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Astrophysics and Astronomy

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Old Dominion University

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2014

Articles 1 - 10 of 10

Full-Text Articles in Physical Sciences and Mathematics

Searching For Chemical Signatures Of Multiple Stellar Populations In The Old, Massive Open Cluster Ngc 6791, Angela Bragaglia, Christopher Sneden, Eugenio Carretta, Raffaele G. Gratton, Sara Lucatello, Peter F. Bernath, James S. A. Brooke, Ram S. Ram Nov 2014

Searching For Chemical Signatures Of Multiple Stellar Populations In The Old, Massive Open Cluster Ngc 6791, Angela Bragaglia, Christopher Sneden, Eugenio Carretta, Raffaele G. Gratton, Sara Lucatello, Peter F. Bernath, James S. A. Brooke, Ram S. Ram

Chemistry & Biochemistry Faculty Publications

Galactic open and globular clusters (OCs, GCs) appear to inhabit separate regions of the age-mass plane. However, the transition between them is not easily defined because there is some overlap between high-mass, old OCs and low-mass, young GCs. We are exploring the possibility of a clear-cut separation between OCs and GCs using an abundance feature that has been found so far only in GCs: (anti)correlations between light elements. Among the coupled abundance trends, the Na-O anticorrelation is the most widely studied. These anticorrelations are the signature of self-enrichment, i.e., of a formation mechanism that implies multiple generations of stars. Here …

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Small Carbon Chains In Circumstellar Envelopes, R. J. Hargreaves, K. Hinkle, P. F. Bernath Nov 2014

Small Carbon Chains In Circumstellar Envelopes, R. J. Hargreaves, K. Hinkle, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

Observations of carbon-rich circumstellar envelopes were made using the Phoenix spectrograph on the Gemini South telescope to determine the abundance of small carbon chain molecules. Vibration-rotation lines of the ν3 antisymmetric stretch of C3 near 2040 cm-1 (4.902 μm) have been used to determine the column density for four carbon-rich circumstellar envelopes: CRL 865, CRL 1922, CRL 2023 and IRC +10216. We additionally calculate the column density of C5 for IRC +10216, and provide an upper limit for five more objects. An upper limit estimate for the C7 column density is also provided for IRC+10216. A …

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Line Lists For The A2Π-X 2Σ+ (Red) And B2Σ+-X 2Σ+ (Violet) Systems Of Cn, 13c14n, And 12c15n, And Application To Astronomicalspectra, Christopher Sneden, Sara Lucatello, Ram S. Ram, James S. A. Brooke, Peter Bernath Oct 2014

Line Lists For The A2Π-X 2Σ+ (Red) And B2Σ+-X 2Σ+ (Violet) Systems Of Cn, 13c14n, And 12c15n, And Application To Astronomicalspectra, Christopher Sneden, Sara Lucatello, Ram S. Ram, James S. A. Brooke, Peter Bernath

Chemistry & Biochemistry Faculty Publications

New red and violet system line lists for the CN isotopologues 13C14N and 12C15N have been generated. These new transition data are combined with those previously derived for 12C14N, and applied to the determination of CNO abundances in the solar photosphere and in four red giant stars: Arcturus, the bright, very low-metallicity star HD 122563, and the carbon-enhanced metal-poor stars HD 196944 and HD 201626. When both red and violet system lines are detectable in a star, their derived N abundances are in good agreement. The mean N abundances determined in …

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Semi-Inclusive Charged-Current Neutrino-Nucleus Reactions, O. Moreno, T. W. Donnelly, J. W. Van Orden, W. P. Ford Jul 2014

Semi-Inclusive Charged-Current Neutrino-Nucleus Reactions, O. Moreno, T. W. Donnelly, J. W. Van Orden, W. P. Ford

Physics Faculty Publications

The general, universal formalism for semi-inclusive charged-current (anti) neutrino-nucleus reactions is given for studies of any hadronic system, namely, either nuclei or the nucleon itself. The detailed developments are presented with the former in mind and are further specialized to cases where the final-state charged lepton and an ejected nucleon are presumed to be detected. General kinematics for such processes are summarized, and then explicit expressions are developed for the leptonic and hadronic tensors involved and for the corresponding responses according to the usual charge, longitudinal and transverse projections, keeping finite the masses of all particles involved. In the case …

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Improved Line Data For The Swan System 12c13c Isotopologue, Ram S. Ram, James S. A. Brooke, Peter F. Bernath, Christopher Sneden, Sara Lucatello Mar 2014

Improved Line Data For The Swan System 12c13c Isotopologue, Ram S. Ram, James S. A. Brooke, Peter F. Bernath, Christopher Sneden, Sara Lucatello

Chemistry & Biochemistry Faculty Publications

We present new, accurate predictions for rotational line positions, excitation energies, and transition probabilities of the 12C 13C isotopologue Swan d3Π-a3Π 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 12C13C lines. Transition probabilities were derived from recent computations of transition dipole moments and related quantities. The 12C13C line data were combined with similar data for 12C2, reported in a companion paper, and applied …

