Origins of the Ambient Solar Wind: Implications for Space Weather

The Sun's outer atmosphere is heated to temperatures of millions of degrees, and solar plasma flows out into interplanetary space at supersonic speeds. This paper reviews our current understanding of these interrelated problems: coronal heating and the acceleration of the ambient solar wind. We also discuss where the community stands in its ability to forecast how variations in the solar wind (i.e., fast and slow wind streams) impact the Earth. Although the last few decades have seen significant progress in observations and modeling, we still do not have a complete understanding of the relevant physical processes, nor do we have a quantitatively precise census of which coronal structures contribute to specific types of solar wind. Fast streams are known to be connected to the central regions of large coronal holes. Slow streams, however, appear to come from a wide range of sources, including streamers, pseudostreamers, coronal loops, active regions, and coronal hole boundaries. Complicating our understanding even more is the fact that processes such as turbulence, stream-stream interactions, and Coulomb collisions can make it difficult to unambiguously map a parcel measured at 1 AU back down to its coronal source. We also review recent progress -- in theoretical modeling, observational data analysis, and forecasting techniques that sit at the interface between data and theory -- that gives us hope that the above problems are indeed solvable.Comment: Accepted for publication in Space Science Reviews. Special issue connected with a 2016 ISSI workshop on "The Scientific Foundations of Space Weather." 44 pages, 9 figure

Digital Representation of the Geologic Map of the Little Horn 30' x 60' Quadrangle, Southwestern Arizona

Digital Representation of the Geological Map of the Salome 30’ x 60’ Quadrangle, West-Central Arizona, by S.M. Richard, J.E. Spencer, & S.J. Reynolds, digitized by Jennifer P. Thieme and edited by Stephen M. RichardDocuments in the AZGS Document Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact [email protected]

Effect of Water Addition during Preparation on the Early-Time Photodynamics of CH3NH3PbI3 Perovskite Layers

The effect of water addition during preparation of a CH3NH3PbI3 layer on the photodynamics is studied by femtosecond transient absorption. Both the regular perovskite and the aqueous analogue show charge thermalisation on a timescale of about 500fs. This process is, however, less pronounced in the latter layer. The spectral feature associated with hot charges does not fully decay on this timescale, but also shows a long-lived (sub-ns) component. As water molecules may interfere with the hydrogen bonding between the CH3NH3 + cations and the inorganic cage, this effect is possibly caused by immobilisation of cation motion, suggesting a key role of CH3NH3 + dipole reorientation in charge thermalisation. This effect shows the possibility of controlling hot charge carrier cooling to overcome the Shockley-Queisser limit