We report findings from multihour 0.2Љ resolution movies of solar quiescent prominences (QPs) observed with the Solar Optical Telescope (SOT) on the Hinode satellite. The observations verify previous findings of filamentary downflows and vortices in QPs. SOT observations also verify large-scale transverse oscillations in QPs, with periods of 20-40 minutes and amplitudes of 2-5 Mm. The upward propagation speed of several waves is found to be ∼10 km s , comparable to the sound speed of a 10,000 K plasma, implying that the waves are magnetoacoustic in and Ha bandpasses of SOT. The new flows are seen in about half of the QPs observed by SOT to date. The dark upflows resemble buoyant starting plumes in both their velocity profile and flow structure. We discuss thermal and magnetic mechanisms as possible causes of the plumes.

Hinode/Solar Optical Telescope (SOT) observations reveal two new dynamic modes in quiescent solar prominences: large-scale (20-50 Mm) "arches" or "bubbles" that "inflate" from below into prominences, and smaller-scale (2-6 Mm) dark turbulent upflows. These novel dynamics are related in that they are always dark in visible-light spectral bands, they rise through the bright prominence emission with approximately constant speeds, and the small-scale upflows are sometimes observed to emanate from the top of the larger bubbles. Here we present detailed kinematic measurements of the small-scale turbulent upflows seen in several prominences in the SOT database. The dark upflows typically initiate vertically from 5 to 10 Mm wide dark cavities between the bottom of the prominence and the top of the chromospheric spicule layer. Small perturbations on the order of 1 Mm or less in size grow on the upper boundaries of cavities to generate plumes up to 4-6 Mm across at their largest widths. All plumes develop highly turbulent profiles, including occasional Kelvin-Helmholtz vortex "roll-up" of the leading edge. The flows typically rise 10-15 Mm before decelerating to equilibrium. We measure the flowfield characteristics with a manual tracing method and with the Nonlinear Affine Velocity Estimator (NAVE) "optical flow" code to derive velocity, acceleration, lifetime, and height data for several representative plumes. Maximum initial speeds are in the range of 20-30 km s −1 , which is supersonic for a ∼10,000 K plasma. The plumes decelerate in the final few Mm of their trajectories resulting in mean ascent speeds of 13-17 km s −1. Typical lifetimes range from 300 to 1000 s (∼5-15 minutes). The area growth rate of the plumes (observed as two-dimensional objects in the plane of the sky) is initially linear and ranges from 20,000 to 30,000 km 2 s −1 reaching maximum projected areas from 2 to 15 Mm 2. Maximum contrast of the dark flows relative to the bright prominence plasma in SOT images is negative and ranges from −10% for smaller flows to −50% for larger flows. Passive scalar "cork movies" derived from NAVE measurements show that prominence plasma is entrained by the upflows, helping to counter the ubiquitous downflow streams in the prominence. Plume formation shows no clear temporal periodicity. However, it is common to find "active cavities" beneath prominences that can spawn many upflows in succession before going dormant. The mean flow recurrence time in these active locations is roughly 300-500 s (5-8 minutes). Locations remain active on timescales of tens of minutes up to several hours. Using a column density ratio measurement and reasonable assumptions on plume and prominence geometries, we estimate that the mass density in the dark cavities is at most 20% of the visible prominence density, implying that a single large plume could supply up to 1% of the mass of a typical quiescent prominence. We hypothesize that the plumes are generated from a Rayleigh-Taylor instability taking place on the boundary between the buoyant cav...

The immense volume of data generated by the suite of instruments on the Solar Dynamics Observatory (SDO) requires new tools for efficient identifying and accessing data that is most relevant for research. We have developed the Heliophysics Events Knowledgebase (HEK) to fill this need. The HEK system combines automated data mining using feature-detection methods and high-performance visualization systems for data markup. In addition, web services and clients are provided for searching the resulting metadata, reviewing results, and efficiently accessing the data. We review these components and present examples of their use with SDO data.

The "middle corona" is a critical transition between the highly disparate physical regimes of the lower and outer solar corona. Nonetheless, it remains poorly understood due to the difficulty of observing this faint region (1.5-3 R☉). New observations from the GOES Solar Ultraviolet Imager in August and September 2018 provide the first comprehensive look at this region's characteristics and long-term evolution in extreme ultraviolet (EUV). Our analysis shows that the dominant emission mechanism here is resonant scattering rather than collisional excitation, consistent with recent model predictions. Our observations highlight that solar wind structures in the heliosphere originate from complex dynamics manifesting in the middle corona that do not occur at lower heights. These data emphasize that low-coronal phenomena can be strongly influenced by inflows from above, not only by photospheric motion, a factor largely overlooked in current models of coronal evolution. This study reveals the full kinematic profile of the initiation of several coronal mass ejections, filling a crucial observational gap that has hindered understanding of the origins of solar eruptions. These new data uniquely demonstrate how EUV observations of the middle corona provide strong new constraints on models seeking to unify the corona and heliosphere. Our EUV Observations and the Middle CoronaThe solar corona is the primary driver of almost all plasma dynamics throughout the solar system 1 . However, the precise nature of the connection between the corona and the heliosphere remains surprisingly poorly understood 2 . Recent solar and heliospheric observations taken by Parker Solar Probe, well within Mercury's orbit, revealed a highly structured environment shaped by flows and ejecta interacting with the corona's complex magnetic field 3,4,5,6 . The influence of these flows on the heliosphere and structural evolution

We have investigated the relationship between magnetic activity and coronal structures using soft X-ray data from the Yohkoh soft X-ray telescope and magnetic field data from the Kitt Peak Solar Observatory for the period of 1991-2001 and EUV data from the Solar and Heliospheric Observatory EUV Imaging Telescope for 1996-2001. The data are reduced to Carrington synoptic maps, which reveal two types of migrating structures of coronal activity at low and high latitudes in the time-latitudinal distribution. The low-latitude coronal structures, migrating equatorward, correspond to photospheric sunspot activity, and the high-latitude structures migrating toward the poles reflect polar activity of the Sun. We present the following new results: 1. The migrating high-latitude coronal magnetic structures are revealed in the soft X-ray data as complete bright giant loops connecting the magnetic field of the following part of active regions with the polar field. They appear during the rising phase and maximum of the solar cycle and show quasi-periodic impulsive variations with a 1-1.5 yr period. 2. The soft X-ray intensity of these loops has a strong power-law correlation with the photospheric magnetic flux. The power-law index, which on average is close to 2, shows variations with the solar cycle: it is higher for the period of the declining phase and minimum of solar activity than for the rising phase and maximum.