A high HDO/H2_{2}O ratio in the Class I protostar L1551 IRS5

Water is a very abundant molecule in star-forming regions. Its deuterium fractionation is an important tool for understanding its formation and evolution during the star and planet formation processes. While the HDO/H$_2$O ratio has been determined toward several Class 0 protostars and comets, the number of studies toward Class I protostars is limited. We aim to study the water deuteration toward the Class I binary protostar L1551 IRS5 and to investigate the effect of evolutionary stage and environment on variations in the water D/H ratio. Observations were made using the NOEMA interferometer. The HDO 3$_{1,2}$-2$_{2,1}$ transition at 225.9 GHz and the H$_2^{18}$O 3$_{1,3}$-2$_{2,0}$ transition at 203.4 GHz were covered with a spatial resolution of 0.5'' $\times$ 0.8'', while the HDO 4$_{2,2}$-4$_{2,3}$ transition at 143.7 GHz was observed with a resolution of 2.0'' $\times$ 2.5''. We used both LTE and non-LTE models. The three transitions are detected. The line profiles display two peaks, one at $\sim$6 km s$^{-1}$ and one at $\sim$9 km s$^{-1}$. We derive an HDO/H$_2$O ratio of (2.1 $\pm$ 0.8) $\times$ 10$^{-3}$ for the redshifted component and a lower limit of $>$ 0.3 $\times$ 10$^{-3}$ for the blueshifted component due to the blending with the redshifted CH$_3$OCH$_3$ emission. The HDO/H$_2$O in L1551 IRS5 is similar to the ratios in isolated Class 0 sources and to the Class I V883 Ori, while it is significantly higher than in the clustered Class 0 sources and the comets. This suggests that the chemistry of protostars in low source densities clouds share more similarities with the isolated sources than the protostars of very dense clusters. If Class 0 protostars with few sources around and isolated Class 0 objects are comparable in the HDO/H$_2$O ratio, it would mean that there is little water reprocessing from the Class 0 to Class I protostellar stage.Comment: Accepted in A&A, 10 pages, 8 figure

Regular Dimpled Nickel Surfaces for Improved Efficiency of the Oxygen Evolution Reaction

Persistent bubble accumulation during the oxygen evolution reaction (OER) can effectively block catalytically active surface sites and reduce overall system performance. The OER is an essential half-reaction with relevance to metal–air batteries, fuel cells, and water electrolysis for power to gas applications. The renewable energy sector could benefit from the identification of surface morphologies that can effectively reduce the accumulation of bubbles on electrocatalytic surfaces. In this work, regular dimpled nickel (Ni) features were prepared to investigate how electrode morphology and therefore its roughness and wetting properties may affect the efficiency of the OER. The dimpled Ni features were prepared using spherical poly(styrene) (PS) templates with a diameter of 1 μm. The electrodeposition against regular, self-assembled arrays of PS templates was tuned to produce four types of dimpled features each with a different depth. Enhancements to the OER efficiency were observed for some types of dimpled Ni features when compared to a planar electrodeposited Ni electrode, while the dimpled features that were the most recessed demonstrated reduced efficiencies for the OER. The findings from this study emphasize the influences of electrode surface morphology on processes involving electrocatalytic gas evolution

The Eighth Data Release of the Sloan Digital Sky Survey: First Data from SDSS-III

The Sloan Digital Sky Survey (SDSS) started a new phase in August 2008, with new instrumentation and new surveys focused on Galactic structure and chemical evolution, measurements of the baryon oscillation feature in the clustering of galaxies and the quasar Ly alpha forest, and a radial velocity search for planets around ~8000 stars. This paper describes the first data release of SDSS-III (and the eighth counting from the beginning of the SDSS). The release includes five-band imaging of roughly 5200 deg^2 in the Southern Galactic Cap, bringing the total footprint of the SDSS imaging to 14,555 deg^2, or over a third of the Celestial Sphere. All the imaging data have been reprocessed with an improved sky-subtraction algorithm and a final, self-consistent photometric recalibration and flat-field determination. This release also includes all data from the second phase of the Sloan Extension for Galactic Understanding and Evolution (SEGUE-2), consisting of spectroscopy of approximately 118,000 stars at both high and low Galactic latitudes. All the more than half a million stellar spectra obtained with the SDSS spectrograph have been reprocessed through an improved stellar parameters pipeline, which has better determination of metallicity for high metallicity stars.Comment: Astrophysical Journal Supplements, in press (minor updates from submitted version

