27 results match your criteria Astrophysical Journal Supplement Series[Journal]

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Inference of the Local Interstellar Spectra of Cosmic-Ray Nuclei ⩽ 28 with the GalProp-HelMod Framework.

Astrophys J Suppl Ser 2020 Oct 29;250(2). Epub 2020 Sep 29.

INFN, Milano-Bicocca, Milano, Italy.

Composition and spectra of Galactic cosmic rays (CRs) are vital for studies of high-energy processes in a variety of environments and on different scales, for interpretation of -ray and microwave observations, for disentangling possible signatures of new phenomena, and for understanding of our local Galactic neighborhood. Since its launch, AMS-02 has delivered outstanding-quality measurements of the spectra of , , and nuclei: H-O, Ne, Mg, Si. These measurements resulted in a number of breakthroughs; however, spectra of heavier nuclei and especially low-abundance nuclei are not expected until later in the mission. Read More

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October 2020

SiO, SiO, and SiO emission from 67 oxygen-rich stars. A survey of 61 maser lines from 7 to 1 mm.

Astrophys J Suppl Ser 2021 Apr 26;253(2). Epub 2021 Mar 26.

Joint Institute for VLBI ERIC (JIVE), Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands.

Circumstellar environments of oxygen-rich stars are among the strongest SiO maser emitters. Physical processes such as collisions, infrared pumping and overlaps favors the inversion of level population and produce maser emission at different vibrational states. Despite numerous observational and theoretical efforts, we still do not have an unified picture including all the physical processes involved in the SiO maser emission. Read More

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Octahedron-based Projections as Intermediate Representations for Computer Imaging: TOAST, TEA, and More.

Astrophys J Suppl Ser 2019 Jan;240(2)

American Astronomical Society 1667 K St NW Suite 800 Washington, DC 20006, USA.

This paper defines and discusses a set of rectangular all-sky projections that have no singular points, notably the Tesselated Octahedral Adaptive Spherical Transformation (or TOAST) developed initially for the WorldWide Telescope. These have proven to be useful as intermediate representations for imaging data where the application transforms dynamically from a standardized internal format to a specific format (projection, scaling, orientation, etc.) requested by the user. Read More

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January 2019

Electron Energy Partition across Interplanetary Shocks. I. Methodology and Data Product.

Astrophys J Suppl Ser 2019 Jul;243(1)

University of California Berkeley, Space Sciences Laboratory, Berkeley, CA, USA.

Analyses of 15,314 electron velocity distribution functions (VDFs) within ±2 hr of 52 interplanetary (IP) shocks observed by the spacecraft near 1 au are introduced. The electron VDFs are fit to the sum of three model functions for the cold dense core, hot tenuous halo, and field-aligned beam/strahl component. The best results were found by modeling the core as either a bi-kappa or a symmetric (or asymmetric) bi-self-similar VDF, while both the halo and beam/strahl components were best fit to bi-kappa VDF. Read More

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SIFTING FOR SAPPHIRES: SYSTEMATIC SELECTION OF TIDAL DISRUPTION EVENTS IN iPTF.

Astrophys J Suppl Ser 2018 Oct 27;238(2). Epub 2018 Sep 27.

Oskar Klein Centre, Department of Physics, Stockholm University, SE 106 91 Stockholm, Sweden.

We present results from a systematic selection of tidal disruption events (TDEs) in a wide-area (4800 deg), + band, Intermediate Palomar Transient Factory (iPTF) experiment. Our selection targets typical optically-selected TDEs: bright (>60% flux increase) and blue transients residing in the center of red galaxies. Using photometric selection criteria to down-select from a total of 493 nuclear transients to a sample of 26 sources, we then use follow-up UV imaging with the Neil Gehrels Swift Telescope, ground-based optical spectroscopy, and light curve fitting to classify them as 14 Type Ia supernovae (SNe Ia), 9 highly variable active galactic nuclei (AGNs), 2 confirmed TDEs, and 1 potential core-collapse supernova. Read More

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October 2018

Climates of Warm Earth-like Planets I: 3-D Model Simulations.

Astrophys J Suppl Ser 2018 Dec 5;239(2). Epub 2018 Dec 5.

NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY, 10025, USA.

We present a large ensemble of simulations of an Earth-like world with increasing insolation and rotation rate. Unlike previous work utilizing idealized aquaplanet configurations we focus our simulations on modern Earth-like topography. The orbital period is the same as modern Earth, but with zero obliquity and eccentricity. Read More

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December 2018

RELATIVISTIC MR-MP ENERGY LEVELS FOR L-SHELL IONS OF SULFUR AND ARGON.

