Browsing by Subject "spectra"
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Item Accretion Disk Temperatures Of QSOs: Constraints From The Emission Lines(2013-06) Bonning, E. W.; Shields, Gregory A.; Stevens, A. C.; Salviander, Sarah; Shields, Gregory A.; Stevens, A. C.; Salviander, SarahWe compare QSO emission-line spectra to predictions based on theoretical ionizing continua of accretion disks. The observed line intensities do not show the expected trend of higher ionization with theoretical accretion disk temperature as predicted from the black hole mass and accretion rate. Consistent with earlier studies, this suggests that the inner disk does not reach temperatures as high as expected from standard disk theory. Modified radial temperature profiles, taking account of winds or advection in the inner disk, achieve better agreement with observation. The emission lines of radio-detected and radio-undetected sources show different trends as a function of the theoretically predicted disk temperature.Item Accretion Onto Planetary Mass Companions of Low-Mass Young Stars(2014-03) Zhou, Yifan; Herczeg, Gregory J.; Kraus, Adam L.; Metchev, Stanimir; Cruz, Kelle L.; Kraus, Adam L.Measurements of accretion rates onto planetary mass objects may distinguish between different planet Formation mechanisms, which predict different accretion histories. In this Letter, we use Hubble Space Telescope (HST)/WFC3 UVIS optical photometry to measure accretion rates onto three accreting objects, GSC 06214-00210 b, GQ Lup b, and DH Tau b, that are at the planet/brown dwarf boundary and are companions to solar mass stars. The excess optical emission in the excess accretion continuum yields mass accretion rates of 10(-9)-10(-11) M-circle dot yr(-1) for these three objects. Their accretion rates are an order of magnitude higher than expected from the correlation between mass and accretion rates measured from the UV excess, which is applicable if these wide planetary mass companions formed by protostellar core fragmentation. The high accretion rates and large separation from the central star demonstrate the presence of massive disks around these objects. Models for the Formation and evolution of wide planetary mass companions should account for their large accretion rates. High ratios of Ha luminosity over accretion luminosity for objects with low accretion rates suggest that searches for Ha emission may be an efficient way to find accreting planets.Item Application of Single-Station Sigma and Site-Response Characterization in a Probabilistic Seismic-Hazard Analysis for a New Nuclear Site(2014-08) Rodriguez-Marek, A.; Rathje, E. M.; Bommer, J. J.; Scherbaum, F.; Stafford, P. J.; Rathje, E. M.Aleatory variability in ground-motion prediction, represented by the standard deviation (sigma) of a ground-motion prediction equation, exerts a very strong influence on the results of probabilistic seismic-hazard analysis (PSHA). This is especially so at the low annual exceedance frequencies considered for nuclear facilities; in these cases, even small reductions in sigma can have a marked effect on the hazard estimates. Proper separation and quantification of aleatory variability and epistemic uncertainty can lead to defensible reductions in sigma. One such approach is the single-station sigma concept, which removes that part of sigma corresponding to repeatable site-specific effects. However, the site-to-site component must then be constrained by site-specific measurements or else modeled as epistemic uncertainty and incorporated into the modeling of site effects. The practical application of the single-station sigma concept, including the characterization of the dynamic properties of the site and the incorporation of site-response effects into the hazard calculations, is illustrated for a PSHA conducted at a rock site under consideration for the potential construction of a nuclear power plant.Item Collision-Induced Absorption By Supermolecular Complexes From A New Potential Energy And Induced Dipole Surface, Suited For Calculations Up To Thousands Of