Dr
Sylvaine TURCK-CHIÈZE
(CEA)
01/08/2017, 09:00
Atomic Opacities
Invited talks
Stellar opacities are fundamental ingredients of stellar evolution. They contribute to the age of stars and determine the transfer of energy in stellar interiors for a great variety of stars. This transfer of energy results from complex and difficult atomic calculations that must be performed for a large number of species and for specific mixtures through a large range of temperature and...
Prof.
Sarbani Basu
(Yale University)
01/08/2017, 09:40
Atomic Opacities
Invited talks
Helioseismology has allowed us to determine the structure and dynamics of the Sun to an unprecedented accuracy and precision. This allows us to test different solar models against the Sun to determine which model is good. By comparing models constructed with different physics, we can determine which physics inputs work better, and thus use the Sun as a laboratory to test the physics of stellar...
Dr
Regner Trampedach
(Space Science Institute)
01/08/2017, 10:20
Atomic Opacities
Contributed talks
Is the Sun likely to have a more opaque interior than previously thought?
The solar oxygen- (or abundance-) problem can be solved with higher interior opacities, reconciling abundance analysis based on 3D convective atmospheres, with the helioseismic structure of the solar interior. This has been known for more than a decade. But last year we learned that the absorption by just iron,...
Dr
Jean-Christophe Pain
(Commissariat a l'Energie Atomique (CEA))
01/08/2017, 11:00
Atomic Opacities
Invited talks
The opacities computed by different codes for astrophysical applications may show significant differences. In this work, we discuss some important issues, such as the number of configurations, levels and lines included in the calculations, the accounting for configuration interaction or the breakdown of statistical methods. The essential role of laboratory experiments to check the quality of...
Dr
David Kilcrease
(LANL)
01/08/2017, 11:40
Atomic Opacities
Invited talks
Radiative opacities are important quantities that contribute to the prediction of radiation transport in astrophysical objects. To calculate these opacities requires a knowledge of all electron energy level populations that can contribute significantly to photoabsorption and photon scattering in the mostly plasma environments of these objects. This can be a daunting task. Unlike a...
Dr
Robert Kurucz
(Harvard-Smithsonian Center for Astrophysics)
01/08/2017, 12:20
Atomic Opacities
Invited talks
I present a progress report on including all the lines in the line lists, including all the lines in the opacities, and including all the lines in the model atmosphere and spectrum synthesis calculations. The increased opacity will improve stellar atmosphere, pulsation, asteroseismology, nova, supernova, and other radiation-hydrodynamics calculations. I also report on using stellar atlases to...
Prof.
Peter Bernath
(Old Dominion University)
01/08/2017, 14:00
Molecular Opacities
Invited talks
The atmospheres of cool astronomical objects are full of molecules. The spectra of cool stars, brown dwarfs, planets and exoplanets are dominated by molecular bands and the classification of these objects depends largely on molecular features. Compared to atoms, molecules have many more lines because of vibrational and rotational degrees of freedom, which lead to complex spectra from the...
Dr
Xinchuan Huang
(SETI/NASA Ames)
01/08/2017, 14:40
Molecular Opacities
Invited talks
The fast-growing infrared databases are still not complete or accurate enough to subtract the IR contributions of simple astrophysical molecules so that scientists may identify more "hidden flowers", or to carry out accurate IR simulations at very high temperature. Reasons include, but not limited to, the spectrum complexity, experimental difficulty, and the lack of robust theoretical models. ...
Prof.
Peter Bernath
(Old Dominion University)
01/08/2017, 15:20
Molecular Opacities
Contributed talks
Molecular opacities are based on line lists for small molecules and absorption cross sections for larger molecules. In this talk research results from our laboratory will be surveyed on the preparation of line lists for diatomic molecules such as CN, NH, OH, OH$^+$, C$_2$, etc. using experimental measurements with a Fourier transform spectrometer for line positions and ab initio dipole moment...
Prof.
Nuria Calvet
(University of Michigan)
01/08/2017, 16:00
Molecular Opacities
Invited talks
Stars are born surrounded by protoplanetary disks, formed as rotating molecular cloud cores collapse conserving angular momentum. The makeup of these disks is originally similar to the ISM, namely, around 99% gas and 1% solid grains, “dust”. These proportions change with time with most of the gas ending in the stars and planets or being photoevaporated, and solids remaining in rocky planets...
