Coronal loops trace out bipolar, arch-like magnetic fields above the Sun's surface. Recent measurements that combine rotational tomography, extreme ultraviolet imaging, and potential-field extrapolation have shown the existence of large loops with inverted temperature profiles; i.e., loops for which the apex temperature is a local minimum, not a maximum. These "down loops" appear to exist primarily in equatorial quiet regions near solar minimum. We simulate both these and the more prevalent large-scale "up loops" by modeling coronal heating as a time-steady superposition of: (1) dissipation of incompressible Alfvén-wave turbulence, and (2) dissipation of compressive waves formed by mode conversion from the initial population of Alfvén waves. We found that when a large percentage (> 99%) of the Alfvén waves undergo this conversion, heating is greatly concentrated at the footpoints and stable "down loops" are created. In some cases we found loops with three maxima that are also gravitationally stable. Models that agree with the tomographic temperature data exhibit higher gas pressures for "down loops" than for "up loops," which is consistent with observations. These models also show a narrow range of Alfvén wave amplitudes: 3 to 6 km s −1 at the coronal base. This is low in comparison to typical observed amplitudes of 20 to 30 km s −1 in bright X-ray loops. However, the large-scale loops we model are believed to comprise a weaker diffuse background that fills much of the volume of the corona. By constraining the physics of loops that underlie quiescent streamers, we hope to better understand the formation of the slow solar wind.

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We observed occultations by Pluto during a predicted series of events in 2014 July with the 1 m telescope of the Mt. John Observatory in New Zealand. The predictions were based on updated astrometry obtained in the previous months at the USNO, CTIO, and Lowell Observatories. We successfully detected occultations by Pluto of an

The Sun's combined corona/heliosphere system is a hot (i.e., nearly fully ionized) and expanding plasma composed of mostly hydrogen, some helium, and a small fraction of heavier elements. Despite the negligibly small masses of the free electrons in such a plasma, these particles are important to maintaining overall quasi-neutrality and a zero-current electrostatic balance. In situ measurements have revealed that the electron velocity distribution function (VDF) often shows four relatively distinct components: (a) an approximately Maxwellian core, often close to being in thermal equilibrium with the protons, (b) a higher-energy isotropic halo, usually with a mild power-law tail in velocity space, (c) a magnetic-field-aligned beam or strahl that indicates connectivity to the near-Sun corona, and (d) a much higher-energy isotropic power-law super-halo