Kelvin(2010-06) Abel, M.; Frommhold, L.; Wang, F.; Gustafsson, M.; Li, X. P.; Hunt, K. L. C.; Abel, Martin; Frommhold, LotharAbsorption by pairs of H-2 molecules is an important opacity source in the atmospheres of the outer planets, and thus of special astronomical interest. The emission spectra of cool white dwarf stars differ significantly from the expected blackbody spectra, amongst other reasons due to absorption by H-2 H-2, H-2 He, and H-2-H collisional complexes in the stellar atmospheres. To model the radiative processes in these atmospheres, which have temperatures of several thousand kelvin, one needs accurate knowledge of the induced dipole (ID) and potential energy surfaces (PES) of such collisional complexes. These come from quantum-chemical calculations with the H-2 bonds stretched or compressed far from equilibrium. Laboratory measurements of collision-induced (CI) absorption exist only at much lower temperature. For H-2 pairs at room temperature, the calculated spectra of the rototranslational band, the fundamental band, and the first overtone match the experimental data very well. In addition, with the newly obtained IDS it became possible to reproduce the measurements in the far blue wing of the rototranslational spectrum of H-2 at 77.5 K, as well as at 300 K. Similarly good agreement between theory and measurement is seen in the fundamental band of molecular deuterium at room temperature. Furthermore, we also show the calculated absorption spectra of H-2-He at 600 K and of H-2-H-2 at 2,000 K, for which there are no experimental data for comparison.Item Comment On The Black Hole Recoil Candidate Quasar SDSS J092712.65+294344.0(2009-05) Shields, Gregory A.; Bonning, E. W.; Salviander, Sarah; Shields, Gregory A.; Bonning, E. W.; Salviander, SarahThe Sloan Digital Sky Survey (SDSS) quasar J092712.65+294344.0 has been proposed as a candidate for a supermassive black hole (similar to 10(8.8) M(circle dot)) ejected at high speed from the host galactic nucleus by gravitational radiation recoil, or alternatively for a supermassive black hole binary. This is based on a blueshift of 2650 km s(-1) of the broad emission lines ("b-system") relative to the narrow emission lines ("r-system") presumed to reflect the galaxy velocity. New observations with the Hobby-Eberly Telescope (HET) confirm the essential features of the spectrum. We note a third redshift system, characterized by weak, narrow emission lines of [O III] and [O II] at an intermediate velocity 900 km s(-1) redward of the broad-line velocity ("i-system"). A composite spectrum of SDSS QSOs similar to J0927+2943 illustrates the feasibility of detecting the calcium K absorption line in spectra of sufficient quality. The i-system may represent the QSO host galaxy or a companion. Photoionization requires the black hole to be similar to 3 kpc from the r-system emitting gas, implying that we are observing the system only 10(6) yr after the recoil event and contributing to the low probability of observing such a system. The HET observations give an upper limit of 10 km s(-1) per year on the rate of change of the velocity difference between the r- and b-systems, constraining the orbital phase in the binary model. These considerations and the presence of a cluster of galaxies apparently containing J0927+2943 favor the idea that this system represents a superposition of two active galactic nuclei.Item Comparison of Time Series and Random-Vibration Theory Site-Response Methods(2013-06) Kottke, Albert R.; Rathje, Ellen M.; Rathje, Ellen M.The random-vibration theory (RVT) approach to equivalent-linear site-response analysis is often used to simulate site amplification, particularly when large numbers of simulations are required for incorporation into probabilistic seismic-hazard analysis. The fact that RVT site-response analysis does not require the specification of input-time series makes it an attractive alternative to other site-response methods. However, some studies have indicated that the site amplification predicted by RVT site-response analysis systematically differs from that predicted by time-series