Dr
Caroline Morley
(Harvard University)
01/08/2017, 16:40
Molecular Opacities
Invited talks
The formation of clouds and hazes in exoplanet and brown dwarf atmospheres shapes their observed spectra. The species that condense readily in these atmospheres range from the common, like water and ammonia ices, to the more obscure, like sodium sulfide and potassium chloride. One of the most important dust species is silicate, including enstatite and forsterite. Optical properties for these...
Dr
Georges Alecian
(CNRS, Observatoire de Paris)
02/08/2017, 09:00
Atomic Opacities
Invited talks
Atomic diffusion processes may significantly change the distribution of chemical elements inside the stars. Being slow, these processes gain importance in zones where the mixing processes are very weak or absent, i.e. in the radiative zones. However, the modified abundances in these stable zones may contaminate zones where mixing occurs. In some cases, the internal structure of the star can be...
Dr
Morgan Deal
(Observatoire de Paris)
02/08/2017, 09:40
Atomic Opacities
Contributed talks
Atomic diffusion, including the effect of radiative accelerations on individual elements, leads to important variations of the chemical composition inside the stars. The accumulation in specific layers of the elements, which are the main contributors of the local opacity, leads to hydrodynamical instabilities that modify the internal stellar structure and surface abundances. In this talk we...
Mr
Jakub Fišák
(Masaryk University)
02/08/2017, 10:00
Atomic Opacities
Contributed talks
There are many different opacity sources in the stellar atmospheres.
Because of limited computational time and memory the less important
opacity sources are usually neglected in stellar atmosphere models.
Rayleigh scattering is one of such opacities that are frequently neglected
in model atmospheres. But this neglect could not be valid for every case.
We study influence of the Rayleigh...
Dr
James Bailey
(Sandia National Laboratories)
02/08/2017, 10:21
Atomic Opacities
Contributed talks
Laboratory opacity experiments have been developed at the Sandia Z facility over the last fifteen years. Model predictions for iron opacity are notably different from measurements performed at conditions similar to the boundary between the solar radiation and convection zone [J.E. Bailey et al., Nature 517, 56 (2015)]. In this presentation we describe the experimental methods, some of the...
Dr
Taisuke Nagayama
(Sandia National Laboratories)
02/08/2017, 11:00
Atomic Opacities
Invited talks
Model predictions for iron opacity are notably different from measurements performed at matter conditions similar to the boundary between the solar radiation and convection zones [1]. The calculated iron opacities have narrower spectral lines, weaker quasi-continuum at short wavelength, and deeper opacity windows than the measurements. If correct, these measurements help resolve a decade old...
Dr
Ted Perry
(Los Alamos National Laboratory)
02/08/2017, 11:40
Atomic Opacities
Invited talks
Recent iron opacity experiments on the Sandia National Laboratories Z machine have shown up to factors of two discrepancies between theory and experiment. Much effort has been put into looking at the experiment and the opacity theories but a resolution of the discrepancies has not been forthcoming. It is emphasized that the discrepancies present a fundamental theoretical challenge. To help...
Dr
Arnaud Colaitis
(LLNL / CELIA)
02/08/2017, 12:20
Atomic Opacities
Invited talks
It has been known for practically two decades that facilities like OMEGA should be well adapted to study the stellar plasma physics. Experiments on various laser facilities (LULI2000, OMEGA, ORION) and on pulsed-power devices (Z pinches at the Sandia laboratory and Imperial College) have put in evidence the astrophysical problems to solve, the challenges ahead and the different techniques to...
Prof.
Shashi Kanbur
(SUNY Oswego)
02/08/2017, 14:00
Atomic Opacities
Invited talks
We review the role of opacities in classical stellar pulsation - specifically in Cepheids and RR Lyres: two groups of pulsating variable stars that have crucial roles in the age and distance scale. We review the success of a previous revision of astrophysical opacities in ameliorating the Cepheid bump mass discrepancy and assess the possible impact of a further increase in Rosseland mean...
Prof.
Jiri Krticka
(Masaryk University)
02/08/2017, 14:40
Atomic Opacities
Contributed talks
Opacity variation across the stellar surface is the key aspect of the spectral
energy distribution (SED) variability in chemically peculiar stars. The opacity
variations are caused by the presence of surface spots with enhanced (or
depleted) abundance of individual elements. Simulations of the SED variability
of chemically peculiar stars with abundances derived from Doppler...