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Einstein A Coefficients And Oscillator Strengths For The A 2Π-X2Σ+ (Red) And B 2Σ+-X2Σ+ (Violet) Systems And Rovibrational Transitions In The X2Σ+ State Of Cn, James S. A. Brooke, Ram S. Ram, Colin M. Western, Gang Li, David W. Schwenke, Peter F. Bernath Feb 2014

Einstein A Coefficients And Oscillator Strengths For The A 2Π-X2Σ+ (Red) And B 2Σ+-X2Σ+ (Violet) Systems And Rovibrational Transitions In The X2Σ+ State Of Cn, James S. A. Brooke, Ram S. Ram, Colin M. Western, Gang Li, David W. Schwenke, Peter F. Bernath

Chemistry & Biochemistry Faculty Publications

Line strengths have been calculated in the form of Einstein A coefficients and f-values for a large number of bands of the A 2Π-X 2Σ+ and B 2Σ+-X 2Σ+ systems and rovibrational transitions within the X 2Σ+ state of CN using Western's PGOPHER program. The J dependence of the transition dipole moment matrix elements (the Herman-Wallis effect) has been taken into account. Rydberg-Klein-Rees potential energy functions for the A 2Π, B 2Σ+ , and X 2Σ+ states were computed using spectroscopic constants from the …

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Exomol Molecular Line Lists V: The Ro-Vibrational Spectra Of Nacl And Kcl, Emma J. Barton, Christopher Chiu, Shirin Golpayegani, Sergei N. Yurchenko, Jonathan Tennyson, Daniel J. Frohman, Peter F. Bernath Jan 2014

Exomol Molecular Line Lists V: The Ro-Vibrational Spectra Of Nacl And Kcl, Emma J. Barton, Christopher Chiu, Shirin Golpayegani, Sergei N. Yurchenko, Jonathan Tennyson, Daniel J. Frohman, Peter F. Bernath

Chemistry & Biochemistry Faculty Publications

Accurate rotation-vibration line lists for two molecules, NaCl and KCl, in their ground electronic states are presented. These line lists are suitable for temperatures relevant to exoplanetary atmospheres and cool stars (up to 3000 K). Isotopologues 23Na35Cl, 23Na37Cl, 39K35Cl, 39K37Cl, 41K35Cl and 41K37Cl are considered. Laboratory data were used to refine ab initio potential energy curves in order to compute accurate ro-vibrational energy levels. Einstein A coefficients are generated using newly determined ab initio dipole moment curves calculated using the CCSD(T) method. …

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Neutral Pion Cross Section And Spin Asymmetries At Intermediate Pseudorapidity In Polarized Proton Collisions At √ S = 200 Gev, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, S. Bültmann, I. Koralt, D. Plyku, Star Collaboration Jan 2014

Neutral Pion Cross Section And Spin Asymmetries At Intermediate Pseudorapidity In Polarized Proton Collisions At √ S = 200 Gev, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, S. Bültmann, I. Koralt, D. Plyku, Star Collaboration

Physics Faculty Publications

The differential cross section and spin asymmetries for neutral pions produced within the intermediate pseudorapidity range 0.8<η/c and is found to agree with a next-to-leading order perturbative QCD calculation. The longitudinal double-spin asymmetry ALL is measured in the same pseudorapidity range and spans a range of Bjorken-x down to x≈0.01. The measured ALL is consistent with model predictions for varying degrees of gluon polarization. The parity-violating asymmetry AL is also measured and found to be consistent with zero. The transverse single-spin asymmetry AN is measured over a previously unexplored kinematic range in Feynman-x and PT. Such measurements may aid our understanding of the onset and kinematic dependence of the large asymmetries observed …

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Ch In Stellar Atmospheres: An Extensive Linelist, T. Masseron, B. Plez, S. Van Eck, R. Colin, I. Daoutidis, M. Godefroid, P.-F. Coheur, P. Bernath, A. Jorissen, N. Christleib Jan 2014

Ch In Stellar Atmospheres: An Extensive Linelist, T. Masseron, B. Plez, S. Van Eck, R. Colin, I. Daoutidis, M. Godefroid, P.-F. Coheur, P. Bernath, A. Jorissen, N. Christleib

Chemistry & Biochemistry Faculty Publications

The advent of high-resolution spectrographs and detailed stellar atmosphere modelling has strengthened the need for accurate molecular data. Carbon-enhanced metal-poor (CEMP) stars spectra are interesting objects with which to study transitions from the CH molecule. We combine programs for spectral analysis of molecules and stellar-radiative transfer codes to build an extensive CH linelist, including predissociation broadening as well as newly identified levels. We show examples of strong predissociation CH lines in CEMP stars, and we stress the important role played by the CH features in the Bond-Neff feature depressing the spectra of barium stars by as much as 0.2 mag …

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Molecular Opacities For Exoplanets, P. F. Bernath Jan 2014

Molecular Opacities For Exoplanets, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

Spectroscopic observations of exoplanets are now possible by transit methods and direct emission. Spectroscopic requirements for exoplanets are reviewed based on existing measurements and model predictions for hot Jupiters and super-Earths. Molecular opacities needed to simulate astronomical observations can be obtained from laboratory measurements, ab initio calculations or a combination of the two approaches. This discussion article focuses mainly on laboratory measurements of hot molecules as needed for exoplanet spectroscopy.

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