approaches. This study confirms that RVT site-response analysis predicts site amplification at the natural site frequencies as much as 20%-50% larger than time-series analysis, with the largest overprediction occurring for sites with smaller natural frequencies and sites underlain by hard rock. The overprediction is caused by an increase in duration generated by the site response, which is not taken into account in the RVT calculation. Correcting for this change in duration brings the RVT results within 20% of the time-series results. A similar duration effect is observed for the RVT shear-strain calculation used to estimate the equivalent-linear strain-compatible soil properties. An alternative to applying a duration correction to improve the agreement between RVT and time-series analysis is the modeling of shear-wave velocity variability. It is shown that introducing shear-wave velocity variability through Monte Carlo simulation brings the RVT results consistently within +/- 20% of the time-series results.Item Comprehensive Observations Of The Bright And Energetic Type Lax Sn 2012Z: Interpretation As A Chandrasekhar Mass White Dwarf Explosion(2015-01) Stritzinger, M. D.; Valenti, S.; Hoeflich, P.; Baron, E.; Phillips, M. M.; Taddia, F.; Foley, R. J.; Hsiao, E. Y.; Jha, S. W.; McCully, C.; Pandya, V.; Simon, J. D.; Benetti, S.; Brown, P. J.; Burns, C. R.; Campillay, A.; Contreras, C.; Forster, F.; Holmbo, S.; Marion, G. H.; Morrell, N.; Pignata, G.; G. H. MarionWe present ultraviolet through near-infrared (NIR) broadband photometry, and visual-wavelength and NIR spectroscopy of the Type lax supernova (SN) 2012Z. The data set consists of both early- and late-time observations, including the first late phase NIR spectrum obtained for a spectroscopically classified SN lax. Simple model calculations of its bolometric light curve suggest SN 2012Z produced similar to 0.3 M-circle dot of Ni-56, ejected about a Chandrasekhar mass of material, and had an explosion energy of similar to 10(51) erg, making it one of the brightest (M-B = -18.3 mag) and most energetic SN Iax yet observed. The late phase (+269d) NIR spectrum of SN 2012Z is found to broadly resemble similar epoch spectra of normal SNe Ia; however, like other SNe Iax, corresponding visual-wavelength spectra differ substantially from all supernova types. Constraints from the distribution of intermediate mass elements, e.g., silicon and magnesium, indicate that the outer ejecta did not experience significant mixing during or after burning, and the late phase NIR line profiles suggests most of the Ni-56 is produced during high density burning. The various observational properties of SN 2012Z are found to be consistent with the theoretical expectations of a Chandrasekhar mass white dwarf progenitor that experiences a pulsational delayed detonation, which produced several tenths of a solar mass of Ni-56 during the deflagration burning phase and little (or no) Ni-56 during the detonation phase. Within this scenario only a moderate amount of Rayleigh-Taylor mixing occurs both during the deflagration and fallback phase of the pulsation, and the layered structure of the intermediate mass elements is a product of the subsequent denotation phase. The fact that the SNe lax population does not follow a tight brightness-decline relation similar to SNe Ia can then be understood in the framework of variable amounts of mixing during pulsational rebound and variable amounts of Ni-56 production during the early subsonic phase of expansion.Item Discovery of A GeV Blazar Shining Through the Galactic Plane(2010-08) Vandenbroucke, J.; Buehler, R.; Ajello, M.; Bechtol, K.; Bellini, A.; Bolte, M.; Cheung, C. C.; Civano, F.; Donato, D.; Fuhrmann, L.; Funk, S.; Healey, S. E.; Hill, A. B.; Knigge, C.; Madejski, G. M.; Romani, R. W.; Santander-Garcia, M.; Shaw, M. S.; Steeghs, D.; Torres, M. A. P.; Van Etten, A.; Williams, Kurtis A.; Williams, Kurtis A.The Fermi Large Area Telescope (LAT) discovered a new gamma-ray source near the Galactic plane, Fermi J0109+6134, when it flared brightly in 2010 February. The low Galactic latitude (b = -1 degrees.2) indicated that the source could be located within the Galaxy, which motivated rapid multi-wavelength follow-up including radio, optical, and X-ray observations. We report the results of analyzing all 19 months of LAT data for the source, and of X-ray observations with both Swift and the Chandra X-ray Observatory. We determined the source redshift, z = 0.783, using a Keck Low-Resolution Imaging Spectrometer observation. Finally, we compiled a broadband spectral energy distribution (SED) from both historical and new observations contemporaneous with the 2010 February flare. The redshift, SED, optical line width, X-ray absorption, and multi-band variability indicate that this new GeV source is a blazar seen through the Galactic plane. Because several of the optical emission lines have equivalent width > 5 angstrom, this blazar belongs in the flat-spectrum radio quasar category.Item Discovery Of A Wolf-Rayet Star Through Detection Of Its Photometric Variability(2012-06) Littlefield, Colin; Garnavich, Peter; Marion, G. H.; Vinko, Jozsef; McClelland, Colin; Rettig, Terrence; Wheeler, J. Craig; Vinko, Jozsef; Wheeler, J. CraigWe report the serendipitous discovery of a heavily reddened Wolf-Rayet star that we name WR 142b. While photometrically monitoring a cataclysmic variable, we detected weak variability in a nearby field star. Low-resolution spectroscopy revealed a strong emission line at 7100 angstrom, suggesting an unusual object and prompting further study. A spectrum taken with the Hobby-Eberly Telescope confirms strong He II emission and an N IV 7112 angstrom line consistent with a nitrogen-rich Wolf-Rayet star of spectral class WN6. Analysis of the He II line strengths reveals no detectable hydrogen in WR 142b. A blue-sensitive spectrum obtained with the Large Binocular Telescope shows no evidence for a hot companion star. The continuum shape and emission line ratios imply a reddening of E(B - V) = 2.2-2.6 mag. We estimate that the distance to WR 142b is 1.4 +/- 0.3 kpc.Item Double-Peaked Narrow-Line Active Galactic Nuclei. II. The Case Of Equal Peaks(2012-06) Smith, K. L.; Shields, Gregory A.; Salviander, Sarah; Stevens, A. C.; Rosario, D. J.; Smith, K. L.; Shields, Gregory A.; Salviander, Sarah; Stevens, A. C.Active galactic nuclei (AGNs) with double-peaked narrow lines (DPAGNs) may be caused by kiloparsec-scale binary AGNs, bipolar outflows, or rotating gaseous disks. We examine the class of DPAGNs in which the two narrow-line components have closely similar intensity as being especially likely to involve disks or jets. Two spectroscopic indicators support this likelihood. For DPAGNs from Smith et al., the "equal-peaked" objects (EPAGNs) have [Ne V]/[O III] ratios lower than for a control sample of non-double-peaked AGNs. This is unexpected for a pair of normal AGNs in a galactic merger, but may be consistent with [O III] emission from a rotating ring with relatively little gas at small radii. Also, [O III]/H beta ratios of the redshifted and blueshifted systems in the EPAGN are more similar to each other than in a control sample, suggestive of a single ionizing source and inconsistent with the binary interpretation.Item Early Observations And Analysis Of The Type Ia SN 2014J In M82(2015-01) Marion, G. H.; Sand, D. J.; Hsiao, Eric Y.; Banerjee, D. P. K.; Valenti, S.; Stritzinger, Maximillian D.; Vinko, Jozsef; Joshi, V.; Venkataraman, V.; Ashok, N. M.; Amanullah, R.; Binzel, R. P.; Bochanski, J. J.; Bryngelson, G. L.; Burns, Christopher R.; Drozdov, D.; Fieber-Beyer, S. K.; Graham, M. L.; Howell, D. Andrew; Johansson, J.; Kirshner, Robert P.; Milne, P. A.; Parrent, J.; Silverman, Jeffrey M.; Vervack Jr, R. J.; Wheeler, J. Craig; Marion, G. H.; Vinko, Jozsef; Silverman, Jeffrey M.; Wheeler, J. CraigWe present optical and near infrared (NIR) observations of the nearby Type Ia SN 2014J. Seventeen optical and 23 NIR spectra were obtained from 10 days before (-10d) to 10 days after (+10d) the time of maximum B-band brightness. The relative strengths of absorption features and their patterns of development can be compared at