Signatures of transition region explosive events in hydrogen Ly-beta profiles
Abstract
Transition-region (TR) explosive events (EEs) are small-scale dynamic phenomena often observed in the far and extreme ultraviolet (FUV/EUV) spectral lines formed in the solar transition region. In this contribution, we investigate the relationship between the peak emission of hydrogen Ly-beta profiles and the emission of C II (103.7nm) and O VI (103.2nm) lines to search for signatures of explosive events in Ly-beta profiles. Two rasters made by the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) instrument on board SOHO in a quiet-Sun region and an equatorial coronal hole were selected for our study. Explosive events were identified from profiles of C II and O VI, respectively. We compared Ly-beta profiles during EEs with those averaged in the entire quiet-Sun and coronal-hole regions. We find that the central part of Ly-beta profiles reverses more and the distance of the two peaks becomes larger during EEs, both in the coronal hole and in the quiet Sun. The average Ly-beta profile of the EEs detected by C II has an obviously stronger blue peak. During EEs, there is a clear correlation between the increased peak emission of Ly-beta profiles and the enhanced wing emission of the C II and O VI lines. The correlation is more pronounced for the Ly-beta peaks and C II wings, and less significant for the Ly-beta blue peak and O VI blue wing. We also find that the Ly-beta profiles are more reversed in the coronal hole than in the quiet Sun. We suggest that the jets produced by EEs emit Doppler-shifted Ly-beta photons, causing enhanced emission at positions of the peaks of Ly-beta profiles. The more-reversed Ly-beta profiles confirm the presence of a higher opacity in the coronal hole than in the quiet Sun. The finding that EEs modify the Ly-beta line profile in QS and CHs implies that one should be careful in the modeling and interpretation of relevant observational data.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFMSH11B1646X
- Keywords:
-
- 7546 SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY / Transition region;
- 7549 SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY / Ultraviolet emissions