Astrophys J Suppl Ser 2018 Oct 23;238(2). Epub 2018 Oct 23.

Physics Division, LLNL, P.O. Box 808, Livermore, CA 94551, USA.

Calculated level energies for valence and K-vacancy states are provided for the ion series S VII - S XIV and Ar IX - Ar XVI. The calculations were performed with the relativistic Multi-Reference Mxller-Plesset Perturbation Theory method (MR-MP). The data set includes all the level energies with configurations 1 2() , 1 2() , 1 2() , 1 2() , 2() and 2() , where 1 ≤ ≤ 8, ≤ 5 and ≤ 3. Read More

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October 2018

PLANETARY CANDIDATES OBSERVED BY . VIII. A FULLY AUTOMATED CATALOG WITH MEASURED COMPLETENESS AND RELIABILITY BASED ON DATA RELEASE 25.

Astrophys J Suppl Ser 2018 Apr 9;235(2). Epub 2018 Apr 9.

NASA Ames Research Center, Moffett Field, CA 94035, USA.

We present the Kepler Object of Interest (KOI) catalog of transiting exoplanets based on searching four years of time series photometry (Data Release 25, Q1-Q17). The catalog contains 8054 KOIs of which 4034 are planet candidates with periods between 0.25 and 632 days. Read More

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RELATIVISTIC MR-MP ENERGY LEVELS FOR L-SHELL IONS OF SILICON.

Astrophys J Suppl Ser 2018;234. Epub 2018 Jan 15.

Physics Division, LLNL, P.O. Box 808, Livermore, CA 94551, USA.

Level energies are reported for Si V, Si VI, Si VII, Si VIII, Si IX, Si X, Si XI and Si XII. The energies have been calculated with the relativistic Multi-Reference Møller-Plesset Perturbation Theory method and include valence and K-vacancy states with up to 5. The accuracy of the calculated level energies is established by comparison with the recommended data listed in the National Institute of Standards and Technology (NIST) on-line database. Read More

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January 2018

An Infrared Spectroscopic Study Toward the Formation of Alkylphosphonic Acids and Their Precursors in Extraterrestrial Environments.

Astrophys J Suppl Ser 2018 Jan 12;234(1). Epub 2018 Jan 12.

W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA;

The only known phosphorus-containing organic compounds of extraterrestrial origin, alkylphosphonic acids, were discovered in the Murchison meteorite and have accelerated the hypothesis that reduced oxidation states of phosphorus were delivered to early Earth and served as a prebiotic source of phosphorus. While previous studies looking into the formation of these alkylphosphonic acids have focused on the iron-nickel phosphide mineral schreibersite and phosphorous acid as a source of phosphorus, this work utilizes phosphine (PH), which has been discovered in the circumstellar envelope of IRC +10216, in the atmosphere of Jupiter and Saturn, and believed to be the phosphorus carrier in comet 67P/Churyumov-Gerasimenko. Phosphine ices prepared with interstellar molecules such as carbon dioxide, water, and methane were subjected to electron irradiation, which simulates the secondary electrons produced from galactic cosmic rays penetrating the ice, and probed using infrared spectroscopy to understand the possible formation of alkylphosphonic acids and their precursors on interstellar icy grains that could become incorporated into meteorites such as Murchison. Read More

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January 2018

The Planetary Nebula Survey (HerPlaNS): A Comprehensive Dusty Photoionization Model of NGC6781.

Astrophys J Suppl Ser 2017 Aug 18;231(2). Epub 2017 Aug 18.

Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B-3001, Leuven, Belgium.

We perform a comprehensive analysis of the planetary nebula (PN) NGC 6781 to investigate the physical conditions of each of its ionized, atomic, and molecular gas and dust components and the object's evolution, based on panchromatic observational data ranging from UV to radio. Empirical nebular elemental abundances, compared with theoretical predictions via nucleosynthesis models of asymptotic giant branch (AGB) stars, indicate that the progenitor is a solar-metallicity, 2.25-3. Read More

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Exploring the SDSS Dataset with Linked Scatter Plots: I. EMP, CEMP, and CV Stars.

Astrophys J Suppl Ser 2017 Feb 9;228(2). Epub 2017 Feb 9.

NASA Ames Research Center, NASA Advanced Supercomputing Facility, Moffett Field, CA, 94035-1000, USA.