one day intervals throughout most of this period. Carbon is not detected in the optical spectra, but we identify C I lambda 1.0693 in the NIR spectra. Mg II lines with high oscillator strengths have higher initial velocities than other Mg II lines. We show that the velocity differences can be explained by differences in optical depths due to oscillator strengths. The spectra of SN 2014J show that it is a normal SN Ia, but many parameters are near the boundaries between normal and high-velocity subclasses. The velocities for OI, Mg II, Si II, S Ca a, and Fell suggest that SN 2014J has a layered structure with little or no mixing. That result is consistent with the delayed detonation explosion models. We also report photometric observations, obtained from -10d to +29d, in the UBVRIJH and K-s bands. The template fitting package SNooPy is used to interpret the light curves and to derive photometric parameters. Using R-v = 1.46, which is consistent with previous studies, SNooPy finds that A(v) = 1.80 for E(B - V)(host) = 1.23 +/- 0.06 mag. The maximum B-band brightness of -19.19 +/- 0.10 mag was reached on February 1.74 UT +/- 0.13 days and the supernova has a decline parameter, Delta m(15), of 1.12 +/- 0.02 mag.Item Evidence For A Correlation Between The Si II Lambda 4000 Width And Type Ia Supernova Color(2011-06) Nordin, Jakob; Ostman, Linda; Goobar, Ariel; Balland, C.; Lampeitl, Hubert; Nichol, Robert C.; Sako, Masao; Schneider, Donald P.; Smith, Mathew; Sollerman, Jesper; Wheeler, J. Craig; Wheeler, J. CraigWe study the pseudo-equivalent width of the Si II lambda 4000 feature of Type Ia supernovae (SNe Ia) in the redshift range 0.0024 <= z <= 0.634. We find that this spectral indicator correlates with the light curve color excess (SALT2c) as well as previously defined spectroscopic subclasses (Branch types) and the evolution of the Si II lambda 6150 velocity, i.e., the so-called velocity gradient. Based on our study of 55 objects from different surveys, we find indications that the Si II lambda 4000 spectral indicator could provide important information to improve cosmological distance measurements with SNe Ia.Item Evidence Of Resonant Mode Coupling And The Relationship Between Low And High Frequencies In A Rapidly Rotating A Star(2014-03) Breger, Michel; Montgomery, Michael H.; Breger, Michel; Montgomery, Michael H.In the theory of resonant mode coupling, the parent and child modes are directly related in frequency and phase. The oscillations present in the fast rotating delta Sct star KIC 8054146 allow us to test the most general and generic aspects of such a theory. The only direct way to separate the parent and coupled (child) modes is to examine the correlations in amplitude variability between the different frequencies. For the dominant family of related frequencies, only a single mode and a triplet are the origins of nine dominant frequency peaks ranging from 2.93 to 66.30 cycles day(-1) (as well as dozens of small-amplitude combination modes and a predicted and detected third high-frequency triplet). The mode-coupling model correctly predicts the large amplitude variations of the coupled modes as a product of the amplitudes of the parent modes, while the phase changes are also correctly modeled. This differs from the behavior of " (n)ormal" combination frequencies in that the amplitudes are three orders of magnitude larger and may exceed even the amplitudes of the parent modes. We show that two dominant low frequencies at 5.86 and 2.93 cycles day(-1) in the gravity-mode region are not harmonics of each other, and their properties follow those of the almost equidistant high-frequency triplet. We note that the previously puzzling situation of finding two strong peaks in the low-frequency region related by nearly a factor of two in frequency has been seen in other delta Sct stars as well.Item The Exceptionally Luminous Type Ia Supernova 2007If(2010-06) Yuan, F.; Quimby, Robert M.; Wheeler, J. Craig; Vinko, Jozsef; Chatzopoulos, Emmanouil; Akerlof, C. W.; Kulkarni, S.; Miller, J. M.; McKay, T. A.; Aharonian, F.; Wheeler, J. Craig; Vinko, Jozsef; Chatzopoulos, EmmanouilSN 