New Observations of Balmer Continuum Flux in Solar Flares Instrument Description and First Results

0462089 - ASÚ 2017 RIV NL eng J - Článek v odborném periodiku
Kotrč, Pavel - Procházka, O. - Heinzel, Petr
New Observations of Balmer Continuum Flux in Solar Flares Instrument Description and First Results.
Solar Physics. Roč. 291, č. 3 (2016), s. 779-789. ISSN 0038-0938. E-ISSN 1573-093X
Grant CEP: GA ČR GAP209/12/1652
Grant ostatní: EC(XE) 295272; EC(XE) 606862
Program: FP7-PEOPLE; FP7
Institucionální podpora: RVO:67985815
Klíčová slova: flares * spectrum * Balmer continuum
Kód oboru RIV: BN - Astronomie a nebeská mechanika, astrofyzika
Impakt faktor: 2.682, rok: 2016

Here we describe a new post-focal instrument, the image selector, with which the Balmer continuum flux can be measured from the whole flare area, in analogy to successful detections of flaring dMe stars. The system was developed and put into operation at the horizontal solar telescope HSFA2 of the OndA (TM) ejov Observatory. We measure the total flux by a fast spectrometer from a limited but well-defined region on the solar disk. Using a system of diaphragms, the disturbing contribution of a bright solar disk can be eliminated as much as possible. Light curves of the measured flux in the spectral range 350 -aEuro parts per thousand 440 nm are processed, together with the images of the flaring area delimited by the appropriate diaphragm. The spectral flux data are flat-fielded, calibrated, and processed to be compared with model predictions. Our analysis of the data proves that the described device is sufficiently sensitive to detect variations in the Balmer continuum during solar flares. Assuming that the Balmer-continuum kernels have at least a similar size as those visible in , we find the flux increase in the Balmer continuum to reach 230 -aEuro parts per thousand 550 % of the quiet continuum during the observed X-class flare. We also found temporal changes in the Balmer continuum flux starting well before the onset of the flare in .
Trvalý link: http://hdl.handle.net/11104/0261621