We present the results of a search for EMP, CEMP, and cataclysmic variable stars using a new exploration tool based on linked scatter plots (LSPs). Our approach is especially designed to work with very large spectrum data sets such as the SDSS, LAMOST, RAVE, and Gaia data sets and can be applied to stellar, galaxy, and quasar spectra. As a demonstration, we conduct a search for EMP, CEMP, and cataclysmic variable stars in the SDSS DR10 data set. Read More

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February 2017

IMPROVED Cr II log( ) VALUES AND ABUNDANCE DETERMINATIONS IN THE PHOTOSPHERES OF THE SUN AND METAL-POOR STAR HD 84937.

Astrophys J Suppl Ser 2017 Jan 20;228(1). Epub 2017 Jan 20.

Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019, USA.

New emission branching fraction (BF) measurements for 183 lines of the second spectrum of chromium (Cr II) and new radiative lifetime measurements from laser-induced fluorescence for 8 levels of Cr are reported. The goals of this study are to improve transition probability measurements in Cr II and reconcile solar and stellar Cr abundance values based on Cr I and Cr II lines. Eighteen spectra from three Fourier Transform Spectrometers supplemented with ultraviolet spectra from a high-resolution echelle spectrometer are used in the BF measurements. Read More

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January 2017

The Infrared Spectra of Polycyclic Aromatic Hydrocarbons with Excess Peripheral H Atoms (H-PAHs) and their Relation to the 3.4 and 6.9 µm PAH Emission Features.

Astrophys J Suppl Ser 2013;205(1). Epub 2013 Mar 1.

SETI Institute, 189 Bernardo Ave, Suite 100, Mountain View, CA 94043.

Polycyclic aromatic hydrocarbons (PAHs) are likely responsible for the family of infrared emission features seen in a wide variety of astrophysical environments. A potentially important subclass of these materials are PAHs whose edges contain excess H atoms (H-PAHs). This type of compound may be present in space, but it has been difficult to assess this possibility because of a lack of suitable laboratory spectra to assist with analysis of astronomical data. Read More

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A line survey of Orion KL from 325 to 360 GHz.

Astrophys J Suppl Ser 1997 Jan;108(1):301-37

Department of Physics, California Institute of Technology, Pasadena 91125, USA.

We present a high-sensitivity spectral line survey of the high-mass star-forming region Orion KL in the 325-360 GHz frequency band. The survey was conducted at the Caltech Submillimeter Observatory on Mauna Kea, Hawaii. The sensitivity achieved is typically 0. Read More

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January 1997

Parameterization of spectral distributions for pion and kaon production in proton-proton collisions.

Astrophys J Suppl Ser 1995 Apr;97(2):571-4

Physics Department, University of Wisconsin, La Crosse 54601, USA.

Accurate semi-empirical parameterizations of the energy-differential cross sections for charged pion and kaon production from proton-proton collisions are presented at energies relevant to cosmic rays. The parameterizations depend on the outgoing meson momentum and also the proton energy, and are able to be reduced to very simple analytical formulas suitable for cosmic-ray transport. Read More

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The molecular emission-line spectrum of IRC +10216 between 330 and 358 GHz.

Astrophys J Suppl Ser 1994 Sep;94(1):147-62

Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena 91125, USA.

We have conducted a spectral line survey of IRC +10216 using the Caltech Submillimeter Observatory to an average sensitivity of < or approximately 95 mK. A deconvolution algorithm has been used to derive the continuous single-sideband spectrum from 330.2 to 358. Read More

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September 1994

Cross section parameterizations for cosmic-ray nuclei. II. Double nucleon removal.

Astrophys J Suppl Ser 1994 Jan;90:115-7

Physics Department, University of Wisconsin, La Crosse 54601, USA.

Parameterizations of double nucleon removal from the electromagnetic and strong interactions of cosmic rays with nuclei are presented. These parameterizations are an extension of previous single nucleon removal parameterizations and combined they represent the dominant part of the electromagnetic dissociation encountered by a cosmic ray on its traversal through matter. Such parameterizations should be very useful in studying cosmic-ray transport through the interstellar medium, the Earth's atmosphere, spacecraft walls, and extraterrestrial matter. Read More

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January 1994

The spectrum of Orion-KL at 2 millimeters (150-160 GHz).

Astrophys J Suppl Ser 1993 Nov;89(1):155-87

Department of Chemistry, Arizona State University, Tempe 85287-1604, USA.

A spectral survey of Orion-KL has been carried out in the 2 mm atmospheric window in the frequency range 149.6-159.6 GHz, using the FCRAO 14 m telescope. Read More

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November 1993

Mid- and far-infrared spectroscopy of ices: optical constants and integrated absorbances.

