Publications (3)1.52 Total impact
Article: Optical and Near-Infrared Photometric Observation during the Superoutburst of the WZ Sge-Type Dwarf Nova, V455 Andromedae[show abstract] [hide abstract]
ABSTRACT: We report on optical and infrared photometric observations of a WZ Sge-type dwarf nova, V455 And during a superoutburst in 2007. These observations were performed with the KANATA (V, J, and K_s bands) and MITSuME (g', Rc, and Ic bands) telescopes. Our 6-band simultaneous observations allowed us to investigate the temporal variation of the temperature and the size of the emitting region associated with the superoutburst and short-term modulations, such as early and ordinary superhumps. A hot (>11000 K) accretion disk suddenly disappeared when the superoutburst finished, while blackbody emission, probably from the disk, still remained dominant in the optical region with a moderately high temperature (~8000 K). This indicates that a substantial amount of gas was stored in the disk even after the outburst. This remnant matter may be a sign of an expected mass-reservoir which can trigger echo outbursts observed in several WZ Sge stars. The color variation associated with superhumps indicates that viscous heating in a superhump source stopped on the way to the superhump maximum, and a subsequent expansion of a low-temperature region made the maximum. The color variation of early superhumps was totally different from that of superhumps: the object was bluest at the early superhump minimum. The temperature of the early superhump light source was lower than that of an underlying component, indicating that the early superhump light source was a vertically expanded low-temperature region at the outermost part of the disk. Comment: 14 pages, 12 figures, PASJ accepted08/2009;
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ABSTRACT: This paper studies a new real-time phase-shifting method for the analysis of isochromatic and isoclinic parameters in photoelasticity. By rotating an analyzer at a constant rate and an output quarter-wave plate at a double rate of the analyzer and recording images by a CCD camera continuously, sequential images which brightness is integrated by sensors in a CCD camera during phase-shifting are obtained. Then, the distributions of the isochromatic and isoclinic parameters are obtained immediately and quantitatively using the proposed phase-shifting algorithm. The proposed method can be applied to high-speed inspection of optical elements or glass products. Also, it is expected that slowly varying time-dependent problems can be analyzed by the proposed method.Experimental Mechanics 02/2003; 43(1):83-89. · 1.52 Impact Factor
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ABSTRACT: This paper describes high-speed phase-shifting method for the real-time analysis of isochromatic and isoclinic parameters in photoelasticity. By rotating an analyzer at a constant rate and an output quarter-wave plate at a double rate of the analyzer and recording images by a CCD camera continuously, sequential phase-shifted images whose brightness is integrated by sensors are obtained. Then, the distributions of the isochromatic and isoclinic parameters are obtained at a video rate using the proposed phase-shifting algorithm. The phase distributions of the isochromatic and isoclinic parameters of a disk under the static and increasing loadings are simulated. Then, an application of the proposed method to a problem under increasing load is demonstrated and the time variation of the isochromatic parameter is evaluated.Optics and Lasers in Engineering.