The COMBS survey I : Chemical Origins of Metal-Poor Stars in the Galactic Bulge

19 pages, 5 tables, accepted to MNRASChemistry and kinematic studies can determine the origins of stellar population across the Milky Way. The metallicity distribution function of the bulge indicates that it comprises multiple populations, the more metal-poor end of which is particularly poorly understood. It is currently unknown if metal-poor bulge stars ([Fe/H] <−1 dex) are part of the stellar halo in the inner most region, or a distinct bulge population or a combination of these. Cosmological simulations also indicate that the metal-poor bulge stars may be the oldest stars in the Galaxy. In this study, we successfully target metal-poor bulge stars selected using SkyMapper photometry. We determine the stellar parameters of 26 stars and their elemental abundances for 22 elements using R∼ 47 000 VLT/UVES spectra and contrast their elemental properties with that of other Galactic stellar populations. We find that the elemental abundances we derive for our metal-poor bulge stars have lower overall scatter than typically found in the halo. This indicates that these stars may be a distinct population confined to the bulge. If these stars are, alternatively, part of the innermost distribution of the halo, this indicates that the halo is more chemically homogeneous at small Galactic radii than at large radii. We also find two stars whose chemistry is consistent with second-generation globular cluster stars. This paper is the first part of the Chemical Origins of Metal-poor Bulge Stars (COMBS) survey that will chemodynamically characterize the metal-poor bulge population.Peer reviewedFinal Published versio

HST Imaging of Globular Clusters in the Edge--on Spiral Galaxies NGC 4565 and NGC 5907

We present a study of the globular cluster systems of two edge-on spiral galaxies, NGC4565 and NGC5907, from WFPC2 images in the F450W and F814W filters. The globular cluster systems of both galaxies appear to be similar to the Galactic globular cluster system. In particular, we derive total numbers of globular clusters of N_{GC}(4565)= 204+/-38 {+87}{-53} and N_{GC}(5907)=170+/-41 {+47}{-72} (where the first are statistical, the second potential systematic errors) for NGC4565 and NGC5907, respectively. This determination is based on a comparison to the Milky Way system, for which we adopt a total number of globular clusters of 180+/-20. The specific frequency of both galaxies is S_N~0.6: indistinguishable from the value for the Milky Way. The similarity in the globular cluster systems of the two galaxies is noteworthy since they have significantly different thick disks and bulge-to-disk ratios. This would suggest that these two components do not play a major role in the building up of a globular cluster system around late-type galaxies.Comment: Accepted for publication in the Astronomical Journal, 17 pages incl 5 figures, AAS style two columns. Also available at http://www.eso.org/~mkissler, Color version of figure 1 only available at http://www.eso.org/~mkissler (B/W version included

GNOSIS: the first instrument to use fibre Bragg gratings for OH suppression

GNOSIS is a prototype astrophotonic instrument that utilizes OH suppression fibres consisting of fibre Bragg gratings and photonic lanterns to suppress the 103 brightest atmospheric emission doublets between 1.47-1.7 microns. GNOSIS was commissioned at the 3.9-meter Anglo-Australian Telescope with the IRIS2 spectrograph to demonstrate the potential of OH suppression fibres, but may be potentially used with any telescope and spectrograph combination. Unlike previous atmospheric suppression techniques GNOSIS suppresses the lines before dispersion and in a manner that depends purely on wavelength. We present the instrument design and report the results of laboratory and on-sky tests from commissioning. While these tests demonstrated high throughput and excellent suppression of the skylines by the OH suppression fibres, surprisingly GNOSIS produced no significant reduction in the interline background and the sensitivity of GNOSIS and IRIS2 is about the same as IRIS2. It is unclear whether the lack of reduction in the interline background is due to physical sources or systematic errors as the observations are detector noise-dominated. OH suppression fibres could potentially impact ground-based astronomy at the level of adaptive optics or greater. However, until a clear reduction in the interline background and the corresponding increasing in sensitivity is demonstrated optimized OH suppression fibres paired with a fibre-fed spectrograph will at least provide a real benefits at low resolving powers.Comment: 15 pages, 13 figures, accepted to A

Water-Nymphs of the Platte

Little known, but hauntingly beautiful and valuable to the environment as well, clams and mussels inhabit many Nebraska lakes and rivers. In the first survey of the entire Platte River, the authors found 11 species. We surveyed mollusks (clams and snails) of the Platte River during the summers of 1990 and 1991. With the exception of the Big Bend reach of the river in Dawson, Buffalo, and Hall counties, no mussels were found in the river\u27s main channel. But in backwaters, lakes and sand-pits along the river, we found 11 species of mussels at 49 different sites from east to west across the state. Among them we found the Asiatic clam, a non-native, pest species, for the first time in the state, placing it several hundred miles west of the present eastern population of eastern Iowa and Missour

Current status of the Northern Long-eared Myotis (\u3ci\u3eMyotis septentrionalis\u3c/i\u3e) in northwestern Nebraska

