Astrid Veronig

As a part of my PhD study, I have carried out a statistical analysis of the Neupert effect in solar flares using data from GOES and BATSE (Veronig, Dennis, Vrsnak et al., A&A, in press). The main result was that particularly in weak flares it seems that additional heating mechanisms other than electron beams play an important role for the flare energetics. However, the interpretation of the results is still somehow ambiguous due to unknown/uncertain correlations among the soft (hard) X-ray fluxes and the relevant physical parameters as well as due to uncertainties related to weak events.

My intention is to extend the Neupert effect study using RHESSI data, which measures both hard X-rays and soft X-rays down to 3 keV with the same detectors. Moreover, the high sensitivity of RHESSI makes it particular useful for detailed investigations of the Neupert effect in weak flares. Thus, it should be possible with much better accuracy than in previous studies to investigate the role of nonthermal electrons in weak events, and to see if there are differences with regard to intense flares.

Another topic, which I plan to address, are correlative H-alpha and hard X-ray studies using RHESSI imaging data and H-alpha observations from the Kanzelhoehe Solar Observatory (affiliated to the University of Graz), which performs daily full-disk H-alpha images with 2 sec cadence as ground-based support of RHESSI. Preliminary routines for flare detection and segmentation in H-alpha images have been developed, which (after being improved) shall provide an easy access for correlative studies.