Astrophys J Suppl Ser 1993 Jun;86:713-870

NASA/Ames Research Center, Moffett Field, CA 94035, USA.

Laboratory spectra through the mid-infrared (4000 to 500 cm-1 [2.5-20 micrometers]) have been used to calculate the optical constants (n and k) and integrated absorption coefficients (A) for a variety of pure and mixed molecular ices of relevance to astrophysics. The ices studied were H2O, CH3OH, CO2, OCS, CH4, CO2 + CH4, CO2 + OCS, CO + CH4, CO + OCS, O2 + CH4, O2 + OCS, N2 + CH4, N2 + OCS, H2O + CH4, H2O + OCS, and H2O + CH3OH + CO + NH3. Read More

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Cross section parameterizations for cosmic-ray nuclei. I. Single nucleon removal.

Astrophys J Suppl Ser 1993 May;86(1):307-12

Physics Department, University of Wisconsin, La Crosse 54601.

Parameterizations of single nucleon removal from the electromagnetic and strong interactions of cosmic rays with nuclei are presented. These parameterizations are based upon the theoretical models developed by Baur, Bertulani, Benesh, Cook, Vary, Norbury, and Townsend. They should be very suitable for use in cosmic-ray propagation through interstellar space, Earth's atmosphere, lunar samples, meteorites, spacecraft walls, and lunar and martian habitats. Read More

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Improved collisional excitation rates for interstellar water.

Astrophys J Suppl Ser 1993 Mar;85:181-5

NASA Goddard Space Flight Center, Institute for Space Studies, New York 10025.

Theoretical rate constants among the lowest 45 para and 45 ortho rotational levels of water in collisions with He atoms have been calculated for temperatures between 20 and 2000 K using a recently improved theoretical interaction potential. These values are about 30%-40% larger than those reported previously (Palma et al. 1988b) but relative sizes of different state-to-state rates have not changed significantly. Read More

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Interstellar polycyclic aromatic hydrocarbons: the infrared emission bands, the excitation/emission mechanism, and the astrophysical implications.

Astrophys J Suppl Ser 1989 Dec;71:733-75

Space Science Division, NASA-Ames Research Center, USA.

This article presents a comprehensive treatment of the polycyclic aromatic hydrocarbon (PAH) hypothesis. The interstellar, infrared spectral features which have been attributed to emission from highly vibrationally excited PAHs are discussed in detail. These include major (most intense) bands at 3040, 1615, "1310," 1150, and 885 cm-1 (3. Read More

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December 1989

Collisional excitation of interstellar water.

Astrophys J Suppl Ser 1988 Oct;68:287-318

Chemistry Department, Columbia University, USA.

Rates for rotational excitation of water molecules in collisions with He atoms have been obtained from a new, accurate theoretical interaction potential. Rates among the lowest 40 ortho levels are given for kinetic temperatures to 1400 K and among the lowest 29 para levels for kinetic temperatures to 800 K. Read More

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October 1988

Collisional excitation of interstellar cyclopropenylidene.

Astrophys J Suppl Ser 1987 Sep;65(1):175-91

NASA/Goddard Space Flight Center, Institute for Space Studies, New York, USA.

Theoretical rotational excitation rates were computed for C3H2 in collisions with He atoms at temperatures from 30 to 120 K. The intermolecular forces were obtained from accurate self-consistent field and perturbation theory calculations, and collision dynamics were treated within the infinite-order sudden approximation. The accuracy of the latter was examined by comparing with the more exact coupled states approximation. Read More

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September 1987

Photochemistry of the atmosphere of Titan: comparison between model and observations.

Astrophys J Suppl Ser 1984 Jul;55(3):465-506

Division of Geological and Planetary Sciences, California Institute of Technology, USA.

The photochemistry of simple molecules containing carbon, hydrogen, nitrogen, and oxygen atoms in the atmosphere of Titan has been investigated using updated chemical schemes and our own estimates of a number of key rate coefficients. Proper exospheric boundary conditions, vertical transport, and condensation processes at the tropopause have been incorporated into the model. It is argued that he composition, climatology, and evolution of Titan's atmosphere are controlled by five major processes: (a) photolysis and photosensitized dissociation of CH4; (b) conversion of H to H2 and escape of hydrogen; (c) synthesis of higher hydrocarbons; (d) coupling between nitrogen and hydrocarbons; (e) coupling between oxygen and hydrocarbons. Read More

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