Oran R. White

Initial CHIP He I Observations of Solar Limb Activity

A new instrument capable of 3-min time resolution full-disk and limb observations in the Hei 1083 nm spectral line has been in operation at the High Altitude Observatorys Mauna Loa Solar Observatory (MLSO) since April 1996. We discuss instrument capabilities and performance and present some initial observations of limb activity from the first year of instrument operation. We compare limb Hei and Hα observations of quiescent and active prominences, comment on the role of Doppler shifts in interpreting the Hei observations, and illustrate the use of disk/limb Hei observations of a CME-associated eruptive filament in mass-ejection studies.

Impulsive EUV bursts observed in Civ with OSO-8

Time sequences of profiles of the λ1548 line of C iv containing 51 EUV bursts observed in or near active regions are analyzed to determine the brightness, Doppler shift and line broadening characteristics of the bursts. The bursts have mean lifetimes of approximately 150s, and mean increases in brightness at burst maximum of four-fold as observed with a field of view of 2″ × 20″. Mean burst diameters are estimated to be 3″, or smaller. All but three of the bursts show Doppler shifts with velocities sometimes exceeding 75 km s−1; 31 are dominated by red shifts and 17 are dominated by blue shifts. Approximately half of the latter group have red-shifted precursors. We interpret the bursts as prominence material, such as surges and coronal rain, moving through the field of view of the spectrometer.

Temporal properties of He I 1083 nm dark points

AbstractThe intensity of a sample of large, high-contrast and isolated dark points has been observed with full-disk images in the light of Heu2009i 1083xa0nm from the Chromospheric Helium line Intensity Photometer (CHIP) on Mauna Loa, Hawaii. Temporal variations in the intensity encompassing a broad range of time scales have been recorded. Long-term changes in the intensity, although highly variable, are characterized by e-folding times on the order of 5 h. Superposed on these variations are frequent intensity variations, which occur over time scales ranging from the typical observing cadence of 3xa0min, to tens of minutes. Microflares-involving intensity changes of at least 50% over periods of minutes are observed frequently. Rapid cadence (n

Phase Differences Between Intensity and Doppler-Shift and Between Two EUV Emission Lines of SI II for 300 SEC and 95 SEC Chromospheric Oscillations.

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OSO-8 Observations of Mean Vertical Motions in the Solar Transition Region

n min) observations reveal differences between rise and decay times and shorter-term variations in the intensity profiles of these microflares.