The Baryon Oscillation Spectroscopic Survey of SDSS-III

The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the scale of baryon acoustic oscillations (BAO) in the clustering of matter over a larger volume than the combined efforts of all previous spectroscopic surveys of large scale structure. BOSS uses 1.5 million luminous galaxies as faint as i=19.9 over 10,000 square degrees to measure BAO to redshifts z<0.7. Observations of neutral hydrogen in the Lyman alpha forest in more than 150,000 quasar spectra (g<22) will constrain BAO over the redshift range 2.15<z<3.5. Early results from BOSS include the first detection of the large-scale three-dimensional clustering of the Lyman alpha forest and a strong detection from the Data Release 9 data set of the BAO in the clustering of massive galaxies at an effective redshift z = 0.57. We project that BOSS will yield measurements of the angular diameter distance D_A to an accuracy of 1.0% at redshifts z=0.3 and z=0.57 and measurements of H(z) to 1.8% and 1.7% at the same redshifts. Forecasts for Lyman alpha forest constraints predict a measurement of an overall dilation factor that scales the highly degenerate D_A(z) and H^{-1}(z) parameters to an accuracy of 1.9% at z~2.5 when the survey is complete. Here, we provide an overview of the selection of spectroscopic targets, planning of observations, and analysis of data and data quality of BOSS.Comment: 49 pages, 16 figures, accepted by A

The Ninth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Baryon Oscillation Spectroscopic Survey

The Sloan Digital Sky Survey III (SDSS-III) presents the first spectroscopic data from the Baryon Oscillation Spectroscopic Survey (BOSS). This ninth data release (DR9) of the SDSS project includes 535,995 new galaxy spectra (median z=0.52), 102,100 new quasar spectra (median z=2.32), and 90,897 new stellar spectra, along with the data presented in previous data releases. These spectra were obtained with the new BOSS spectrograph and were taken between 2009 December and 2011 July. In addition, the stellar parameters pipeline, which determines radial velocities, surface temperatures, surface gravities, and metallicities of stars, has been updated and refined with improvements in temperature estimates for stars with T_eff<5000 K and in metallicity estimates for stars with [Fe/H]>-0.5. DR9 includes new stellar parameters for all stars presented in DR8, including stars from SDSS-I and II, as well as those observed as part of the SDSS-III Sloan Extension for Galactic Understanding and Exploration-2 (SEGUE-2). The astrometry error introduced in the DR8 imaging catalogs has been corrected in the DR9 data products. The next data release for SDSS-III will be in Summer 2013, which will present the first data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) along with another year of data from BOSS, followed by the final SDSS-III data release in December 2014.Comment: 9 figures; 2 tables. Submitted to ApJS. DR9 is available at http://www.sdss3.org/dr

The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since July 2014. This paper describes the second data release from this phase, and the fourteenth from SDSS overall (making this, Data Release Fourteen or DR14). This release makes public data taken by SDSS-IV in its first two years of operation (July 2014-2016). Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey (eBOSS); the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data driven machine learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS website (www.sdss.org) has been updated for this release, and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020, and will be followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14 happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov 2017 (this is the "post-print" and "post-proofs" version; minor corrections only from v1, and most of errors found in proofs corrected

The Sloan Digital Sky Survey quasar catalog: tenth data release

We present the Data Release 10 Quasar (DR10Q) catalog from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III. The catalog includes all BOSS objects that were targeted as quasar candidates during the first 2.5 years of the survey and that are confirmed as quasars via visual inspection of the spectra, have luminosities M-i[z = 2] 2.15 (117 668) is similar to 5 times greater than the number of z > 2.15 quasars known prior to BOSS. Redshifts and FWHMs are provided for the strongest emission lines (C IV, C III, Mg II). The catalog identifies 16 461 broad absorption line quasars and gives their characteristics. For each object, the catalog presents five-band (u, g, r, i, z) CCD-based photometry with typical accuracy of 0.03 mag and information on the optical morphology and selection method. The catalog also contains X-ray, ultraviolet, near-infrared, and radio emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra cover the wavelength region 3600-10 500 angstrom at a spectral resolution in the range 1300 < R < 2500; the spectra can be retrieved from the SDSS Catalog Archive Server. We also provide a supplemental list of an additional 2376 quasars that have been identified among the galaxy targets of the SDSS-III/BOSS

