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Origin of helical coronal disturbances from the Sun  

Kuniko Hori   Submitted: 2000-06-12 15:04

By combining data from the Nobeyama Radioheliograph and the LASCO coronagraph aboard the {it SoHO} spacecraft, we report two helical coronal disturbances accompanying white-light coronal mass ejections (CMEs). These are activated prominences at the base, rotating around each vertical axis while moving on the solar surface with projected speeds of geq 50 km s-1. The activity continues in a CME core and in a neighboring streamer growing over 6 Rodot. Neither flare activity nor radio bursts were observed during the two events. We suggest that the apparent presence/absence of a CME core depends on the density of the eruptive material associated with the CME.

Authors: K. Hori

Publication Status: ApJ (in press)
Last Modified: 2000-06-12 15:04
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Microwave Observation of Eruptive Solar Events with and without Flare Activity  

Kuniko Hori   Submitted: 1999-11-11 01:05

We present microwave (17 GHz) observations of eruptive activity in four solar coronal events with the Nobeyama Radioheliograph. These are weak events occurring at or near the solar limb associated with several types of activity: polar crown activity, prominence eruptions, and arcade flares. Morphological evolution of microwave sources in these events shows the following characterist- characteristic features in common: The activity starts as a mound-shaped source (1.0-4.5 imes104 km in height), above which a compact blob (le 1.0 im- 1.0 imes104 km in size) appears later and expands horizontally toward the top of another low-lying mound. Finally a faint arch with a filamentary structure is formed, bridging the two mounds (0.2-2.0 imes105 km in horizontal scale size). Thus, the activity seems to propagate through the arch corridor from the initially activated mound to the secondary. During this process, the activity level increases, as indicated by an increase of the brightness temperature of the mound and the blob as well as by the formation of the arch and the eruption of the blob. These common features suggest that basically the same energy build-up and release process takes place in all of the four events, in spite of the large difference in the total released energy. Here we propose magnetic reconnection progressing in between the blob and the mound as the basic process, as indicated by high-temperature plasma there, seen in soft X-rays. Our findings support a theoretically predicted analogy between filament (or prominence) activity and flare onset.

Authors: K. Hori, T. Kosugi, K. Fujiki, H. Koshiishi, and K. Shibasaki

Publication Status: ApJ 532, 2000 (in press)
Last Modified: 1999-11-11 01:05
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Origin of helical coronal disturbances from the Sun
Microwave Observation of Eruptive Solar Events with and without Flare Activity

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