR (MC-RR) were analyzed by LC-MS to elucidate the probable pathways of degradation of these toxins. Results indicate preliminary products of sonolysis of MCs are due to the hydroxyl radical attack on the benzene ring and diene of the Adda peptide residue and cleavage of the Mdha-Ala peptide bond. The effect of pH on the toxin degradation was evaluated since the pH of the solution changes upon ultrasonic irradiation and varies with the water quality of treatable waters. The initial rate of MC-LR degradation is greater at acidic pH and coincides with the change in hydrophobic character of MC-LR as a function of pH. Hydrogen and organic peroxides are formed during ultrasonic irradiation, but can be eliminated by adding Fe(II). The addition of Fe(II) also accelerates the degradation of MC-LR, presumably by promoting the formation of hydroxyl radicals via conversion of ultrasonically produced H2O2. These findings suggest that sonolysis can effectively degrade MCs in drinking water. PMID:16830565

  19. Optimization of medium for one-step fermentation of inulin extract from Jerusalem artichoke tubers using Paenibacillus polymyxa ZJ-9 to produce R,R-2,3-butanediol.

    PubMed

    Gao, Jian; Xu, Hong; Li, Qiu-jie; Feng, Xiao-hai; Li, Sha

    2010-09-01

    The medium for one-step fermentation of raw inulin extract from Jerusalem artichoke tubers by Paenibacillus polymyxa ZJ-9 to produce R,R-2,3-butanediol (R,R-2,3-BD) was developed. Inulin, K(2)HPO(4) and NH(4)Cl were found to be the key factors in the fermentation according to the results obtained from the Plackett-Burman experimental design. The optimal concentration range of the three factors was examined by the steepest ascent path, and their optimal concentration was further investigated according to the Box-Behnken design and determined to be 77.14 g/L, 3.09 g/L and 0.93 g/L, respectively. Under the optimal conditions, the concentration of the obtained R,R-2,3-BD was 36.92 g/L, at more than 98% optical purity. Compared with other investigated carbon resources, fermentation of the raw inulin extract afforded the highest yield of R,R-2,3-BD. This process featured one-step fermentation of inulin without further hydrolyzing, which greatly decreased the raw material cost and thus facilitated its practical application.

  20. Fourier Decomposition and Properties of the Variable Stars in the Globular Cluster NGC 4833

    NASA Astrophysics Data System (ADS)

    Reed, Hunter M.; Pajkos, Michael A.; Murphy, Brian W.; Darragh, Andrew

    2016-01-01

    Globular clusters provide an ideal setting to study stellar evolution of stars of similar composition and age. RR Lyrae stars found in globular clusters have a variety of uses in probing the physical characteristics of the stellar population itself and its evolution. Building upon our previous study, we focus on the RR Lyrae stars in the globular cluster NGC 4833. From March through June 2014, we used the Southeastern Association for Research in Astronomy 0.6-meter telescope located at CTIO to collect nearly 1,500 images of NGC 4833 in the B, V, R, and I bands. Using difference image analysis we identified 40 variable stars. Of these, 20 were RR Lyrae stars with 10 being of type RR0, 7 of type RR1, and 3 of type RR2. Additionally, 6 SX Phe, 5 eclipsing binaries, and 9 long period variables were identified. The average period of the type RR0, RR1, and RR2 type variables were 0.69597 days, 0.39547 days, and 0.30654 days, respectively. The periods of the RR Lyrae stars and ratio of N1/(N0+N1) of 0.41 is indicative of an Oosterhoff Type II cluster. The observations of the RR Lyrae stars were of very high quality and phase coverage allowing us to perform Fourier decomposition of their light curves. From this Fourier decomposition we were able to determine the physical characteristics of the RR Lyrae stars. We found the mean iron abundance to be [Fe/H]JKZW = -1.87 ± 0.06, the mean apparent V-magnitude RR0 and RR1 type variables to be VRR = 15.51 ± 0.11, a mean absolute V-magnitude of MV = 0.636 ± 0.053; and an effective temperature for RR0's and RR1's of log10Teff = 3.797 and log10Teff = 3.855, respectively. The multi-band photometry allowed us to determine the reddening of the cluster, E(B-V) = 0.342 ± 0.021, which resulted in a distance of D(kpc) = 5.91 ± 0.31 to NGC 4833.

  1. VARIABLE STARS IN THE GLOBULAR CLUSTER NGC 2808

    SciTech Connect

    Kunder, Andrea; Walker, Alistair R.; Stetson, Peter B.; Catelan, Marcio; Amigo, Pia E-mail: mcatelan@astro.puc.cl

    2013-02-01

    The first calibrated broadband BVI time-series photometry is presented for the variable stars in NGC 2808, with observations spanning a range of 28 years. We have also redetermined the variability types and periods for the variable stars identified previously by Corwin et al., revising the number of probable fundamental-mode RR Lyrae variables (RR0) to 11 and the number of first-overtone variables (RR1) to five. Our observations were insufficient to discern the nature of the previously identified RR1 star, V24, and the tentatively identified RR1 star, V13. These two variables are {approx}0.8 mag brighter than the RR Lyrae variables, appear to have somewhat erratic period and/or luminosity changes, and lie inside the RR Lyrae instability strip. Curiously, all but one of the RR Lyrae stars studied in this relatively metal-rich cluster exhibit the Blazhko phenomenon, an effect thought to occur with higher frequency in metal-poor environments. The mean periods of the RR0 and RR1 variables are (P){sub RR0} = 0.56 {+-} 0.01 d and

    {sub RR1} = 0.30 {+-} 0.02 d, respectively, supporting an Oosterhoff I classification of the cluster. On the other hand, the number ratio of RR1-to-RR0-type variables is high, though not unprecedented, for an Oosterhoff I cluster. The RR Lyrae variables have no period shifts at a given amplitude compared to the M3 variables, making it unlikely that these variables are He enhanced. Using the recent recalibration of the RR Lyrae luminosity scale by Catelan and Cortes, a mean distance modulus of (m - M){sub V} = 15.57 {+-} 0.13 mag for NGC 2808 is obtained, in good agreement with that determined here from its type II Cepheid and SX Phoenicis population. Our data have also allowed the discovery of two new candidate SX Phoenicis stars and an eclipsing binary in the blue straggler region of the NGC 2808 color-magnitude diagram.

  2. HST Snapshot Study of Variable Stars in Globular Clusters: Inner Region of NGC 6441

    NASA Technical Reports Server (NTRS)

    Pritzl, Barton J.; Smith, Horace A.; Stetson, Peter B.; Catelan, Marcio; Sweigart, Allen V.; Layden, Andrew C.; Rich, R. Michael

    2003-01-01

    We present the results of a Hubble Space Telescope snapshot program to survey the inner region of the metal-rich globular cluster NGC 6441 for its variable stars. A total of 57 variable stars was found including 38 RR Lyrae stars, 6 Population II Cepheids, and 12 long period variables. Twenty-four of the RR Lyrae stars and all of the Population II Cepheids were previously undiscovered in ground-based surveys. Of the RR Lyrae stars observed in h s survey, 26 are pulsating in the fundamental mode with a mean period of 0.753 d and 12 are first-overtone mode pulsators with a mean period of 0.365 d. These values match up very well with those found in ground-based surveys. Combining all the available data for NGC 6441, we find mean periods of 0.759 d and 0.375 d for the RRab and RRc stars, respectively. We also find that the RR Lyrae in this survey are located in the same regions of a period-amplitude diagram as those found in ground-based surveys. The overall ratio of RRc to total RR Lyrae is 0.33. Although NGC 6441 is a metal-rich globular cluster and would, on that ground, be expected either to have few RR Lyrae stars, or to be an Oosterhoff type I system, its RR Lyrae more closely resemble those in Oosterhoff type II globular clusters. However, even compared to typical Oosterhoff type II systems, the mean period of its RRab stars is unusually long. We also derived I-band period-luminosity relations for the RR Lyrae stars. Of the six Population II Cepheids, five are of W Virginis type and one is a BL Herculis variable star. This makes NGC 6441, along with NGC 6388, the most metal-rich globular cluster known to contain these types of variable stars. Another variable, V118, may also be a Population II Cepheid given its long period and its separation in magnitude from the RR Lyrae stars. We examine the period-luminosity relation for these Population II Cepheids and compare it to those in other globular clusters and in the Large Magellanic Cloud. We argue that there does

  3. Power law behavior of RR-interval variability in healthy middle-aged persons, patients with recent acute myocardial infarction, and patients with heart transplants

    NASA Technical Reports Server (NTRS)

    Bigger, J. T. Jr; Steinman, R. C.; Rolnitzky, L. M.; Fleiss, J. L.; Albrecht, P.; Cohen, R. J.

    1996-01-01

    BACKGROUND. The purposes of the present study were (1) to establish normal values for the regression of log(power) on log(frequency) for, RR-interval fluctuations in healthy middle-aged persons, (2) to determine the effects of myocardial infarction on the regression of log(power) on log(frequency), (3) to determine the effect of cardiac denervation on the regression of log(power) on log(frequency), and (4) to assess the ability of power law regression parameters to predict death after myocardial infarction. METHODS AND RESULTS. We studied three groups: (1) 715 patients with recent myocardial infarction; (2) 274 healthy persons age and sex matched to the infarct sample; and (3) 19 patients with heart transplants. Twenty-four-hour RR-interval power spectra were computed using fast Fourier transforms and log(power) was regressed on log(frequency) between 10(-4) and 10(-2) Hz. There was a power law relation between log(power) and log(frequency). That is, the function described a descending straight line that had a slope of approximately -1 in healthy subjects. For the myocardial infarction group, the regression line for log(power) on log(frequency) was shifted downward and had a steeper negative slope (-1.15). The transplant (denervated) group showed a larger downward shift in the regression line and a much steeper negative slope (-2.08). The correlation between traditional power spectral bands and slope was weak, and that with log(power) at 10(-4) Hz was only moderate. Slope and log(power) at 10(-4) Hz were used to predict mortality and were compared with the predictive value of traditional power spectral bands. Slope and log(power) at 10(-4) Hz were excellent predictors of all-cause mortality or arrhythmic death. To optimize the prediction of death, we calculated a log(power) intercept that was uncorrelated with the slope of the power law regression line. We found that the combination of slope and zero-correlation log(power) was an outstanding predictor, with a

  4. Two-color photographic photometry of variables in the globular cluster M28

    SciTech Connect

    Wehlau, A.; Butterworth, S. )

    1990-09-01

    Visual magnitudes have been measured for 20 variables on 32 plates of M28. These have been combined with previously published as well as newly determined blue magnitudes in order to obtain colors for the variables. Blue and visual light curves are presented for 15 of the the variables, including one W Virginis star V4, one RV Tauri star V17, one field Mira variable V7, nine cluster RR Lyrae stars, and three field RR Lyrae stars. It is shown that V14, previously thought to be a c type RR Lyrae star, is to the red of the instability strip. The visual light curve of V9 suggests that the star may be a member of a binary or a very close optical double. Possible evidence for differential reddening in the vicinity of M28 is presented. The bimodal distribution of the periods of the RR Lyrae stars in M28 may indicate a spread in metallicity among the RR Lyrae variables. 16 refs.

  5. [Correlations between the coefficient of variation of RR intervals and sympathetic nerve activity following superior tilting in normotensive subjects and in patients with essential hypertension].

    PubMed

    Shimazaki, M; Kikuchi, K; Yamaji, I; Kobayakawa, H; Yamamoto, M; Kudo, C; Wada, A; Mukai, H; Iimura, O

    1991-01-01

    The relationship between changes in sympathetic nerve activity and those in parasympathetic tone with a change in position was investigated in patients with essential hypertension using the coefficient of variation of RR intervals on electrocardiograms (CVRR). Mean arterial pressure (MAP), heart rate (HR), plasma noradrenaline concentration (pNA) and CVRR were measured in a supine position at rest and 20 min after having the head tilted 60 degrees superiorly in 10 normotensives (NT: 51.9 +/- 3.0 yrs) and 7 essential hypertensive patients (EHT: 51.0 +/- 2.8 yrs). After changing the position, CVRR decreased significantly in the NT, but not in the EHT; whereas, significant increases of both HR and pNA without significant changes in MAP were shown in both groups. A significant negative correlation between percentage changes in CVRR (% delta CVRR) and pNA (% delta pNA) were observed in the NT, but not in the EHT. However, there was no relationship of % delta CVRR to % delta MAP or to % delta HR in either group. It was suggested from the changes in CVRR that suppression of the parasympathetic tone, which occurs in the NT group corresponding to sympathetic augmentation to present a decrease in blood pressure with a change in position, may be impaired in the EHT group.

  6. Coefficient of variation of R-R intervals in electrocardiogram is a sensitive marker of anemia induced by autonomic neuropathy in type 1 diabetes.

    PubMed

    Saito, Takatoshi; Tojo, Katsuyoshi; Nishimura, Rimei; Kageyama, Shigeru; Tajima, Naoko

    2007-10-01

    The present study investigated the relationship between hemoglobin (Hb) levels and autonomic failure using a sensitive marker, coefficient of variation of R-R intervals in electrocardiogram (CVR-R) in order to clarify a cause of normocytic normochromic anemia in type 1 diabetic patients without overt nephropathy. We recruited 46 patients with type 1 diabetes and measured creatinine clearance (Ccr), HbA1c, albuminuria, Hb levels and CVR-R of all patients. In addition, the status of diabetic retinopathy and neuropathy were also evaluated. Serum erythropoietin (EPO), Fe, total iron binding capacity, lactate dehydrogenase, total bilirubin levels and number of reticulocytes and mean corpuscular volume were also measured to distinguish types of anemia. To survey the statistical correlation existing between Hb and body mass index (BMI), Ccr, HbA1c, albuminuria or retinopathy, multiple regression analysis was performed. Serum EPO, Fe, TIBC, LDH and TB levels and number of reticulocytes and MCV were within normal limits. Multiple regression analysis disclosed that HbA1c, nephropathy evaluated by albuminuria and Ccr, and retinopathy has no concern with Hb level. There is only significant relationship between Hb levels and CVR-R. Similar results were obtained even if we analyzed a group of male and female separately. We conclude that CVR-R has the strong relationship on anemia without overt nephropathy in type 1 diabetes, indicating that autonomic failure contributes on the progression of anemia via a poor response of EPO to anemia.

  7. [The coefficient of variation of RR intervals (CVRR) on electrocardiogram in patients with essential hypertension with reference to aging, hemodynamics and sympatho-adrenomedullary function].

    PubMed

    Shimazaki, M; Kikuchi, K; Kobayakawa, H; Yamamoto, M; Kudoh, C; Wada, A; Sakamoto, T; Sawai, N; Mukai, H; Iimura, O

    1991-09-01

    To evaluate the significance of parasympathetic nerve activity in essential hypertension, we measured the coefficients of variation of RR intervals (CVRR) on electrocardiogram and examined the relationships between CVRR and aging, hemodynamics and sympatho-adrenomedullary function in normotensive subjects (NT) and in patients with essential hypertension (EHT). Mean arterial pressure (MAP), heart rate (HR), plasma noradrenaline concentration (pNA), plasma adrenaline concentration (pAd) and CVRR resting in a supine position were simultaneously measured in 37 NT (33.8 +/- 2.0 years) and 47 mild-to-moderate EHT (51.3 +/- 1.5 years). In both NT and EHT, significantly negative correlations between CVRR and age (NT: r = -0.54, p less than 0.001, EHT: r = -0.41, p less than 0.005) were observed, however, CVRR correlated with neither MAP, HR nor pAd. CVRR tended to correlate negatively with pNA (r = -0.27, p less than 0.1) in NT, unlike in EHT. The mean value of CVRR in EHT (n = 10, age: 38.3 +/- 1.6 years, CVRR: 3.61 +/- 0.37%) was significantly (p less than 0.005) lower than in age-matched NT (n = 10, age: 38.3 +/- 2.5 years, CVRR: 5.76 +/- 0.45%). These results indicate that the parasympathetic tone suggested by CVRR may be related to aging and sympathetic nerve activity, and that parasympathetic function might be impaired in EHT.

  8. Photometric activity of UX orionis stars and related objects in the near infrared and optical: CO Ori, RR Tau, UX Ori, and VV Ser

    NASA Astrophysics Data System (ADS)

    Shenavrin, V. I.; Rostopchina-Shakhovskaya, A. N.; Grinin, V. P.; Demidova, T. V.; Shakhovskoi, D. N.; Belan, S. P.

    2016-08-01

    This paper continues a study of the photometric activity of UX Ori stars in the optical and near-infrared ( JHKLM bands) initiated in 2000. For comparison, the list of program stars contains two Herbig Ae stars that are photometrically quiet in the optical: MWC480 andHD179218. Fadings ofUXOri stars in the optical ( V band) due to sporadic increases of the circumstellar extinction are also observed in the infrared (IR), but with decreasing amplitude. Two stars, RR Tau and UX Ori, displayed photometric events when V -band fadings were accompanied by an increase in IR fluxes. Among the two Herbig Ae stars that are photometrically quiet in the optical, MWC 480 proved to be fairly active in the IR. Unlike the UX Ori stars, the variation amplitude of MWC 480 increases from the J band to the M band. In the course of the observations, no deep fadings in the IR bands were detected. This indicates that eclipses of the program stars have a local nature, and are due to extinction variations in the innermost regions of the circumstellar disks. The results presented testify to an important role of the alignment of the circumstellar disks relative to the direction towards the observer in determining the observed IR variability of young stars.

  9. In silico metabolic engineering of Bacillus subtilis for improved production of riboflavin, Egl-237, (R,R)-2,3-butanediol and isobutanol.

    PubMed

    Hao, Tong; Han, Binbin; Ma, Hongwu; Fu, Jing; Wang, Hui; Wang, Zhiwen; Tang, Bincai; Chen, Tao; Zhao, Xueming

    2013-08-01

    Bacillus subtilis is a Gram-positive sporiferous bacterium widely used in a variety of industrial fields as a producer of high-quality vitamins, enzymes and proteins. Many genetic modifications and evolutionary engineering optimisations aiming at obtaining a better performing strain for its products have been studied. As genome-scale metabolic network models have gained significant popularity as effective tools in metabolic phenotype studies, we reconstructed a genome-scale metabolic network of B. subtilis-iBsu1147. The accuracy of iBsu1147 is validated by growth on various carbon sources, single gene knockout and large fragment non-essential gene knockout simulations. The model is used for the in silico metabolic engineering design of reactions over/underexpressed or knockout for increasing the production of four important products of B. subtilis: riboflavin, cellulase Egl-237, (R,R)-2,3-butanediol and isobutanol. The simulation predicted candidate reactions related to the improvement of strain performance on related products. The prediction is partly supported by previously published results. Due to the complexity of the biological system, it is difficult to manually find the factors that are not directly related to the production of the target compounds. The in silico predictions provide more choices for further strain improvement for these products. PMID:23666098

  10. Conventional (MG-BR46 Conquista) and transgenic (BRS Valiosa RR) soybeans have no mutagenic effects and may protect against induced-DNA damage in vivo.

    PubMed

    Venâncio, Vinicius P; Silva, João Paulo L; Almeida, Alaor A; Brigagão, Maísa R P L; Azevedo, Luciana

    2012-01-01

    In the present study, we evaluated the pesticide and metal concentrations as well as the antimutagenic and mutagenic properties of commercial soybeans (Glycine max). Male Swiss mice were fed diets containing 1%, 10%, or 20% (w/w) transgenic soybeans (BRS Valiosa RR) or parental isogenic conventional soybeans (MG-BR46 Conquista). Cyclophosphamide (50 mg kg⁻¹ b.w.) was added in a single dose 24 h before euthanasia as an induction agent. There was no difference in the composition (ash, total fat, protein, moisture, and carbohydrates) of the diets containing the same soybean concentration. The results show that the commercially available Brazilian soybeans tested are free of organochlorine, organophosphate, and carbamate pesticides and contain acceptable heavy metal concentrations. Both cyclophosphamide and soybean treatments were not sufficient to cause detectable oxidative damage on liver by the levels of malondialdehyde and protein carbonyl. The transgenic soybeans are also nonmutagenic and have protective effects against DNA damage similar to those of conventional soybeans but to a lesser percentage (64%-101% for conventional and 23%-33% for transgenic diets).

  11. Antiallodynic effects of alpha lipoic acid in an optimized RR-EAE mouse model of MS-neuropathic pain are accompanied by attenuation of upregulated BDNF-TrkB-ERK signaling in the dorsal horn of the spinal cord.

