Polarimetric Properties of Flux-Ropes and Sheared Arcades in Coronal Prominence Cavities

The coronal magnetic field is the primary driver of solar dynamic events. Linear and circular polarization signals of certain infrared coronal emission lines contain information about the magnetic field, and to access this information, either a forward or an inversion method must be used. We study three coronal magnetic configurations that are applicable to polar-crown filament cavities by doing forward calculations to produce synthetic polarization data. We analyze these forward data to determine the distinguishing characteristics of each model. We conclude that it is possible to distinguish between cylindrical flux ropes, spheromak flux ropes, and sheared arcades using coronal polarization measurements. If one of these models is found to be consistent with observational measurements, it will mean positive identification of the magnetic morphology that surrounds certain quiescent filaments, which will lead to a greater understanding of how they form and why they erupt.Comment: 22 pages, 8 figures, Solar Physics topical issue: Coronal Magnetis

On the structure and evolution of a polar crown prominence/filament system

Polar crown prominences are made of chromospheric plasma partially circling the Suns poles between 60 and 70 degree latitude. We aim to diagnose the 3D dynamics of a polar crown prominence using high cadence EUV images from the Solar Dynamics Observatory (SDO)/AIA at 304 and 171A and the Ahead spacecraft of the Solar Terrestrial Relations Observatory (STEREO-A)/EUVI at 195A. Using time series across specific structures we compare flows across the disk in 195A with the prominence dynamics seen on the limb. The densest prominence material forms vertical columns which are separated by many tens of Mm and connected by dynamic bridges of plasma that are clearly visible in 304/171A two-color images. We also observe intermittent but repetitious flows with velocity 15 km/s in the prominence that appear to be associated with EUV bright points on the solar disk. The boundary between the prominence and the overlying cavity appears as a sharp edge. We discuss the structure of the coronal cavity seen both above and around the prominence. SDO/HMI and GONG magnetograms are used to infer the underlying magnetic topology. The evolution and structure of the prominence with respect to the magnetic field seems to agree with the filament linkage model.Comment: 24 pages, 14 figures, Accepted for publication in Solar Physics Journal, Movies can be found at http://www2.mps.mpg.de/data/outgoing/panesar

3D MHD Flux Emergence Experiments: Idealized models and coronal interactions

This paper reviews some of the many 3D numerical experiments of the emergence of magnetic fields from the solar interior and the subsequent interaction with the pre-existing coronal magnetic field. The models described here are idealized, in the sense that the internal energy equation only involves the adiabatic, Ohmic and viscous shock heating terms. However, provided the main aim is to investigate the dynamical evolution, this is adequate. Many interesting observational phenomena are explained by these models in a self-consistent manner.Comment: Review article, accepted for publication in Solar Physic

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

Observable Social Cognition – A Rating Scale: an interview-based assessment for schizophrenia

Individuals with schizophrenia consistently show impairments in social cognition (SC). SC has become a potential treatment target due to its association with functional outcomes. An alternative method of assessment is to administer an observer-based scale incorporating an informant’s “first hand” impressions in ratings

Progressive transformation of a flux rope to an ICME

The solar wind conditions at one astronomical unit (AU) can be strongly disturbed by the interplanetary coronal mass ejections (ICMEs). A subset, called magnetic clouds (MCs), is formed by twisted flux ropes that transport an important amount of magnetic flux and helicity which is released in CMEs. At 1 AU from the Sun, the magnetic structure of MCs is generally modeled neglecting their expansion during the spacecraft crossing. However, in some cases, MCs present a significant expansion. We present here an analysis of the huge and significantly expanding MC observed by the Wind spacecraft during 9 and 10 November, 2004. After determining an approximated orientation for the flux rope using the minimum variance method, we precise the orientation of the cloud axis relating its front and rear magnetic discontinuities using a direct method. This method takes into account the conservation of the azimuthal magnetic flux between the in- and out-bound branches, and is valid for a finite impact parameter (i.e., not necessarily a small distance between the spacecraft trajectory and the cloud axis). Moreover, using the direct method, we find that the ICME is formed by a flux rope (MC) followed by an extended coherent magnetic region. These observations are interpreted considering the existence of a previous larger flux rope, which partially reconnected with its environment in the front. These findings imply that the ejected flux rope is progressively peeled by reconnection and transformed to the observed ICME (with a remnant flux rope in the front part).Comment: Solar Physics (in press