Dr
Aaron Sigut
(The University of Western Ontario)
02/08/2017, 15:00
Atomic Opacities
Contributed talks
I will describe the operation and atomic data requirements of the Bedisk and Beray codes which can be used to compute synthetic spectra and images for a star surrounded by a circumstellar disk. The Bedisk code computes the thermal structure of the disk based on the central star's photoionizing radiation field by enforcing radiative equilibrium in a gas of a user-specified chemical composition....
Dr
Alex Lobel
(Royal Observatory of Belgium)
02/08/2017, 15:20
Atomic Opacities
Contributed talks
BRASS is an international networking project of the Federal Government of Belgium for the development of a new public database providing accurate fundamental atomic data of vital importance for stellar spectroscopic research. We present an update of its mid-term development status. The BRASS database will offer atomic line data we thoroughly test by comparing theoretical and observed stellar...
Dr
Clara Sousa-Silva
(MIT)
02/08/2017, 16:00
Molecular Opacities
Contributed talks
The search for biosignatures requires a sophisticated understanding of exoplanet atmospheres and the molecules within them. Current atmospheric models consider only a few dominant molecules, all of which can lead to false positives in the remote detection of life.
The rich tapestry of life makes use of thousands of molecular species that could contribute towards a biosphere and its...
42.
Monte Carlo simulations of biophysical factors for viability of life in exoplanetary atmospheres
Prof.
Anil Pradhan
(Ohio State University)
02/08/2017, 16:20
Molecular Opacities
Contributed talks
We propose to adapt the Monte Carlo package GEANT4, developed by CERN, to simulate the effects of radiation fields of stars on exoplanet atmospheres and explore the possibility of DNA-based lifeforms. Stellar spectral profiles from cool dwarfs will be subject to quasi-monochromatic intensity modulations by chemical constituents of exoplanetary atmospheres, represented as phantoms using...
Dr
Iouli Gordon
(Harvard-Smithsonian Center for Astrophysics)
03/08/2017, 09:00
Molecular Opacities
Invited talks
The HITRAN database is an international standard for reference molecular spectroscopic data. It is widely used in many fields of engineering and science including astrophysics. In this talk the new edition (HITRAN2016) will be introduced. It features almost 50 molecules in the line-by-line section of the database, over 300 molecules in the cross-sectional part, as well as aerosol and...
38.
The ExoMol project: molecular line lists for the opacity of exoplanets and other hot atmospheres
Prof.
Jonathan Tennyson
(University College London)
03/08/2017, 09:40
Molecular Opacities
Invited talks
The ExoMol project provides comprehensive line lists with the aim of providing data for all molecules likely to be observable in exoplanet atmospheres in the foreseeable future [1]. This is a huge undertaking which involves providing in excess of a hundred of billion spectral lines for a large variety of molecular species [2]. The physics of molecular absorptions is complex and varies between...
Dr
Mark Zammit
(Los Alamos National Laboratory)
03/08/2017, 10:20
Molecular Opacities
Contributed talks
Studies of molecular plasmas both in local thermodynamic equilibrium (LTE) and non-LTE require state-resolved (electronic, vibrational and rotationally resolved) transition cross sections or rate coefficients to calculate populations (for non-LTE plasmas), opacities and emissivities. For both electron- and photon-molecule data there is a lack of comprehensive state-resolved data available,...
Prof.
Anil Pradhan
(Ohio State University), Prof.
Sultana Nahar
(Ohio State University)
03/08/2017, 11:00
Atomic Opacities
Invited talks
The Opacity Project was launched in 1983 with the goal of calculating astrophysical opacities using state-of-the-art atomic physics based on the coupled channel (CC) approximation employing the powerful R-Matrix (RM) method [1]. Over the next decade, a suite of extended RM codes were developed to compute large-scale bound-bound transition strengths and bound-free photoionization cross sections...
Mr
Lianshui zhao
(The Ohio State University)
03/08/2017, 11:40
Atomic Opacities
Contributed talks
We have carried out converged close coupling R-Matrix (CCC-RM) calculations for photoionization of Ne-like Fe XVII and demonstrated orders-of-magnitude enhancements in cross section due to successive core excitations. Convergence criteria are: (i) inclusion of sufficient number of residual ion Fe XVIII core states, (ii) high-resolution of myriad autoionizing resonances, and (iii) high-energy...
