Observations of the Sun's corona during the space era have led to a picture of relatively constant, but cyclically varying solar output and structure. Longer-term, more indirect measurements, such as from 10 Be, coupled by other albeit less reliable contemporaneous reports, however, suggest periods of significant departure from this standard. The Maunder Minimum was one such epoch where:(1) sunspots effectively disappeared for long intervals during a 70 yr period; (2) eclipse observations suggested the distinct lack of a visible K-corona but possible appearance of the F-corona; (3) reports of aurora were notably reduced; and (4) cosmic ray intensities at Earth were inferred to be substantially higher. Using a global thermodynamic MHD model, we have constructed a range of possible coronal configurations for the Maunder Minimum period and compared their predictions with these limited observational constraints. We conclude that the most likely state of the corona during-at least-the later portion of the Maunder Minimum was not merely that of the 2008/2009 solar minimum, as has been suggested recently, but rather a state devoid of any large-scale structure, driven by a photospheric field composed of only ephemeral regions, and likely substantially reduced in strength. Moreover, we suggest that the Sun evolved from a 2008/2009-like configuration at the start of the Maunder Minimum toward an ephemeral-only configuration by the end of it, supporting a prediction that we may be on the cusp of a new grand solar minimum.
New XRT observations of the north polar region taken from the X-ray Telescope
(XRT) of the Hinode (Solar-B) spacecraft are used to analyze several time
sequences showing small loop brightenings with a long ray above. We focus on
the recorded transverse displacement of the jet and discuss scenarios to
explain the main features of the events: the relationship with the expected
surface magnetism, the rapid and sudden radial motion, and possibly the
heating, based on the assumption that the jet occurs above a null point of the
coronal magnetic field. We conclude that 3-D reconnection models are needed to
explain the observational details of these events.Comment: 11 pages 8 figure
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