    PubMed

    Khan, Nemat; Gordon, Richard; Woodruff, Trent M; Smith, Maree T

    2015-06-01

    Neuropathic pain may affect patients with multiple sclerosis (MS) even in early disease. In an experimental autoimmune encephalomyelitis (EAE)-mouse model of MS, chronic alpha lipoic acid (ALA) treatment reduced clinical disease severity, but MS-neuropathic pain was not assessed. Hence, we investigated the pain-relieving efficacy and mode of action of ALA using our optimized relapsing-remitting (RR)-EAE mouse model of MS-associated neuropathic pain. C57BL/6 mice were immunized with MOG35-55 and adjuvants (Quil A and pertussis toxin) to induce RR-EAE; sham-mice received adjuvants only. RR-EAE mice received subcutaneous ALA (3 or 10 mg kg(-1) day(-1)) or vehicle for 21 days (15-35 d.p.i.; [days postimmunization]); sham-mice received vehicle. Hindpaw hypersensitivity was assessed blinded using von Frey filaments. Following euthanasia (day 35 d.p.i.), lumbar spinal cords were removed for immunohistochemical and molecular biological assessments. Fully developed mechanical allodynia in the bilateral hindpaws of vehicle-treated RR-EAE mice was accompanied by marked CD3(+) T-cell infiltration, microglia activation, and increased brain-derived neurotrophic factor (BDNF)-tyrosine kinase B (TrkB) signaling in the dorsal horn of the lumbar spinal cord. Consequently, phospho-ERK, a marker of central sensitization in neuropathic pain, was upregulated in the spinal dorsal horn. Importantly, hindpaw hypersensitivity was completely attenuated in RR-EAE mice administered ALA at 10 mg kg(-1) day(-1) but not 3 mg kg(-1) day(-1). The antiallodynic effect of ALA (10 mg kg(-1) day(-1)) was associated with a marked reduction in the aforementioned spinal dorsal horn markers to match their respective levels in the vehicle-treated sham-mice. Our findings suggest that ALA at 10 mg kg(-1) day(-1) produced its antiallodynic effects in RR-EAE mice by reducing augmented CD3(+) T-cell infiltration and BDNF-TrkB-ERK signaling in the spinal dorsal horn. PMID:26171221

  12. Quantitative Variations of Intracellular Microcystin-LR, -RR and -YR in Samples Collected from Four Locations in Hartbeespoort Dam in North West Province (South Africa) During the 2010/2011 Summer Season

    PubMed Central

    Mbukwa, Elbert A.; Msagati, Titus A.M.; Mamba, Bhekie B.

    2012-01-01

    The Hartbeespoort (HBP) Dam is a reservoir used for agricultural, domestic supply of raw potable water and recreational activities in South Africa’s North-West Province. Eutrophication and cyanobacterial blooms have long been a cause of water-quality problems in this reservoir. The most prevalent bloom-forming species is Microcystis aeruginosa, often producing the toxin microcystin, a hepatotoxin which can negatively impact aquatic animal and human health, and poses a problem for potable water supply. Algal samples were collected monthly from four pre-determined sites in the dam during the summer months (December 2010–March 2011). Intracellular microcystins (MCs) were extracted using SPE C18 cartridges, followed by separation, identification and quantification using LC-ESI-MS techniques. Quantitative variation studies of MCs were conducted with respect to MC congener isolated, sampling site and month. Three main MC congeners (MC-RR, -LR and-YR) were isolated, identified and quantified. In addition, three minor MCs (MC-WR, MC-(H4)YR and (D-Asp3, Dha7)MC-RR were also identified, but were not quantified. The MC dominance followed the order MC-RR>MC-LR>MC-YR across all sites and time. The maximum and minimum concentrations were 268 µg/g and 0.14 µg/g DW for MC-RR and MC-YR, respectively, of the total MCs quantified from this study. One-way ANOVA showed that there were no significant differences between average MC concentrations recorded across months (P = 0.62), there was, however, a marginally-significant difference in concentrations among MC congeners (P = 0.06). ANCOVA revealed a highly significant interaction between sites and MC congeners on MC concentration (P < 0.001). PMID:23202758

  13. Quantitative variations of intracellular microcystin-LR, -RR and -YR in samples collected from four locations in Hartbeespoort Dam in North West Province (South Africa) during the 2010/2011 summer season.

    PubMed

    Mbukwa, Elbert A; Msagati, Titus A M; Mamba, Bhekie B

    2012-10-01

    The Hartbeespoort (HBP) Dam is a reservoir used for agricultural, domestic supply of raw potable water and recreational activities in South Africa's North-West Province. Eutrophication and cyanobacterial blooms have long been a cause of water-quality problems in this reservoir. The most prevalent bloom-forming species is Microcystis aeruginosa, often producing the toxin microcystin, a hepatotoxin which can negatively impact aquatic animal and human health, and poses a problem for potable water supply. Algal samples were collected monthly from four pre-determined sites in the dam during the summer months (December 2010-March 2011). Intracellular microcystins (MCs) were extracted using SPE C(18)cartridges, followed by separation, identification and quantification using LC-ESI-MS techniques. Quantitative variation studies of MCs were conducted with respect to MC congener isolated, sampling site and month. Three main MC congeners (MC-RR, -LR and-YR) were isolated, identified and quantified. In addition, three minor MCs (MC-WR, MC-(H(4))YR and (D-Asp(3), Dha(7))MC-RR were also identified, but were not quantified. The MC dominance followed the order MC-RR>MC-LR>MC-YR across all sites and time. The maximum and minimum concentrations were 268 µg/g and 0.14 µg/g DW for MC-RR and MC-YR, respectively, of the total MCs quantified from this study. One-way ANOVA showed that there were no significant differences between average MC concentrations recorded across months (P = 0.62), there was, however, a marginally-significant difference in concentrations among MC congeners (P = 0.06). ANCOVA revealed a highly significant interaction between sites and MC congeners on MC concentration (P < 0.001).

  14. Variable Stars in the Field of the Hydra II Ultra-Faint Dwarf Galaxy

    NASA Astrophysics Data System (ADS)

    Vivas, Anna Katherina; Olsen, Knut A.; Blum, Robert D.; Nidever, David L.; Walker, Alistair R.; Martin, Nicolas; Besla, Gurtina; Gallart, Carme; Van Der Marel, Roeland P.; Majewski, Steven R.; Munoz, Ricardo; Kaleida, Catherine C.; Saha, Abhijit; Conn, Blair; Jin, Shoko

    2016-06-01

    We searched for variable stars in Hydra II, one of the recently discovered ultra-faint dwarf satellites of the Milky Way, using gri time-series obtained with the Dark Energy Camera (DECam) at Cerro Tololo Inter-American Observatory, Chile. We discovered one RR Lyrae star in the galaxy which was used to derive a distance of 154±8 kpc to this system and to re-calculate its absolute magnitude and half-light radius.A comparison with other RR Lyrae stars in ultra-faint systems indicates similar pulsational properties among them, which are different to those found among halo field stars and those in the largest of the Milky Way satellites. We also report the discovery of 31 additional short period variables in the field of view (RR Lyrae, SX Phe, eclipsing binaries, and a likely anomalous cepheid) which are likely not related with Hydra II.

  15. Changes in autonomic function as determined by ECG R-R interval variability in sandal, shoe and leather workers exposed to n-hexane, xylene and toluene.

    PubMed

    Murata, K; Araki, S; Yokoyama, K; Yamashita, K; Okajima, F; Nakaaki, K

    1994-01-01

    To clarify if autonomic nervous system effects might be associated with exposure to organic solvents, 30 sandal, shoe and leather workers exposed to n-hexane, xylene, and toluene, and 25 unexposed controls were examined using the coefficient of variation in electrocardiographic R-R intervals (CVRR), combined with the distribution of nerve conduction velocities (DCV). The C-CVRSA and C-CVMWSA (two component CVs of the CVRR reflecting parasympathetic and sympathetic activities, respectively) were also computed from component spectral powers using autoregressive spectral and component analyses. Concentrations of the metabolites of the solvents in urine samples taken in the morning before work were 0-3.18 (mean 1.39) mg/l for 2,5-hexanedione, 0.10-0.43 (mean 0.19) g/g creatinine (Cn) for methylhippuric acid, and 0.05-2.53 (mean 0.41) g/g Cn for hippuric acid. In the solvent workers, the CVRR and C-CVRSA were reduced significantly when compared with the unexposed controls. The faster velocities of the DCV as well as the sensory median nerve conduction velocity (SCV) were significantly slowed in the solvent-exposed workers. The SCV was significantly correlated with the CVRR and C-CVMWSA among the solvent workers. These data suggest that chronic exposure to some organic solvents may affect cardiac autonomic function (mainly, parasympathetic activity) in addition to faster myelinated fibers of the peripheral nerves. However, the absence of significant dose-effect relations among the solvent workers makes it difficult to definitively attribute the differences to specific solvent exposures. PMID:7715857

  16. Comparison of Polar® RS800G3™ heart rate monitor with Polar® S810i™ and electrocardiogram to obtain the series of RR intervals and analysis of heart rate variability at rest.

    PubMed

    Barbosa, Marianne Penachini da Costa de Rezende; da Silva, Natália Turri; de Azevedo, Fábio Mícolis; Pastre, Carlos Marcelo; Vanderlei, Luiz Carlos Marques

    2016-03-01

    The Polar® RS800G3™ rate monitor was released in the market to replace the Polar® S810i™, and few studies have assessed that the RR series obtained by this equipment is reliable for analysis of heart rate variability (HRV). We compared HRV indexes among the devices Polar® RS800G3™, Polar® S810i™ and eletrocardiogram (ECG) to know whether the series of Polar® RS800G3™ are as reliable as those devices already validated. We analysed data from 30 healthy young adults, male, with an average age of 20·66 ± 1·40 years, which had captured the heart rate beat to beat in the three devices simultaneously with spontaneously breathing, first in the supine position and subsequently sit both for 30 min. The obtained series of RR intervals was used to calculate the indexes of HRV in the time domain (SDNN and RMSSD) and in the frequency domain (LF, HF and LF/HF). There were no significant differences in HRV indexes calculated from series obtained by the three devices, regardless of the position analysed, and a high correlation coefficient was observed. The results suggest that the Polar® RS800G3™ is able to capture series of RR intervals for analysis of HRV indexes as reliable as those obtained by ECG and Polar® S810i™.

  17. TIME-SERIES BVI PHOTOMETRY FOR THE GLOBULAR CLUSTER NGC 6981 {sup ,} {sup ,}

    SciTech Connect

    Amigo, P.; Catelan, M.; Zoccali, M.; Stetson, P. B.; Smith, H. A. E-mail: mzoccali@astro.puc.cl E-mail: Peter.Stetson@nrc-cnrc.gc.ca

    2013-11-01

    We present new BVI photometry of the globular cluster NGC 6981, based mostly on ground-based CCD archival images. We present a new color-magnitude diagram (CMD) that reaches almost four magnitudes below the turn-off level. We performed new derivations of metallicity and morphological parameters of the evolved sequences, in good agreement with the results of previous authors, and obtain a value of [Fe/H] ≅ –1.50 in the new UVES scale. We also identify the cluster's blue straggler population. Comparing the radial distribution of these stars with the red giant branch population, we find that the blue stragglers are more centrally concentrated, as found in previous studies of blue stragglers in globular clusters. Taking advantage of the large field of view covered by our study, we analyzed the surface density profile of the cluster, and find extratidal main sequence stars out to r ≈ 14.'1, or about twice the tidal radius. We speculate that the presence of these stars may be due to tidal disruption in the course of NGC 6981's orbit, in which case tidal tails associated with the cluster may exist. We also take a fresh look at the variable stars in the cluster, recovering all previously known variables, including three SX Phoenicis stars. We also add three previously unknown RR Lyrae (one c-type and two ab-type) to the total census. Finally, comparing our CMD with unpublished data for M3 (NGC 5272), a cluster with a similar metallicity and horizontal branch morphology, we found that both objects are essentially coeval.

  18. Time-series BVI Photometry for the Globular Cluster NGC 6981

    NASA Astrophysics Data System (ADS)

    Amigo, P.; Stetson, P. B.; Catelan, M.; Zoccali, M.; Smith, H. A.

    2013-11-01

    We present new BVI photometry of the globular cluster NGC 6981, based mostly on ground-based CCD archival images. We present a new color-magnitude diagram (CMD) that reaches almost four magnitudes below the turn-off level. We performed new derivations of metallicity and morphological parameters of the evolved sequences, in good agreement with the results of previous authors, and obtain a value of [Fe/H] ~= -1.50 in the new UVES scale. We also identify the cluster's blue straggler population. Comparing the radial distribution of these stars with the red giant branch population, we find that the blue stragglers are more centrally concentrated, as found in previous studies of blue stragglers in globular clusters. Taking advantage of the large field of view covered by our study, we analyzed the surface density profile of the cluster, and find extratidal main sequence stars out to r ≈ 14.'1, or about twice the tidal radius. We speculate that the presence of these stars may be due to tidal disruption in the course of NGC 6981's orbit, in which case tidal tails associated with the cluster may exist. We also take a fresh look at the variable stars in the cluster, recovering all previously known variables, including three SX Phoenicis stars. We also add three previously unknown RR Lyrae (one c-type and two ab-type) to the total census. Finally, comparing our CMD with unpublished data for M3 (NGC 5272), a cluster with a similar metallicity and horizontal branch morphology, we found that both objects are essentially coeval. This paper makes use of data obtained from the Isaac Newton Group Archive, which is maintained as part of the CASU Astronomical Data Centre at the Institute of Astronomy, Cambridge.

  19. THE LEO IV DWARF SPHEROIDAL GALAXY: COLOR-MAGNITUDE DIAGRAM AND PULSATING STARS

    SciTech Connect

    Moretti, Maria Ida; Dall'Ora, Massimo; Ripepi, Vincenzo E-mail: dallora@na.astro.it

    2009-07-10

    We present the first V, B - V color-magnitude diagram of the Leo IV dwarf spheroidal galaxy, a faint Milky Way satellite recently discovered by the Sloan Digital Sky Survey. We have obtained B, V time-series photometry reaching about half a magnitude below the Leo IV turnoff, which we detect at V = 24.7 mag, and have performed the first study of the variable star population. We have identified three RR Lyrae stars (all fundamental-mode pulsators, RRab) and one SX Phoenicis variable in the galaxy. In the period-amplitude diagram the Leo IV RR Lyrae stars are located close to the loci of Oosterhoff type I systems and the evolved fundamental-mode RR Lyrae stars in the Galactic globular cluster M3. However, their mean pulsation period, (Pab) = 0.655 days, would suggest an Oosterhoff type II classification for this galaxy. The RR Lyrae stars trace very well the galaxy's horizontal branch, setting its average magnitude at (V {sub RR}) = 21.48 {+-} 0.03 mag (standard deviation of the mean). This leads to a distance modulus of {mu}{sub 0} = 20.94 {+-} 0.07 mag, corresponding to a distance of 154 {+-} 5 kpc, by adopting for the Leo IV dSph a reddening E(B - V) = 0.04 {+-} 0.01 mag and a metallicity of [Fe/H] = -2.31 {+-} 0.10.

  20. Accuracy of Conventional PCR Targeting the 16S rRNA Gene with the Ot-16sRF1 and Ot-16sRR1 Primers for Diagnosis of Scrub Typhus: a Case-Control Study.

    PubMed

    Kim, Choon-Mee; Cho, Min Keun; Kim, Dong-Min; Yun, Na-Ra; Kim, Seok Won; Jang, Sook Jin; Ahn, Young-Joon; Lim, Donghoon

    2016-01-01

    We retrospectively evaluated the accuracy of conventional PCR targeting the 16S rRNA gene (16S C-PCR) using the Ot-16sRF1/Ot-16sRR1 primers for diagnosing scrub typhus. The diagnosis of Orientia tsutsugamushi infection by 16S C-PCR presented an increased sensitivity of 87.0% and specificity of 100% compared with those obtained with other targets and is thus a simple and clinically useful method with good diagnostic accuracy.

  1. Insights into Chi recognition from the structure of an AddAB-type helicase–nuclease complex

    PubMed Central

    Saikrishnan, Kayarat; Yeeles, Joseph T; Gilhooly, Neville S; Krajewski, Wojciech W; Dillingham, Mark S; Wigley, Dale B

    2012-01-01

    In bacterial cells, processing of double-stranded DNA breaks for repair by homologous recombination is dependent upon the recombination hotspot sequence Chi and is catalysed by either an AddAB- or RecBCD-type helicase–nuclease. Here, we report the crystal structure of AddAB bound to DNA. The structure allows identification of a putative Chi-recognition site in an inactivated helicase domain of the AddB subunit. By generating mutant protein complexes that do not respond to Chi, we show that residues responsible for Chi recognition are located in positions equivalent to the signature motifs of a conventional helicase. Comparison with the related RecBCD complex, which recognizes a different Chi sequence, provides further insight into the structural basis for sequence-specific ssDNA recognition. The structure suggests a simple mechanism for DNA break processing, explains how AddAB and RecBCD can accomplish the same overall reaction with different sets of functional modules and reveals details of the role of an Fe–S cluster in protein stability and DNA binding. PMID:22307084

  2. Rational synthesis of AB-type N-substituted core-functionalized naphthalene diimides (cNDIs).

    PubMed

    Berezin, Andrey A; Sciutto, Andrea; Demitri, Nicola; Bonifazi, Davide

    2015-04-17

    Acid-mediated transformation of tetraethyl 2,6-diethoxynaphthalene-1,4,5,8-tetracarboxylate selectively affords the core-substituted naphthalene-anhydride-ester (cNAE) in quantitative yield. This anhydride can be selectively converted into hetero-N-substituted core-functionalized naphthalene diimides (cNDIs) through sequential condensation reactions in the presence of the precursor amine with very high isolated yields over four steps. The approach can be applied to prepare a large variety of heterocyclic, aromatic, and aliphatic heterodiimides.

  3. Rational synthesis of AB-type N-substituted core-functionalized naphthalene diimides (cNDIs).

    PubMed

    Berezin, Andrey A; Sciutto, Andrea; Demitri, Nicola; Bonifazi, Davide

    2015-04-17

    Acid-mediated transformation of tetraethyl 2,6-diethoxynaphthalene-1,4,5,8-tetracarboxylate selectively affords the core-substituted naphthalene-anhydride-ester (cNAE) in quantitative yield. This anhydride can be selectively converted into hetero-N-substituted core-functionalized naphthalene diimides (cNDIs) through sequential condensation reactions in the presence of the precursor amine with very high isolated yields over four steps. The approach can be applied to prepare a large variety of heterocyclic, aromatic, and aliphatic heterodiimides. PMID:25822286

  4. THE VARIABLE STAR POPULATION OF THE GLOBULAR CLUSTER B514 IN THE ANDROMEDA GALAXY

    SciTech Connect

    Clementini, Gisella; Contreras, Rodrigo; Federici, Luciana; Cacciari, Carla; Merighi, Roberto; Fusi Pecci, Flavio; Smith, Horace A.; Catelan, Marcio; Marconi, Marcella; Kinemuchi, Karen; Pritzl, Barton J. E-mail: kuehncha@msu.ed E-mail: beers@pa.msu.ed E-mail: marcella@na.astro.i E-mail: kinemuchi@astro.ufl.ed

    2009-10-20

    A rich harvest of RR Lyrae stars has been identified for the first time in B514, a metal-poor ([Fe/H] approx- 1.95 +- 0.10 dex) globular cluster (GC) of the Andromeda galaxy (M31), based on Hubble Space Telescope Wide Field Planetary Camera 2 and Advanced Camera for Surveys time-series observations. We have detected and derived periods for 89 RR Lyrae stars (82 fundamental-mode, RRab, and 7 first-overtone, RRc, pulsators, respectively) among 161 candidate variables identified in the cluster. The average period of the RR Lyrae variables ((Pab) = 0.58 days and (Pc) = 0.35 days, for RRab and RRc pulsators, respectively) and the position in the period-amplitude diagram both suggest that B514 is likely an Oosterhoff type I cluster. This appears to be in disagreement with the general behavior of the metal-poor GCs in the Milky Way, which show instead Oosterhoff type II pulsation properties. The average apparent magnitude of the RR Lyrae stars sets the mean level of the cluster horizontal branch at (V(RR)) = 25.18 +- 0.02 (sigma = 0.16 mag, on 81 stars). By adopting a reddening E(B - V) = 0.07 +- 0.02 mag, the above metallicity and M {sub V} = 0.44 +- 0.05 mag for the RR Lyrae variables of this metallicity, we derive a distance modulus of mu{sub 0} = 24.52 +- 0.08 mag, corresponding to a distance of about 800 +- 30 kpc, based on a value of M {sub V} that sets mu{sub 0}(LMC)=18.52 mag.