Dr
Stephanie Hansen
(Sandia National Laboratory)
03/08/2017, 12:00
Atomic Opacities
Invited talks
Opacity calculations of multi-electron ions in hot, dense plasmas, such as iron in the solar photosphere, require a complete accounting of myriad radiative transitions. One strategy for developing generally reliable and computationally tractable opacity models is to simplify some portion of these transitions while preserving a high level of fidelity in others. This approach ensures both...
Dr
Franck Delahaye
(Observatoire de Paris, France)
03/08/2017, 14:00
Atomic Opacities
Invited talks
The present debate on the reliability of the opacities for astrophysics, ignited initially by the solar convection zone problem, has reached the present climax with the new measurement of the Fe opacities on the Z-machine at the Sandia National Laboratory (Bailey et al. 2015). In order to understand the differences between all the theoretical results, on the one side, and experiments on the...
Dr
James Colgan
(LANL)
03/08/2017, 14:40
Atomic Opacities
Contributed talks
A new set of Los Alamos OPLIB opacity tables for the elements hydrogen through zinc have recently been released [1] and are available online [2]. Our tables have been computed using the Los Alamos ATOMIC code [3,4], which make use of atomic structure calculations from the Los Alamos suite of atomic physics codes [5] that include fine-structure detail for all the elements considered. The...
Prof.
Doron Gazit
(Hebrew University of Jerusalem;Racah Institute of Physics)
03/08/2017, 15:01
Atomic Opacities
Invited talks
Plasma effects in the extreme properties of the solar interior are a major source of uncertainty in the calculation of solar opacities. With the decade old problem of solar opacity in mind, I use the atomic code STAR to show a recent study of two major plasma effects on the solar profile, namely ionic correlations and line broadening. These effects are untested in the relevant thermodynamic...
Dr
Patrick Palmeri
(Physique Atomique et Astrophysique, Université de Mons - UMONS, B-7000 Mons, Belgium)
03/08/2017, 16:00
Atomic Opacities
Contributed talks
X-ray emission lines from accreting black holes, most notably K-lines, have observed
widths and shifts which imply an origin very close to the compact object [1]. The
intensity of these lines can provide insight into the effects of special and general relativity
in the emitting region as well as insight into some properties of the compact object itself.
Magnetohydrodynamics simulations of...
Dr
Javier Garcia
(California Institute of Technology)
03/08/2017, 16:20
Atomic Opacities
Contributed talks
In most accreting black hole systems copious X-rays are emitted from the
inner-most regions commonly observed accompanied by a reflection spectrum, which
shows signatures of energetic photons being reprocessed by the optical thick
material of an accretion disk. Given their abundance and fluorescence yield,
K-shell lines from iron are the most prominent in the X-ray reflected...
Dr
Patrick Palmeri
(Physique Atomique et Astrophysique, Université de Mons - UMONS, B-7000 Mons, Belgium)
04/08/2017, 09:00
Atomic Opacities
Contributed talks
Accurate oscillator strengths for electric
dipole transitions in singly ionized yttrium
(Y II) are needed
for the determination of the yttrium abundance
in stellar atmospheres. A recent example is the
determination of the abundance ratio [Y/Mg] in
solar twins that provides a sensitive chronometer
for Galactic evolution [1,2]. Moreover, high excitation
lines have additional diagnostic...
Dr
Muhammet Fatih Hasoglu
(Hasan Kalyoncu University)
04/08/2017, 09:20
Atomic Opacities
Contributed talks
As a part of an ongoing theoretical atomic physics and laboratory astrophysics research program at WMU, we have calculated highly accurate atomic photoabsorption cross sections using the most robust theoretical methods available. These include the widely used Belfast R-matrix, C. F. Fischer's MCHF, and Strathclyde AUTOSTRUCTURE computer program packages, and are further optimized to treat all...
Dr
Jagjit Kaur
(Western Michigan University)
04/08/2017, 09:40
Atomic Opacities
Contributed talks
To model the spectral features observed with astronomical observatories, an accurate and complete description of relevant atomic processes occurring in stellar environments is required. Among these are the important dielectronic recombination (DR) and radiative recombination (RR) processes, which we have investigated for the entire silicon-like isoelectronic sequence. We report reliable DR and...
