101 research outputs found

    Reason For Rejoice

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    This collection of short stories features characters who face unexpected situations arising from ordinary circumstances. Most of the characters find themselves compelled to react in ways that may even surprise themselves. A young woman finds her first feeling of joy in a long time in the face of her mother’s possible death. Best friends recall their years spent doing drugs and ignoring responsibility. When a woman confronts her fear of sex, she finds herself literally in another world. Rather than sticking with one form, several stories depart from traditional structures. One flash fiction piece is told in the first-person collective voice; another story evolves into magical realism; two are linked, and one story is told as an elegy. What matters are the characters, their struggles, and their relationships with one another

    Near-Infrared H2 and Continuum Survey of Extended Green Objects

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    The Spitzer GLIMPSE survey has revealed a number of "Extended Green Objects" (EGOs) which display extended emission at 4.5 micron. These EGOs are potential candidates for high mass protostellar outflows. We have used high resolution (< 1") H2 1-0 S(1) line, K, and H-band images from the United Kingdom Infrared Telescope to study 34 EGOs to investigate their nature. We found that 12 EGOs exhibit H2 outflows (two with chains of H2 knotty structures; five with extended H2 bipolar structures; three with extended H2 lobes; two with pairs of H2 knots). In the 12 EGOs with H2 outflows, three of them exhibit similar morphologies between the 4.5 micron and H2 emission. However, the remaining 9 EGOs show that the H2 features are more extended than the continuum features, and the H2 emission is seldom associated with continuum emission. Furthermore, the morphologies of the near-infrared continuum and 4.5 micron emission are similar to each other for those EGOs with K-band emission, implying that at least a part of the IRAC-band continuum emission of EGOs comes from scattered light from the embedded YSOs.Comment: accepted for publication in ApJ

    Emission-line Helium Abundances in Highly Obscured Nebulae

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    This paper outlines a way to determine the ICF using only infrared data. We identify four line pairs, [NeIII] 36\micron/[NeII] 12.8\micron, [NeIII]~15.6\micron /[NeII] 12.8\micron, [ArIII] 9\micron/[ArII] 6.9\micron, and [ArIII] 21\micron/[ArII] 6.9\micron, that are sensitive to the He ICF. This happens because the ions cover a wide range of ionization, the line pairs are not sensitive to electron temperature, they have similar critical densities, and are formed within the He+^+/H+^+ region of the nebula. We compute a very wide range of photoionization models appropriate for galactic HII regions. The models cover a wide range of densities, ionization parameters, stellar temperatures, and use continua from four very different stellar atmospheres. The results show that each line pair has a critical intensity ratio above which the He ICF is always small. Below these values the ICF depends very strongly on details of the models for three of the ratios, and so other information would be needed to determine the helium abundance. The [Ar III] 9\micron/[ArII] 6.9\micron ratio can indicate the ICF directly due to the near exact match in the critical densities of the two lines. Finally, continua predicted by the latest generation of stellar atmospheres are sufficiently hard that they routinely produce significantly negative ICFs.Comment: Accepted by PASP. Scheduled for the October 1999 issue. 11 pages, 5 figure

    Metrology Camera System of Prime Focus Spectrograph for Subaru Telescope

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    The Prime Focus Spectrograph (PFS) is a new optical/near-infrared multi-fiber spectrograph designed for the prime focus of the 8.2m Subaru telescope. PFS will cover a 1.3 degree diameter field with 2394 fibers to complement the imaging capabilities of Hyper SuprimeCam. To retain high throughput, the final positioning accuracy between the fibers and observing targets of PFS is required to be less than 10um. The metrology camera system (MCS) serves as the optical encoder of the fiber motors for the configuring of fibers. MCS provides the fiber positions within a 5um error over the 45 cm focal plane. The information from MCS will be fed into the fiber positioner control system for the closed loop control. MCS will be located at the Cassegrain focus of Subaru telescope in order to to cover the whole focal plane with one 50M pixel Canon CMOS camera. It is a 380mm Schmidt type telescope which generates a uniform spot size with a 10 micron FWHM across the field for reasonable sampling of PSF. Carbon fiber tubes are used to provide a stable structure over the operating conditions without focus adjustments. The CMOS sensor can be read in 0.8s to reduce the overhead for the fiber configuration. The positions of all fibers can be obtained within 0.5s after the readout of the frame. This enables the overall fiber configuration to be less than 2 minutes. MCS will be installed inside a standard Subaru Cassgrain Box. All components that generate heat are located inside a glycol cooled cabinet to reduce the possible image motion due to heat. The optics and camera for MCS have been delivered and tested. The mechanical parts and supporting structure are ready as of spring 2016. The integration of MCS will start in the summer of 2016.Comment: 11 pages, 15 figures. SPIE proceeding. arXiv admin note: text overlap with arXiv:1408.287

    Stable and Unstable Regimes of Mass Accretion onto RW Aur A

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    We present monitoring observations of the active T Tauri star RW Aur, from 2010 October to 2015 January, using optical high-resolution (R>10000) spectroscopy with CFHT-ESPaDOnS. Optical photometry in the literature shows bright, stable fluxes over most of this period, with lower fluxes (by 2-3 mag.) in 2010 and 2014. In the bright period our spectra show clear photospheric absorption, complicated variation in the Ca II 8542 A emission}profile shapes, and a large variation in redshifted absorption in the O I 7772 and 8446 A and He I 5876 A lines, suggesting unstable mass accretion during this period. In contrast, these line profiles are relatively uniform during the faint periods, suggesting stable mass accretion. During the faint periods the photospheric absorption lines are absent or marginal, and the averaged Li I profile shows redshifted absorption due to an inflow. We discuss (1) occultation by circumstellar material or a companion and (2) changes in the activity of mass accretion to explain the above results, together with near-infrared and X-ray observations from 2011-2015. Neither scenario can simply explain all the observed trends, and more theoretical work is needed to further investigate their feasibilities.Comment: 23 pages, 11 figures, 4 tables, accepted by Astrophysical Journal; some typos corrected on 4/18/201
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