Observations of Coronal Mass Ejections with the Coronal Multichannel Polarimeter

The Coronal Multichannel Polarimeter (CoMP) measures not only the polarization of coronal emission, but also the full radiance profiles of coronal emission lines. For the first time, CoMP observations provide high-cadence image sequences of the coronal line intensity, Doppler shift and line width simultaneously in a large field of view. By studying the Doppler shift and line width we may explore more of the physical processes of CME initiation and propagation. Here we identify a list of CMEs observed by CoMP and present the first results of these observations. Our preliminary analysis shows that CMEs are usually associated with greatly increased Doppler shift and enhanced line width. These new observations provide not only valuable information to constrain CME models and probe various processes during the initial propagation of CMEs in the low corona, but also offer a possible cost-effective and low-risk means of space weather monitoring.Comment: 6 figures. Will appear in the special issue of Coronal Magnetism, Sol. Phy

COMPOSITION AND VARIATION OF FATTY ACIDS AMONG GROUNDNUT CULTIVARS IN UGANDA

Groundnuts ( Arachis hypogaea L.) contain approximately 44-56% oil made up of fatty acids. Oleic and linoleic acids comprise about 80% of fatty acids in groundnuts. Groundnuts with >80% oleic are beneficial health-wise and also improve groundnut quality, flavour, and extended shelf-life, which is beneficial to traders. In Uganda, however, little is known about the fatty acids content of commercially available cultivars. This study was undertaken to determine the fatty acid composition of the most recently released commercially available groundnut cultivars in Uganda. Eleven groundnut genotypes were profiled for different fatty acids using gas chromatography (GC). Data were recorded in percentages from chromatographs and totaled up to about 100%. Oleic to linoleic ratios (O/L) and iodine values were calculated from fatty acid data. Groundnut genotypes tested differed significantly (P<0.05) in oleic, linoleic, palmitic, behenic, gadoleic, arachidic and palmitoleic acids. Oleic acid was highest in Lot 197 line, and linoleic acid was lowest in the same line. Oleic acid was lowest in Serenut 7 (43.19%) and linoleic acid was highest in the same line (33.45%). The lowest iodine value was observed in 197 (84.14); and the highest in Serenut 9T (96.59). Significant correlations (P<0.001) were observed between most of the fatty acids, except between arachidic versus gadoleic, stearic and gamma linoleic.L\u2019Arachide ( Arachis hypogaea L.) contient approximativement 44-55% d\u2019huile faites d\u2019acides gras. Les acides ol\ue9ique et linol\ue9ique constituent environ 80% des acides gras dans l\u2019arachide. Les arachides avec plus de 80% d\u2019ol\ue9iques sont b\ue9n\ue9fiques pour la sant\ue9 et aussi am\ue9liorent la qualit\ue9 de l\u2019arachide, le go\ufbt, et une longue dur\ue9e de conservation, avantageux pour les commer\ue7ants. En Ouganda, toutefois, tr\ue8s peu d\u2019informations sont disponibles concernant la teneur en acides gras des cultivars commercialement disponibles. Cette \ue9tude a \ue9t\ue9 entreprise pour d\ue9terminer la composition en acide gras de la majorit\ue9 des cultivars d\u2019arachides r\ue9cemment lib\ue9r\ue9s et commercialement disponibles en Ouganda. Onze g\ue9notypes d\u2019arachide ont \ue9t\ue9 profil\ue9s pour les diff\ue9rents acides gras en utilisant le gaz chromatographie (GC). Les donn\ue9es ont\ua0\ue9t\ue9 collect\ue9es des chromatographes en pourcentages et additionn\ue9es jusqu\u2019\ue0 environ 100%. Les rapports d\u2019ol\ue9iques au linol\ue9iques (O/L) et les valeurs d\u2019iode ont \ue9t\ue9 calcul\ue9es \ue0 partir des donn\ue9es des acides gras. Les g\ue9notypes d\u2019arachide test\ue9s ont \ue9t\ue9 significativement (P<0,05) diff\ue9rents en acides ol\ue9ique, linol\ue9ique, palmitique, b\ue9h\ue9nique, gadol\ue9ique, arachidique et palmitoleique. L\u2019acide ol\ue9ique \ue9tait le plus \ue9lev\ue9 dans la lign\ue9e Lot 197, et l\u2019acide linol\ue9ique \ue9tait le plus faible dans la m\ueame lign\ue9e. L\u2019acide ol\ue9ique \ue9tait le plus faible en Serenut 7 (43,19%) et l\u2019acide linol\ue9ique \ue9tait le plus \ue9lev\ue9 dans la m\ueame lign\ue9e (33,45%). La plus faible valeur de l\u2019iode \ue9tait observ\ue9e dans 197 (84,14)\ua0; et la valeur la plus \ue9lev\ue9e dans Serenut 9T (96,59). Des corr\ue9lations significatives (P<0,001) \ue9taient observ\ue9e entre la majorit\ue9 des acides gras, sauf entre l\u2019acide arachidique contre les acides gadol\ue9ique, st\ue9arique et gamma linol\ue9ique

