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Related papers: Radiative Transfer Effects in He I Emission Lines

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Transmission of He-Ne (632 nm, 10 mW) Gaussian laser beam through Hexane and Water based magnetic nanofluids containing Fe3O4 nanoparticles show strong non-linear and magneto-optical effects. Application of external magnetic field (up to…

Soft Condensed Matter · Physics 2015-09-17 Chintamani Pai , H. Muthurajan , Nooris Momin , Radha Srinivasan , R. Nagarajan

We present optical spectra of the nearby Type Ia supernova SN 2011fe at 100, 205, 311, 349, and 578 days post-maximum light, as well as an ultraviolet spectrum obtained with Hubble Space Telescope at 360 days post-maximum light. We compare…

Using the semiclassical perturbation method, electron-, proton-, and ionized helium-impact line widths and shifts for the nine Cr I spectral lines from the $4p^7P^0-4d^7D$ multiplet, have been calculated for a perturbers density of…

Astrophysics · Physics 2009-11-10 M. S. Dimitrijevic , T. Ryabchikova , L. C. Popovic , D. Shulyak , S. Khan

Precision measurements of the cosmic microwave background temperature anisotropy on scales $\ell > 500$ will be available in the near future. Successful interpretation of these data is dependent on a detailed understanding of the damping…

Astrophysics · Physics 2008-11-26 Eric R. Switzer , Christopher M. Hirata

The determination of the heavy element abundances from giant extragalactic H II regions has been generally based on collisionally excited lines. We will discuss the reasons to study the characteristics of recombination lines, and then use…

Astrophysics · Physics 2007-05-23 Antonio Peimbert , Manuel Peimbert

Mid-infrared atomic and ionic line ratios measured in spectra of pre-main sequence stars are sensitive indicators of the hardness of the radiation field impinging on the disk surface. We present a low-resolution Spitzer IRS search for [Ar…

Earth and Planetary Astrophysics · Physics 2015-06-11 Judit Szulágyi , Ilaria Pascucci , Péter Ábrahám , Dániel Apai , Jeroen Bouwman , Attila Moór

A new, fully dynamic and self-consistent radiation hydrodynamics code, suitable for the calculation of supernovae light curves and continuum spectra, is described. It is a multigroup (frequency-dependent) code and includes all important…

Astrophysics · Physics 2009-10-22 Xiao-he Zhang , Peter Sutherland

We present the first non-LTE time-dependent radiative-transfer simulations of supernovae (SNe) II-Plateau (II-P) covering both the photospheric and nebular phases, from ~10 to >~1000d after the explosion, and based on 1.2B piston-driven…

Solar and Stellar Astrophysics · Physics 2015-05-19 Luc Dessart , D. John Hillier

We present nebular phase optical imaging and spectroscopy and near/mid-IR imaging of the Type II SN 2006bc. Observations reveal the central wavelength of the symmetric H$\alpha$ line profile to be red-shifted with respect to the host galaxy…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Joseph S. Gallagher , B. E. K. Sugerman , Geoffrey C. Clayton , J. E. Andrews , J. Clem , M. J. Barlow , B. Ercolano , J. Fabbri , M. Otsuka , R. Wesson , M. Meixner

The light curves of type-II supernovae (SNe) are believed to be highly affected by recombination of hydrogen that takes place in their envelopes. In this work, we analytically investigate the transition from a fully ionized envelope to a…

High Energy Astrophysical Phenomena · Physics 2019-07-10 Tamar Faran , Tomer Goldfriend , Ehud Nakar , Re'em Sari

We study the formation of photospheric emission lines in O stars and show that the rectangular profiles, sometimes double peaked, that are observed for some stars are a direct consequence of rotation, and it is unnecessary to invoke an…

Solar and Stellar Astrophysics · Physics 2015-06-05 D. John Hillier , Jean-Claude Bouret , Thierry Lanz , Joseph R. Busche

A non-LTE radiative transfer treatment of cis-methyl formate (HCOOCH3) rotational lines is presented for the first time using a set of theoretical collisional rate coefficients. These coefficients have been computed in the temperature range…

Astrophysics of Galaxies · Physics 2015-06-18 Alexandre Faure , Anthony J. Remijan , Krzysztof Szalewicz , Laurent Wiesenfeld

Supernovae of Type IIb contain large fractions of helium and traces of hydrogen, which can be observed in the early and late spectra. Estimates of the hydrogen and helium mass and distribution are mainly based on early-time spectroscopy and…

High Energy Astrophysical Phenomena · Physics 2015-05-19 I. Maurer , P. Mazzali , S. Taubenberger , S. Hachinger

We present high-resolution (FWHM ~ 0.3-1.5 km/s) spectra of interstellar Ca I absorption toward 30 Galactic stars. Comparisons of the column densities of Ca I, Ca II, K I, and other species -- for individual components identified in the…

Astrophysics · Physics 2009-11-07 Daniel E. Welty , L. M. Hobbs , Donald C. Morton

The 133.5 nm lines are important observables for the NASA/SMEX mission Interface Region Imaging Spectrograph (IRIS). To make 3D non-LTE radiative transfer computationally feasible it is crucial to have a model atom with as few levels as…

Solar and Stellar Astrophysics · Physics 2015-09-30 Bhavna Rathore , Mats Carlsson

The radiative transfer equation for spectral lines from an extended gas is derived from first principles, treating the gas as a system of many atoms/molecules rather than isolated ones. Line broadening effects are assumed to be dominated by…

Astrophysics of Galaxies · Physics 2026-01-14 Boy Lankhaar

We apply a recently developed theoretical model of helium emission to observations of both the Orion Nebula and a sample of extragalactic H II regions. In the Orion analysis, we eliminate some weak and blended lines and compare theory and…

Astrophysics · Physics 2008-11-26 R. L. Porter , G. J. Ferland , K. B. MacAdam

We present MUSE deep integral-field unit spectroscopy of three planetary nebulae(PNe) with high abundance discrepancy factors (ADF > 20): NGC 6778, M 1-42 and Hf 2-2. We have constructed flux maps for more than 40 emission lines, and use…

Accurately determining the elemental abundances of a low metallicity nebula strongly depends on measuring the density (n$_e$) and temperature (T$_e$) of the gas. Because these two parameters are inherently degenerate when derived solely…

We have analyzed the temperature, velocity and density of H2 gas in NGC 7023 with a high-resolution near-infrared spectrum of the northwestern filament of the reflection nebula. By observing NGC 7023 in the H and K bands at R ~ 45,000 with…

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