663 research outputs found

    The Logbook, A Publication of the Wayne E. Meyer Institute of Systems Engineering / May 2004

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    www.nps.navy.mil/meyerinstitute Email:[email protected] Phone:(831) 656-7847 Fax:(831) 656-2336 Naval Postgraduate School, 777 Dyer Rd., Mail Code 97, Monterey, CAArticles include: Turnover Time, Joint Executive Systems Engineering and Management Program (SEM-PD21), and Integrated Campus Projects and the Meyer Institute.Naval Postgraduate School, Monterey, C

    The Logbook, A Publication of the Wayne E. Meyer Institute of Systems Engineering / December 2003

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    www.nps.navy.mil/meyerinstitute Email:[email protected] Phone:(831) 656-7847 Fax:(831) 656-2336 Naval Postgraduate School, 777 Dyer Rd., Mail Code 97, Monterey, CAArticles including: Systems Analysis Certificate Program Takes Off! etc.Naval Postgraduate School, Monterey, C

    Metallicity of Red Giants in the Galactic Bulge from Near-Infrared Spectroscopy

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    We present K-band spectra of more than 110 M giants in Galactic bulge fields interior to -4 degrees and as close as 0.2 degrees of the Galactic Center. From the equivalent widths of three features in these spectra, EW(Na),EW(Ca), and EW(CO) we calculate [Fe/H] for the stars with a calibration derived from globular clusters Stephens et al (2000). The mean [Fe/H] for each field is in good agreement with the results from Frogel et al. (1999) based on the slope of the giant branch method. We find no evidence for a metallicity gradient along the minor or major axes of the inner bulge (R < 0.6 kpc). A metallicity gradient along the minor axis, found earlier, arises when fields located at larger galactic radius are included. However, these more distant fields are located outside of the infrared bulge defined by the COBE/DIRBE observations. We compute the [Fe/H] distribution for the inner bulge and find a mean value of -0.21 dex with a full width dispersion of 0.30 dex, close to the values found for Baade's Window (BW) by Sadler et al. (1996) and to a theoretical prediction for a bulge formed by dissipative collapse Molla et al (2000).Comment: 32 pages, 10 figures, AJ submitte

    An Accurate, Easy to Use Abundace Scale for Globular Clusters Based on 2.2um Spectra of Giant Stars

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    We present a new method for the determination of [Fe/H] for globular clusters. This new method is based on moderate resolution (R~1500) near-IR spectroscopy in the K-band of 6 to 10 of the brightest giants in a cluster. Our calibration is derived from spectra of 105 stars in 15 globular clusters. From measurements of the equivalent widths of three features in these spectra, Na, Ca, and CO, we are able to reproduce the Zinn & West (1984) abundance scale as updated by Harris (1996) to better than 0.10 dex for clusters with near solar [Fe/H] down to an [Fe/H] of -1.8. Three advantages of this method are that it can be used for metal rich, heavily reddened globulars in crowded fields, it does not require any knowledge of any other cluster or stellar parameters such as reddening, distance, or luminosity, and it requires only minimal telescope time. If stellar (J-K)0 and MK values are available as well, the accuracy of the [Fe/H] estimate is further improved. Observations of as few as three stars per cluster still gives an [Fe/H] estimate wich is nearly as reliable as that based on two to three times as many stars. The accuracy of an [Fe/H] value based on observations of CO absorption alone is significantly less than that which results from the three spectroscopic indices. However, we predict that space-based observations of this feature in the integrated light of stellar systems will prove to be of great value for abundance determinations at distances as far as the Coma cluster of galaxies.Comment: 53 pages, 16 Postscript figures. Submitted to the A

    The Mass of the Convective Zone in FGK Main Sequence Stars and the Effect of Accreted Planetary Material on Apparent Metallicity Determinations

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    The mass of the outer convective zone in FGK main sequence stars decreases dramatically with stellar mass. Therefore, any contamination of a star's atmosphere by accreted planetary material should affect hotter stars much more than cool stars. If recent suggestions that high metal abundances in stars with planets are caused by planetesimal accretion are correct, then metallicity enhancements in earlier-type stars with planets should be very pronounced. No such trend is seen, however.Comment: Submitted ApJ Letters March 26th; accepted April 30th. 12 pages, 2 figure

