526 research outputs found

    Photometric Properties of Kiso Ultraviolet-Excess Galaxies in the Lynx-Ursa Major Region

    Get PDF
    We have performed a systematic study of several regions in the sky where the number of galaxies exhibiting star formation (SF) activity is greater than average. We used Kiso ultraviolet-excess galaxies (KUGs) as our SF-enhanced sample. By statistically comparing the KUG and non-KUG distributions, we discovered four KUG-rich regions with a size of 10×10\sim 10^\circ \times 10^\circ. One of these regions corresponds spatially to a filament of length 60h1\sim 60 h^{-1} Mpc in the Lynx-Ursa Major region (α9h10h,δ4248\alpha \sim 9^{\rm h} - 10^{\rm h}, \delta \sim 42^\circ - 48^\circ). We call this ``the Lynx-Ursa Major (LUM) filament''. We obtained V(RI)CV(RI)_{\rm C} surface photometry of 11 of the KUGs in the LUM filament and used these to investigate the integrated colors, distribution of SF regions, morphologies, and local environments. We found that these KUGs consist of distorted spiral galaxies and compact galaxies with blue colors. Their star formation occurs in the entire disk, and is not confined to just the central regions. The colors of the SF regions imply that active star formation in the spiral galaxies occurred 107810^{7 - 8} yr ago, while that of the compact objects occurred 106710^{6-7} yr ago. Though the photometric characteristics of these KUGs are similar to those of interacting galaxies or mergers, most of these KUGs do not show direct evidence of merger processes.Comment: 39 pages LaTeX, using aasms4.sty, 20 figures, ApJS accepted. The Title of the previous one was truncated by the author's mistake, and is corrected. Main body of the paper is unchange

    Optical Alignment System for the PHENIX Muon Tracking Chambers

    Full text link
    A micron-precision optical alignment system (OASys) for the PHENIX muon tracking chambers is developed. To ensure the required mass resolution of vector meson detection, the relative alignment between three tracking station chambers must be monitored with a precision of 25μ\mum. The OASys is a straightness monitoring system comprised of a light source, lens and CCD camera, used for determining the initial placement as well as for monitoring the time dependent movement of the chambers on a micron scale.Comment: Accepted for the publication in Nucl.Instr.Meth.

    Capacitar profissionais para trabalhar/difundir a segurança alimentar e nutricional da comunidade

    Get PDF
    Trabalho apresentado no II Congresso Nacional do PROJETO RONDON, realizado em Florianópolis, SC, no período de 23 a 25 de setembro de 2015 - Universidade Federal de Santa Catarina.O conceito de Segurança alimentar e Nutricional (SAN) é muito amplo, define-se como o direito de todos ao acesso a alimentos de qualidade e em quantidade, sem comprometer o acesso a outras necessidades essenciais. Além disso, a SAN constitui a prática de uma alimentação adequada com alimentos saudáveis, e consumir nutrientes necessários para as atividades diárias de cada cidadão. Sendo assim, foi desenvolvida durante a Operação Bororos - julho/2015, no Conjunto A de atividades no município de Nortelândia/MT, uma oficina que objetivou o esclarecimento dos direitos supracitados a toda população, além de promover o conhecimento sobre os alimentos que estão disponíveis para o consumo, e quais os benefícios que estes podem trazer para a saúde, sua quantidade e variedade adequada. Além de direcionar formas de promoção à alimentação saudável e de auto produção e consumo. Esta oficina foi desenvolvida na Escola Municipal Júlio Praxe de Duarte com auxílio de recursos audiovisuais para 47 pessoas que incluíam profissionais da área da saúde, merendeiras e comunidade em geral. Foram dois dias de atividade no período integral (manhã e tarde), onde no primeiro dia foram desenvolvidas atividades teóricas sobre conceitos de SAN, componentes dos alimentos, grupos alimentares, e aspectos de higiene alimentar. No segundo dia foram desenvolvidas atividades práticas, sendo construída, no período matutino uma horta comunitária no pátio da escola e no período vespertino praticado o monitoramento da SAN para a população, como exemplo, a realização do cálculo do Índice de Massa Corporal (IMC). Foi verificado que houve impacto das informações sobre a população, que se sentiu esclarecida, sendo ouvidos muitos relatos que deixou exposto que o ato de alimentar-se não expressava tanta preocupação com relação a qualidade e propósito dos alimentos. Também constatou-se que o conhecimento sobre como alimentar-se, e o que ingerir, e o porquê consumir tais alimentos apresentaram conceitos novos. Conclui-se desta forma que a atividade promoveu um impacto sobre a comunidade implicando em sua qualidade de vida, e que poderá ser replicada mesmo após a conclusão do trabalho dos rondonistas

