Bulletin of the American Physical Society
2005 36th Meeting of the Division of Atomic, Molecular and Optical Physics
Tuesday–Saturday, May 17–21, 2005; Lincoln, Nebraska
Session B2: Applications of AMO Science to Astrophysics |
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Chair: D. Schultz, Oak Ridge National Laboratory Room: Burnham Yates Conference Center Ballroom II |
Wednesday, May 18, 2005 10:30AM - 11:06AM |
B2.00001: Rovibrationally-Resolved Reactions for Early Universe Chemistry Invited Speaker: Investigations of nonequilibrium chemistry in the postrecombination era of the early Universe and in the formation epoch of the first bound structures only consider total collisional reaction rates, i.e., the dependence on the vibrational and/or rotational level of the reactant and/or product molecular species is neglected. In fact, this is the situation for nearly all cases of astrochemical modeling primarily because of the lack of rovibrationally-resolved data. However, recent studies have suggested that the chemistry may be modified, possibly significantly, if vibrational or rovibrational resolution is considered. I will present new quantal calculations for the forward and reverse reactions, H$^+$ + H $\leftrightarrow$ H$_2^+$($v,J$) + $\nu$, which have considered all 423 bound rovibrational states of H$_2^+$. The reaction cross sections and rate coefficients display significant variation with $v,J$. The role of these processes in a rovibrationally-resolved chemical model will be illustrated for the evolution of H$_2^+$ and H$_2$ in the postrecombination era. [Preview Abstract] |
Wednesday, May 18, 2005 11:06AM - 11:42AM |
B2.00002: Laboratory Cosmology Invited Speaker: Atomic and molecular physics during the early Universe has become a topic of major significance over the last decade. This is due to the recent revolution in our understanding of the cosmological evolution of the Universe. Recent observational, theoretical, and computational advances in cosmology have shifted our understanding of the early Universe from qualitative to quantitative. Concurrent with this shift has been a deeper realization of the cosmological importance of atomic and molecular processes. For example, studies of primordial galaxy and first star formation require accurate models of the hydrogen chemistry during this epoch. As another example, interpreting observations of heavy elements in the high-redshift intergalactic medium (IGM) can be used to constrain the chemical evolution of the early Universe and the formation of the stars which produced these elements. But to do this requires a reliable understanding of the underlying atomic and molecular processes which determine the ionization balance in the IGM. Surprisingly, an accurate understanding is often lacking of the atomic and molecular physics needed to advance these and other cosmological studies. Many of the cosmologically important atomic and molecular processes occur in energy regimes which can be theoretical, computationally, and experimentally challenging or even inaccessible. Here I will report on a series of recent laboratory measurements, theoretical calculations, and modeling studies which we have carried out in order to improve our knowledge of atomic and molecular physics under cosmological conditions and to thereby increase our understanding of the early Universe. [Preview Abstract] |
Wednesday, May 18, 2005 11:42AM - 12:18PM |
B2.00003: X-Ray Emission in the Solar System Invited Speaker: Many objects in the solar system produce x-rays, including the Sun, Venus, Earth, Mars, Jupiter, and comets. A number of emission mechanisms account for this x-ray emission, including scattering and fluorescence of solar x-rays, impact excitation of atoms and molecules by energetic electrons and ions, and by charge transfer of highly charged ions with neutrals. A brief review is provided of these various solar system x-ray sources, but in this talk x-ray emission associated with the Jovian aurora will be emphasized. The first observations of Jupiter made by the Chandra X-Ray Observatory revealed a powerful x-ray aurora located in the polar caps. This x-ray aurora can probably be explained by energetic heavy ion precipitation, either on open field lines connecting to the solar wind or on closed field lines reaching to the outer magnetosphere. Associated electrical currents into the Jovian atmosphere are tens of MA, and this has significant implications for the magnetospheric dynamics and for ionosphere-magnetosphere coupling. [Preview Abstract] |
Wednesday, May 18, 2005 12:18PM - 12:54PM |
B2.00004: Atomic Processes in X-ray Photoioinzed Gas Invited Speaker: It has long been known that photoionization and photoabsorption play a dominant role in determining the state of gas in nebulae surrounding hot stars and in active galaxies. Recent observations of X-ray spectra demonstrate that these processes are also dominant in highly ionized gas near compact objects, and also affect the transmission of X-rays from the majority of astronomical sources. This has led to new insights into the understanding of what is going on in these sources. It has also pointed out the need for a better atomic cross sections for photoionization and absorption, notably for processes involving inner shells. In this talk I will discuss these issues, what is known and where more work is needed. [Preview Abstract] |
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