  5. VARIABLE STARS IN LARGE MAGELLANIC CLOUD GLOBULAR CLUSTERS. I. NGC 1466

    SciTech Connect

    Kuehn, Charles A.; Smith, Horace A.; De Lee, Nathan; Catelan, Marcio; Pritzl, Barton J.; Borissova, Jura E-mail: smith@pa.msu.edu E-mail: mcatelan@astro.puc.cl E-mail: jura.borissova@uv.cl

    2011-10-15

    This is the first in a series of papers studying the variable stars in Large Magellanic Cloud globular clusters. The primary goal of this series is to better understand how the RR Lyrae stars in Oosterhoff-intermediate systems compare to those in Oosterhoff I/II systems. In this paper, we present the results of our new time-series BV photometric study of NGC 1466. A total of 62 variables were identified in the cluster, of which 16 are new discoveries. The variables include 30 RRab stars, 11 RRc stars, 8 RRd stars, 1 candidate RR Lyrae, 2 long-period variables, 1 potential anomalous Cepheid, and 9 variables of undetermined classification. We present photometric parameters for these variables. For the RR Lyrae stars physical properties derived from Fourier analysis of their light curves are presented. The RR Lyrae stars were used to determine a reddening-corrected distance modulus of (m - M){sub 0} = 18.43 {+-} 0.15. We discuss several different indicators of Oosterhoff type and find NGC 1466 to be an Oosterhoff-intermediate object.

  6. The role of tumor histogenesis, FDG-PET, and short-course EPOCH with dose-dense rituximab (SC-EPOCH-RR) in HIV-associated diffuse large B-cell lymphoma

    PubMed Central

    Dunleavy, Kieron; Little, Richard F.; Pittaluga, Stefania; Grant, Nicole; Wayne, Alan S.; Carrasquillo, Jorge A.; Steinberg, Seth M.; Yarchoan, Robert; Jaffe, Elaine S.

    2010-01-01

    This is a phase 2 study to assess the role of tumor histogenesis (subtype), fluorodeoxyglucose positron emission tomography (FDG-PET), and short-course etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin with dose-dense rituximab (SC-EPOCH-RR) in newly diagnosed HIV-associated CD20+ diffuse large B-cell lymphoma. Patients received a minimum of 3 and a maximum of 6 cycles with 1 cycle beyond stable radiographic and FDG-PET scans. Overall, 79% of patients received 3 cycles. Combination antiretroviral therapy was suspended before and resumed after therapy. Thirty-three enrolled patients had a median age of 42 years (range, 9-61 years), and 76% had a high-intermediate or high age-adjusted international prognostic index. At 5 years median follow-up, progression-free and overall survival were 84% and 68%, respectively. There were no treatment-related deaths or new opportunistic infections during treatment, and patients had sustained CD4 cell count recovery and HIV viral control after treatment. FDG-PET after 2 cycles had an excellent negative but poor positive predictive value. Tumor histogenesis was the only characteristic associated with lymphoma-specific outcome with 95% of germinal center B-cell (GCB) versus 44% of non-GCB diffuse large B-cell lymphoma (DLBCL) progression-free at 5 years. SC-EPOCH-RR is highly effective and less immunosuppressive with shorter duration therapy compared with standard strategies. However, new therapeutic advances are needed for non-GCB DLBCL, which remains the important cause of lymphoma-specific death. This trial was registered at www.clinicaltrials.gov as NCT000019253. PMID:20130244

  7. Variable Stars in the Field of the Hydra II Ultra-faint Dwarf Galaxy

    NASA Astrophysics Data System (ADS)

    Vivas, A. Katherina; Olsen, Knut; Blum, Robert; Nidever, David L.; Walker, Alistair R.; Martin, Nicolas F.; Besla, Gurtina; Gallart, Carme; van der Marel, Roeland P.; Majewski, Steven R.; Kaleida, Catherine C.; Muñoz, Ricardo R.; Saha, Abhijit; Conn, Blair C.; Jin, Shoko

    2016-05-01

    We report the discovery of one RR Lyrae star in the ultra-faint satellite galaxy Hydra II based on time series photometry in the g, r and i bands obtained with the Dark Energy Camera at Cerro Tololo Inter-American Observatory, Chile. The association of the RR Lyrae star discovered here with Hydra II is clear because is located at 42\\prime\\prime from the center of the dwarf, well within its half-light radius of 102\\prime\\prime . The RR Lyrae star has a mean magnitude of i=21.30+/- 0.04 which is too faint to be a field halo star. This magnitude translates to a heliocentric distance of 151 ± 8 kpc for Hydra II; this value is ∼ 13% larger than the estimate from the discovery paper based on the average magnitude of several blue horizontal branch star candidates. The new distance implies a slightly larger half-light radius of {76}-10+12 pc and a brighter absolute magnitude of {M}V=-5.1+/- 0.3, which keeps this object within the realm of the dwarf galaxies. A comparison with other RR Lyrae stars in ultra-faint systems indicates similar pulsational properties among them, which are different to those found among halo field stars and those in the largest of the Milky Way satellites. We also report the discovery of 31 additional short period variables in the field of view (RR Lyrae, SX Phe, eclipsing binaries, and a likely anomalous cepheid) which are likely not related with Hydra II.

  8. Structures of exocyclic R,R- and S,S-N(6),N(6)-(2,3-dihydroxybutan-1,4-diyl)-2'-deoxyadenosine adducts induced by 1,2,3,4-diepoxybutane.

    PubMed

    Kowal, Ewa A; Seneviratne, Uthpala; Wickramaratne, Susith; Doherty, Kathleen E; Cao, Xiangkun; Tretyakova, Natalia; Stone, Michael P

    2014-05-19

    1,3-Butadiene (BD) is an industrial and environmental chemical present in urban air and cigarette smoke, and is classified as a human carcinogen. It is oxidized by cytochrome P450 to form 1,2,3,4-diepoxybutane (DEB); DEB bis-alkylates the N(6) position of adenine in DNA. Two enantiomers of bis-N(6)-dA adducts of DEB have been identified: R,R-N(6),N(6)-(2,3-dihydroxybutan-1,4-diyl)-2'-deoxyadenosine (R,R-DHB-dA), and S,S-N(6),N(6)-(2,3-dihydroxybutan-1,4-diyl)-2'-deoxyadenosine (S,S-DHB-dA) [ Seneviratne , U. , Antsypovich , S. , Dorr , D. Q. , Dissanayake , T. , Kotapati , S. , and Tretyakova , N. ( 2010 ) Chem. Res. Toxicol. 23 , 1556 -1567 ]. Herein, the R,R-DHB-dA and S,S-DHB-dA adducts have been incorporated into the 5'-d(C(1)G(2)G(3)A(4)C(5)X(6)A(7)G(8)A(9)A(10)G(11))-3':5'-d(C(12)T(13)T(14)C(15)T(16)T(17)G(18)T(19)C(20)C(21)G(22))-3' duplex [X(6) = R,R-DHB-dA (R(6)) or S,S-DHB-dA (S(6))]. The structures of the duplexes were determined by molecular dynamics calculations, which were restrained by experimental distances obtained from NMR data. Both the R,R- and S,S-DHB-dA adducts are positioned in the major groove of DNA. In both instances, the bulky 3,4-dihydroxypyrrolidine rings are accommodated by an out-of-plane rotation about the C6-N(6) bond of the bis-alkylated adenine. In both instances, the directionality of the dihydroxypyrrolidine ring is evidenced by the pattern of NOEs between the 3,4-dihydroxypyrrolidine protons and DNA. Also in both instances, the anti conformation of the glycosyl bond is maintained, which combined with the out-of-plane rotation about the C6-N(6) bond, allows the complementary thymine, T(17), to remain stacked within the duplex, and form one hydrogen bond with the modified base, between the imine nitrogen of the modified base and the T(17) N3H imino proton. The loss of the second Watson-Crick hydrogen bonding interaction at the lesion sites correlates with the lower thermal stabilities of the R,R- and S,S-DHB-dA duplexes, as

  9. Retraction statement: Dynamics of Cytochrome C Oxidase Activity in Acute Ischemic Stroke' by Selaković, V.M., Jovanović, M.D., Mihajlović, R.R. and Radenović, L.L.J.

    PubMed

    2016-10-01

    The above article from Acta Neurologica Scandinavica, published online on 7 April 2005 in Wiley Online Library (wileyonlinelibrary.com) and in Volume 111, pp. 329-332, has been retracted by agreement between the journal Editor in Chief, Professor Elinor Ben-Menachem, and John Wiley & Sons Ltd. The article has been retracted because a similar article had previously been published in the Jugoslovenska medicinska biohemija in 2003. The authors presumed that since the journal was no longer existing, they felt the need to re-publish their work in Acta Neuorologica Scandinavica. However, in the consideration of the Journal, this constitutes dual publication. References SelakovićVM, JovanovićMD, MihajlovićR, RadenovićLLJ. Cytochrome c oxidase in patients with acute ischaemic brain disease. Jugoslovenska medicinska biohemija. 2003;22:329-334. SelakovićVM, JovanovićMD, MihajlovićRR, RadenovićLLJ. Dynamics of cytochrome c oxidase activity in acute ischemic stroke. Acta Neurol Scand. 2005;111:329-332.

  10. Retraction statement: Dynamics of Cytochrome C Oxidase Activity in Acute Ischemic Stroke' by Selaković, V.M., Jovanović, M.D., Mihajlović, R.R. and Radenović, L.L.J.

    PubMed

    2016-10-01

    The above article from Acta Neurologica Scandinavica, published online on 7 April 2005 in Wiley Online Library (wileyonlinelibrary.com) and in Volume 111, pp. 329-332, has been retracted by agreement between the journal Editor in Chief, Professor Elinor Ben-Menachem, and John Wiley & Sons Ltd. The article has been retracted because a similar article had previously been published in the Jugoslovenska medicinska biohemija in 2003. The authors presumed that since the journal was no longer existing, they felt the need to re-publish their work in Acta Neuorologica Scandinavica. However, in the consideration of the Journal, this constitutes dual publication. References SelakovićVM, JovanovićMD, MihajlovićR, RadenovićLLJ. Cytochrome c oxidase in patients with acute ischaemic brain disease. Jugoslovenska medicinska biohemija. 2003;22:329-334. SelakovićVM, JovanovićMD, MihajlovićRR, RadenovićLLJ. Dynamics of cytochrome c oxidase activity in acute ischemic stroke. Acta Neurol Scand. 2005;111:329-332. PMID:27592845

  11. Photometry of Variable Stars from the THU-NAOC Transient Survey. I. The First Two Years

    NASA Astrophysics Data System (ADS)

    Yao, Xinyu; Wang, Lingzhi; Wang, Xiaofeng; Zhang, Tianmeng; Chen, Juncheng; Yuan, Wenlong; Mo, Jun; Li, Wenxiong; Jin, Zhiping; Wu, Xuefeng; Nie, JunDan; Zhou, Xu

    2015-10-01

    In this paper, we report the detections of stellar variabilities from the first two years of observations of a sky area of about 1300 square degrees from the Tsinghua University–NAOC Transient Survey. A total of 1237 variable stars (including 299 new ones) were detected with a brightness <18.0 mag and a magnitude variation ≳0.1 mag on a timescale from a few hours to a few hundred days. Among such detections, we tentatively identified 661 RR Lyrae stars, 431 binaries, 72 semi-regular pulsators, 29 Mira stars, 11 slow irregular variables, 11 RS Canum Venaticorum stars, 7 Gamma Doradus stars, 5 long-period variables, 3 W Virginis stars, 3 Delta Scuti stars, 2 Anomalous Cepheids, 1 Cepheid, and 1 nova-like star based on their time-series variability index Js and their phased diagrams. Moreover, we found that 14 RR Lyrae stars show the Blazhko effect and 67 contact eclipsing binaries exhibit the O’Connell effect. Since the period and amplitude of light variations of RR Lyrae variables depend on their chemical compositions, their photometric observations can be used to investigate the distribution of metallicity along the direction perpendicular to the Galactic disk. We find that the metallicity of RR Lyrae stars shows large scatter at regions closer to the Galactic plane (e.g., ‑3.0 < [Fe/H] < 0) but tends to converge at [Fe/H] ∼ ‑1.7 at larger Galactic latitudes. This variation may be related to the fact that the RRAB Lyrae stars in the Galactic halo come from globular clusters with different metallicities and vertical distances, i.e., OoI and OoII populations, favoring the dual-halo model.

  12. Dynamic beat-to-beat modeling of the QT-RR interval relationship: analysis of QT prolongation during alterations of autonomic state versus human ether a-go-go-related gene inhibition.

    PubMed

    Fossa, Anthony A; Wisialowski, Todd; Magnano, Anthony; Wolfgang, Eric; Winslow, Roxanne; Gorczyca, William; Crimin, Kimberly; Raunig, David L

    2005-01-01

    Methods to correct the QT interval for heart rate are often in disagreement and may be further confounded by changes in autonomic state. This can be problematic when trying to distinguish the changes in QT interval by either drug-induced delayed repolarization or from autonomic-mediated physiological responses. Assessment of the canine dynamic QT-RR interval relationship was visualized by novel programming of the dynamic beat-to-beat confluence of data or "clouds". To represent the nonuniformity of the clouds, a bootstrap sampling method that computes the mathematical center of the uncorrected beat-to-beat QT value (QTbtb) with upper 95% confidence bounds was adopted and compared with corrected QT (QTc) using standard correction factors. Nitroprusside-induced reflex tachycardia reduced QTbtb by 43 ms, whereas an increase of 55 and 16 ms was obtained using the Bazett (QTcB) and Fridericia (QTcF) formulae, respectively. Phenylephrine-induced reflex bradycardia increased QTbtb by 3 ms but decreased QTcB by 20 ms and QTcF by 12 ms. Delayed repolarization with E-4031 (1-[2-(6-methyl-2-pyridyl)ethyl]-4-methylsulfonylaminobenzoyl)-piperidine), an inhibitor of rectifier potassium current, increased QTbtb by 26 ms but QT prolongation calculations using QTcF and QTcB were between 12 and 52% less, respectively, when small decreases in heart rate (5-8 beats per minute) were apparent. Dynamic assessment of beat-to-beat data, using the bootstrap method, allows quantification of QT interval changes under varying conditions of heart rate, autonomic tone, and direct repolarization that may not be distinguishable with use of standard correction factors.

  13. Classification of M/sub 1/ and M/sub 2/ receptor subtypes in vivo by autoradiography using (/sup 125/I) (R,R) 4IQNB: Implications for imaging receptor subtypes

    SciTech Connect

    Gibson, R.E.; Moody, T.; Kzeszotarski, W.J.; Schneidau, T.S.; Jagoda, E.M.; Reba, R.C.

    1985-05-01

    (/sup 125/I) (R,R) 3-Quinuclidinyl 4-Iodobenzilate (4IQNB) is a high affinity radiotracer for the muscarinic acetylcholine receptor which exhibits differential kinetics of dissociation from the receptor subtypes, M/sub 1/ and M/sub 2/. The authors have determined the relative percentages of M/sub 1/ to M/sub 2/-receptor subtype in six structures of rat brain by equilibrium competition using the selective antagonist, QNX, and by analysis of the off-rate profiles for 4IQNB. The results are comparable and provide: (% M/sub 1/) caudate nucleus - 100%, hippocampus - 92%, cortex - 82%, thalamus - 6%, superior + inferior colliculi - 41%, and pons - 23%. To determine the relative proportions of M/sub 1/ to M/sub 2/ receptors in vivo we examined the distribution of 4IQNB at 2 h and 24 h by autoradiography. At 2 h, both M/sub 1/ and M/sub 2/ receptors will be labeled but at 24 h only the M/sub 1/ receptor will retain radiotracer. At 2 h, all structures of the brain are variably labeled with the cortex, hippocampus, caudate nucleus, olfactory nuclei, nucleus accumbens, pontine nuclei, and anteroventral thalamic nucleus (AV) most heavily labeled. At 24 h, both the pontine and AV, as well as the less heavily labeled hypothalamus, superior colliculus and mesencephalic nuclei, are devoid of radiotracer thus indicating predominantly M/sub 2/ receptor. Quantitation is necessary to determine possible washout of activity from the M/sub 2/ receptors in cortex. Similar time studies in man should provide distinctions between the M/sub 1/ and M/sub 2/ receptor rich structures and the preferential loss of a subtype of receptor due to disease.

  14. Kepler and Hale observations of V523 Lyrae

    NASA Astrophysics Data System (ADS)

    Mason, E.; Howell, S. B.

    2016-05-01

    We present new observations of the cataclysmic variable (CV) V523 Lyr, a member of the open cluster NGC 6791. The Kepler Space telescope obtained photometric observations of this source and we examine the nearly three-year-long light curve. The observations show numerous small amplitude outbursts recurring on average every 33 d, intermittent quasi-periodic oscillations, and a significant fully coherent period of ~3.8 h, which we identify as the orbital period of the binary. Contemporaneous optical spectroscopy of V523 Lyr reveals a faint blue source with broad Balmer absorption lines containing narrow emission cores. Hα is in emission above the continuum. The low amplitude of the photometric signal and no detected velocity motion suggest a low orbital inclination. We discuss the properties of V523 Lyr and show that it is a member of the growing group of anomalous Z Cam type CVs, systems that show stunted outbursts, light curve standstills, and occasional deep drops in brightness.

  15. Update on RR gene flow research

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The United States is a major exporter of alfalfa seed and hay and the organic dairy industry is one of the fastest growing agricultural sectors. Because of this, many alfalfa producers are impacted by market sensitivity to adventitious presence (AP) of GM traits. Our objective was to quantify the ex...

  16. Dwarf spheroidal satellites of M31. I. Variable stars and stellar populations in Andromeda XIX

    SciTech Connect

    Cusano, Felice; Clementini, Gisella; Garofalo, Alessia; Federici, Luciana E-mail: gisella.clementini@oabo.inaf.it E-mail: alessia.garofalo@studio.unibo.it; and others

    2013-12-10

    We present B, V time-series photometry of Andromeda XIX (And XIX), the most extended (half-light radius of 6.'2) of Andromeda's dwarf spheroidal companions, which we observed with the Large Binocular Cameras at the Large Binocular Telescope. We surveyed a 23' × 23' area centered on And XIX and present the deepest color-magnitude diagram (CMD) ever obtained for this galaxy, reaching, at V ∼ 26.3 mag, about one magnitude below the horizontal branch (HB). The CMD shows a prominent and slightly widened red giant branch, along with a predominantly red HB, which extends to the blue to significantly populate the classical instability strip. We have identified 39 pulsating variable stars, of which 31 are of RR Lyrae type and 8 are Anomalous Cepheids (ACs). Twelve of the RR Lyrae variables and three of the ACs are located within And XIX's half light radius. The average period of the fundamental mode RR Lyrae stars ((P {sub ab}) = 0.62 days, σ = 0.03 days) and the period-amplitude diagram qualify And XIX as an Oosterhoff-Intermediate system. From the average luminosity of the RR Lyrae stars ((V(RR)) = 25.34 mag, σ = 0.10 mag), we determine a distance modulus of (m – M){sub 0} = 24.52 ± 0.23 mag in a scale where the distance to the Large Magellanic Cloud (LMC) is 18.5 ± 0.1 mag. The ACs follow a well-defined Period-Wesenheit (PW) relation that appears to be in very good agreement with the PW relationship defined by the ACs in the LMC.

  17. Conformations of [(R,R)-1,5-diaza-cis-decalin] copper (II) complex and its hydrogen bonding interaction with the crystal water: A combined experimental VA, UV-Vis and ECD spectroscopic and DFT study

    NASA Astrophysics Data System (ADS)

    Dezhahang, Zahra; Poopari, Mohammad Reza; Xu, Yunjie

    2012-09-01

    Chiral 1,5-diaza-cis-decalin ligand and its copper-complexes have found considerable applications in catalyzing enantioselective organic reactions. In the present article, (R,R)-1,5-diaza-cis-decalin ligand and its copper (II) hydroxide iodine hydrate complex have been investigated by using vibrational absorption (VA), ultraviolet-visible (UV-Vis), and electronic circular dichroism (ECD) experimental spectroscopic measurements, as well as density functional theory modeling. An extensive theoretical conformational analysis of the ligand has revealed that the ligand can adopt a good number of orientations in terms of its frame conformations, i.e. Chair-Chair, Chair-Boat, and Boat-Boat, the proximal (also denoted as in) and distal (out) positions for its two N atoms, and the equatorial (e) and axial (a) positions of its two amine H atoms. The most dominant conformation at room temperature was predicted to take on the Chair-Chair N-in H-ea configuration, based on the relative Gibbs free energy ordering at the B3LYP/6-31++G(d,p) level. The VA, vibrational CD, UV-Vis, and ECD spectra of the ligand conformers have been simulated. Conformational searches have also been carried out for the titled copper complex at the B3LYP/LanL2DZ level and the dominant conformer was predicted to have the Chair-Chair N-in H-ee configuration for its ligands, with a close to 100% Boltzmann population factor at room temperature. Furthermore, geometry optimizations and spectral simulations have been performed for the hydrogen bonded cluster of the complex with the crystal water. The effects of hydrogen bonding interaction with the crystal water on the VA, VCD, UV-Vis, and ECD spectra have been discussed. The interaction with the water molecule has been found to have significant impacts on the appearance of VA, VCD and ECD spectra and its inclusion is essential to obtain satisfactory interpretations of the experimental VA and ECD spectra.

