Browsing by Subject "line: identification"

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The Abundances Of Polyacetylenes Toward CRL618
(2011-02) Fonfria, J. P.; Cernicharo, J.; Richter, Matthew J.; Lacy, John H.; Lacy, John H.
We present a mid-infrared high spectral resolution spectrum of CRL618 in the frequency ranges 778-784 and 1227-1249 cm(-1) (8.01-8.15 and 12.75-12.85 mu m) taken with the Texas Echelon-cross-Echelle Spectrograph (TEXES) and the Infrared Telescope Facility (IRTF). We have identified more than 170 rovibrational lines arising from C2H2, HCN, C4H2, and C6H2. We have found no unmistakable trace of C8H2. The line profiles display a complex structure suggesting the presence of polyacetylenes in several components of the circumstellar envelope (CSE). We derive total column densities of 2.5x10(17), 3.1x10(17), 2.1x10(17), 9.3x10(16) cm(-2), and less than or similar to 5x10(16) cm(-2) for HCN, C2H2, C4H2, C6H2, and C8H2, respectively. The observations indicate that both the rotational and vibrational temperatures in the innermost CSE depend on the molecule, varying from 100 to 350 K for the rotational temperatures and 100 to 500 K for the vibrational temperatures. Our results support a chemistry in the innermost CSE based on radical-neutral reactions triggered by the intense UV radiation field.
A Catalog Of Near-Infrared Spectra From Type Ia Supernovae
(2009-09) Marion, G. H.; Hoflich, P.; Gerardy, C. L.; Vacca, W. D.; Wheeler, J. C.; Robinson, E. L.; Marion, G. H.; Robinson, E. L.
We present 41 near-infrared (NIR, 0.7-2.5 mu m) spectra from normal Type Ia supernovae (SNe Ia) obtained at epochs ranging from 14 days before to 75 days with respect to the maximum light date in the V band. All data were obtained at the Infrared Telescope Facility using the SpeX instrument. We identify many spectral features, measure the Doppler velocities, and discuss the chemical distribution of explosion products in SNe Ia. We describe procedures for smoothing data, fitting continua, and measuring absorption features to ensure consistency for measurement and analysis. This sample provides the first opportunity to examine and compare a large number of SNe Ia in this wavelength region. NIR data are a rich source of information about explosion products whose signatures are blended or obscured in other spectral regions and NIR observations probe a greater radial depth than optical wavelengths. We analyze similarities and differences in the spectra and we show that the progressive development of spectral features for normal SNe Ia in the NIR is consistent with time. We confirm the presence of O I, Mg II, Ca II, Si II, Fe II, and Co II in these SNe. Possible identifications are made for S I, Si III, Mn II, and Fe III. There is no evidence in these data for H I, He I, C I, or C II. As the explosion products expand and cool, progressively deeper layers are revealed. Thus, a time sequence of spectra examines the chemical structure and provides direct evidence of the physical properties of SNe Ia from the outer layers to deep inside the SN. Measured Doppler velocities indicate that burning products in SNe Ia are distributed in distinct layers with no large-scale mixing. Carbon is not detected in these data, in agreement with previous results with NIR data establishing very low limits on carbon abundance in SNe Ia. Carbon burning products, O and Mg, are plentiful in the outer layers suggesting that the entire progenitor is burned in the explosion. The data provide a resource for investigations of cross-correlations with other data libraries that may further constrain SN Ia physics and improve the effectiveness of SNe Ia as cosmological distance indicators.
The CN Isotopic Ratios In Comets
(2009-08) Manfroid, J.; Jehin, E.; Hutsemekers, D.; Cochran, A.; Zucconi, J. M.; Arpigny, C.; Schulz, R.; Stuwe, J. A.; Ilyin, I.; Cochran, A.