Cosmological implications of baryon acoustic oscillation measurements

We derive constraints on cosmological parameters and tests of dark energy models from the combination of baryon acoustic oscillation (BAO) measurements with cosmic microwave background (CMB) data and a recent reanalysis of Type Ia supernova (SN) data. In particular, we take advantage of high-precision BAO measurements from galaxy clustering and the Lyman-α forest (LyaF) in the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). Treating the BAO scale as an uncalibrated standard ruler, BAO data alone yield a high confidence detection of dark energy; in combination with the CMB angular acoustic scale they further imply a nearly flat universe. Adding the CMB-calibrated physical scale of the sound horizon, the combination of BAO and SN data into an “inverse distance ladder” yields a measurement of H0 =67.3 ± 1.1 km s-1 Mpc-1, with 1.7% precision. This measurement assumes standard prerecombination physics but is insensitive to assumptions about dark energy or space curvature, so agreement with CMB-based estimates that assume a flat Λ CDM cosmology is an important corroboration of this minimal cosmological model. For constant dark energy (Λ), our BAO + SN + CMB combination yields matter density Ωm = 0.301 ± 0.008 and curvature Ωk = -0.003 ± 0.003. When we allow more general forms of evolving dark energy, the BAO + SN + CMB parameter constraints are always consistent with flat Λ CDM values at ≈1σ. While the overall χ2 of model fits is satisfactory, the LyaF BAO measurements are in moderate (2–2.5σ) tension with model predictions. Models with early dark energy that tracks the dominant energy component at high redshift remain consistent with our expansion history constraints, and they yield a higher H0 and lower matter clustering amplitude, improving agreement with some low redshift observations. Expansion history alone yields an upper limit on the summed mass of neutrino species, ∑mν (95% confidence), improving to ∑mν if we include the lensing signal in the Planck CMB power spectrum. In a flat Λ CDM model that allows extra relativistic species, our data combination yields Neff = 3.43 ± 0.26; while the LyaF BAO data prefer higher Neff when excluding galaxy BAO, the galaxy BAO alone favor Neff ≈ 3. When structure growth is extrapolated forward from the CMB to low redshift, standard dark energy models constrained by our data predict a level of matter clustering that is high compared to most, but not all, observational estimates

The Baryon Oscillation Spectroscopic Survey of SDSS-III

The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the scale of baryon acoustic oscillations (BAO) in the clustering of matter over a larger volume than the combined efforts of all previous spectroscopic surveys of large-scale structure. BOSS uses 1.5 million luminous galaxies as faint as i = 19.9 over 10,000 deg(2) to measure BAO to redshifts z < 0.7. Observations of neutral hydrogen in the Ly alpha forest in more than 150,000 quasar spectra (g < 22) will constrain BAO over the redshift range 2.15 < z < 3.5. Early results from BOSS include the first detection of the large-scale three-dimensional clustering of the Ly alpha forest and a strong detection from the Data Release 9 data set of the BAO in the clustering of massive galaxies at an effective redshift z = 0.57. We project that BOSS will yield measurements of the angular diameter distance d(A) to an accuracy of 1.0% at redshifts z = 0.3 and z = 0.57 and measurements of H(z) to 1.8% and 1.7% at the same redshifts. Forecasts for Ly alpha forest constraints predict a measurement of an overall dilation factor that scales the highly degenerate D-A(z) and H-1(z) parameters to an accuracy of 1.9% at z similar to 2.5 when the survey is complete. Here, we provide an overview of the selection of spectroscopic targets, planning of observations, and analysis of data and data quality of BOSS

Erratum: “The eighth data release of the Sloan Digital Sky Survey: first data from SDSS-III” (2011, ApJS, 193, 29)

Section 3.5 of Aihara et al. (2011) described various sources of systematic error in the astrometry of the imaging data of the Sloan Digital Sky Survey (SDSS). In addition to these sources of error, there is an additional and more serious error, which introduces a large systematic shift in the astrometry over a large area around the north celestial pole. The region has irregular boundaries but in places extends as far south as declination δ ≈ 41◦. The sense of the shift is that the positions of all sources in the affected area are offset by roughly 250 mas in a northwest direction. We have updated the SDSS online documentation to reflect these errors, and to provide detailed quality information for each SDSS field