  18. TRACSSS-2: Tracing More Cold Stellar Streams with Spitzer

    NASA Astrophysics Data System (ADS)

    Grillmair, Carl; Kupper, Andreas; Sesar, Branimir; Pearson, Sarah; Rich, Jeffrey; Scowcroft, Vicky; Price-Whelan, Adrian; Johnston, Kathryn

    2016-08-01

    Stellar debris streams may be the most sensitive probes we have of the size and shape of the Milky Way's dark matter distribution. Using the remarkably precise infrared period-luminosity relation for RR Lyrae, Spitzer has already demonstrated the ability to measure distances to better than 2% over nearly the entire volume of the Galaxy. By measuring very accurate mean magnitudes for RR Lyrae in the Anticenter and Styx streams, we will immediately be able to put tighter constrains on the mass and shape of the Galactic halo. These measurements will become still more important in coming years, when they can be used to turn Gaia proper motion measurements into accurate transverse space velocities. These measurements are unlikely to be improved upon in the foreseeable future and may ultimately rank among Spitzer's most enduring legacies.

  19. VizieR Online Data Catalog: BVI photometry of LMC bar variables (Di Fabrizio+, 2005)

    NASA Astrophysics Data System (ADS)

    di Fabrizio, L.; Clementini, G.; Maio, M.; Bragaglia, A.; Carretta, E.; Gratton, R.; Montegriffo, P.; Zoccali, M.

    2005-01-01

    We present the Johnson-Cousins B,V and I time series data obtained for 162 variable stars (135 RR Lyrae, 4 candidate Anomalous Cepheids, 11 Classical Cepheids, 11 eclipsing binaries and 1 delta Scuti star) in two 13x13 square arcmin areas close to the bar of the Large Magellanic Cloud. The photometric observations presented in this paper were carried out at the 1.54m Danish telescope located in La Silla, Chile, on the nights 4-7 January 1999, UT, and 23-24 January 2001, UT, respectively. In the paper we give coordinates, finding charts, periods, epochs, amplitudes, and mean quantities (intensity- and magnitude-averaged luminosities) of the variables with full coverage of the light variations, along with a discussion of the pulsation properties of the RR Lyrae stars in the sample. (8 data files).

  20. SPECTROSCOPIC CONFIRMATION OF THE PISCES OVERDENSITY

    SciTech Connect

    Kollmeier, Juna A.; Shectman, Stephen; Thompson, Ian B.; Preston, George W.; Simon, Joshua D.; Crane, Jeffrey D.; Gould, Andrew; Ivezic, Zeljko; Sesar, Branimir

    2009-11-10

    We present spectroscopic confirmation of the 'Pisces Overdensity', also known as 'Structure J', a photometric overdensity of RR Lyrae stars discovered by the Sloan Digital Sky Survey at an estimated photometric distance of approx85 kpc. We measure radial velocities for eight RR Lyrae stars within Pisces. We find that five of the eight stars have heliocentric radial velocities within a narrow range of -87 km s{sup -1} < v{sub r} < -67 km s{sup -1}, suggesting that the photometric overdensity is mainly due to a physically associated system, probably a dwarf galaxy or a disrupted galaxy. Two of the remaining three stars differ from one another by only 9 km s{sup -1}, but it would be premature to identify them as a second system.

  1. Radial stellar pulsation and three-dimensional convection. III. Comparison of two-dimensional and three-dimensional convection effects on radial pulsation

    SciTech Connect

    Geroux, Christopher M.; Deupree, Robert G.

    2014-03-10

    We have developed a multi-dimensional radiation hydrodynamics code to simulate the interaction of radial stellar pulsation and convection for full-amplitude pulsating models. Convection is computed using large eddy simulations. Here, we perform three-dimensional (3D) simulations of RR Lyrae stars for comparison with previously reported 2D simulations. We find that the time-dependent behavior of the peak convective flux on pulsation phase is very similar in both the 2D and 3D calculations. The growth rates of the pulsation in the 2D calculations are about 0.1% higher than in the 3D calculations. The amplitude of the light curve for a 6500 K RR Lyrae model is essentially the same for our 2D and 3D calculations, as is the rising light curve. There are differences in the slope at various times during falling light.

  2. Variable stars in large Magellanic cloud globular clusters. III. Reticulum

    SciTech Connect

    Kuehn, Charles A.; Dame, Kyra; Smith, Horace A.; De Lee, Nathan E-mail: damekyra@msu.edu E-mail: nathan.delee@vanderbilt.edu; and others

    2013-06-01

    This is the third in a series of papers studying the variable stars in old globular clusters in the Large Magellanic Cloud. The primary goal of this series is to look at how the characteristics and behavior of RR Lyrae stars in Oosterhoff-intermediate systems compare to those of their counterparts in Oosterhoff-I/II systems. In this paper we present the results of our new time-series BVI photometric study of the globular cluster Reticulum. We found a total of 32 variables stars (22 RRab, 4 RRc, and 6 RRd stars) in our field of view. We present photometric parameters and light curves for these stars. We also present physical properties, derived from Fourier analysis of light curves, for some of the RR Lyrae stars. We discuss the Oosterhoff classification of Reticulum and use our results to re-derive the distance modulus and age of the cluster.

  3. Multiple populations in globular clusters and the origin of the Oosterhoff dichotomy

    NASA Astrophysics Data System (ADS)

    Jang, S.; Lee, Y.-W.

    2016-05-01

    The globular cluster community is now facing a new paradigm of multiple stellar populations. In light of this, we have recently proposed a new model to explain the origin of the difference in mean period of type ab RR Lyrae variables between the two Oosterhoff groups. In our model, the instability strip in the metal-poor group II clusters, such as M15, is populated by second-generation stars (G2) with mildly enhanced helium and CNO abundances, while the RR Lyraes in the relatively metal-rich group I clusters such as M3 are produced mostly by first-generation stars (G1) without these enhancements. When these models are extended to all metallicity regimes, the observed dichotomies in the inner and outer halo globular clusters can be naturally reproduced. We found that specific star formation histories are required for the inner and outer halos, which is consistent with the dual origin of the Milky Way halo.

  4. The Distance to the Large Magellanic Cloud

    SciTech Connect

    Popowski, P

    2000-01-31

    The author demonstrates that the two unexpected results in the local Universe: anomalous intrinsic (V--I){sub 0} colors of RR Lyrae stars and clump giants in the Galactic center, and very short distances to Magellanic Clouds inferred from clump giants, can be at least partially resolved with a modified coefficient of selective extinction A{sub V}/E(V--I). With this modification, the author found a new clump-giant distance modulus to the Large Magellanic Cloud, {mu}{sub LMC} = 18.27 {+-} 0.07, which is 0.09 larger than the Udalski (1998b) result. When distance estimates from the red clump, RR Lyrae stars and the eclipsing binary HV2274 are combined, one obtains {mu}{sub LMC} = 18.31 {+-} 0.04 (internal).

  5. Stacking the invisibles: A guided search for low-luminosity Milky Way satellites

    SciTech Connect

    Sesar, Branimir; Banholzer, Sophianna R.; Cohen, Judith G.; Levitan, David; Kulkarni, Shrinivas R.; Prince, Thomas A.; Martin, Nicolas F.; Rix, Hans-Walter; Grillmair, Carl J.; Laher, Russ R.; Surace, Jason A.; Ofek, Eran O.

    2014-10-01

    Almost every known low-luminosity Milky Way dwarf spheroidal (dSph) satellite galaxy contains at least one RR Lyrae star. Assuming that a fraction of distant (60 < d {sub helio} < 100 kpc) Galactic halo RR Lyrae stars are members of yet to be discovered low-luminosity dSph galaxies, we perform a guided search for these low-luminosity dSph galaxies. In order to detect the presence of dSph galaxies, we combine stars selected from more than 123 sightlines centered on RR Lyrae stars identified by the Palomar Transient Factory. We find that this method is sensitive enough to detect the presence of Segue 1-like galaxies (M{sub V}=−1.5{sub −0.8}{sup +0.6}, r{sub h} = 30 pc) even if only ∼20 sightlines were occupied by such dSph galaxies. Yet, when our method is applied to the Sloan Digital Sky Survey Data Release 10 imaging catalog, no signal is detected. An application of our method to sightlines occupied by pairs of close (<200 pc) horizontal branch stars, also did not yield a detection. Thus, we place upper limits on the number of low-luminosity dSph galaxies with half-light radii from 30 pc to 120 pc, and in the probed volume of the halo. Stronger constraints on the luminosity function may be obtained by applying our method to sightlines centered on RR Lyrae stars selected from the Pan-STARRS1 survey, and eventually, from the Large Synoptic Survey Telescope. In Appendix A, we present spectroscopic observations of an RRab star in the Boötes 3 dSph and a light curve of an RRab star near the Boötes 2 dSph.

  6. Analysis of light curve of LP Camelopardalis

    NASA Astrophysics Data System (ADS)

    Prudil, Z.; Skarka, M.; Zejda, M.

    2016-05-01

    We present photometric analysis of the RRab type pulsating star LP Cam. The star was observed at Brno Observatory and Planetarium during nine nights. Measurements were calibrated to the Johnson photometric system. Four captured and thirteen previously published maxima timings allowed us to refine the pulsation period and the zero epoch. The light curve was Fourier decomposed to estimate physical parameters using empirical relations. Our results suggest that LP Cam is a common RR Lyrae star with high, almost solar metallicity.

  7. Constraining RRc candidates using SDSS colours

    NASA Astrophysics Data System (ADS)

    Banyai, E.; Plachy, E.; Molnar, L.; Dobos, L.; Szabo, R.

    2016-05-01

    The light variations of first-overtone RR Lyrae stars and contact eclipsing binaries can be difficult to distinguish. The Catalina Periodic Variable Star catalog contains several misclassified objects, despite the classification efforts by Drake et al. (2014). They used metallicity and surface gravity derived from spectroscopic data (from the SDSS database) to rule out binaries. Our aim is to further constrain the catalog using SDSS colours to estimate physical parameters for stars that did not have spectroscopic data.

  8. Period Adjustment of TT Scuti

    NASA Astrophysics Data System (ADS)

    Cederbloom, Steve E.

    1985-12-01

    The RR Lyrae variable TT Scuti was studied using photographic photometry. The O-C data show a possible downwards curve, which would indicate a decreasing period, but the results are not conclusive. New linear elements are: JD(max) = 2439384.915 + 0.45293855 E. A limit for the maximum rate of change of the period is -0.03 +/- 0.04 cycles per million years.

  9. Variable Stars and Stellar Populations in Andromeda XXI. II. Another Merged Galaxy Satellite of M31?

    NASA Astrophysics Data System (ADS)

    Cusano, Felice; Garofalo, Alessia; Clementini, Gisella; Cignoni, Michele; Federici, Luciana; Marconi, Marcella; Musella, Ilaria; Ripepi, Vincenzo; Speziali, Roberto; Sani, Eleonora; Merighi, Roberto

    2015-06-01

    B and V time-series photometry of the M31 dwarf spheroidal satellite Andromeda XXI (And XXI) was obtained with the Large Binocular Cameras at the Large Binocular Telescope. We have identified 50 variables in And XXI, of which 41 are RR Lyrae stars (37 fundamental-mode—RRab, and 4 first-overtone-RRc, pulsators) and 9 are Anomalous Cepheids (ACs). The average period of the RRab stars (< {P}{ab}> =0.64 days) and the period-amplitude diagram place And XXI in the class of Oosterhoff II—Oosterhoff-Intermediate objects. From the average luminosity of the RR Lyrae stars we derived the galaxy distance modulus of (m - M)0 = 24.40 ± 0.17 mag, which is smaller than previous literature estimates, although still consistent with them within 1σ. The galaxy color-magnitude diagram shows evidence for the presence of three different stellar generations in And XXI: (1) an old (˜12 Gyr) and metal-poor ([Fe/H] = -1.7 dex) component traced by the RR Lyrae stars; (2) a slightly younger (10-6 Gyr) and more metal-rich ([Fe/H] = -1.5 dex) component populating the red horizontal branch, and (3) an intermediate age (˜1 Gyr) component with the same metallicity that produced the ACs. Finally, we provide hints that And XXI could be the result of a minor merging event between two dwarf galaxies. Based on data collected with the LBC at the LBT.

  10. VARIABLE STARS IN LARGE MAGELLANIC CLOUD GLOBULAR CLUSTERS. II. NGC 1786

    SciTech Connect

    Kuehn, Charles A.; Smith, Horace A.; De Lee, Nathan; Catelan, Marcio; Pritzl, Barton J.; Borissova, Jura E-mail: smith@pa.msu.edu E-mail: mcatelan@astro.puc.cl E-mail: jura.borissova@uv.cl

    2012-12-01

    This is the second in a series of papers studying the variable stars in Large Magellanic Cloud globular clusters. The primary goal of this series is to study how RR Lyrae stars in Oosterhoff-intermediate systems compare to their counterparts in Oosterhoff I/II systems. In this paper, we present the results of our new time-series B-V photometric study of the globular cluster NGC 1786. A total of 65 variable stars were identified in our field of view. These variables include 53 RR Lyraes (27 RRab, 18 RRc, and 8 RRd), 3 classical Cepheids, 1 Type II Cepheid, 1 Anomalous Cepheid, 2 eclipsing binaries, 3 Delta Scuti/SX Phoenicis variables, and 2 variables of undetermined type. Photometric parameters for these variables are presented. We present physical properties for some of the RR Lyrae stars, derived from Fourier analysis of their light curves. We discuss several different indicators of Oosterhoff type which indicate that the Oosterhoff classification of NGC 1786 is not as clear cut as what is seen in most globular clusters.

  11. A NEW CENSUS OF THE VARIABLE STAR POPULATION IN THE GLOBULAR CLUSTER NGC 2419

    SciTech Connect

    Di Criscienzo, M.; Greco, C.; Ripepi, V.; Dall' Ora, M.; Marconi, M.; Musella, I.; Clementini, G.; Federici, L.; Di Fabrizio, L.

    2011-03-15

    We present B, V, and I CCD light curves for 101 variable stars belonging to the globular cluster NGC 2419, 60 of which are new discoveries, based on data sets obtained at the Telescopio Nazionale Galileo, the Subaru telescope, and the Hubble Space Telescope. The sample includes 75 RR Lyrae stars (38 RRab, 36 RRc, and one RRd), one Population II Cepheid, 12 SX Phoenicis variables, two {delta} Scuti stars, three binary systems, five long-period variables, and three variables of uncertain classification. The pulsation properties of the RR Lyrae variables are close to those of Oosterhoff type II clusters, consistent with the low metal abundance and the cluster horizontal branch morphology, disfavoring (but not totally ruling out) an extragalactic hypothesis for the origin of NGC 2419. The observed properties of RR Lyrae and SX Phoenicis stars are used to estimate the cluster reddening and distance, using a number of different methods. Our final value is {mu}{sub 0} (NGC 2419) = 19.71 {+-} 0.08 mag (D = 87.5 {+-} 3.3 kpc), with E(B - V) = 0.08 {+-} 0.01 mag, [Fe/H] = -2.1 dex on the Zinn and West metallicity scale, and a value of M{sub V} that sets {mu}{sub 0} (LMC) = 18.52 mag. This value is in good agreement with the most recent literature estimates of the distance to NGC 2419.

  12. VARIABILITY AND STAR FORMATION IN LEO T, THE LOWEST LUMINOSITY STAR-FORMING GALAXY KNOWN TODAY

    SciTech Connect

    Clementini, Gisella; Cignoni, Michele; Ramos, Rodrigo Contreras; Federici, Luciana; Tosi, Monica; Ripepi, Vincenzo; Marconi, Marcella; Musella, Ilaria E-mail: rodrigo.contreras@oabo.inaf.it E-mail: monica.tosi@oabo.inaf.it E-mail: ripepi@na.astro.it E-mail: ilaria@na.astro.it

    2012-09-10

    We present results from the first combined study of variable stars and star formation history (SFH) of the Milky Way 'ultra-faint' dwarf (UFD) galaxy Leo T, based on F606W and F814W multi-epoch archive observations obtained with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. We have detected 14 variable stars in the galaxy. They include one fundamental-mode RR Lyrae star and 11 Anomalous Cepheids with periods shorter than 1 day, thus suggesting the occurrence of multiple star formation episodes in this UFD, of which one about 10 Gyr ago produced the RR Lyrae star. A new estimate of the distance to Leo T of 409{sup +29}{sub -27} kpc (distance modulus of 23.06 {+-} 0.15 mag) was derived from the galaxy's RR Lyrae star. Our V, V - I color-magnitude diagram (CMD) of Leo T reaches V {approx} 29 mag and shows features typical of a galaxy in transition between dwarf irregular and dwarf spheroidal types. A quantitative analysis of the SFH, based on the comparison of the observed V, V - I CMD with the expected distribution of stars for different evolutionary scenarios, confirms that Leo T has a complex SFH dominated by two enhanced periods about 1.5 and 9 Gyr ago, respectively. The distribution of stars and gas shows that the galaxy has a fairly asymmetric structure.

  13. VizieR Online Data Catalog: EPOCH Project. EROS-2 LMC periodic variables (Kim+, 2014)

    NASA Astrophysics Data System (ADS)

    Kim, D.-W.; Protopapas, P.; Bailer-Jones, C. A. L.; Byun, Y.-I.; Chang, S.-W.; Marquette, J.-B.; Shin, M.-S.

    2014-03-01

    The EPOCH (EROS-2 periodic variable star classification using machine learning) project aims to detect periodic variable stars in the EROS-2 light curve database. In order to classify these variables, we first build a training set by compiling known variables in the Large Magellanic Could area from the OGLE and MACHO surveys. We crossmatch these variables with the EROS-2 sources and extract 22 variability features from 28,392 light curves of the corresponding EROS-2 sources. We then use Random Forests to classify the EROS-2 sources in the training set. We design the model to separate not only Delta Scuti stars, RR Lyraes, Cepheids, eclipsing binaries and long-period variables, the "superclasses", but also their subclasses, such as RRab, RRc, RRd and RRe for RR Lyraes, and similarly for the other variable types. We apply the trained model to the entire EROS-2 LMC database containing about 29 million sources and find 117,234 periodic variable candidates. Out of these 117,234 periodic variables, 55,285 have not been discovered by either OGLE or MACHO variability studies. This set comprises 1906 Delta Scuti stars, 6,607 RR Lyraes, 638 Cepheids, 178 Type II Cepheids, 34,562 eclipsing binaries and 11,394 long-period variables. (1 data file).