Coronal Diagnostics from Narrowband Images around 30.4 nm

Images taken in the band centered at 30.4 nm are routinely used to map the radiance of the He II Ly alpha line on the solar disk. That line is one of the strongest, if not the strongest, line in the EUV observed in the solar spectrum, and one of the few lines in that wavelength range providing information on the upper chromosphere or lower transition region. However, when observing the off-limb corona the contribution from the nearby Si XI 30.3 nm line can become significant. In this work we aim at estimating the relative contribution of those two lines in the solar corona around the minimum of solar activity. We combine measurements from CDS taken in August 2008 with temperature and density profiles from semiempirical models of the corona to compute the radiances of the two lines, and of other representative coronal lines (e.g., Mg X 62.5 nm, Si XII 52.1 nm). Considering both diagnosed quantities from line ratios (temperatures and densities) and line radiances in absolute units, we obtain a good overall match between observations and models. We find that the Si XI line dominates the He II line from just above the limb up to ~2 R_Sun in streamers, while its contribution to narrowband imaging in the 30.4 nm band is expected to become smaller, even negligible in the corona beyond ~2 - 3 R_Sun, the precise value being strongly dependent on the coronal temperature profile.Comment: 26 pages, 11 figures; to be published in: Solar Physic

Triggering an eruptive flare by emerging flux in a solar active-region complex

A flare and fast coronal mass ejection originated between solar active regions NOAA 11514 and 11515 on July 1, 2012 in response to flux emergence in front of the leading sunspot of the trailing region 11515. Analyzing the evolution of the photospheric magnetic flux and the coronal structure, we find that the flux emergence triggered the eruption by interaction with overlying flux in a non-standard way. The new flux neither had the opposite orientation nor a location near the polarity inversion line, which are favorable for strong reconnection with the arcade flux under which it emerged. Moreover, its flux content remained significantly smaller than that of the arcade (approximately 40 %). However, a loop system rooted in the trailing active region ran in part under the arcade between the active regions, passing over the site of flux emergence. The reconnection with the emerging flux, leading to a series of jet emissions into the loop system, caused a strong but confined rise of the loop system. This lifted the arcade between the two active regions, weakening its downward tension force and thus destabilizing the considerably sheared flux under the arcade. The complex event was also associated with supporting precursor activity in an enhanced network near the active regions, acting on the large-scale overlying flux, and with two simultaneous confined flares within the active regions.Comment: Accepted for publication in Topical Issue of Solar Physics: Solar and Stellar Flares. 25 pages, 12 figure