Mr
Jérôme Deprince
(Physique Atomique et Astrophysique, Université de Mons - UMONS, B-7000 Mons, Belgium), Dr
Patrick Palmeri
(Physique Atomique et Astrophysique, Université de Mons - UMONS, B-7000 Mons, Belgium)
Atomic Opacities
Poster presentations
The observed widths and shifts of X-ray emission K-lines from accreting black holes imply that they are formed in a region very close to the compact object [1]. The intensity of these lines can give some insight into the effects of special and general relativity in the emitting region as well as information about some properties of the compact object itself. Magnetohydrodynamics simulations of...
Prof.
Jiri Krticka
(Masaryk University)
Atomic Opacities
Poster presentations
We describe our own global (unified) hydrodynamical models of expanding
atmospheres of hot stars. The models solve hydrodynamic, kinetic
equilibrium (also known as NLTE), and comoving-frame (CMF) radiative
transfer equations consistently from the (nearly) hydrostatic
photosphere to the supersonic wind. The model input parameters are the
stellar effective temperature, radius, mass, and...
Dr
Morgan Deal
(Observatoire de Paris)
Atomic Opacities
Poster presentations
A number of Main Sequence B-type stars, like $\nu$ Eri, $\kappa$ Cen, a Car, $\kappa$ Vel, present oscillations which may be accounted for by opacity mechanisms, provided that the stellar opacity be larger than the standard computed one, at least in some specific layers. This has been studied by several authors, who computed "ad hoc" opacity profiles able to reproduce the observations. Here we...
Dr
Moncef Bouledroua
(Département de Médecine and Laboratoire de Physique des Rayonnements, Badji Mokhtar University, Annaba, Algeria)
Molecular Opacities
Poster presentations
In a recent paper [Barlow *et al.*, Science **342,** 1343 (2013)], the ArH$^{+}$ ionic system has been detected in the Crab Nebula. We accordingly propose to examine in this work the radiative association of the argon ions $^{36}$Ar$^{+}$ and $^{38}$Ar$^{+}$ with atomic hydrogen and calculate the related temperature-dependent rate coefficients. To do so, we have to construct the transition...
Ms
Alisa Galishnikova
(Moscow Institute of Physics and Technology, Dolgoprudny, Russia), Mr
Egor Novoselov
(Moscow Institute of Physics and Technology, Dolgoprudny, Russia)
Atomic Opacities
Poster presentations
The wave propagation [1] theory based on Kravtsov & Orlov approach outlined the general aspects of the theory of radio light curve and polarization formation for radio pulsars. It allowed us to describe general properties of mean profiles such as the position angle of the linear polarization *p.a.* and the circular polarization for the realistic structure of the magnetic field in the pulsar...
Ms
Madhushani Wickramarathna
(Western Michigan University)
Atomic Opacities
Poster presentations
Double photoionization calculations are performed for atomic oxygen which leaves a residual ion core with a complicated electron structure. An R-matrix with pseudostates (RMPS) method (P. G. Burke, R-matrix Theory of Atomic Collisions, Springer, 2011) is successfully applied to compute the double photoionization cross sections that are in overall agreement with recent experimental results at...
Mr
Menahem Krief
(Hebrew University of Jerusalem;Racah Institute of Physics)
Atomic Opacities
Poster presentations
We present a novel implementation of the STA model, called STAR (STA-Revised), which was written from scratch. The model is based on the theory of Bar-Shalom and Oreg [1] with various improvements. A comparison with other atomic codes was performed and a good agreement was reached. The model is used to calculate and analyze solar opacities. We also implemented a model for the solution of the...
Dr
Moncef Bouledroua
(Faculté de Médecine & L.P.R., Badji Mokhtar University, B.P. 205, Annaba 23000, Algeria)
Molecular Opacities
Poster presentations
The atmospheric chemistry revealed the importance of the ionic nitrogen in the ionosphere. This is why, over the last few decades, the diffusion and mobility phenomena of this ion have been widely investigated experimentally at different temperatures. More recent experiments of ionic open-shell systems, such as C$^{+}$ and N$^{+}$ ions, evolving in very weakly ionized plasmas have been...
Mr
Mike Laverick
(KU Leuven)
Atomic Opacities
Poster presentations
Accurate atomic data is a vital component of almost every branch of astrophysics. All models and descriptions of stellar evolution, atmospheres, formation and internal structures are governed by the fundamental atomic data available to the astrophysical community. As such, errors and uncertainties in adopted atomic data can systematically propagate throughout the entire field of...