  14. MACHO project 9 million star color-magnitude diagram of the large magellanic cloud

    SciTech Connect

    Alcock, C; Allsman, R A; Alves, D R; Axelrod, T S; Basu, A; Becker, A C; Bennett, D P; Cook, K H; Drake, A J; Freeman, K C; Geha, M; Griest, K; King,L; Lehner, M J; Marshall, S L; Minniti, D; Nelson, C; Peterson, B A; Popowski, P; Pratt, M R; Quinn, P J; Stubbs, C W; Sutherland, W.; Tomaney, A B; Vandehei, T.; Welch, D L

    2000-01-31

    The authors present a 9 million star color-magnitude diagram (9M CMD) of the Large Magellanic Cloud (LMC) bar. The 9M CMD reveals a complex superposition of different age and metallicity stellar populations, with important stellar evolutionary phases occurring over three orders of magnitude in number density. First, they count the non-variable red and blue supergiants, the associated Cepheid variables, and measure the stellar effective temperatures defining the Cepheid instability strip. Lifetime predictions of stellar evolution theory are tested, with implications for the origin of low-luminosity Cepheids. The highly-evolved asymptotic giant branch (AGB) stars in the 9M CMD have a bimodal distribution in brightness, which they interpret as discrete old populations ({ge} 1 Gyr). The faint AGB sequence may be metal-poor and very old. Comparing the mean properties of giant branch and horizontal branch (HB) stars in the 9M CMD to those of clusters, they identify NGC 411 and M3 as templates for the admixture of old stellar populations in the bar. However, there are several indications that the old and metal-poor field population has a red HB morphology: the RR Lyrae variables lie preferentially on the red edge of the instability strip, the AGB-bump is very red, and the ratio of AGB-bump stars to RR Lyraes is quite large. If the HB second parameter is age, the old and metal-poor field population in the bar likely formed after the oldest LMC clusters. Lifetime predictions of stellar evolution theory lead us to associate a significant fraction of the {approx} 1 million red HB clump giants in the 9M CMD with the same old and metal-poor population producing the RR Lyraes and the AGB-bump. In this case, compared to the age-dependent luminosity predictions of stellar evolution theory, the red HB clump is too bright relative to the RR Lyraes and AGB-bump. Last, they show that the surface density profile of RR Lyraes is fit by an exponential, favoring a disk-like rather than

  15. VARIABLE STARS IN THE ULTRA-FAINT DWARF SPHEROIDAL GALAXY URSA MAJOR I

    SciTech Connect

    Garofalo, Alessia; Moretti, Maria Ida; Cusano, Felice; Clementini, Gisella; Ripepi, Vincenzo; Dall'Ora, Massimo; Coppola, Giuseppina; Musella, Ilaria; Marconi, Marcella E-mail: fcusano@na.astro.it E-mail: ripepi@na.astro.it E-mail: imoretti@na.astro.it E-mail: ilaria@na.astro.it

    2013-04-10

    We have performed the first study of the variable star population of Ursa Major I (UMa I), an ultra-faint dwarf satellite recently discovered around the Milky Way (MW) by the Sloan Digital Sky Survey. Combining time series observations in the B and V bands from four different telescopes, we have identified seven RR Lyrae stars in UMa I, of which five are fundamental-mode (RRab) and two are first-overtone pulsators (RRc). Our V, B - V color-magnitude diagram of UMa I reaches V {approx} 23 mag (at a signal-to-noise ratio of {approx}6) and shows features typical of a single old stellar population. The mean pulsation period of the RRab stars (P{sub ab}) = 0.628, {sigma} = 0.071 days (or (P{sub ab}) = 0.599, {sigma} = 0.032 days, if V4, the longest period and brightest variable, is discarded) and the position on the period-amplitude diagram suggest an Oosterhoff-intermediate classification for the galaxy. The RR Lyrae stars trace the galaxy horizontal branch (HB) at an average apparent magnitude of (V(RR)) = 20.43 {+-} 0.02 mag (average on six stars and discarding V4), giving in turn a distance modulus for UMa I of (m - M){sub 0} = 19.94 {+-} 0.13 mag, distance d = 97.3{sup +6.0}{sub -5.7} kpc, in the scale where the distance modulus of the Large Magellanic Cloud is 18.5 {+-} 0.1 mag. Isodensity contours of UMa I red giants and HB stars (including the RR Lyrae stars identified in this study) show that the galaxy has an S-shaped structure, which is likely caused by the tidal interaction with the MW. Photometric metallicities were derived for six of the UMa I RR Lyrae stars from the parameters of the Fourier decomposition of the V-band light curves, leading to an average metal abundance of [Fe/H] = -2.29 dex ({sigma} = 0.06 dex, average on six stars) on the Carretta et al. metallicity scale.

  16. PSQM-based RR and NR video quality metrics

    NASA Astrophysics Data System (ADS)

    Lu, Zhongkang; Lin, Weisi; Ong, Eeping; Yang, Xiaokang; Yao, Susu

    2003-06-01

    This paper presents a new and general concept, PQSM (Perceptual Quality Significance Map), to be used in measuring the visual distortion. It makes use of the selectivity characteristic of HVS (Human Visual System) that it pays more attention to certain area/regions of visual signal due to one or more of the following factors: salient features in image/video, cues from domain knowledge, and association of other media (e.g., speech or audio). PQSM is an array whose elements represent the relative perceptual-quality significance levels for the corresponding area/regions for images or video. Due to its generality, PQSM can be incorporated into any visual distortion metrics: to improve effectiveness or/and efficiency of perceptual metrics; or even to enhance a PSNR-based metric. A three-stage PQSM estimation method is also proposed in this paper, with an implementation of motion, texture, luminance, skin-color and face mapping. Experimental results show the scheme can improve the performance of current image/video distortion metrics.

  17. Web 2.0 for R&R

    ERIC Educational Resources Information Center

    Raths, David

    2009-01-01

    Are colleges and universities doing enough to take advantage of Web 2.0 and social networking tools in their recruitment and retention efforts? "Not even close," says Sam Richard, a 23-year-old junior in the College of Public Programs at Arizona State University in Phoenix. Richard is one of six students in ASU's Student Ambassadors for…

  18. R+R2 gravity as R+ back reaction

    NASA Astrophysics Data System (ADS)

    Kung, J. H.

    1995-12-01

    The quadratic theory of gravity is a complicated constraint system. We investigate some consequences of treating quadratic terms perturbatively (higher derivative version of back reaction effects), which is consistent with the way the existence of quadratic terms was originally established (radiative loop effects and renormalization procedures which induced quadratic terms). We show that this approach overcomes some well-known problems associated with higher derivative theories, i.e., the physical gravitational degree of freedom remains unchanged from those of Einstein gravity. Using such an approach we first study the classical cosmology of R+βR2 theory coupled to matter with a characteristic ρ~a(t)-n dependence on the scale factor. We show that for n>4 (i.e., p>1/3ρ) and for a particular sign of β, corresponding to the nontachyon case, there is no big bang in the traditional sense. And, therefore, a contracting FRW universe (k>0, k=0, k<0) will rebounce to an expansion phase without a total gravitational collapse. We then quantize the corresponding minisuperspace model that resulted from treating the βR2 as a perturbation. We conclude that the potential W(a), in the Wheeler-De Witt equation [-∂2/∂a2+2W(a)]ψ(a)=0, develops a repulsive barrier near a~=0 again for n>4 (i.e., p>1/3ρ) and for the sign of β that corresponds to the nontachyon case. Since a~=0 is a classically forbidden region, the probability of finding a universe with a singularity (a=0) is exponentially suppressed. Unlike the quantum cosmology of Einstein's gravity, the formalism has dictated an appropriate boundary (initial) condition. Classical and quantum analyses demonstrate that a minimum radius of collapse increases for a larger value of ||β||. It is also shown that, to first order in β, the βR2 term has no effect during the radiation (p=1/3ρ) and inflationary (p=-ρ) era. Therefore, a de Sitter phase can be readily generated by incorporating a scalar field.

  19. RR-SAP causality in heart transplant recipients.

    PubMed

    Porta, Alberto; Magagnin, Valentina; Bassani, Tito; Tobaldini, Eleonora; Montano, Nicola; van de Borne, Philippe

    2010-01-01

    An information domain approach to the assessment of causality was applied to the beat-to-beat variability of heart period and systolic arterial pressure to test the open loop condition along baroreflex in heart transplant recipients. The closed loop between heart period and systolic arterial pressure was detected as open at the level of the baroreflex if systolic arterial pressure is more easily predictable from heart period than vice versa according to a conditional entropy approach. We found that in short-term heart transplant (STHT) recipients (less than 2 years after transplantation) the closed loop between heart period and systolic arterial pressure was open at the level of baroreflex. Baroreflex appeared to be involved in the heart period regulation in long-term heart transplant (LTHT) recipients (more than 2 years after transplantation). The significant linear correlation of causality index on the number of months after transplantation suggests that baroreflex control recovers after transplantation.

  20. [Preparative purification and characterization of [Dha7] microcystin RR].

    PubMed

    Chen, Xiao-guo; Yang, Li-li; Xiao, Bang-ding; Wu, Xing-qiang; Dong, Xin-yang

    2007-09-01

    One variant of microcystins was isolated and purified with cyanobacteria natural bloom as the starting material, which was collected in Dianchi Lake, China. The separation protocol involved extraction of cyanobacterial cells by 75% aqueous methanol, isolation by reversed-phase flash chromatography, and purification by reversed-phase semipreparative HPLC. The structure and purity of purified microcystin was identified with electrospray ionization mass spectrometry, UV spectrophotometer, and analytical HPLC. The purified microcystin was assigned as [Dha7]MCRR (purity > 95%), which was a demethylated variant of MCRR. The structure of purified microcystin was identified as cyclo-(Ala-Arg-MeAsp-Arg-Adda-Glu-Dha) with molecular weight of 1023. There was a maximum absorbance at 239 nm in its UV spectrum (200-300 nm). This variant of microcystins occurred frequently, and sometimes could become the main variant in waterbloom from Dianchi Lake.

  1. Environmental Control for Regional Library Facilities. RR-80-3.

    ERIC Educational Resources Information Center

    King, Richard G., Jr.

    This report presents an overview of the damage to library materials caused by uncontrollable environmental variables. The control of atmospheric pollutants, temperature, and humidity are discussed with regard to damage, standards, and the costs of deterioration due to these factors. Twelve references are listed. (FM)

  2. A stellar population synthesis approach to the Oosterhoff dichotomy

    NASA Astrophysics Data System (ADS)

    Sollima, A.; Cassisi, S.; Fiorentino, G.; Gratton, R. G.

    2014-10-01

    We use colour-magnitude diagram synthesis together with theoretical relations from non-linear pulsation models to approach the long-standing problem of the Oosterhoff dichotomy related to the distribution of the mean periods of fundamental RR Lyrae variables in globular clusters. By adopting the chemical composition determined from spectroscopic observations and a criterion to account for the hysteresis mechanism, we tuned age and mass loss to simultaneously reproduce the morphology of both the turn-off and the horizontal branch of a sample of 17 globular clusters of the Milky Way and of nearby dwarf galaxies in the crucial metallicity range (-1.9 < [Fe/H] < -1.4) where the Oostheroff transition is apparent. We find that the Oosterhoff dichotomy among Galactic globular clusters is naturally reproduced by models. The analysis of the relative impact of the various involved parameters indicates that the main responsibles of the dichotomy are the peculiar distribution of clusters in the age-metallicity plane and the hysteresis. In particular, there is a clear connection between the two main branches of the age-metallicity relation for Galactic globular clusters and the Oosterhoff groups. The properties of clusters' RR Lyrae belonging to other Oostheroff groups (OoInt and OoIII) are instead not well reproduced. While for OoIII clusters a larger helium abundance for a fraction of the cluster's stars can reconcile the model prediction with observations, some other parameter affecting both the horizontal branch morphology and the RR Lyrae periods is required to reproduce the behaviour of OoInt clusters.

  3. Variable Stars and Stellar Populations in Andromeda XXV. III. A Central Cluster or the Galaxy Nucleus?

    NASA Astrophysics Data System (ADS)

    Cusano, Felice; Garofalo, Alessia; Clementini, Gisella; Cignoni, Michele; Federici, Luciana; Marconi, Marcella; Ripepi, Vincenzo; Musella, Ilaria; Testa, Vincenzo; Carini, Roberta; Faccini, Marco

    2016-09-01

    We present B and V time series photometry of Andromeda XXV, the third galaxy in our program on the Andromeda’s satellites, which we have imaged with the Large Binocular Cameras of the Large Binocular Telescope. The field of Andromeda XXV is found to contain 62 variable stars, for which we present light curves and characteristics of the light variation (period, amplitudes, variability type, mean magnitudes, etc.). The sample includes 57 RR Lyrae variables (46 fundamental-mode—RRab, and 11 first-overtone—RRc, pulsators), 3 anomalous Cepheids, 1 eclipsing binary system, and 1 unclassified variable. The average period of the RRab stars (< {Pab}> =0.60 σ = 0.04 days) and the period-amplitude diagram place Andromeda XXV in the class of the Oosterhoff-Intermediate objects. From the average luminosity of the RR Lyrae stars we derive for the galaxy a distance modulus of (m-M)0 = 24.63 ± 0.17 mag. The color-magnitude diagram reveals the presence in Andromeda XXV of a single, metal-poor ([Fe/H] = -1.8 dex) stellar population as old as ˜10-12 Gyr, traced by a conspicuous red giant branch and the large population of RR Lyrae stars. We discovered a spherically shaped high density of stars near the galaxy center. This structure appears to be at a distance consistent with Andromeda XXV and we suggest it could either be a star cluster or the nucleus of Andromeda XXV. We provide a summary and compare the number and characteristics of the pulsating stars in the M31 satellites analyzed so far for variability. Based on data collected with the Large Binocular Cameras at the Large Binocular Telescope.

  4. The EPOCH Project. I. Periodic variable stars in the EROS-2 LMC database

    NASA Astrophysics Data System (ADS)

    Kim, Dae-Won; Protopapas, Pavlos; Bailer-Jones, Coryn A. L.; Byun, Yong-Ik; Chang, Seo-Won; Marquette, Jean-Baptiste; Shin, Min-Su

    2014-06-01

    The EPOCH (EROS-2 periodic variable star classification using machine learning) project aims to detect periodic variable stars in the EROS-2 light curve database. In this paper, we present the first result of the classification of periodic variable stars in the EROS-2 LMC database. To classify these variables, we first built a training set by compiling known variables in the Large Magellanic Cloud area from the OGLE and MACHO surveys. We crossmatched these variables with the EROS-2 sources and extracted 22 variability features from 28 392 light curves of the corresponding EROS-2 sources. We then used the random forest method to classify the EROS-2 sources in the training set. We designed the model to separate not only δ Scuti stars, RR Lyraes, Cepheids, eclipsing binaries, and long-period variables, the superclasses, but also their subclasses, such as RRab, RRc, RRd, and RRe for RR Lyraes, and similarly for the other variable types. The model trained using only the superclasses shows 99% recall and precision, while the model trained on all subclasses shows 87% recall and precision. We applied the trained model to the entire EROS-2 LMC database, which contains about 29 million sources, and found 117 234 periodic variable candidates. Out of these 117 234 periodic variables, 55 285 have not been discovered by either OGLE or MACHO variability studies. This set comprises 1906 δ Scuti stars, 6607 RR Lyraes, 638 Cepheids, 178 Type II Cepheids, 34 562 eclipsing binaries, and 11 394 long-period variables. catalog of these EROS-2 LMC periodic variable stars is available at http://stardb.yonsei.ac.kr and at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/566/A43

  5. Variable Stars in Large Magellanic Cloud Globular Clusters. II. NGC 1786

    NASA Astrophysics Data System (ADS)

    Kuehn, Charles A.; Smith, Horace A.; Catelan, Márcio; Pritzl, Barton J.; De Lee, Nathan; Borissova, Jura

    2012-12-01

    This is the second in a series of papers studying the variable stars in Large Magellanic Cloud globular clusters. The primary goal of this series is to study how RR Lyrae stars in Oosterhoff-intermediate systems compare to their counterparts in Oosterhoff I/II systems. In this paper, we present the results of our new time-series B-V photometric study of the globular cluster NGC 1786. A total of 65 variable stars were identified in our field of view. These variables include 53 RR Lyraes (27 RRab, 18 RRc, and 8 RRd), 3 classical Cepheids, 1 Type II Cepheid, 1 Anomalous Cepheid, 2 eclipsing binaries, 3 Delta Scuti/SX Phoenicis variables, and 2 variables of undetermined type. Photometric parameters for these variables are presented. We present physical properties for some of the RR Lyrae stars, derived from Fourier analysis of their light curves. We discuss several different indicators of Oosterhoff type which indicate that the Oosterhoff classification of NGC 1786 is not as clear cut as what is seen in most globular clusters. Based on observations taken with the SMARTS 1.3 m telescope operated by the SMARTS Consortium and observations taken at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia, e Inovação (MCTI) da República Federativa do Brasil, the U.S. National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).

  6. Variable stars in the VVV globular clusters. I. 2MASS-GC 02 and Terzan 10

    SciTech Connect

    Alonso-García, Javier; Dékány, István; Catelan, Márcio; Ramos, Rodrigo Contreras; Gran, Felipe; Leyton, Paul; Minniti, Dante; Amigo, Pía E-mail: idekany@astro.puc.cl E-mail: rcontrer@astro.puc.cl E-mail: pia.amigo@uv.cl E-mail: dante@astrofisica.cl

    2015-03-01

    The VISTA Variables in the Vía Láctea (VVV) ESO Public Survey is opening a new window to study inner Galactic globular clusters (GCs) using their variable stars. These GCs have been neglected in the past due to the difficulties caused by the presence of elevated extinction and high field stellar densities in their lines of sight. However, the discovery and study of any present variables in these clusters, especially RR Lyrae stars, can help to greatly improve the accuracy of their physical parameters. It can also help to shed some light on the questions raised by the intriguing Oosterhoff dichotomy in the Galactic GC system. In a series of papers we plan to explore variable stars in the GCs falling inside the field of the VVV survey. In this first paper, we search for and study the variables present in two highly reddened, moderately metal-poor, faint, inner Galactic GCs: 2MASS-GC 02 and Terzan 10. We report the discovery of sizable populations of RR Lyrae stars in both GCs. We use near-infrared period–luminosity relations to determine the color excess of each RR Lyrae star, from which we obtain both accurate distances to the GCs and the ratios of the selective-to-total extinction in their directions. We find the extinction toward both clusters to be elevated, non-standard, and highly differential. We also find both clusters to be closer to the Galactic center than previously thought, with Terzan 10 being on the far side of the Galactic bulge. Finally, we discuss their Oosterhoff properties, and conclude that both clusters stand out from the dichotomy followed by most Galactic GCs.

  7. Target selection of classical pulsating variables for space-based photometry

    NASA Astrophysics Data System (ADS)

    Plachy, E.; Molnar, L.; Szabo, R.; Kolenberg, K.; Banyai, E.

    2016-05-01

    In a few years the Kepler and TESS missions will provide ultra- precise photometry for thousands of RR Lyrae and hundreds of Cepheid stars. In the extended Kepler mission all targets are proposed in the Guest Observer (GO) Program, while the TESS space telescope will work with full frame images and a ~15-16th mag brightness limit with the possibility of short cadence measurements for a limited number of pre-selected objects. This paper highlights some details of the enormous and important work of the target selection process made by the members of Working Group 7 (WG#7) of the Kepler and TESS Asteroseismic Science Consortium.

  8. Estrellas variables en campos de cúmulos abiertos galácticos detectadas en el relevamiento VVV

    NASA Astrophysics Data System (ADS)

    Palma, T.; Dékany, I.; Clariá, J. J.; Minniti, D.; Alonso-García, J. A.; Ramírez Alegría, S.; Bonatto, C.

    2016-08-01

    The present project constitutes a massive search for variable stars in the field of open clusters projected on highly reddened regions of the galactic disk and bulge. This search is being performed using -, - and -band observations of the near-infrared variability Survey Vista variables in the Via Lactea. We present the first results obtained in four open clusters projected on the Galactic bulge. The new variables discovered in the current work, 182 in total, are classified on the basis of their light curves and their locations in the corresponding color-magnitude diagrams. Among the newly discovered variable stars, Cepheids, RR Lyrae, Scuti, eclipsing binaries and other types have been found.

  9. VizieR Online Data Catalog: Eclipsing binaries in LMC (Muraveva+, 2014)

    NASA Astrophysics Data System (ADS)

    Muraveva, T.; Clementini, G.; Maceroni, C.; Evans, C. J.; Moretti, M. I.; Cioni, M.-R. L.; Marquette, J. B.; Ripepi, V.; de Grijs, R.; Groenewegen, M. A. T.; Piatti, A. E.; van Loon, J. T.

    2015-03-01

    The EROS-2 microlensing survey has monitored about 88deg2 LMC discovering a large number of CCs, RR Lyrae stars, binaries and long period variables (LPVs), both in the centre and in the outer regions of the galaxy. The survey was carried out with the Marly 1-m telescope at ESO, La Silla, from 1996 July to 2003 February. Observations were performed in two wide passbands, the so-called REROS band centred close to the IC standard band, and the BEROS band intermediate between the standard V and R bands. (6 data files).

  10. Using a classroom variable star in introductory astronomy courses

    NASA Astrophysics Data System (ADS)

    Dupuy, David L.

    1986-11-01

    A digitally synthesized classroom variable star has been constructed for lecture demonstrations to illustrate three types of variable stars, with real-life light curves for RR Lyrae, eclipsing binary, and multiperiodic stars. The artificial star has been used both as a classroom demonstration as well as in the laboratory, and students gain some experience in data acquisition. A simple classroom photometer is also described, with a large digital readout for classroom use. The data for the light curves is stored in an EPROM memory chip and may be changed to suit the instructor's preferences.

  11. On the pulsation and evolutionary properties of helium burning radially pulsating variables

    NASA Astrophysics Data System (ADS)

    Bono, G.; Pietrinferni, A.; Marconi, M.; Braga, V. F.; Fiorentino, G.; Stetson, P. B.; Buonanno, R.; Castellani, M.; Dall'Ora, M.; Fabrizio, M.; Ferraro, I.; Giuffrida, G.; Iannicola, G.; Marengo, M.; Magurno, D.; Martinez-Vazquez, C. E.; Matsunaga, N.; Monelli, M.; Neeley, J.; Rastello, S.; Salaris, M.; Short, L.; Stellingwerf, R. F.

