Local Coordinator:
Craig DeForest and Julia Saba
Technical Summary:
The solar corona is extremely complex. Besides coronal loops within active regions (ARs), there are loops which connect different ARs, even across the equator, as well as loops which connect ARs to quiet Sun several arcminutes away (Strong et al. 1994, Strong 1994). When a structure becomes unstable and starts to expand, it will very probably meet and interact with other magnetic loops. Such events may lead to a re-organization of the coronal structure. On a short time scale( a few hours to a day), such re-organization has been observed following filament eruptions or disparition brusques (Watanabe et al. 1992, McAllister et al 1992, Tsuneta et al. 1992, Watanabe et al. 1993, Kahn et al. 1993, Hanaoka et al. 1994). In some cases, small transient coronal holes were reported to form as a result of such events (Watanabe et al. 1992, 1994).
Since observations of multiple layers of the solar atmosphere are required to understand such events (Schmieder 1992, Raadu and Schmieder 1988), we propose to study combined data on disparition brusques from the corona (Yohkoh/SXT), the transition region (SOHO/CDS, SUMER, and EIT ), the chromosphere (MSDP, Tenerife), and the photosphere (SOHO/MDI). MSDP provides spectral data in Halpha and Ca lines in 2 D (typically 0.5 by 4 arc min).
Complete text of proposal.