2007if was the third over-luminous Type Ia supernova (SN Ia) detected after 2003fg and 2006gz. We present the photometric and spectroscopic observations of the SN and its host by ROTSE-III, HET, and Keck. From the H a line identified in the host spectra, we determine a redshift of 0.0736. At this distance, the SN reached an absolute magnitude of -20.4, brighter than any other SNe Ia ever observed. If the source of luminosity is radioactive decay, a large amount of radioactive nickel (similar to 1.5 M(circle dot)) is required to power the peak luminosity, more than can be produced realistically in a Chandrasekhar mass progenitor. Low expansion velocity, similar to that of 2003fg, is also measured around the maximum light. The observations may suggest that SN 2007if was from a massive white dwarf progenitor, plausibly exploding with mass well beyond 1.4 M(circle dot). Alternatively, we investigate circumstellar interaction that may contribute to the excess luminosity.Item The Fast Declining Type Ia Supernova 2003Gs, And Evidence For A Significant Dispersion In Near-Infrared Absolute Magnitudes Of Fast Decliners At Maximum Light(2009-12) Krisciunas, Kevin; Marion, G. H.; Suntzeff, Nicholas B.; Blanc, Guillaume; Bufano, Filomena; Candia, Pablo; Cartier, Regis; Elias-Rosa, Nancy; Espinoza, Juan; Gonzalez, David; Gonzalez, Luis; Gonzalez, Serio; Gooding, Samuel D.; Hamuy, Mario; Knox, Ethan A.; Milne, Peter A.; Morrell, Nidia; Phillips, Mark M.; Stritzinger, Maximillian; Thomas-Osip, Joanna; Marion, G. H.We obtained optical photometry of SN 2003gs on 49 nights, from 2 to 494 days after T(B(max)). We also obtained near-IR photometry on 21 nights. SN 2003gs was the first fast declining Type Ia SN that has been well observed since SN 1999by. While it was subluminous in optical bands compared to more slowly declining Type Ia SNe, it was not subluminous at maximum light in the near-IR bands. There appears to be a bimodal distribution in the near-IR absolute magnitudes of Type Ia SNe at maximum light. Those that peak in the near-IR after T(B(max)) are subluminous in the all bands. Those that peak in the near-IR prior to T(B(max)), such as SN 2003gs, have effectively the same near-IR absolute magnitudes at maximum light regardless of the decline rate Delta m(15)(B). Near-IR spectral evidence suggests that opacities in the outer layers of SN 2003gs are reduced much earlier than for normal Type Ia SNe. That may allow gamma rays that power the luminosity to escape more rapidly and accelerate the decline rate. This conclusion is consistent with the photometric behavior of SN 2003gs in the IR, which indicates a faster than normal decline from approximately normal peak brightness.Item First Unambiguous Detection of the Return of Pulsations in the Accreting White Dwarf SDSS J074531.92+453829.6 After an Outburst(2011-02) Mukadam, Anjum S.; Townsley, D. M.; Szkody, P.; Gansicke, B. T.; Winget, D. E.; Hermes, J. J.; Howell, Steve B.; Teske, J.; Patterson, J.; Kemp, J.; Armstrong, Eve; Winget, D. E.; Hermes, J. J.The primary white dwarf of the cataclysmic variable SDSS J074531.92+453829.6 was discovered to exhibit non-radial pulsations in 2006 January. This accreting white dwarf underwent its first recorded dwarf nova outburst in 2006 October, during which its brightness increased by more than 5 mag. A Hubble Space Telescope (HST) ultraviolet spectrum, obtained one year after the outburst, revealed a white dwarf temperature of 16,500 K, hotter than all other known accreting white dwarf pulsators. This implies that the accreting primary white dwarf of SDSS J074531.92+453829.6 was heated to temperatures beyond the instability strip during the outburst. Optical observations acquired a year after the outburst did not reveal any evidence of pulsations, suggesting that the white dwarf had not cooled to quiescence by then. We recently acquired optical high-speed time-series photometry on this cataclysmic variable SDSS J074531.92+453829.6 more than three years after its outburst to find that pulsations have now returned to the primary white