    2016-05-01

    We discuss pulsation and evolutionary properties of low- (RR Lyrae, Type II Cepheids) and intermediate-mass (Anomalous Cepheids) radial variables. We focus our attention on the topology of the instability strip and the distribution of the quoted variables in the Hertzsprung-Russell diagram. We discuss their evolutionary status and the dependence on the metallicity. Moreover, we address the diagnostics (period derivative, difference in luminosity, stellar mass) that can provide solid constraints on their progenitors and on the role that binarity and environment have in shaping their current pulsation characteristics. Finally, we briefly outline their use as standard candles.

  12. Seattle Area High School Astronomy Projects: 4 local teachers present their work with students.

    NASA Astrophysics Data System (ADS)

    Muhs, Eric C.

    2006-12-01

    4 Seattle area high school teachers will present work with students as part of the opening session of High School Teacher Day. Vince San Pietro of Shorecrest HS will discuss a project involving teachers and students in characterizing RR Lyrae candidate stars using the University of Washington’s Manastash Ridge Observatory. Rebecca Fowler of Skyline HS will present her work with student teams in the Team America rocketry contest. Phil Cooper, also of Skyline, will talk about a telescope making project. And Eric Muhs of Roosevelt HS, will show a student-built, free-floating, self-orienting robot that flew aboard NASA’s zero gravity airplane last May.

  13. Results of the OGLE-II and OGLE-III surveys .

    NASA Astrophysics Data System (ADS)

    Soszyński, I.

    We present the most important results concerning variable stars obtained during the second and the third stage of the Optical Gravitational Lensing Experiment (OGLE). Since 1997 about 1011 photometric points for about 200 million stars in the Galaxy and Magellanic Clouds have been collected. Among them there is a full variety of variable stars of all types: Cepheids, RR Lyrae stars, pulsating Red and Blue Giants, eclipsing and ellipsoidal variables, cataclysmic variables, planetary transits, and many others. The photometric data of all identified variables are available to the astronomical community from the OGLE Internet Archive.

  14. OGLE and pulsating stars

    NASA Astrophysics Data System (ADS)

    Udalski, A.

    2016-05-01

    OGLE-IV is currently one of the largest sky variability surveys worldwide, focused on the densest stellar regions of the sky. The survey covers over 3000 square degrees and monitors regularly over a billion sources. The main targets include the inner Galactic bulge and the Magellanic System. Supplementary shallower Galaxy Variability Survey covers the extended Galactic bulge and 2/3 of the whole Galactic disk. The current status, prospects, and the latest results of the OGLE-IV survey focused on pulsating stars, in particular RR Lyrae variables, are presented.

  15. Detection of Periodicity Based on Independence Tests - II. Improved Serial Independence Measure

    NASA Astrophysics Data System (ADS)

    Zucker, Shay

    2016-03-01

    We introduce an improvement to a periodicity metric we have introduced in a previous paper. We improve on the Hoeffding-test periodicity metric, using the Blum-Kiefer-Rosenblatt (BKR) test. Besides a consistent improvement over the Hoeffding-test approach, the BKR approach turns out to perform superbly when applied to very short time series of sawtooth-like shapes. The expected astronomical implications are much more detections of RR-Lyrae stars and Cepheids in sparse photometric data bases, and of eccentric Keplerian radial-velocity (RV) curves, such as those of exoplanets in RV surveys.

  16. Orbital period variation study of massive Beta-Lyrae eclipsing binary IU Auriga

    NASA Astrophysics Data System (ADS)

    Yilan, Erkan; Bulut, İbrahim

    2016-07-01

    The system IU Aur is a semi-detached close binary system with an orbital period of 1.81 days, containing a massive star. The O-C diagram of this binary was analyzed with the least-squares method by using all available times of minima. We have found a periodic change of orbital period of IU Aur. This change has been explained by the gravitational effects of a third companion on the binay star. The orbit Parameters of the third body have been derived from the analysis of the O-C curve. The analysis indicates that the eclipsing binary revolves around a third-body with a mass of about M_{3}>10M_{⊙} in a highly eccentric orbit.

  17. Skylab ultraviolet stellar spectra - Emission lines from the Beta Lyrae system

    NASA Technical Reports Server (NTRS)

    Kondo, Y.; Parsons, S. B.; Wray, J. D.; Benedict, G. F.; Henize, K. G.; Mccluskey, G. E.

    1976-01-01

    Observations of Beta Lyr with the Skylab S-019 ultraviolet objective-prism spectrograph show numerous emission lines in the region from 1400 to 2300 A. Some variations in line strength between phases 0.25 and 0.50 are seen, which probably explain the shallowness of the OAO-2 light curve at 1910 A. Many of the emission lines are probably due to intercombination transitions, thus confirming the concept that the emission is produced by collisional excitation in low-density clouds of hot gas.

  18. THE KEPLER LIGHT CURVE OF V344 Lyrae: CONSTRAINING THE THERMAL-VISCOUS LIMIT CYCLE INSTABILITY

    SciTech Connect

    Cannizzo, J. K.; Howell, S. B.; Wood, M. A.; Smale, A. P. E-mail: Martin.D.Still@nasa.go

    2010-12-20

    We present time-dependent modeling based on the accretion disk limit cycle model for a 270 d light curve of the short-period SU UMa-type dwarf nova V344 Lyr taken by Kepler. The unprecedented precision and cadence (1 minute) far surpass that generally available for long-term light curves. The data encompass two superoutbursts and 17 normal (i.e., short) outbursts. The main decay of the superoutbursts is nearly perfectly exponential, decaying at a rate {approx}12 d mag{sup -1}, while the much more rapid decays of the normal outbursts exhibit a faster-than-exponential shape. Our modeling using the basic accretion disk limit cycle can produce the main features of the V344 Lyr light curve, including the peak outburst brightness. Nevertheless, there are obvious deficiencies in our model light curves. (1) The rise times we calculate, both for the normal and superoutbursts, are too fast. (2) The superoutbursts are too short. (3) The shoulders on the rise to superoutburst have more structure than the shoulders in the observed superoutbursts and are too slow, comprising about a third to half of the total viscous plateau, rather than the {approx}10% observed. However, one of the {alpha}{sub cold} {r_reversible} {alpha}{sub hot} interpolation schemes we investigate (one that is physically motivated) does yield longer superoutbursts with suitably short, less structured shoulders.

  19. The 1991-2012 light curve of the old nova HR Lyrae

    SciTech Connect

    Honeycutt, R. K.; Shears, J.; Kafka, S.; Robertson, J. W.; Henden, A. A. E-mail: bunburyobservatory@hotmail.com E-mail: Jeff.Robertson@atu.edu

    2014-05-01

    The 22 yr light curve of HR Lyr, acquired with a typical cadence of 2-6 days, is examined for periodic and quasi-periodic variations. No persistent periodicities are revealed. Rather, the light curve variations often take the form of nearly linear rises and falls having typical e-folding times of about 100 days. Occasional ∼0.6 mag outbursts are also seen, with properties similar to those of small outbursts found in some nova-like cataclysmic variables. When the photometry is formed into yearly averages, a decline of 0.012 ± 0.005 mag yr{sup –1} is apparent, consistent with the fading of irradiation-induced M-dot following the nova. The equivalent width of Hα is tabulated at three epochs over the interval 1986-2008 in order to compare with a recent result for DK Lac in which Hα was found to be fading 50 yr after the nova. However, our results for such a fading in HR Lyr are inconclusive.

  20. V344 Lyrae: A Touchtone SU UMa Cataclysmic Variable in the Kepler Field

    NASA Technical Reports Server (NTRS)

    Smale, Alan P.; Wood, Matt A.; Still, Martin D.; Howell, Steve B.; Cannizzo, John K.

    2012-01-01

    We report on the analysis of the Kepler short-cadence (SC) light curve of V344 Lyr obtained during 2009 June 20 through 2010 Mar 19 (Q2-Q4). The system is an SU UMa star showing dwarf nova outbursts and superoutbursts, and promises to be a touchstone for CV studies for the foreseeable future. The system displays both positive and negative super humps with periods of 2.20 and 2.06-hr, respectively, and we identify an orbital period of 2.11-hr. The positive super humps have a maximum amplitude of approximately 0.025-mag, the negative super humps a maximum amplitude of approximately 0.8 mag, and the orbital period at quiescence has an amplitude of approximately 0.025 mag. The quality of the Kepler data is such that we can test vigorously the models for accretion disk dynamics that have been emerging in the past several years. The SC data for V344 Lyr are consistent with the model that two physical sources yield positive superhumps: early in the superoutburst. the superhump signal is generated by viscous dissipation within the periodically flexing disk. but late in the superoutburst, the signal is generated as the accretion stream bright spot sweeps around the rim of the non-axisymmetric disk. The disk super humps are roughly anti-phased with the stream/late superhumps. The V344 Lyr data also reveal negative super humps arising from accretion onto a tilted disk precessing in the retrograde direction, and suggest that negative superhumps may appear during the decline of DN outbursts. The period of negative superhumps has a positive P(raised dot) in between outbursts.

  1. Ultraviolet photometry from the Orbiting Astronomical Observatory. XXII Ultraviolet light variation of Beta Lyrae

    NASA Technical Reports Server (NTRS)

    Kondo, Y.; Mccluskey, G. E.; Eaton, J. A.

    1976-01-01

    Six-color ultraviolet light curves of the complex eclipsing binary system Beta Lyr were obtained with the OAO-2 Wisconsin Experiment Package. The filters had a typical width at half maximum of 150 to 200 A and were centered at 1430, 1550, 1910, 2460, 2980, and 3320 A. The most striking characteristics of the ultraviolet light curves are that the secondary minimum deepens at shorter wavelengths. This indicates that we are not observing the eclipse effect of two stars having roughly a Planckian distribution of energy. In combination with the high-resolution far-ultraviolet spectra of Beta Lyr recently obtained with Copernicus (OAO-3) Princeton Telescope Spectrometer, it is concluded that the far-ultraviolet light curves are dominated by emission from the high-temperature gas surrounding the binary system. The ultraviolet observations of OAO-2 and Copernicus are consistent with a model in which the enigmatic secondary component involves a gravitationally collapsed object; i.e., a black hole. However, alternative models are also admissible.

  2. The Kepler Light Curve of V344 Lyrae: Constraining the Thermal-viscous Limit Cycle Instability

    NASA Astrophysics Data System (ADS)

    Cannizzo, J. K.; Still, M. D.; Howell, S. B.; Wood, M. A.; Smale, A. P.

    2010-12-01

    We present time-dependent modeling based on the accretion disk limit cycle model for a 270 d light curve of the short-period SU UMa-type dwarf nova V344 Lyr taken by Kepler. The unprecedented precision and cadence (1 minute) far surpass that generally available for long-term light curves. The data encompass two superoutbursts and 17 normal (i.e., short) outbursts. The main decay of the superoutbursts is nearly perfectly exponential, decaying at a rate ~12 d mag-1, while the much more rapid decays of the normal outbursts exhibit a faster-than-exponential shape. Our modeling using the basic accretion disk limit cycle can produce the main features of the V344 Lyr light curve, including the peak outburst brightness. Nevertheless, there are obvious deficiencies in our model light curves. (1) The rise times we calculate, both for the normal and superoutbursts, are too fast. (2) The superoutbursts are too short. (3) The shoulders on the rise to superoutburst have more structure than the shoulders in the observed superoutbursts and are too slow, comprising about a third to half of the total viscous plateau, rather than the ~10% observed. However, one of the αcold <--> αhot interpolation schemes we investigate (one that is physically motivated) does yield longer superoutbursts with suitably short, less structured shoulders.

  3. Strange Nonchaotic Stars

    NASA Astrophysics Data System (ADS)

    Lindner, John F.; Kohar, Vivek; Kia, Behnam; Hippke, Michael; Learned, John G.; Ditto, William L.

    2015-08-01

    Exploiting the unprecedented capabilities of the planet-hunting Kepler space telescope, which stared at 150 000 stars for four years, we discuss recent evidence that certain stars dim and brighten in complex patterns with fractal features. Such stars pulsate at primary and secondary frequencies whose ratios are near the famous golden mean, the most irrational number. A nonlinear system driven by an irrational ratio of frequencies is generically attracted toward a “strange” behavior that is geometrically fractal without displaying the “butterfly effect” of chaos. Strange nonchaotic attractors have been observed in laboratory experiments and have been hypothesized to describe the electrochemical activity of the brain, but a bluish white star 16 000 light years from Earth in the constellation Lyra may manifest, in the scale-free distribution of its minor frequency components, the first strange nonchaotic attractor observed in the wild. The recognition of stellar strange nonchaotic dynamics may improve the classification of these stars and refine the physical modeling of their interiors. We also discuss nonlinear analysis of other RR Lyrae stars in Kepler field of view and discuss some toy models for modeling these stars.References: 1) Hippke, Michael, et al. "Pulsation period variations in the RRc Lyrae star KIC 5520878." The Astrophysical Journal 798.1 (2015): 42.2) Lindner, John F., et al. "Strange nonchaotic stars." Phys. Rev. Lett. 114, 054101 (2015)

  4. Is the Short Distance Scale a Result of a Problem with the LMC Photometric Zero Point?

    SciTech Connect

    Popowski, P

    2004-03-29

    I present a promising route to harmonize distance measurements based on clump giants and RR Lyrae stars. This is achieved by comparing the brightness of these distance indicators in three environments: the solar neighborhood, Galactic bulge and Large Magellanic Cloud (LMC). As a result of harmonizing the distance scales in the solar neighborhood and Baade's Window, I derive the new absolute magnitude of RR Lyrae stars, M{sub v}(RR) at [Fe/H] = -1.6 (0.59 {+-} 0.05, 0.70 {+-} 0.05). Being somewhat brighter than the statistical parallax solution, but fainter than typical results of the main sequence fitting to Hipparcos data, these values of M{sub V}(RR) favor intermediate or old ages of globular clusters. Harmonizing the distance scales in the LMC and Baade's Window, I show that the most likely distance modulus to the LMC, {mu}{sub LMC} is in the range 18.24 - 18.44. The Hubble constant of about 70 km/s/Mpc reported by the HST Key Project is based on the assumption that the distance modulus to the LMC equals 18.50. The results presented here indicate that the Hubble Constant may be up to 12% higher. This in turn would call for a younger Universe and could result in some tension between the age of the Universe and the ages of globular clusters. I argue that the remaining uncertainty in the distance to the LMC is now a question of one, single photometric reference point rather than discrepancies between different standard candles.

  5. Constraints on helium enhancement in the globular cluster M4 (NGC 6121): The horizontal branch test

    SciTech Connect

    Valcarce, A. A. R.; De Medeiros, J. R.; Catelan, M.; Alonso-García, J.; Cortés, C.

    2014-02-20

    Recent pieces of evidence have revealed that most, and possibly all, globular star clusters are composed of groups of stars that formed in multiple episodes with different chemical compositions. In this sense, it has also been argued that variations in the initial helium abundance (Y) from one population to the next are also the rule, rather than the exception. In the case of the metal-intermediate globular cluster M4 (NGC 6121), recent high-resolution spectroscopic observations of blue horizontal branch (HB) stars (i.e., HB stars hotter than the RR Lyrae instability strip) suggest that a large fraction of blue HB stars are second-generation stars formed with high helium abundances. In this paper, we test this scenario by using recent photometric and spectroscopic data together with theoretical evolutionary computations for different Y values. Comparing the photometric data with the theoretically derived color-magnitude diagrams, we find that the bulk of the blue HB stars in M4 have ΔY ≲ 0.01 with respect to the cluster's red HB stars (i.e., HB stars cooler than the RR Lyrae strip)—a result which is corroborated by comparison with spectroscopically derived gravities and temperatures, which also favor little He enhancement. However, the possible existence of a minority population on the blue HB of the cluster with a significant He enhancement level is also discussed.

  6. A catalogue of helium abundance indicators from globular cluster photometry

    NASA Astrophysics Data System (ADS)

    Sandquist, Eric L.

    2000-04-01

    We present a survey of helium abundance indicators derived from a comprehensive study of globular cluster photometry in the literature. For each of the three indicators used, we conduct a thorough error analysis, and identify systematic errors in the computational procedures. For the population ratio RNHBNRGB, we find that there is no evidence of a trend with metallicity, although there appears to be real scatter in the values derived. Although this indicator is the one best able to provide useful absolute helium abundances, the mean value is Y~0.20, indicating the probable presence of additional systematic error. For the magnitude difference from the horizontal branch to the main sequence Δ and the RR Lyrae mass-luminosity exponent A, it is only possible to determine relative helium abundances reliably. This is due to continuing uncertainties in the absolute metallicity scale for Δ, and uncertainty in the RR Lyrae temperature scale for A. Both indicators imply that the helium abundance is approximately constant as a function of [Fe/H]. According to the A indicator, both Oosterhoff I and II group clusters have constant values independent of [Fe/H] and horizontal branch type. In addition, the two groups have slopes dlog/d[Fe/H] that are consistent with each other, but significantly smaller than the slope for the combined sample.

  7. Variable stars in Local Group Galaxies - II. Sculptor dSph

    NASA Astrophysics Data System (ADS)

    Martínez-Vázquez, C. E.; Stetson, P. B.; Monelli, M.; Bernard, E. J.; Fiorentino, G.; Gallart, C.; Bono, G.; Cassisi, S.; Dall'Ora, M.; Ferraro, I.; Iannicola, G.; Walker, A. R.

    2016-08-01

    We present the identification of 634 variable stars in the Milky Way dSph satellite Sculptor based on archival ground-based optical observations spanning ˜24 years and covering ˜ 2.5 deg2. We employed the same methodologies as the "Homogeneous Photometry" series published by Stetson. In particular, we have identified and characterized the largest (536) RR Lyrae sample so far in a Milky Way dSph satellite. We have also detected four Anomalous Cepheids, 23 SX Phoenicis stars, five eclipsing binaries, three field variable stars, three peculiar variable stars located above the horizontal branch - near to the locus of BL Herculis - that we are unable to classify properly. Additionally we identify 37 Long Period Variables plus 23 probable variable stars, for which the current data do not allow us to determine the period. We report positions and finding charts for all the variable stars, and basic properties (period, amplitude, mean magnitude) and light curves for 574 of them. We discuss the properties of the RR Lyrae stars in the Bailey diagram, which supports the coexistence of subpopulations with different chemical compositions. We estimate the mean mass of Anomalous Cepheids (˜1.5M⊙) and SX Phoenicis stars (˜1M⊙). We discuss in detail the nature of the former. The connections between the properties of the different families of variable stars are discussed in the context of the star formation history of the Sculptor dSph galaxy.

  8. AH Leo and the Blazhko Effect

    NASA Astrophysics Data System (ADS)

    Phillips, J.; Gay, P. L.

    2004-12-01

    We obtained 563 V-Band observations of AH Leo between January 27 and May 12, 2004. All observations were obtained with a 12-inch Schmidt-Cassegrain located on the island of Saipan, in the Commonwealth of the Northern Mariana Islands. We show that AH Leo is a type RRab RR Lyrae star with a minimum magnitude of V=14.658 magnitudes, a maximum amplitude of 0.989 magnitudes and a minimum amplitude of perhaps just 0.4 magnitudes. Its primary period is 0.4662609 days. Our observations also confirm the presence of the Blazhko effect, which had previously been detected by Smith and Gay (private communication) in 1993 and 1994. We estimate the Blazhko period to be roughly 20-days, however poor phase coverage at maximum light makes exact determination impossible. We also note that the bump during minimum, which is common in many RR Lyraes, varied throughout the Blazhko cycle, demonstrating amplitudes between 0 and 0.15 magnitudes. We would like to thank Sarah Maddison and Swinburne Astronomy Online for supporting this project

  9. Variable stars in Local Group Galaxies - II. Sculptor dSph

    NASA Astrophysics Data System (ADS)

    Martínez-Vázquez, C. E.; Stetson, P. B.; Monelli, M.; Bernard, E. J.; Fiorentino, G.; Gallart, C.; Bono, G.; Cassisi, S.; Dall'Ora, M.; Ferraro, I.; Iannicola, G.; Walker, A. R.

