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Observational evidence for velocity convergence toward magnetic neutral lines as a factor in CME initiation

Luhmann, Janet; Li, Yan; Fisher, George +1 more

One of the major challenges of space weather research and modeling is the identification of the mechanism(s) for coronal mass ejections (CMEs). A leading candidate tested in several recent numerical simulations is photospheric magnetic flux cancellation by velocity convergence toward the neutral line of an active region having sheared or twisted m…

The photospheric boundary of Sun-to-Earth coupled models

Linker, J. A.; Mikić, Z.; Fisher, G. H. +3 more

The least understood component of the Sun-to-Earth coupled system is the solar atmosphere—the visible layers of the Sun that encompass the photosphere, chromosphere, transition region and low corona. Coronal mass ejections (CMEs), principal drivers of space weather, are magnetically driven phenomena that are thought to originate in the low solar c…

Excess facular emission from an isolated active region during solar minimum: the example of NOAA AR 7978

Sanahuja, B.; Fröhlich, C.; Ortiz, A. +1 more

The facular contribution to solar irradiance variations on the short time scale is studied by analyzing a simple case of an isolated active region that crossed the solar disk during the 1996 minimum of activity, NOAA AR 7978. Its passage during several Carrington rotations, specifically from rotation 1911 to 1916, allows us to analyze the evolutio…