dwarf. Moreover, the observed pulsation periods agree with pre-outburst periods within the uncertainties of a few seconds. This discovery is significant because it indicates that the outburst did not affect the interior stellar structure, which governs the observed pulsation frequencies. It also suggests that the surface of the white dwarf has now cooled to quiescence. Using this discovery in addition to the prior HST temperature measurement of 16,500 K, we have been able to constrain the matter accreted during the 2006 outburst. This is the first time an accreting white dwarf was unambiguously observed to resume pulsating after an outburst.Item First-Year Spectroscopy For The Sloan Digital Sky Survey-II Supernova Survey(2008-05) Zheng, Chen; Romani, Roger W.; Sako, Masao; Marriner, John; Bassett, Bruce; Becker, Andrew; Choi, Changsu; Cinabro, David; DeJongh, Fritz; Depoy, Darren L.; Dilday, Ben; Doi, Mamoru; Frieman, Joshua A.; Garnavich, Peter M.; Hogan, Craig J.; Holtzman, Jon; Im, Myungshin; Jha, Saurabh; Kessler, Richard; Konishi, Kohki; Lampeitl, Hubert; Marshall, Jennifer L.; McGinnis, David; Miknaitis, Gajus; Nichol, Robert C.; Prieto, Jose L.; Riess, Adam G.; Richmond, Michael W.; Schneider, Donald P.; Smith, Mathew; Takanashi, Naohiro; Tokita, Kouichi; Van der Heyden, Kurt; Yasuda, Naoki; Assef, Roberto J.; Barentine, John; Bender, Ralf; Blandford, Roger D.; Bremer, Malcolm; Brewington, Howard; Collins, Chris A.; Crotts, Arlin; Dembicky, Jack; Eastman, Jason; Edge, Alastair; Elson, Ed; Eyler, Michael E.; Filippenko, Alexi V.; Foley, Ryan J.; Frank, Stephan; Goobar, Ariel; Harvanek, Michael; Hopp, Ulrich; Ihara, Yutaka; Kahn, Steven; Ketzeback, William; Kleinman, Scott J.; Kollatschny, Wolfram; Krzesinski, Jurek; Leloudas, Giorgos; Long, Daniel C.; Lucey, John; Malanushenko, Elena; Malanushenko, Viktor; McMillan, Russet J.; Morgan, Christopher W.; Morokuma, Tomoki; Nitta, Atsuko; Ostman, Linda; Pan, Kaike; Romer, A. Kathy; Saurage, Gabrelle; Schlesinger, Katie; Snedden, Stephanie A.; Sollerman, Jasper; Stritzinger, Maximillian; Watson, Linda C.; Watters, Shannon; Wheeler, J. Craig; York, Donald; Barentine, John; Wheeler, J. CraigThis paper presents spectroscopy of supernovae (SNe) discovered in the first season of the Sloan Digital Sky Survey-II SN Survey. This program searches for and measures multi-band light curves of SNe in the redshift range z = 0.05-0.4, complementing existing surveys at lower and higher redshifts. Our goal is to better characterize the SN population, with a particular focus on SNe Ia, improving their utility as cosmological distance indicators and as probes of dark energy. Our SN spectroscopy program features rapid-response observations using telescopes of a range of apertures, and provides confirmation of the SN and host-galaxy types as well as precise redshifts. We describe here the target identification and prioritization, data reduction, redshift measurement, and classification of 129 SNe Ia, 16 spectroscopically probable SNe Ia, 7 SNe Ib/c, and 11 SNe II from the first season. We also describe our efforts to measure and remove the substantial host-galaxy contamination existing in the majority of our SN spectra.Item The Gould's Belt Very Large Array Survey. I. The Ophiuchus Complex(2013-09) Dzib, Sergio A.; Loinard, Laurent; Mioduszewski, Amy J.; Rodriguez, Luis F.; Ortiz-Leon, Gisela N.; Pech, Gerardo; Rivera, Juana L.; Torres, Rosa M.; Boden, Andrew F.; Hartmann, Lee; Evans, Neal J.; Briceno, Cesar; Tobin, John; Evans, Neal J.We present large-scale (similar to 2000 arcmin(2)), deep (similar to 20 mu Jy), high-resolution (similar to 1 '') radio observations of theOphiuchus star-forming complex obtained with the Karl G. Jansky Very Large Array at lambda = 4 and 6 cm. In total, 189 sources were detected, 56 of them associated with known young stellar sources, and 4 with known extragalactic objects; the other 129 remain unclassified, but most of them are most probably background quasars. The vast majority of the young stars detected at radio wavelengths have spectral types K or M, although we also detect four objects of