72 research outputs found

    Analysis of B and Be Star Populations of the Double Cluster h and chi Persei

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    We present blue optical spectra of 92 members of h and chi Per obtained with the WIYN telescope at Kitt Peak National Observatory. From these spectra, several stellar parameters were measured for the B-type stars, including V sin i, T_eff, log g_polar, M_star, and R_star. Stromgren photometry was used to measure T_eff and log g_polar for the Be stars. We also analyze photometric data of cluster members and discuss the near-to-mid IR excesses of Be stars.Comment: 4 pages, to appear in the proceedings of IAU Symposium 266: Star Cluster

    Investigation of mid-infrared AlInSb LEDs with an n-i-p structure

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    We report on the investigation on mid-infrared AlInSb LEDs with an n-i-p structure. Compared to the conventional AlInSb LEDs with a p-i-n structure, a better current spreading corresponding to a uniform current distribution in the active region is expected in the n-i-p structure because of a high electron mobility in the n-type AlInSb material. The output optical power of laterally injected LEDs were investigated as a function of the device geometry by COMSOL simulations and confirmed by experimental results

    Liquid-filled hard gelatin capsules : excipient/capsule compatibility studies

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    Encapsulation of pharmaceutical formulations as liquids or semisolids, within hard gelatin capsules, presents an important oral dosage strategy for poorly water-soluble drugs, resulting in good bioavailability and reproducible drug absorption. In addition, this technology offers an inherently safer process than powder filled capsules and tablets for highly potent or cytotoxic drugs by avoiding dust generation. Here we present a compatibility study of hard gelatin capsules with common excipients in absence of active pharmaceutical

    The Evolution of Protoplanetary Disks Around Millisecond Pulsars: The PSR 1257 +12 System

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    We model the evolution of protoplanetary disks surrounding millisecond pulsars, using PSR 1257+12 as a test case. Initial conditions were chosen to correspond to initial angular momenta expected for supernova-fallback disks and disks formed from the tidal disruption of a companion star. Models were run under two models for the viscous evolution of disks: fully viscous and layered accretion disk models. Supernova-fallback disks result in a distribution of solids confined to within 1-2 AU and produce the requisite material to form the three known planets surrounding PSR 1257+12. Tidal disruption disks tend to slightly underproduce solids interior to 1 AU, required for forming the pulsar planets, while overproducing the amount of solids where no body, lunar mass or greater, exists. Disks evolving under 'layered' accretion spread somewhat less and deposit a higher column density of solids into the disk. In all cases, circumpulsar gas dissipates on ≲105\lesssim 10^{5} year timescales, making formation of gas giant planets highly unlikely.Comment: 16 pages, 17 figures, Accepted for publication in The Astrophysical Journal (September 20, 2007 issue

    The Rise and Fall of Debris Disks: MIPS Observations of h and chi Persei and the Evolution of Mid-IR Emission from Planet Formation

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    We describe Spitzer/MIPS observations of the double cluster, h and χ\chi Persei, covering a ∼\sim 0.6 square-degree area surrounding the cores of both clusters. The data are combined with IRAC and 2MASS data to investigate ∼\sim 616 sources from 1.25-24 μm\mu m. We use the long-baseline KsK_{s}-[24] color to identify two populations with IR excess indicative of circumstellar material: Be stars with 24 μm\mu m excess from optically-thin free free emission and 17 fainter sources (J∼\sim 14-15) with [24] excess consistent with a circumstellar disk. The frequency of IR excess for the fainter sources increases from 4.5 μm\mu m through 24 μm\mu m. The IR excess is likely due to debris from the planet formation process. The wavelength-dependent behavior is consistent with an inside-out clearing of circumstellar disks. A comparison of the 24 μm\mu m excess population in h and χ\chi Per sources with results for other clusters shows that 24 μm\mu m emission from debris disks 'rises' from 5 to 10 Myr, peaks at ∼\sim 10-15 Myr, and then 'falls' from ∼\sim 15/20 Myr to 1 Gyr.Comment: 48 pages, 15 figures, accepted for publication in The Astrophysical Journa

    Data Reduction Pipeline for the CHARIS Integral-Field Spectrograph I: Detector Readout Calibration and Data Cube Extraction

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    We present the data reduction pipeline for CHARIS, a high-contrast integral-field spectrograph for the Subaru Telescope. The pipeline constructs a ramp from the raw reads using the measured nonlinear pixel response, and reconstructs the data cube using one of three extraction algorithms: aperture photometry, optimal extraction, or χ2\chi^2 fitting. We measure and apply both a detector flatfield and a lenslet flatfield and reconstruct the wavelength- and position-dependent lenslet point-spread function (PSF) from images taken with a tunable laser. We use these measured PSFs to implement a χ2\chi^2-based extraction of the data cube, with typical residuals of ~5% due to imperfect models of the undersampled lenslet PSFs. The full two-dimensional residual of the χ2\chi^2 extraction allows us to model and remove correlated read noise, dramatically improving CHARIS' performance. The χ2\chi^2 extraction produces a data cube that has been deconvolved with the line-spread function, and never performs any interpolations of either the data or the individual lenslet spectra. The extracted data cube also includes uncertainties for each spatial and spectral measurement. CHARIS' software is parallelized, written in Python and Cython, and freely available on github with a separate documentation page. Astrometric and spectrophotometric calibrations of the data cubes and PSF subtraction will be treated in a forthcoming paper.Comment: 18 pages, 15 figures, 3 tables, replaced with JATIS accepted version (emulateapj formatted here). Software at https://github.com/PrincetonUniversity/charis-dep and documentation at http://princetonuniversity.github.io/charis-de
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