The Northern Long-eared Myotis (Myotis septentrionalis; Order: Chiroptera) occurs in eastern, southern, and northern Nebraska, but its current distribution in northwestern parts of the state is unclear due to its recent arrival to the region. We investigated the status of this species in the Pine Ridge via mist net (2011-2014) and acoustic surveys (2014). We documented nine species of bats in the region, including M. septentrionalis. Of 423 total bats, M. septentrionalis was represented by four individuals, the fewest of all species during our four-year survey. We only documented M. septentrionalis in Sheridan County; this county is where the species was first reported in the Pine Ridge. Possibly acoustic calls of M. septentrionalis were recorded along the White River in Dawes County, but they likely represented variant calls from other Myotis species, such as the Little Brown Myotis (Myotis lucifugus). Until more conclusive evidence is obtained from Dawes County, we do not consider M. septentrionalis as part of the bat fauna from the county. Captures of three lactating M. septentrionalis are the best evidence of a reproducing population in the Pine Ridge. We conclude that the Northern Long-eared Myotis currently is not widely distributed in northwestern Nebraska, especially during summer when females bear and raise young. During migratory periods, however, limited evidence suggests individuals occur across a broader area using more habitats while in route to and from hibernacula. Periodic surveys are warranted to monitor the status of this species in the region. Additional research to determine summer and winter roosts would promote and help to conserve habitats for this species in Nebraska as M. septentrionalis recently was listed as federally threatened in the United States

Some hydrolytic reactions of beta-lactams

This thesis describes the synthesis and alkaline ring fission of some β-lactams. Three series of β-lactams were studied: those of type (A) bearing a substituent on the ring nitrogen; 1,3,4-trisubstituted 3-lactams (B); and the spiro-3-lactams of type (C). [See diagrams within thesis - Abstract.] Three synthetic routes were used for the synthesis of the p-lactams, namely (a) the Reformatsky Reaction using an imine and a bromoacetate ester, (b) the cyclization of a 3-bromopropionamide, and (c) the addition of an acid chloride across an imino group. In the acid chloride-imine reaction it was shown that, contrary to previous reports, the reaction will proceed successfully with an U-benzyloxycarbonylaminoacyl chloride, and that conditions of high-dilution are not necessary in order to obtain high yields. The results of hydrolytic studies indicate that intramolecular assistance by an amido-group alpha to the β-lactam carbonyl is not of significance in the hydrolysis of these β-lactams in the conditions employed (0.1-1.0 M sodium hydroxide). Hydrolyses were also conducted in the presence of micelle forming agents and the results obtained show that the effect of these upon the rate of hydrolytic fission is dependent upon the nature of the substituenis present on the β-lactam ring

The ACS Nearby Galaxy Survey Treasury

The ACS Nearby Galaxy Survey Treasury (ANGST) is a systematic survey to establish a legacy of uniform multi-color photometry of resolved stars for a volume-limited sample of nearby galaxies (D<4 Mpc). The survey volume encompasses 69 galaxies in diverse environments, including close pairs, small & large groups, filaments, and truly isolated regions. The galaxies include a nearly complete range of morphological types spanning a factor of ~10^4 in luminosity and star formation rate. The survey data consists of images taken with ACS on HST, supplemented with archival data and new WFPC2 imaging taken after the failure of ACS. Survey images include wide field tilings covering the full radial extent of each galaxy, and single deep pointings in uncrowded regions of the most massive galaxies in the volume. The new wide field imaging in ANGST reaches median 50% completenesses of m_F475W=28.0 mag, m_F606W=27.3 mag, and m_F814W=27.3 mag, several magnitudes below the tip of the red giant branch (TRGB). The deep fields reach magnitudes sufficient to fully resolve the structure in the red clump. The resulting photometric catalogs are publicly accessible and contain over 34 million photometric measurements of >14 million stars. In this paper we present the details of the sample selection, imaging, data reduction, and the resulting photometric catalogs, along with an analysis of the photometric uncertainties (systematic and random), for both the ACS and WFPC2 imaging. We also present uniformly derived relative distances measured from the apparent magnitude of the TRGB.Comment: 54 pages, including 24 pages of figures and 16 pages of tables. Project website and data available at http://www.nearbygalaxies.org/ . Data is also available through MAST. Scheduled to appear in the Astrophysical Journal Supplements. (Replaced to fix several figures that were damaged during compression

Electromagnetic Wave Theory and Applications

Contains reports on twelve research projects.Joint Services Electronics Program (Contract DAALO3-86-K-0002)National Science Foundation (Grant ECS 85-04381)National Aeronautics and Space Administration/Goddard Space Flight Center (Contract NAG5-270)National Aeronautics and Space Administration/Goddard Space Flight Center (Contract NAG5-725)U.S. Navy - Office of Naval Research (Contract N00014-83-K-0258)U.S. Navy - Office of Naval Research (Contract N00014-86-K-0533)U.S. Army - Research Office Durham (Contract DAAG29-85-K-0079)International Business Machines, Inc.National Aeronautics and Space Administration/Goddard Space Flight Center (Contract NAG5-269)Simulation TechnologiesSchlumberger-Doll Researc