    The Stellar Content of Obscured Galactic Giant H II Regions III.: W31

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    We present near infrared (J, H, and K) photometry and moderate resolution (lambda/Deltalambda = 3000) K-band spectroscopy of the embedded stellar cluster in the giant H II region W31. Four of the brightest five cluster members are early O--type stars based on their spectra. We derive a spectro--photometric distance for W31 of 3.4 +/- 0.3 kpc using these new spectral types and infrared photometry. The brightest cluster source at K is a red object which lies in the region of the J - H vs. H - K color--color plot inhabited by stars with excess emission in the K-band. This point source has an H plus K-band spectrum which shows no photospheric features, which we interpret as being the result of veiling by local dust emission. Strong Brackett series emission and permitted FeII emission are detected in this source; the latter feature is suggestive of a dense inflow or outflow. The near infrared position of this red source is consistent with the position of a 5 GHz thermal radio source seen in previous high angular resolution VLA images. We also identify several other K-band sources containing excess emission with compact radio sources. These objects may represent stars in the W31 cluster still embedded in their birth cocoons.Comment: LaTeX2e/aastex, 29 pages including 9 figures, 3 table

    Mass production of volume phase holographic gratings for the VIRUS spectrograph array

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    The Visible Integral-field Replicable Unit Spectrograph (VIRUS) is a baseline array of 150 copies of a simple, fiber-fed integral field spectrograph that will be deployed on the Hobby-Eberly Telescope (HET). VIRUS is the first optical astronomical instrument to be replicated on an industrial scale, and represents a relatively inexpensive solution for carrying out large-area spectroscopic surveys, such as the HET Dark Energy Experiment (HETDEX). Each spectrograph contains a volume phase holographic (VPH) grating with a 138 mm diameter clear aperture as its dispersing element. The instrument utilizes the grating in first-order for 350-550 nm. Including witness samples, a suite of 170 VPH gratings has been mass produced for VIRUS. Here, we present the design of the VIRUS VPH gratings and a discussion of their mass production. We additionally present the design and functionality of a custom apparatus that has been used to rapidly test the first-order diffraction efficiency of the gratings for various discrete wavelengths within the VIRUS spectral range. This device has been used to perform both in-situ tests to monitor the effects of adjustments to the production prescription as well as to carry out the final acceptance tests of the gratings' diffraction efficiency. Finally, we present the as-built performance results for the entire suite of VPH gratings.Comment: 16 pages, 11 figures, 2 tables. To be published in Proc. SPIE, 2014, "Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation", 9151-53. The work presented in this article follows from arXiv:1207:448

    Discovery of a Boxy Peanut Shaped Bulge in the Near Infrared

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    We report on the discovery of a boxy/peanut shaped bulge in the highly inclined barred Seyfert 2 galaxy NGC~7582. The peanut shape is clearly evident in near infrared JHKJHK images but obscured by extinction from dust in visible BVRBVR images. This suggests that near infrared imaging surveys will discover a larger number of boxy/peanut morphologies than visible surveys, particularly in galaxies with heavy extinction such as NGC~7582. The bulge in NGC~7582 exhibits strong boxiness compared to other boxy/peanut shaped bulges. If the starburst was mediated by the bar, then it is likely that the bar formed in less than a few bar rotation periods or a few ×108\times 10^8 years ago. If the bar also caused the peanut, then the peanut would have formed quickly; on a timescale of a few bar rotation periods.Comment: AAS Latex and Postcript Figures, accepted for publication in Ap

    Juicio de límites entre el Perú y Bolivia prueba peruana presentada al Gobierno de la Republica Argentina

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    T. 2. Organización audiencial -- t. 4. Virreinato de Buenos Aires -- t. 5. Gobernaciones diversas -- t. 6 Gobernaciones de Álvarez Maldonado -- t. 8. Chunchos -- t. 9. Mojo

    Confirmation of the Planetary Microlensing Signal and Star and Planet Mass Determinations for Event OGLE-2005-BLG-169

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    We present Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) observations of the source and lens stars for planetary microlensing event OGLE-2005-BLG-169, which confirm the relative proper motion prediction due to the planetary light curve signal observed for this event. This (and the companion Keck result) provide the first confirmation of a planetary microlensing signal, for which the deviation was only 2%. The follow-up observations determine the flux of the planetary host star in multiple passbands and remove light curve model ambiguity caused by sparse sampling of part of the light curve. This leads to a precise determination of the properties of the OGLE-2005-BLG-169Lb planetary system. Combining the constraints from the microlensing light curve with the photometry and astrometry of the HST/WFC3 data, we find star and planet masses of M_* = 0.69+- 0.02 M_solar and m_p = 14.1 +- 0.9 M_earth. The planetary microlens system is located toward the Galactic bulge at a distance of D_L = 4.1 +- 0.4 kpc, and the projected star-planet separation is a_perp = 3.5 +- 0.3 AU, corresponding to a semi-major axis of a = 4.0 (+2.2 -0.6) AU.Comment: 21 pages, including 5 figures, published in Ap
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