Balmer continuum enhancement detected in a mini flare observed with IRIS

0548090 - ASÚ 2022 RIV FR eng J - Journal Article
Joshi, R. - Schmieder, B. - Heinzel, Petr - Tomin, J. - Chandra, R. - Vilmer, N.
Balmer continuum enhancement detected in a mini flare observed with IRIS.
Astronomy & Astrophysics. Roč. 654, October (2021), č. článku A31. ISSN 0004-6361. E-ISSN 1432-0746
R&D Projects: GA ČR(CZ) GA19-09489S
Institutional support: RVO:67985815
Keywords : Sun * chromosphere * flares
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 6.240, year: 2021
Method of publishing: Open access

The aim of the paper is to distinguish between these two mechanisms for the excess of the Balmer continuum observed in a flare. The favorable argument of a relation between the Balmer continuum excess and the HXR emission is that there is a good time coincidence between them. In addition, the shape of the maximum brightness in the 2832 SJIs, which is mainly due to this Balmer continuum excess, is similar to that of the Fermi/GBM light curve. The electron-beam flux estimated from Fermi/GBM between 10(9) and 10(10) erg s(-1) cm(-2) is consistent with the beam flux required in non-LTE radiative transfer models to obtain the excess of Balmer continuum emission observed in this IRIS spectra. Conclusions. The low-energy input by nonthermal electrons above 20 keV is sufficient to produce the enhancement in the Balmer continuum emission. This could be explained by the topology of the reconnection site. The reconnection starts in a tiny bald-patch region, which is transformed dynamically into an X-point current sheet. The size of the interacting region would be below the spatial resolution of the instrument.
Permanent Link: http://hdl.handle.net/11104/0324205