    2016-11-01

    We present the identification of 634 variable stars in the Milky Way dwarf spheroidal (dSph) satellite Sculptor based on archival ground-based optical observations spanning ˜24 yr and covering ˜2.5 deg2. We employed the same methodologies as the `Homogeneous Photometry' series published by Stetson. In particular, we have identified and characterized one of the largest (536) RR Lyrae samples so far in a Milky Way dSph satellite. We have also detected four Anomalous Cepheids, 23 SX Phoenicis stars, five eclipsing binaries, three field variable stars, three peculiar variable stars located above the horizontal branch - near to the locus of BL Herculis - that we are unable to classify properly. Additionally, we identify 37 long period variables plus 23 probable variable stars, for which the current data do not allow us to determine the period. We report positions and finding charts for all the variable stars, and basic properties (period, amplitude, mean magnitude) and light curves for 574 of them. We discuss the properties of the RR Lyrae stars in the Bailey diagram, which supports the coexistence of subpopulations with different chemical compositions. We estimate the mean mass of Anomalous Cepheids (˜1.5 M⊙) and SX Phoenicis stars (˜1 M⊙). We discuss in detail the nature of the former. The connections between the properties of the different families of variable stars are discussed in the context of the star formation history of the Sculptor dSph galaxy.

  10. VizieR Online Data Catalog: Photometry in globular cluster NGC 6229 (Carney+, 1991)

    NASA Astrophysics Data System (ADS)

    Carney, B. W.; Fullton, L. K.; Trammell, S. R.

    2016-06-01

    We present CCD-based BV photometry for over 1100 stars in and around the globular cluster NGC 6229. For the first time, the cluster's entire giant branch and its horizontal branch are delineated, from which metallicity ([Fe/H]~-1.4) and distance (d⊙_~28kpc; dGC~27kpc) estimates ensue. NGC 6229 is found to have a relatively blue horizontal branch for its intermediate metallicity, which is unusual for an outer halo cluster. Its low R value (defined as NHB/NRG) hints that the blue color of its horizontal branch is due to a lower than average helium abundance. Three possible new variable stars are identified, including one RR Lyrae and two long-period variables. We present a brief review of our knowledge of basic data for the 13 globular clusters lying more than 24 kpc from the Galactic center. The unusually red horizontal branch phenomenon is common only among the outermost clusters. An average R value for these clusters suggests the effect is not caused by an overabundance of helium. The Oosterhoff dichotomy apparently persists into the outer halo, although the number of clusters with RR Lyrae variables is small. (1 data file).

  11. Spectral identification of the u-band variable sources in two LAMOST fields

    NASA Astrophysics Data System (ADS)

    Cao, Tian-Wen; Yang, Ming; Wu, Hong; Zhang, Tian-Meng; Shi, Jian-Rong; Zhang, Hao-Tong; Yang, Fan; Zhao, Jing-Kun; Zhou, Xu; Fan, Zhou; Jiang, Zhao-Ji; Ma, Jun; Wang, Jia-Li; Wu, Zhen-Yu; Zou, Hu; Zhou, Zhi-Min; Nie, Jun-Dan; Luo, A.-Li; Wu, Xue-Bing; Zhao, Yong-Heng

    2016-09-01

    We selected 82 u-band variable objects based on the u-band photometry data from SCUSS and SDSS, in the field of LAMOST Complete Spectroscopic Survey of Pointing Area at Southern Galactic Cap. The magnitude variation of the targets is restricted to larger than 0.2 mag and limiting magnitude down to 19.0 mag in u-band. According to the spectra from LAMOST, there are 11 quasars with redshift between 0.4 and 1.8, 60 variable stars and 11 unidentified targets. The variable stars include one active M-dwarf with a series of Balmer emission lines, seven Horizontal Branch stars containing six RR Lyrae stars matching with SIMBAD, and one giant, one AGB star and two RR Lyrae candidates by different color selections. All these variable stars mainly locate near the main sequence in the g--r vs. u--g diagram. The quasars are well distinguished from stars by both u--g color and variation in u-band.

  12. New Variable Stars Discovered by Data Mining Images Taken During Recent Asteroid Photometric Observations. Results from the Year 2015

    NASA Astrophysics Data System (ADS)

    Papini, R.; Franco, L.; Marchini, A.; Salvaggio, F.

    2015-12-01

    During the past year the authors observed several asteroids for the purpose of determining the rotational period. Typically, this task requires a time series images acquisition on a single field for all the night, weather permitting, for a few nights although not consecutive. Routinely checking this "goldmine," allowed us to discover 14 variable stars not yet listed in catalogs or databases. While the most of the new variables are eclipsing binaries (GSC 01394-01889, GSC 00853-00371, CSS_J171124.7-004042, GSC05065-00218, UCAC4-386-142199, UCAC4 398-127457, UCAC4 384-148138, UCAC4 398-127590, UCAC4-383-155837, GSC-05752-01113, GSC 05765-01271), a few belong to RR Lyrae class (UCAC4 388-136835, 2MASS J20060657-1230376, UCAC4 386-142583). Since asteroid work is definitely time-consuming, follow-up is quite a difficult task for a small group. Further observations of these new variables are therefore strongly encouraged in order to better characterize these stars, especially RR Lyrae ones whose data combined with those taken during professional surveys seem to suggest the presence of a Blazhko effect.

  13. A study of variable stars in the open cluster NGC 1582 and its surrounding field

    NASA Astrophysics Data System (ADS)

    Song, Fang-Fang; Esamdin, Ali; Ma, Lu; Liu, Jin-Zhong; Zhang, Yu; Niu, Hu-Biao; Yang, Tao-Zhi

    2016-10-01

    This paper presents Charge-Coupled Device time-series photometric observations of the open cluster NGC 1582 and its surrounding field with Johnson B, V and R filters by using the Nanshan 1 m telescope administered by Xinjiang Astronomical Observatory. 19 variable stars and three variable candidates were detected in a 45‧ × 48.75‧ field around the cluster. 12 of the variable stars are newly-discovered variable objects. The physical properties, classifications and memberships of these 22 objects are studied through their light curves, their positions on the color-magnitude diagram and with archival data from the Naval Observatory Merged Astrometric Dataset. Among these objects, five are eclipsing binary systems, six are pulsating variable stars including one known δ Scuti star and one newly-discovered RR Lyrae star. The distance to the RR Lyrae star is estimated to be 7.9 ± 0.3 kpc, indicating that the star is located far behind the cluster. Four variable stars are probable members of the cluster, and 13 of the 22 objects are confirmed to be field stars.

  14. A COMPREHENSIVE, WIDE-FIELD STUDY OF PULSATING STARS IN THE CARINA DWARF SPHEROIDAL GALAXY

    SciTech Connect

    Vivas, A. Katherina; Mateo, Mario E-mail: mmateo@umich.edu

    2013-12-01

    We report the detection of 388 pulsating variable stars (and some additional miscellaneous variables) in the Carina dwarf spheroidal galaxy over an area covering the full visible extent of the galaxy and extending a few times beyond its photometric (King) tidal radius along the direction of its major axis. Included in this total are 340 newly discovered dwarf Cepheids (DCs), which are mostly located ∼2.5 mag below the horizontal branch and have very short periods (<0.1 days), typical of their class and consistent with their location on the upper part of the extended main sequence of the younger populations of the galaxy. Several extra-tidal DCs were found in our survey up to a distance of ∼1° from the center of Carina. Our sample also includes RR Lyrae stars and anomalous Cepheids, some of which were found outside the galaxy's tidal radius as well. This supports past works that suggest that Carina is undergoing tidal disruption. We use the period-luminosity relationship for DCs to estimate a distance modulus of μ{sub 0} = 20.17 ± 0.10 mag, in very good agreement with the estimate from RR Lyrae stars. We find some important differences in the properties of the DCs of Carina and those in Fornax and the LMC, the only extragalactic samples of DCs currently known. These differences may reflect a metallicity spread, depth along the line of sight, and/or different evolutionary paths of the DC stars.

  15. THE CHEMICAL COMPOSITIONS OF NON-VARIABLE RED AND BLUE FIELD HORIZONTAL BRANCH STARS

    SciTech Connect

    For Biqing; Sneden, Christopher

    2010-12-15

    We present a new detailed abundance study of field red horizontal branch (RHB) and blue horizontal branch (BHB) non-variable stars. High resolution and high signal-to-noise ratio echelle spectra of 11 RHB and 12 BHB were obtained with the McDonald 2.7 m telescope, and the RHB sample was augmented by reanalysis of spectra of 25 stars from a recent survey. We derived stellar atmospheric parameters based on spectroscopic constraints and computed relative abundance ratios for 24 species of 19 elements. The species include Si II and Ca II, which have not been previously studied in RHB and BHB (T{sub eff} < 9000 K) stars. The abundance ratios are generally consistent with those of similar-metallicity field stars in different evolutionary stages. We estimated the masses of the RHB and BHB stars by comparing their T{sub eff}-log g positions with HB model evolutionary tracks. The mass distribution suggests that our program stars possess masses of {approx}0.5 M{sub sun}. Finally, we compared the temperature distributions of field RHB and BHB stars with field RR Lyraes in the metallicity range -0.8{approx}> [Fe/H] {approx}>-2.5. This yielded effective temperature estimates of 5900 K and 7400 K for the red and blue edges of the RR Lyrae instability strip.

  16. Variable Stars in Large Magellanic Cloud Globular Clusters. III. Reticulum

    NASA Astrophysics Data System (ADS)

    Kuehn, Charles A.; Dame, Kyra; Smith, Horace A.; Catelan, Márcio; Jeon, Young-Beom; Nemec, James M.; Walker, Alistair R.; Kunder, Andrea; Pritzl, Barton J.; De Lee, Nathan; Borissova, Jura

    2013-06-01

    This is the third in a series of papers studying the variable stars in old globular clusters in the Large Magellanic Cloud. The primary goal of this series is to look at how the characteristics and behavior of RR Lyrae stars in Oosterhoff-intermediate systems compare to those of their counterparts in Oosterhoff-I/II systems. In this paper we present the results of our new time-series BVI photometric study of the globular cluster Reticulum. We found a total of 32 variables stars (22 RRab, 4 RRc, and 6 RRd stars) in our field of view. We present photometric parameters and light curves for these stars. We also present physical properties, derived from Fourier analysis of light curves, for some of the RR Lyrae stars. We discuss the Oosterhoff classification of Reticulum and use our results to re-derive the distance modulus and age of the cluster. Based on observations taken with the SMARTS 1.3 m telescope operated by the SMARTS Consortium and observations taken at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia, e Inovação (MCTI) da República Federativa do Brasil, the U.S. National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).

  17. PROPER MOTIONS IN KAPTEYN SELECTED AREA 103: A PRELIMINARY ORBIT FOR THE VIRGO STELLAR STREAM

    SciTech Connect

    Casetti-Dinescu, Dana I.; Girard, Terrence M.; Van Altena, William F.; Majewski, Steven R.; Carlin, Jeffrey L.; Vivas, A. Katherina; Wilhelm, Ronald; Beers, Timothy C.

    2009-08-10

    We present absolute proper motions in Kapteyn Selected Area (SA) 103. This field is located 7 deg. west of the center of the Virgo Stellar Stream (VSS), and has a well-defined main sequence representing the stream. In SA 103, we identify one RR Lyrae star as a member of the VSS, according to its metallicity, radial velocity, and distance. VSS candidate turnoff and subgiant stars have proper motions consistent with that of the RR Lyrae star. The three-dimensional velocity data imply an orbit with a pericenter of {approx}11 kpc and an apocenter of {approx}90 kpc. Thus, the VSS comprises tidal debris found near the pericenter of a highly destructive orbit. Examining the six globular clusters at distances larger than 50 kpc from the Galactic center, and the proposed orbit of the VSS, we find one tentative association, NGC 2419. We speculate that NGC 2419 is possibly the nucleus of a disrupted system of which the VSS is a part.

  18. The Sound Parameter Effect in Metal-Rich Globular Clusters

    NASA Technical Reports Server (NTRS)

    Hall, D. K

    1998-01-01

    Recent Hubble Space Telescope observations have found that the horizontal branches (HBs) in the metal-rich globular clusters NGC 6388 and NGC 6441 slope upward with decreasing B - V. Such a slope is not predicted by canonical HB models and cannot be produced by either a greater cluster age or enhanced mass loss along the red giant branch (RGB). The peculiar HB morphology in these clusters may provide an important clue for understanding the second-parameter effect. We have carried out extensive evolutionary calculations and numerical simulations in order to explore three noncanonical scenarios for explaining the sloped HBs in NGC 6388 and NGC 6441: (1) a high cluster helium abundance scenario, in which the HB evolution is characterized by long blue loops; (2) a rotation scenario, in which internal rotation during the RGB phase increases the HB core mass; and (3) a helium-mixing scenario, in which deep mixing on the RGB enhances the envelope helium abundance. All of these scenarios predict sloped HBs with anomalously bright RR Lyrae variables. We compare this prediction with the properties of the two known RR Lyrae variables in NGC 6388. Additional observational tests of these scenarios are suggested.

  19. Method of LSD profile asymmetry for estimating the center of mass velocities of pulsating stars

    NASA Astrophysics Data System (ADS)

    Britavskiy, Nikolay; Pancino, Elena; Romano, Donatella; Tsymbal, Vadim

    2015-08-01

    We present radial velocity analysis for 20 solar neighborhood RR Lyrae and 3 Population II Cepheids. High-resolution spectra were observed with either TNG/SARG or VLT/UVES over varying phases. To estimate the center of mass (barycentric) velocities of the program stars, we utilized two independent methods. First, the 'classic' method was employed, which is based on RR Lyrae radial velocity curve templates. Second, we provide the new method that used absorption line profile asymmetry to determine both the pulsation and the barycentric velocities even with a low number of high-resolution spectra and in cases where the phase of the observations is uncertain. This new method is based on a Least Squares Deconvolution (LSD) of the line profiles in order to analyze line asymmetry that occurs in the spectra of pulsating stars. By applying this method to our sample stars we attain accurate measurements (± 1 km/s) of the pulsation component of the radial velocity. This results in determination of the barycentric velocity to within 5 km/s even with a low number of high-resolution spectra. A detailed investigation of LSD profile asymmetry shows the variable nature of the project factor at different pulsation phases, which should be taken into account in the detailed spectroscopic analysis of pulsating stars.

  20. Method of LSD profile asymmetry for estimating the center of mass velocities of pulsating stars

    NASA Astrophysics Data System (ADS)

    Britavskiy, N.; Pancino, E.; Tsymbal, V.; Romano, D.; Cacciari, C.; Clementini, C.

    2016-05-01

    We present radial velocity analysis for 20 solar neighborhood RR Lyrae and 3 Population II Cepheids. High-resolution spectra were observed with either TNG/SARG or VLT/UVES over varying phases. To estimate the center of mass (barycentric) velocities of the program stars, we utilized two independent methods. First, the 'classic' method was employed, which is based on RR Lyrae radial velocity curve templates. Second, we provide the new method that used absorption line profile asymmetry to determine both the pulsation and the barycentric velocities even with a low number of high-resolution spectra and in cases where the phase of the observations is uncertain. This new method is based on a least squares deconvolution (LSD) of the line profiles in order to an- alyze line asymmetry that occurs in the spectra of pulsating stars. By applying this method to our sample stars we attain accurate measurements (+- 2 kms^-1) of the pulsation component of the radial velocity. This results in determination of the barycentric velocity to within 5 kms^-1 even with a low number of high- resolution spectra. A detailed investigation of LSD profile asymmetry shows the variable nature of the project factor at different pulsation phases, which should be taken into account in the detailed spectroscopic analysis of pulsating stars.

  1. Constraining dust extinction properties via the VVV survey

    NASA Astrophysics Data System (ADS)

    Majaess, D.; Turner, D.; Dékány, I.; Minniti, D.; Gieren, W.

    2016-10-01

    Near-infrared color-excess and extinction ratios are essential for establishing the cosmic distance scale and probing the Galaxy, particularly when analyzing targets attenuated by significant dust. A robust determination of those ratios followed from leveraging new infrared observations from the VVV survey, wherein numerous bulge RR Lyrae and Type II Cepheids were discovered, in addition to BVJHKs(3.4 → 22) μm data for classical Cepheids and O stars occupying the broader Galaxy. The apparent optical color-excess ratios vary significantly with Galactic longitude (ℓ), whereas the near-infrared results are comparatively constant with ℓ and Galactocentric distance (< E(J-overline{3.5 μ m)/E(J-K_s) > =1.28 ± 0.03}). The results derived imply that classical Cepheids and O stars display separate optical trends (RV,BV) with ℓ, which appear to disfavor theories advocating a strict and marked decrease in dust size with increasing Galactocentric distance. The classical Cepheid, Type II Cepheid, and RR Lyrae variables are characterized by ⟨AJ/E(J-Ks)⟩ = ⟨RJ,JKs⟩ = 1.49 ± 0.05 (⟨AKs/AJ⟩ = 0.33 ± 0.02), whereas the O stars are expectedly impacted by emission beyond 3.6 μm. The mean optical ratios characterizing classical Cepheids and O stars are approximately ⟨RV,BV⟩ 3.1 and ⟨RV,BV⟩ 3.3, respectively.

  2. HALO VELOCITY GROUPS IN THE PISCES OVERDENSITY

    SciTech Connect

    Sesar, Branimir; Ivezic, Zeljko; Vivas, A. Katherina; Duffau, Sonia E-mail: zi@u.washington.ed E-mail: sonia.duffau@gmail.co

    2010-07-01

    We report spectroscopic observations of five faint (V {approx} 20) RR Lyrae stars associated with the Pisces overdensity conducted with the Gemini South Telescope. At a heliocentric and galactocentric distance of {approx}80 kpc, this is the most distant substructure in the Galactic halo known to date. We combined our observations with literature data and confirmed that the substructure is composed of two different kinematic groups. The main group contains eight stars and has (V{sub gsr}) = 50 km s{sup -1}, while the second group contains four stars at a velocity of (V{sub gsr}) = -52 km s{sup -1}, where V{sub gsr} is the radial velocity in the galactocentric standard of rest. The metallicity distribution of RR Lyrae stars in the Pisces overdensity is centered on [Fe/H] = -1.5 dex and has a width of 0.3 dex. The new data allowed us to establish that both groups are spatially extended making it very unlikely that they are bound systems, and are more likely to be debris of a tidally disrupted galaxy or galaxies. Due to small sky coverage, it is still unclear whether these groups have the same or different progenitors.

  3. THE GALEX TIME DOMAIN SURVEY. I. SELECTION AND CLASSIFICATION OF OVER A THOUSAND ULTRAVIOLET VARIABLE SOURCES

    SciTech Connect

    Gezari, S.; Martin, D. C.; Forster, K.; Neill, J. D.; Morrissey, P.; Wyder, T. K.; Huber, M.; Burgett, W. S.; Chambers, K. C.; Kaiser, N.; Magnier, E. A.; Tonry, J. L.; Heckman, T.; Bianchi, L.; Neff, S. G.; Seibert, M.; Schiminovich, D.; Price, P. A.

    2013-03-20

    We present the selection and classification of over a thousand ultraviolet (UV) variable sources discovered in {approx}40 deg{sup 2} of GALEX Time Domain Survey (TDS) NUV images observed with a cadence of 2 days and a baseline of observations of {approx}3 years. The GALEX TDS fields were designed to be in spatial and temporal coordination with the Pan-STARRS1 Medium Deep Survey, which provides deep optical imaging and simultaneous optical transient detections via image differencing. We characterize the GALEX photometric errors empirically as a function of mean magnitude, and select sources that vary at the 5{sigma} level in at least one epoch. We measure the statistical properties of the UV variability, including the structure function on timescales of days and years. We report classifications for the GALEX TDS sample using a combination of optical host colors and morphology, UV light curve characteristics, and matches to archival X-ray, and spectroscopy catalogs. We classify 62% of the sources as active galaxies (358 quasars and 305 active galactic nuclei), and 10% as variable stars (including 37 RR Lyrae, 53 M dwarf flare stars, and 2 cataclysmic variables). We detect a large-amplitude tail in the UV variability distribution for M-dwarf flare stars and RR Lyrae, reaching up to |{Delta}m| = 4.6 mag and 2.9 mag, respectively. The mean amplitude of the structure function for quasars on year timescales is five times larger than observed at optical wavelengths. The remaining unclassified sources include UV-bright extragalactic transients, two of which have been spectroscopically confirmed to be a young core-collapse supernova and a flare from the tidal disruption of a star by dormant supermassive black hole. We calculate a surface density for variable sources in the UV with NUV < 23 mag and |{Delta}m| > 0.2 mag of {approx}8.0, 7.7, and 1.8 deg{sup -2} for quasars, active galactic nuclei, and RR Lyrae stars, respectively. We also calculate a surface density rate in the

  4. The Galex Time Domain Survey. I. Selection And Classification of Over a Thousand Ultraviolet Variable Sources

    NASA Technical Reports Server (NTRS)

    Gezari, S.; Martin, D. C.; Forster, K.; Neill, J. D.; Huber, M.; Heckman, T.; Bianchi, L.; Morrissey, P.; Neff, S. G.; Seibert, M.; Schiminovich, D.; Wyder, T. K.; Burgett, W. S.; Chambers, K. C.; Kaiser, N.; Magnier, E. A.; Price, P. A.; Tonry, J. L.