Our aim is to determine the isotopic ratios (12)C/(13)C and (14)N/(15)N in a variety of comets and link these measurements to the formation and evolution of the solar system. The (12)C/(13)C and (14)N/(15)N isotopic ratios are measured for the CN radical by means of high-resolution optical spectra of the R branch of the B-X (0, 0) violet band. 23 comets from different dynamical classes have been observed, sometimes at various heliocentric and nucleocentric distances, in order to estimate possible variations of the isotopic ratios in parent molecules. The (12)C/(13)C and (14)N/(15)N isotopic ratios in CN are remarkably constant (average values of, respectively, 91.0 +/- 3.6 and 147.8 +/- 5.7) within our measurement errors, for all comets whatever their origin or heliocentric distance. While the carbon isotopic ratio does agree with the terrestrial value (89), the nitrogen ratio is a factor of two lower than the terrestrial value (272), indicating a fractionation in the early solar system, or in the protosolar nebula, common to all the comets of our sample. This points towards a common origin of the comets independently of their birthplaces, and a relationship between HCN and CN.
High-Resolution H-Band Spectroscopy Of Be Stars With SDSS-III/Apogee. I. New Be Stars, Line Identifications, And Line Profiles
(2015-01) Chojnowski, S. Drew; Whelan, David G.; Wisniewski, John P.; Majewski, Steven R.; Hall, Matthew; Shetrone, Matthew; Beaton, Rachael; Burton, Adam; Damke, Guillermo; Eikenberry, Steve; Hasselquist, Sten; Holtzman, Jon A.; Meszaros, Szabolcs; Nidever, David; Schneider, Donald P.; Wilson, John; Zasowski, Gail; Bizyaev, Dmitry; Brewington, Howard; Brinkmann, J.; Ebelke, Garrett; Frinchaboy, Peter M.; Kinemuchi, Karen; Malanushenko, Elena; Malanushenko, Viktor; Marchante, Moses; Oravetz, Daniel; Pan, Kaike K.; Simmons, Audrey; Shetrone, Matthew D.
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) has amassed the largest ever collection of multi-epoch, high-resolution (R similar to 22, 500), H-band spectra for B-type emission line (Be) stars. These stars were targeted by APOGEE as telluric standard stars and subsequently identified via visual inspection as Be stars based on H I Brackett series emission or shell absorption in addition to otherwise smooth continua and occasionally non-hydrogen emission features. The 128/238 APOGEE Be stars for which emission had never previously been reported serve to increase the total number of known Be stars by similar to 6%. Because the H band is relatively unexplored compared to other wavelength regimes, we focus here on identification of the H-band lines and analysis of the emission peak velocity separations (Delta v(p)) and emission peak intensity ratios (V/R) of the usually double-peaked H I and nonhydrogen emission lines. H I Br11 emission is found to preferentially form in the circumstellar disks at an average distance of similar to 2.2 stellar radii. Increasing Delta v(p) toward the weaker Br12-Br20 lines suggests these lines are formed interior to Br11. By contrast, the observed IR Fe II emission lines present evidence of having significantly larger formation radii; distinctive phase lags between IR Fe II and H I Brackett emission lines further supports that these species arise from different radii in Be disks. Several emission lines have been identified for the first time including C I 16895, a prominent feature in the spectra for almost a fifth of the sample and, as inferred from relatively large Delta v(p) compared to the Br11-Br20, a tracer of the inner regions of Be disks. Emission lines at 15760 angstrom and 16781 angstrom remain unidentified, but usually appear along with and always have similar line profile morphology to Fe II 16878. Unlike the typical metallic lines observed for Be stars in the optical, the H-band metallic lines, such as Fe II 16878, never exhibit any evidence of shell absorption, even when the H I lines are clearly shell-dominated. The first known example of a quasi-triple-peaked Br11 line profile is reported for HD 253659, one of several stars exhibiting intra- and/or extraspecies V/R and radial velocity variation within individual spectra. Br11 profiles are presented for all discussed stars, as are full APOGEE spectra for a portion of the sample.
High-Velocity Line Forming Regions In The Type Ia Supernova 2009ig
(2013-11) Marion, G. H.; Vinko, Jozsef; Wheeler, J. Craig; Foley, Ryan J.; Hsiao, Eric Y.; Brown, Peter J.; Challis, Peter; Filippenko, Alexei V.; Garnavich, Peter; Kirshner, Robert P.; Landsman, Wayne B.; Parrent, Jerod T.; Pritchard, Tyler A.; Roming, Peter W. A.; Silverman, Jeffrey M.; Wang, Xiaofeng; Marion, G. H.; Vinko, Jozsef; Wheeler, J. Craig; Silverman, Jeffrey M.
