118,166 research outputs found

    Nested shells reveal the rejuvenation of the Orion-Eridanus superbubble

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    The Orion-Eridanus superbubble is the prototypical superbubble due to its proximity and evolutionary state. Here, we provide a synthesis of recent observational data from WISE and Planck with archival data, allowing to draw a new and more complete picture on the history and evolution of the Orion-Eridanus region. We discuss the general morphological structures and observational characteristics of the superbubble, and derive quantitative properties of the gas- and dust inside Barnard's Loop. We reveal that Barnard's Loop is a complete bubble structure which, together with the lambda Ori region and other smaller-scale bubbles, expands within the Orion-Eridanus superbubble. We argue that the Orion-Eridanus superbubble is larger and more complex than previously thought, and that it can be viewed as a series of nested shells, superimposed along the line of sight. During the lifetime of the superbubble, HII region champagne flows and thermal evaporation of embedded clouds continuously mass-load the superbubble interior, while winds or supernovae from the Orion OB association rejuvenate the superbubble by sweeping up the material from the interior cavities in an episodic fashion, possibly triggering the formation of new stars that form shells of their own. The steady supply of material into the superbubble cavity implies that dust processing from interior supernova remnants is more efficient than previously thought. The cycle of mass-loading, interior cleansing, and star formation repeats until the molecular reservoir is depleted or the clouds have been disrupted. While the nested shells come and go, the superbubble remains for tens of millions of years.Comment: 20 pages, 6 figures, accepted for publication in Ap

    Fundamental frequency height as a resource for the management of overlap in talk-in-interaction.

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    Overlapping talk is common in talk-in-interaction. Much of the previous research on this topic agrees that speaker overlaps can be either turn competitive or noncompetitive. An investigation of the differences in prosodic design between these two classes of overlaps can offer insight into how speakers use and orient to prosody as a resource for turn competition. In this paper, we investigate the role of fundamental frequency (F0) as a resource for turn competition in overlapping speech. Our methodological approach combines detailed conversation analysis of overlap instances with acoustic measurements of F0 in the overlapping sequence and in its local context. The analyses are based on a collection of overlap instances drawn from the ICSI Meeting corpus. We found that overlappers mark an overlapping incoming as competitive by raising F0 above their norm for turn beginnings, and retaining this higher F0 until the point of overlap resolution. Overlappees may respond to these competitive incomings by returning competition, in which case they raise their F0 too. Our results thus provide instrumental support for earlier claims made on impressionistic evidence, namely that participants in talk-in-interaction systematically manipulate F0 height when competing for the turn

    Matter formed at the BNL relativistic heavy ion collider

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    We suggest that the "new form of matter" found just above TcT_c by RHIC is made up of tightly bound quark-antiquark pairs, essentially 32 chirally restored (more precisely, nearly massless) mesons of the quantum numbers of π\pi, σ\sigma, ρ\rho and a1a_1. Taking the results of lattice gauge simulations (LGS) for the color Coulomb potential from the work of the Bielefeld group and feeding this into a relativistic two-body code, after modifying the heavy-quark lattice results so as to include the velocity-velocity interaction, all ground-state eigenvalues of the 32 mesons go to zero at TcT_c just as they do from below TcT_c as predicted by the vector manifestation (VM in short) of hidden local symmetry. This could explain the rapid rise in entropy up to TcT_c found in LGS calculations. We argue that how the dynamics work can be understood from the behavior of the hard and soft glue.Comment: Final versio

    Investigation of integrating sphere measurement parameters

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    Directional and bidirectional reflectance of MgO sphere wall coatings, and directional characteristics of photomultiplier tub

    Condensers and or evaporators in convective and radiative environments

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    Condensers and/or evaporators in convective and radiative environment

    A latitudinal survey of hydroxyl airglow emissions Final report, 1 Apr. 1969 - 31 Mar. 1970

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    Airborne photometer instrumentation and measurement data on high latitude hydroxyl airglow emissio

    Modification of the Brink-Axel Hypothesis for High Temperature Nuclear Weak Interactions

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    We present shell model calculations of electron capture strength distributions in A=28 nuclei and computations of the corresponding capture rates in supernova core conditions. We find that in these nuclei the Brink-Axel hypothesis for the distribution of Gamow-Teller strength fails at low and moderate initial excitation energy, but may be a valid tool at high excitation. The redistribution of GT strength at high initial excitation may affect capture rates during collapse. If these trends which we have found in lighter nuclei also apply for the heavier nuclei which provide the principal channels for neutronization during stellar collapse, then there could be two implications for supernova core electron capture physics. First, a modified Brink-Axel hypothesis could be a valid approximation for use in collapse codes. Second, the electron capture strength may be moved down significantly in transition energy, which would likely have the effect of increasing the overall electron capture rate during stellar collapse.Comment: 15 pages, 19 figure

    Neutrino Pair Emission from Hot Nuclei During Stellar Collapse

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    We present shell-model calculations showing that residual interaction-induced configuration mixing enhances the rate of neutral current de-excitation of thermally excited nuclei into neutrino-antineutrino pairs. Though our calculations reinforce the conclusions of previous studies that this process is the dominant source of neutrino pairs near the onset of neutrino trapping during stellar collapse, our shell-model result has the effect of increasing the energy of these pairs, possibly altering their role in entropy transport in supernovae.Comment: 9 pages, 8 figure
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