    2013-01-01

    We present the selection and classification of over a thousand ultraviolet (UV) variable sources discovered in approximately 40 deg(exp 2) of GALEX Time Domain Survey (TDS) NUV images observed with a cadence of 2 days and a baseline of observations of approximately 3 years. The GALEX TDS fields were designed to be in spatial and temporal coordination with the Pan-STARRS1 Medium Deep Survey, which provides deep optical imaging and simultaneous optical transient detections via image differencing. We characterize the GALEX photometric errors empirically as a function of mean magnitude, and select sources that vary at the 5 sigma level in at least one epoch. We measure the statistical properties of the UV variability, including the structure function on timescales of days and years. We report classifications for the GALEX TDS sample using a combination of optical host colors and morphology, UV light curve characteristics, and matches to archival X-ray, and spectroscopy catalogs. We classify 62% of the sources as active galaxies (358 quasars and 305 active galactic nuclei), and 10% as variable stars (including 37 RR Lyrae, 53 M dwarf flare stars, and 2 cataclysmic variables). We detect a large-amplitude tail in the UV variability distribution for M-dwarf flare stars and RR Lyrae, reaching up to absolute value(?m) = 4.6 mag and 2.9 mag, respectively. The mean amplitude of the structure function for quasars on year timescales is five times larger than observed at optical wavelengths. The remaining unclassified sources include UV-bright extragalactic transients, two of which have been spectroscopically confirmed to be a young core-collapse supernova and a flare from the tidal disruption of a star by dormant supermassive black hole. We calculate a surface density for variable sources in the UV with NUV less than 23 mag and absolute value(?m) greater than 0.2 mag of approximately 8.0, 7.7, and 1.8 deg(exp -2) for quasars, active galactic nuclei, and RR Lyrae stars

  5. The Kepler Light Curves of V1504 Cygni and V344 Lyrae: A Study of the Outburst Properties

    NASA Technical Reports Server (NTRS)

    Cannizzo, John K.; Smale, Alan P.; Still, Martin D.; Wood, Matt A.; Howell, Steve B.

    2011-01-01

    We examine the Kepler light curves of V1504 Cyg and V344 Lyr, encompassing approximately 460 d at 1 min cadence. During this span each system exhibited approximately 40 outbursts, including four superoutbursts. We find that, in both systems, the normal outbursts lying between two superoutbursts increase in duration by a factor approximately 1.2 - 1.7, and then reset to a small value after the following superoutburst. In V344 Lyr the trend of quiescent intervals between normal outbursts is to increase to a local maximum about half way through the supercycle the interval from one superoutburst to the next - and then to decrease back to a small value by the time of the next superoutburst, whereas for V1504 Cyg the quiescent intervals are relatively constant during the supercycle. Both of these trends are inconsistent with the Osaki's thermal-tidal model, which robustly predicts a secular increase in the quiescent intervals between normal outbursts during a supercycle. Also, most of the normal outbursts have an asymmetric, fast-rise/slower-decline shape, which would be consistent with outbursts triggered at large radii. The exponential rate of decay of the plateau phase of the superoutbursts is 8 d mag(sup -1) for approximately 1504 Cyg and 12 d mag(sup -1) for V344 Lyr. This time scale gives a direct measure of the VISCOUS time scale III the outer accretion disk given the expectation that the entire disk is in the hot, viscous state during superoutburst. The resulting constraint on the Shakura-Sunyaev parameter, alpha(sub hot) approximately equal to 0.1, is consistent with the value inferred from the fast dwarf nova decays. By looking at the slow decay rate for superoutbursts, which occur in systems below the period gap, in combination with the slow decay rate in one long outburst above the period gap (in U Gem), we infer a steep dependence of the decay rate on orbital period for long outbursts. We argue that this relation implies a steep dependence of alpha(sub cold) on orbital period, which may be consistent with recent findings of Patterson, and is consistent with tidal torquing as being the dominant angular momentum transport mechanism in quiescent disks in interacting binary systems.

  6. MOST photometry of the RRdLyrae variable AQLeo: two radial modes, 32 combination frequencies and beyond

    NASA Astrophysics Data System (ADS)

    Gruberbauer, Michael; Kolenberg, Katrien; Rowe, Jason F.; Huber, Daniel; Matthews, Jaymie M.; Reegen, Piet; Kuschnig, Rainer; Cameron, Chris; Kallinger, Thomas; Weiss, Werner W.; Guenther, David B.; Moffat, Anthony F. J.; Rucinski, Slavek; Sasselov, Dimitar; Walker, Gordon A. H.

    2007-08-01

    Highly precise and nearly uninterrupted optical photometry of the RRLyrae star AQLeo was obtained with the MOST (Microvariability and Oscillations of Stars) satellite over 34.4d in 2005 February-March. AQLeo was the first known double-mode RRLyrae pulsator (RRd star). Three decades after its discovery, MOST observations have revealed that AQLeo oscillates with at least 42 frequencies, of which 32 are linear combinations (up to the sixth order) of the radial fundamental mode and its first overtone. Evidence for period changes of these modes is found in the data. The other intrinsic frequencies may represent an additional non-radial pulsation mode and its harmonics (plus linear combinations) which warrant theoretical modelling. The unprecedented number of frequencies detected with amplitudes down to mmag precision also presents an opportunity to test non-linear theories of mode growth and saturation in RRd stars. MOST is a Canadian Space Agency mission, jointly operated by Dynacon Inc., the University of Toronto Institute for Aerospace Studies and the University of British Columbia, with the assistance of the University of Vienna. E-mail: gruberbauer@astro.univie.ac.at

  7. A reinterpretation of the Triangulum-Andromeda stellar clouds: a population of halo stars kicked out of the Galactic disc

    NASA Astrophysics Data System (ADS)

    Price-Whelan, Adrian M.; Johnston, Kathryn V.; Sheffield, Allyson A.; Laporte, Chervin F. P.; Sesar, Branimir

    2015-09-01

    The Triangulum-Andromeda stellar clouds (TriAnd1 and TriAnd2) are a pair of concentric ring- or shell-like overdensities at large R (≈30 kpc) and Z (≈-10 kpc) in the Galactic halo that are thought to have been formed from the accretion and disruption of a satellite galaxy. This paper critically reexamines this formation scenario by comparing the number ratio of RR Lyrae to M giant stars associated with the TriAnd clouds with other structures in the Galaxy. The current data suggest a stellar population for these overdensities (fRR: MG < 0.38 at 95 per cent confidence) quite unlike any of the known satellites of the Milky Way (fRR: MG ≈ 0.5 for the very largest and fRR: MG ≫ 1 for the smaller satellites) and more like the population of stars born in the much deeper potential well inhabited by the Galactic disc (fRR: MG < 0.01). N-body simulations of a Milky Way-like galaxy perturbed by the impact of a dwarf galaxy demonstrate that, in the right circumstances, concentric rings propagating outwards from that Galactic disc can plausibly produce similar overdensities. These results provide dramatic support for the recent proposal by Xu et al. that, rather than stars accreted from other galaxies, the TriAnd clouds could represent stars kicked out from our own disc. If so, these would be the first populations of disc stars to be found in the Galactic halo and a clear signature of the importance of this second formation mechanism for stellar haloes more generally. Moreover, their existence at the very extremities of the disc places strong constraints on the nature of the interaction that formed them.

  8. Measuring amplitudes of harmonics and combination frequencies in variable stars

    NASA Astrophysics Data System (ADS)

    Bellinger, E. P.; Wysocki, D.; Kanbur, S. M.

    2016-05-01

    Discoveries of RR Lyrae and Cepheid variable stars with multiple modes of pulsation have increased tremendously in recent years. The Fourier spectra of these stars can be quite complicated due to the large number of combination frequencies that can exist between their modes. As a result, light- curve fits to these stars often suffer from undesirable ringing effects that arise from noisy observations and poor phase coverage. These non-physical overfitting artifacts also occur when fitting the harmonics of single-mode stars. Here we present a new method for fitting light curves that is much more robust against these effects. We prove that the amplitude measurement problem is very difficult (NP-hard) and provide a heuristic algorithm for solving it quickly and accurately.

  9. The Hubble constant.

    PubMed

    Tully, R B

    1993-06-01

    Five methods of estimating distances have demonstrated internal reproducibility at the level of 5-20% rms accuracy. The best of these are the cepheid (and RR Lyrae), planetary nebulae, and surface-brightness fluctuation techniques. Luminosity-line width and Dn-sigma methods are less accurate for an individual case but can be applied to large numbers of galaxies. The agreement is excellent between these five procedures. It is determined that Hubble constant H0 = 90 +/- 10 km.s-1.Mpc-1 [1 parsec (pc) = 3.09 x 10(16) m]. It is difficult to reconcile this value with the preferred world model even in the low-density case. The standard model with Omega = 1 may be excluded unless there is something totally misunderstood about the foundation of the distance scale or the ages of stars. PMID:11607391

  10. VARIABLES IN GLOBULAR CLUSTER NGC 5024

    SciTech Connect

    Safonova, M.; Stalin, C. S. E-mail: stalin@iiap.res.in

    2011-12-15

    We present the results of a commissioning campaign to observe Galactic globular clusters for the search of microlensing events. The central 10' Multiplication-Sign 10' region of the globular cluster NGC 5024 was monitored using the 2 m Himalayan Chandra Telescope in R-band for a period of about 8 hr on 2010 March 24. Light curves were obtained for nearly 10,000 stars using a modified Differential Image Analysis technique. We identified all known variables within our field of view and revised the periods and status of some previously reported short-period variables. We report about 70 new variable sources and present their equatorial coordinates, periods, light curves, and possible types. Out of these, 15 are SX Phe stars, 10 are W UMa-type stars, and 14 are probable RR Lyrae stars. Nine of the newly discovered SX Phe stars and one eclipsing binary belong to the blue straggler star population.

  11. Measurement of Precision Geometric Distances to Three Anchor Points in the Local Universe

    NASA Technical Reports Server (NTRS)

    Reid, Mark J.

    2001-01-01

    We proposed a program to measure distances directly with accuracies of 5% to three anchor points in the Local Universe. We planned to accomplish this by conducting Very Long Baseline Interferometry (VLBI) observations of NGC 4258, M 33, and Sgr A*. These distance estimates should have a minimum of systematic uncertainty and can be used to re-calibrate several 'standard candles,' such as Cepheid and RR Lyrae variables. This will place the Galactic and extragalactic distance scales on much firmer ground. The primary contribution of our program will be to provide crucial independent checks and calibrations of extragalactic distance measurements. This will contribute to the ultimate success and impact of the HST Key Project on Extragalactic Distances and the Full-Sky Astrometric Mapping Explorer (FAME). Additionally, since distances are fundamental to astrophysics, our results will affect a large number of general projects on NASA facilities such as the Hubble Space Telescope, Chandra X-ray Observatory, and Next Generation Space Telescope.

  12. Measurement of Precision Geometric Distances to Three Anchor Points in the Local Universe

    NASA Technical Reports Server (NTRS)

    Reid, Mark J.

    2003-01-01

    As stated in previous reports, our program, funded by a NASA/SARA 3-yr grant, is designed to measure distances directly with accuracies of 5% to three anchor points in the Local Universe. We are attacking this problem on three fronts, using Very Long Baseline Interferometry (VLBI) observations of NGC 4258, M 33, and Sgr A*. We plan to provide distance estimates, with a minimum of systematic uncertainty, that can be used to re- calibrate several "standard candles," such as Cepheid and RR Lyrae variables. This Will place the Galactic and extragalactic distance scales on much firmer ground. The program will provide crucial, independent checks and calibrations of extragalactic distance measurements, and will contribute to the ultimate success and impact of the HST Key Project on Extragalactic Distances and any future NASA astrometric missions. Additionally, since distances are fundamental to astrophysics, our results will affect a large number of general projects on NASA facilities such as the HST, CXO, and JWST.

  13. An aligned stream of low-metallicity clusters in the halo of the Milky Way.

    PubMed

    Yoon, Suk-Jin; Lee, Young-Wook

    2002-07-26

    One of the long-standing problems in modern astronomy is the curious division of Galactic globular clusters, the "Oosterhoff dichotomy," according to the properties of their RR Lyrae stars. Here, we find that most of the lowest metallicity ([Fe/H] < -2.0) clusters, which are essential to an understanding of this phenomenon, display a planar alignment in the outer halo. This alignment, combined with evidence from kinematics and stellar population, indicates a captured origin from a satellite galaxy. We show that, together with the horizontal-branch evolutionary effect, the factor producing the dichotomy could be a small time gap between the cluster-formation epochs in the Milky Way and the satellite. The results oppose the traditional view that the metal-poorest clusters represent the indigenous and oldest population of the Galaxy.

  14. Comparative pulsation calculations with OP and OPAL opacities

    NASA Technical Reports Server (NTRS)

    Kanbur, Shashi M.; Simon, Norman R.

    1994-01-01

    Comparative linear nonadiabatic pulsation calculations are presented using the OPAL and Opacity Project opacities. The two sets of opacities include effects due to intermediate coupling and fine structure as well as new abundances. We used two mass luminosity (M-L) relations, one standard (BIT), and one employing substantial convective core overshoot (COV). The two sets of opacities cannot be differentiated on the basis of the stellar pulsation calculations presented here. The BIT relation can model the beat and bump Cepheids with masses between 4 and 7 solar mass, while if the overshoot relation is used, masses between 2 and 6 solar mass are required. In the RR Lyrae regime, we find the inferred masses of globular cluster RRd stars to be little influenced by the choice of OPAL or OP. Finally, the limited modeling we have done is not able to constrain the Cepheid M-L relation based upon period ratios observed in the beat and bump stars.

  15. Introduction to optimization with applications in astronomy and astrophysics

    NASA Astrophysics Data System (ADS)

    Canu, S.; Flamary, R.; Mary, D.

    2016-09-01

    This chapter aims at providing an introduction to numerical optimization with some applications in astronomy and astrophysics. We provide important preliminary definitions that will guide the reader towards different optimization procedures. We discuss three families of optimization problems and describe numerical algorithms allowing, when this is possible, to solve these problems. For each family, we present in detail simple examples and more involved advanced examples. As a final illustration, we focus on two worked-out examples of optimization applied to astronomical data. The first application is a supervised classification of RR-Lyrae stars. The second one is the denoising of galactic spectra formulated by means of sparsity inducing models in a redundant dictionary.

  16. The Hubble constant.

    PubMed Central

    Tully, R B

    1993-01-01

    Five methods of estimating distances have demonstrated internal reproducibility at the level of 5-20% rms accuracy. The best of these are the cepheid (and RR Lyrae), planetary nebulae, and surface-brightness fluctuation techniques. Luminosity-line width and Dn-sigma methods are less accurate for an individual case but can be applied to large numbers of galaxies. The agreement is excellent between these five procedures. It is determined that Hubble constant H0 = 90 +/- 10 km.s-1.Mpc-1 [1 parsec (pc) = 3.09 x 10(16) m]. It is difficult to reconcile this value with the preferred world model even in the low-density case. The standard model with Omega = 1 may be excluded unless there is something totally misunderstood about the foundation of the distance scale or the ages of stars. PMID:11607391

  17. Periodicity search as a tool for disentangling the contaminated colour light curve of CoRoT 102781750

    NASA Astrophysics Data System (ADS)

    Paparó, M.; Chadid, M.; Chapellier, E.; Benkő, J. M.; Szabó, R.; Kolenberg, K.; Guggenberger, E.; Regály, Zs.; Auvergne, M.; Baglin, A.; Weiss, W. W.

    2011-07-01

    Context. The CoRoT space mission (COnvection, ROtation and planetary Transits) launched in December 2006, aims at finding transiting exoplanets and investigating stellar oscillation in adjacent stellar fields, called exo- and seismofields, respectively. Besides the seismofields, CoRoT has a strong potential for seismological research on the exofields. Up to now, only a limited number of RR Lyrae stars have been classified among the CoRoT targets. Knowing the astrophysical importance of the RR Lyrae stars, we attempted to get useful information even from a contaminated light curve of a possible RR Lyrae pulsator. Aims: The star CoRoT 102781750 reveals a puzzle, showing a very complex and altering variation in different "CoRoT colours". We established without doubt that more than a single star was situated within the CoRoT mask. Using a search for periodicity as a tool, our aim is to disentangle the composite light curve and identify the type of sources behind the variability. Methods: Both flux and magnitude light curves were used. Conversion was applied after a jump- and trend-filtering algorithm. We applied different types of period-finding techniques including MuFrAn and Period04. Results: The amplitude and phase peculiarities obtained from the independent analysis of CoRoT r, g, and b colours and ground-based follow-up photometric observations ruled out the possibility of either a background monoperiodic or a Blazhko type RR Lyrae star being in the mask. The main target, an active star, shows at least two spotted areas that reveal a Prot = 8.8 h (f0 = 2.735 c d-1) mean rotation period. The evolution of the active regions helped to derive a period change of dP/dt = 1.6 × 10-6 (18 s over the run) and a differential rotation of α = ΔΩ/Ω = 0.0074. The 0.015m linear decrease and a local 0.005m increase in the dominant period's amplitude are interpreted as a decay of the old spotted region and an appearance of a new one, respectively. A star that is detected only

  18. The Galactic Bulge

    NASA Astrophysics Data System (ADS)

    Barbuy, B.

    2016-06-01

    The Galactic bulge is the least studied component of our Galaxy. Yet, its formation and evolution are key to understand the formation of the Galaxy itself. Studies on the Galactic bulge have increased significantly in the last years, but still there are many points of controversy. This volume contains several contributions from experts in different aspects of the bulge. Issues discussed include the following: the presence of an old spheroidal bulge, or identification of its old stellar population with the thick disk or halo; fraction of stars younger than 10 Gyr is estimated to be of < 5 to 22% depending on method and authors; multiple populations or only a metal-poor and a metal-rich ones; spheroidal or ellipsoidal distribution of RR Lyrae; formation of the bulge from early mergers or from secular evolution of the bar; different methods of mapping extinction; selection and identification of bulge globular clusters.

  19. The LINEAR Photometric Database: Time Domain Information for SDSS Objects

    NASA Astrophysics Data System (ADS)

    Veyette, Mark; Becker, A. C.; Bozic, H.; Carroll, P.; Champey, P.; Draper, Z.; Evans, N.; Filbrandt, A.; Fowler, J.; Gailey, J.; Galin, M.; Ivezic, Z.; Jennings, Z.; Kelley, J.; Kroflin, A.; Laws, C.; Lewarch, E.; Loebman, S.; Mayorga, L.; Mesaric, M.; Morgan, D. P.; Munk, P.; Oluseyi, H.; Palaversa, L.; Patel, M.; Ruzdjak, D.; Schmidt, S.; Sesar, B.; Srdoc, G.; Steakley, K.; Stuart, J. S.; Sudar, D.; Vrbanec, D.; Westman, D. B.; Wheaton, S.; Wozniak, P.

    2012-01-01

    We announce a public database of over 5 billion photometric measurements for about 25 million objects, mostly stars with V<18, obtained by the asteroid survey LINEAR (available through the SkyDot website, skydot.lanl.gov). With 200 observations per object on average, LINEAR data provide time domain information for the brightest 4 magnitudes of SDSS survey objects. By combining information from these databases we have selected and visually classified some 200,000 candidate variable stars. Guided by these classifications, we selected the largest available sample of candidate field SX Phe stars (blue straggler halo stars) and demonstrated its low contamination through follow up observations at a number of telescopes in Croatia and the U.S. We have also constructed samples of several thousand distant RR Lyrae stars, as well as several thousand eclipsing binary stars, and are currently investigating the statistical properties of these data.

  20. Deep HST Photometry of NGC 6388: Age and Horizontal Branch Luminosity

    NASA Technical Reports Server (NTRS)

    Stetson, Peter B.; Catelan, M.; Pritzl, Barton J.; Smith, Horace A.; Kinemuchi, Karen; Layden, Andrew C.; Sweigart, Allen V.; Rich, R. M.

    2006-01-01

    We present the first deep color-magnitude diagram (CMD) of the Galactic globular cluster NGC 6388, obtained with the Hubble Space Telescope, that is able to reach the main-sequence turnoff point of the cluster. From a detailed comparison between the cluster CMD and that of 47 Tucanae (NGC 104), we find that the bulk of the stars in these two clusters have nearly the same age and chemical composition. On the other hand, our results indicate that the blue horizontal branch and RR Lyrae components in NGC 6388 are intrinsically over-luminous, which must be due to one or more, still undetermined, non-canonical second parameter(s) affecting a relatively minor fraction of the stars in NGC 6388.