We report measurements and analysis of high-velocity (HVF) (>20,000 km s(-1)) and photospheric absorption features in a series of spectra of the Type Ia supernova (SN) 2009ig obtained between -14 days and +13 days with respect to the time of maximum B-band luminosity (B-max). We identify lines of Si II, Si III, S II, Ca II, and Fe II that produce both HVF and photospheric-velocity (PVF) absorption features. SN 2009ig is unusual for the large number of lines with detectable HVF in the spectra, but the light-curve parameters correspond to a slightly overluminous but unexceptional SN Ia (M-B = -19.46 mag and Delta m(15)(B) = 0.90 mag). Similarly, the Si II lambda 6355 velocity at the time of B-max is greater than "normal" for an SN Ia, but it is not extreme (upsilon(Si) = 13,400 km s(-1)). The -14 days and -13 days spectra clearly resolve HVF from Si II lambda 6355 as separate absorptions from a detached line forming region. At these very early phases, detached HVF are prevalent in all lines. From -12 days to -6 days, HVF and PVF are detected simultaneously, and the two line forming regions maintain a constant separation of about 8000 km s(-1). After -6 days all absorption features are PVF. The observations of SN 2009ig provide a complete picture of the transition from HVF to PVF. Most SNe Ia show evidence for HVF from multiple lines in spectra obtained before -10 days, and we compare the spectra of SN 2009ig to observations of other SNe. We show that each of the unusual line profiles for Si II lambda 6355 found in early-time spectra of SNe Ia correlate to a specific phase in a common development sequence from HVF to PVF.
Improved Line Data for the Swan System (Cc)-C-12-C-13 Isotopologue
(2014-03) Ram, Ram S.; Brooke, James S. A.; Bernath, Peter F.; Sneden, Christopher; Lucatello, Sara; Sneden, Christopher
We present new, accurate predictions for rotational line positions, excitation energies, and transition probabilities of the (CC)-C-12-C-13 isotopologue Swan d(3)Pi-a(3)Pi system 0-0, 0-1, 0-2, 1-0, 1-1, 1-2, 2-0, 2-1, and 2-2 vibrational bands. The line positions and energy levels were predicted through new analyses of published laboratory data for the (CC)-C-12-C-13 lines. Transition probabilities were derived from recent computations of transition dipole moments and related quantities. The (CC)-C-12-C-13 line data were combined with similar data for C-12(2), reported in a companion paper, and applied to produce synthetic spectra of carbon-rich metal-poor stars that have strong C-2 Swan bands. The matches between synthesized and observed spectra were used to estimate band head positions for a few of the (CC)-C-12-C-13 vibrational bands and to verify that the new computed line data match observed spectra. The much weaker C-2 lines of the bright red giant Arcturus were also synthesized in the band head regions.
the SDSS-III APOGEE Spectral Line List for H-Band Spectroscopy
(2015-12) Shetrone, Matthew; Bizyaev, D.; Lawler, James E.; Prieto, Carlos Allende; Johnson, J. A.; Smith, V. V.; Cunha, K.; Holtzman, J.; Perez, A. E. G.; Meszaros, S.; Sobeck, J.; Zamora, O.; Garcia-Hernandez, D. A.; Souto, D.; Chojnowski, D.; Koesterke, L.; Majewski, S.; Zasowski, G.; Shetrone, Matthew
We present the H-band spectral line lists adopted by the Apache Point Observatory Galactic Evolution Experiment (APOGEE). The APOGEE line lists comprise astrophysical, theoretical, and laboratory sources from the literature, as well as newly evaluated astrophysical oscillator strengths and damping parameters. We discuss the construction of the APOGEE line list, which is one of the critical inputs for the APOGEE Stellar Parameters and Chemical Abundances Pipeline, and present three different versions that have been used at various stages of the project. The methodology for the newly calculated astrophysical line lists is reviewed. The largest of these three line lists contains 134,457 molecular and atomic transitions. In addition to the format adopted to store the data, the line lists are available in MOOG, Synspec, and Turbospectrum formats. The limitations of the line lists along with guidance for its use on different spectral types are discussed. We also present a list of H-band spectral features that are either poorly represented or completely missing in our line list. This list is based on the average of a large number of spectral fit residuals for APOGEE observations spanning a wide range of stellar parameters.