A/F/B types and two brown dwarf candidates. At least half of these young stars are non-thermal (gyrosynchrotron) sources, with active coronas characterized by high levels of variability, negative spectral indices, and (in some cases) significant circular polarization. As expected, there is a clear tendency for the fraction of non-thermal sources to increase from the younger (Class 0/I or flat spectrum) to the more evolved (Class III or weak line T Tauri) stars. The young stars detected both in X-rays and at radio wavelengths broadly follow a Gudel-Benz relation, but with a different normalization than the most radioactive types of stars. Finally, we detect a similar to 70 mJy compact extragalactic source near the center of the Ophiuchus core, which should be used as gain calibrator for any future radio observations of this region.Item A Gravitational Redshift Determination Of The Mean Mass Of DBA White Dwarfs(2010-08) Falcon, R. E.; Winget, D. E.; Montgomery, M. H.; Williams, K. A.; Falcon, Ross E.; Winget, D. E.; Montgomery, M. H.We measure apparent velocities (v(app)) of the H alpha and H beta Balmer line cores for 16 helium-dominated white dwarfs (WDs) using optical spectra taken for the European Southern Observatory SN Ia progenitor survey (SPY). Following the gravitational redshift method employed by Falcon et al. [1], we find a mean apparent velocity of (v(app)) = 39.58 +/- 4.41 km s(-1) and use it to derive a mean mass of < M > = 0.701(-0.046)(+0.042) M(circle dot). Though the sample is small, the mean mass appears to be larger than the mean mass of DAs derived using the same method [0.647(-0.014)(+0.013) M(circle dot), 1]Item A Gravitational Redshift Determination Of The Mean Mass Of White Dwarfs: DBA And DB Stars(2012-10) Falcon, Ross E.; Winget, D. E.; Montgomery, Michael H.; Williams, Kurtis A.; Falcon, Ross E.; Winget, D. E.; Montgomery, Michael H.We measure apparent velocities (nu(app)) of absorption lines for 36 white dwarfs (WDs) with helium-dominated atmospheres-16 dbAs and 20 dbs-using optical spectra taken for the European Southern Observatory SN Ia progenitor survey. We find a difference of 6.9 +/- 6.9 kms(-1) in the average apparent velocity of the H alpha lines versus that of the He I 5876 angstrom lines for our dbAs. This is a measure of the blueshift of this He line due to pressure effects. By using this as a correction, we extend the gravitational redshift method employed by Falcon et al. to use the apparent velocity of the He I 5876 angstrom line and conduct the first gravitational redshift investigation of a group of WDs without visible hydrogen lines. We use biweight estimators to find an average apparent velocity, (BI), (and hence average gravitational redshift, (BI)) for our WDs; from that we derive an average mass, < M >(BI). For the dbAs, we find (BI) = 40.8 +/- 4.7 kms(-1) and derive < M >(BI) = 0.71(-0.05)(+0.04) M-circle dot. Though different from of DAs (32.57 km s(-1)) at the 91% confidence level and suggestive of a larger dbA mean mass than that for normal DAs derived using the same method (0.647(-0.014)(+0.013) M-circle dot; Falcon et al.), we do not claim this as a stringent detection. Rather, we emphasize that the difference between (BI) of the dbAs and of normal DAs is no larger than 9.2 kms(-1), at the 95% confidence level; this corresponds to roughly 0.10 M-circle dot. For the dbs, we find (BI) = 42.9 +/- 8.49 km s(-1) after applying the blueshift correction and determine < M >(BI) = 0.74(-0.09)(+0.08) M-circle dot. The difference between (BI) of the dbs and of DAs is <= 11.5 kms(-1) (similar to 0.12 M-circle dot), at the 95% confidence level. The gravitational redshift method indicates much larger mean masses than the spectroscopic determinations of the same sample by Voss et al. Given the small sample sizes, it is possible that systematic uncertainties are skewing our results due to the potential of kinematic substructures that may not average out. We estimate this to be unlikely, but a larger sample size is necessary to rule out these systematics.
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