    Rotational and Cyclical Variability in gamma Cassiopeia

    Full text link
    We report results of a nine-year monitoring effort on the unusual classical Be with a robotic ground-based (APT) B,V-filtered telescope as well as simultaneous observations in 2004 November with this instrument and the RXTE (X-ray) telescope. Our observations disclosed no correlated optical response to the rapid X-ray flares in this star, nor did the star show any sustained flux changes during the course of either of the two monitored nights in either wavelength regime. Our optical light curves reveal that gamma Cas undergoes \~3%-amplitude cycles with lengths of 60--90 days. Over the nine days we monitored the star with the RXTE, the X-ray flux varied in phase with its optical cycle and with an amplitude predicted from correlated optical/X-ray data from an earlier paper. The amplitudes of the V magnitude cycles are 30--40% larger than the B amplitudes, suggesting the seat of the cycles is circumstellar. The cycle lengths constantly change and can damp or grow on timescales as short as 13 days. We have also discovered a coherent period of 1.21581 +/-0.00002 days in all our data, which is consistent only with rotation. The full amplitude of this variation is 0.0060 in both filters. The derived waveform, somewhat surprisingly, is almost sawtooth in shape. This variation probably originates on the star's surface. This circumstance hints at the existence of a strong magnetic field with a complex topology and an associated heterogeneous surface composition.Comment: 31 pages, 7 figures. Submitted to The Astrophysical Journa

    X-ray and Optical Variations in the Classical Be Star gamma Cas

    Full text link
    gamma Cas (B0.5e) is known to be a unique X-ray source because ot its moderate L_x, hard X-ray spectrum, and light curve punctuated by ubiquitous flares and slow undulations. Its X-ray peculiarities have led to a controversy concerning their origin: either from wind infall onto a putative degenerate companion, as for typical Be/X-ray binaries, or from the Be star per se. Recent progress has been made to address this: (1) the discovery that gamma Cas is an eccentric binary system (P = 203.59 d) with unknown secondary type, (2) the accumulation of RXTE data at 9 epochs in 1996-2000, and (3) the collation of robotic telescope B, V-band photometric observations over 4 seasons. The latter show a 3%, cyclical flux variation with cycle lengths 55-93 days. We find that X-ray fluxes at all 9 epochs show random variations with orbital phase. This contradicts the binary accretion model, which predicts a substantial modulation. However,these fluxes correlate well with the cyclical optical variations. Also, the 6 flux measurements in 2000 closely track the interpolated optical variations between the 2000 and 2001 observing seasons. Since the optical variations represent a far greater energy than that emitted as X-rays, the optical variability cannot arise from X-ray reprocessing. However, the strong correlation between the two suggests that they are driven by a common mechanism. We propose that this mechanism is a cyclical magnetic dynamo excited by a Balbus-Hawley instability located within the inner part of the circumstellar disk. In our model, variations in the field strength directly produce the changes in the magnetically related X-ray activity. Turbulence associated with the dynamo results in changes to the density distribution within the disk and creates the observed optical variations.Comment: 30 dbl-spaced pages, Latex, plus 11 figures. Accepted by Ap

    Inclusive cross section and double helicity asymmetry for pi^0 production in p+p collisions at sqrt(s) = 62.4 GeV

