Chemical Abundances of the Highly Obscured Galactic Globular Clusters 2MASS GC02 and Mercer 5Peñaloza, Francisco; Pessev, Peter; Vaśquez, Sergio; Borissova, Jura; Kurtev, Radostin; Zoccali, Manuela
doi: 10.1086/680597pmid: N/A
We present the first high spectral resolution abundance analysis of two newly discovered Galactic globular clusters, namely, Mercer 5 and 2MASS GC02, residing in regions of high interstellar reddening in the direction of the Galactic center. The data were acquired with the Phoenix high-resolution near-infrared echelle spectrograph at Gemini South (R ∼ 50,000) in the 15,500.0–15,575.0 spectral region. Iron, oxygen, silicon, titanium, and nickel abundances were derived for two red giant stars, in each cluster, by comparing the entire observed spectrum with a grid of synthetic spectra generated with MOOG. We found [Fe/H] values of -0.86 ± 0.12 and -1.08 ± 0.13 for Mercer 5 and 2MASS GC02, respectively. The [O/Fe], [Si/Fe], and [Ti/Fe] ratios of the measured stars of Mercer 5 follow the general trend of both bulge field and cluster stars at this metallicity, and are enhanced by ≥+0.3. The 2MASS GC02 stars have relatively lower ratios, but still compatible with other bulge clusters. Based on metallicity and abundance patterns of both objects, we conclude that these are typical bulge globular clusters.
Elemental Abundance Analyses with DAO Spectrograms XXXVII. The Normal A0 IV Star γ GeminorumAdelman, Saul J.; Gulliver, Austin F.; Kaewkornmaung, Pongsakorn
doi: 10.1086/680998pmid: N/A
We performed a fine analysis of the normal sharp-lined A0 IV star γ Geminorum with spectra having signal-to-noise ratios at the continuum of 500–1200 that were consistent with previous studies of this series. Our spectra have wavelength ranges of λλ3829–4730, 4873–4931, 4983–5042, and 5070–5210. The spectra measured with the program REDUCE have a two-pixel resolution of 0.072 Å. We used ATLAS9 models and the program WIDTH9 to derive the abundances of the metals. Most derived abundances are close to solar with the abundances of the heaviest elements Zr, Ba, La, Ce, and Nd showing greater than solar values. This suggests by comparison with the abundances of other normal and Am stars that γ Gem might exhibit an incipient Am star phenomenon.
A New Luminous Blue Variable in M31Based on observations with the Multiple Mirror Telescope, a joint facility of the Smithsonian Institution and the U ...Humphreys, Roberta M.; Martin, John C.; Gordon, Michael S.
doi: 10.1086/681013pmid: N/A
We report the fifth confirmed Luminous Blue Variable/S Doradus variable in M31. In 2006, J004526.62+415006.3 had the spectrum of hot Fe ii emission line star with strong P Cygni profiles in the Balmer lines. In 2010, its absorption line spectrum resembled an early A-type supergiant with H and Fe ii emission lines with strong P Cygni profiles, and in 2013, the spectrum had fully transitioned to an F-type supergiant due to the formation of the optically thick, cool wind which characterizes LBVs at maximum light. The photometric record supports the LBV/S Doradus nature of the variability. Its bolometric luminosity of ∼-9.65 mag places it on the H–R diagram near the known LBVs, AE And, Var C in M33, and S Dor.
ASAS-SN 13cl: A Newly Discovered Cataclysmic Binary with an Anomalously Warm SecondaryBased on observations obtained at the MDM Observatory, operated ...Thorstensen, John R.
doi: 10.1086/681014pmid: N/A
The spectrum of the recently discovered cataclysmic variable star (CV) ASAS-SN 13cl shows that a secondary star with spectral type K4 (± 2 subclasses) contributes roughly half the optical light. The radial velocities of the secondary are modulated on an orbital period Porb = 4.86 hr with a velocity semiamplitude K = 246 ± 9 km s-1, and the light curve shows ellipsoidal variations and an apparent grazing eclipse. At this orbital period, the secondary stars in most CVs are substantially cooler, with spectral types near M3. ASAS-SN 13cl therefore joins the small group of CVs with anomalously warm secondary stars, which apparently form when the onset of mass transfer occurs after the secondary has undergone significant nuclear evolution.
Position Displacement of Diffuse Interstellar BandsThis paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observ ...Galazutdinov, G.; Krełowski, J.; Beletsky, Y.; Valyavin, G.
doi: 10.1086/681018pmid: N/A
We reconsider the already published phenomenon of the blue shift of diffuse interstellar bands, observed in spectra of HD34078 (AE Aur) and members of the Sco OB1 association, in particular HD152233. We have analyzed 29 diffuse bands. Some of them, already proven as blue-shifted in our earlier study, are now confirmed using another instrument: the 6.5 m Clay telescope equipped with the MIKE spectrograph. The high signal-to-noise ratio (over 600) of our spectra allowed us to reveal even small small-scale displacements of positions (both blue and redshifts) of diffuse bands along the considered lines of sight. In some cases, the magnitude of deviation exceeds 10 km s-1. Also, we prove that profiles of many diffuse bands in spectra of HD34078 suffer significant broadening. The origin of the observed phenomena is discussed.
The Sloan Digital Sky Survey Data Transfer InfrastructureWeaver, Benjamin A.; Blanton, Michael R.; Brinkmann, Jon; Brownstein, Joel R.; Stauffer, Fritz
doi: 10.1086/680999pmid: N/A
The Sloan Digital Sky Survey (SDSS) has been active for approximately 15 years as of this writing. SDSS continues to produce large amounts of data, effectively daily. SDSS needs an effective system for data transfer and management that can operate essentially free of human intervention. In 2008, with the commencement of the third phase of SDSS, SDSS-III, new needs and opportunities motivated a fresh look at the data transfer infrastructure. We have constructed and are releasing a Python package, transfer, that contains all the automation needed for daily data transfer operations. This package has been tested and used successfully for several years. Significant portions of this code will continue to be used as SDSS transitions to its fourth phase, SDSS-IV.
Data Reduction Pipeline for the MMT and Magellan Infrared SpectrographChilingarian, Igor; Beletsky, Yuri; Moran, Sean; Brown, Warren; McLeod, Brian; Fabricant, Daniel
doi: 10.1086/680598pmid: N/A
We describe the new spectroscopic data reduction pipeline for the multi-object MMT/Magellan Infrared Spectrograph. The pipeline is implemented in idl as a stand-alone package and is publicly available in both stable and development versions. We describe novel algorithms for sky subtraction and correction for telluric absorption. We demonstrate that our sky subtraction technique reaches the Poisson limit set by the photon statistics. Our telluric correction uses a hybrid approach by first computing a correction function from an observed stellar spectrum, and then differentially correcting it using a grid of atmosphere transmission models for the target airmass value. The pipeline provides a sufficient level of performance for real time reduction and thus enables data quality control during observations. We reduce an example dataset to demonstrate the high data reduction quality.