    Full text link
    The PHENIX experiment presents results from the RHIC 2006 run with polarized proton collisions at sqrt(s) = 62.4 GeV for inclusive pi^0 production at mid-rapidity. Unpolarized cross section results are measured for transverse momenta p_T = 0.5 to 7 GeV/c. Next-to-leading order perturbative quantum chromodynamics calculations are compared with the data, and while the calculations are consistent with the measurements, next-to-leading logarithmic corrections improve the agreement. Double helicity asymmetries A_LL are presented for p_T = 1 to 4 GeV/c and probe the higher range of Bjorken_x of the gluon (x_g) with better statistical precision than our previous measurements at sqrt(s)=200 GeV. These measurements are sensitive to the gluon polarization in the proton for 0.06 < x_g < 0.4.Comment: 387 authors from 63 institutions, 10 pages, 6 figures, 1 table. Submitted to Physical Review D. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

    Inclusive cross section and single-transverse-spin asymmetry for very forward neutron production in polarized p+p collisions at sqrt(s)=200 GeV

    Full text link
    The energy dependence of the single-transverse-spin asymmetry, A_N, and the cross section for neutron production at very forward angles were measured in the PHENIX experiment at RHIC for polarized p+p collisions at sqrt(s)=200 GeV. The neutrons were observed in forward detectors covering an angular range of up to 2.2 mrad. We report results for neutrons with momentum fraction of x_F=0.45 to 1.0. The energy dependence of the measured cross sections were consistent with x_F scaling, compared to measurements by an ISR experiment which measured neutron production in unpolarized p+p collisions at sqrt(s)=30.6--62.7 GeV. The cross sections for large x_F neutron production for p+p collisions, as well as those in e+p collisions measured at HERA, are described by a pion exchange mechanism. The observed forward neutron asymmetries were large, reaching A_N=-0.08+/-0.02 for x_F=0.8; the measured backward asymmetries, for negative x_F, were consistent with zero. The observed asymmetry for forward neutron production is discussed within the pion exchange framework, with interference between the spin-flip amplitude due to the pion exchange and nonflip amplitudes from all Reggeon exchanges. Within the pion exchange description, the measured neutron asymmetry is sensitive to the contribution of other Reggeon exchanges even for small amplitudes.Comment: 383 authors, 16 pages, 18 figures, 6 tables. Submitted to Phys. Rev. D. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

    ϕ\phi meson production in dd++Au collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV

    Full text link
    The PHENIX experiment has measured ϕ\phi meson production in dd++Au collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV using the dimuon and dielectron decay channels. The ϕ\phi meson is measured in the forward (backward) dd-going (Au-going) direction, 1.2<y<2.21.2<y<2.2 (2.2<y<1.2-2.2<y<-1.2) in the transverse-momentum (pTp_T) range from 1--7 GeV/cc, and at midrapidity y<0.35|y|<0.35 in the pTp_T range below 7 GeV/cc. The ϕ\phi meson invariant yields and nuclear-modification factors as a function of pTp_T, rapidity, and centrality are reported. An enhancement of ϕ\phi meson production is observed in the Au-going direction, while suppression is seen in the dd-going direction, and no modification is observed at midrapidity relative to the yield in pp++pp collisions scaled by the number of binary collisions. Similar behavior was previously observed for inclusive charged hadrons and open heavy flavor indicating similar cold-nuclear-matter effects.Comment: 484 authors, 16 pages, 12 figures, 6 tables. v1 is the version accepted for publication in Phys. Rev. C. Data tables for the points plotted in the figures are given in the paper itsel

    Cross sections and double-helicity asymmetries of midrapidity inclusive charged hadrons in p+p collisions at sqrt(s)=62.4 GeV

    Full text link
    Unpolarized cross sections and double-helicity asymmetries of single-inclusive positive and negative charged hadrons at midrapidity from p+p collisions at sqrt(s)=62.4 GeV are presented. The PHENIX measurements for 1.0 < p_T < 4.5 GeV/c are consistent with perturbative QCD calculations at next-to-leading order in the strong coupling constant, alpha_s. Resummed pQCD calculations including terms with next-to-leading-log accuracy, yielding reduced theoretical uncertainties, also agree with the data. The double-helicity asymmetry, sensitive at leading order to the gluon polarization in a momentum-fraction range of 0.05 ~< x_gluon ~< 0.2, is consistent with recent global parameterizations disfavoring large gluon polarization.Comment: PHENIX Collaboration. 447 authors, 12 pages, 5 figures, 5 tables. Submitted to Physical Review
    corecore