On the Origin of the Flare Emission in IRIS' SJI 2832 Filter: Balmer Continuum or Spectral Lines?

0479177 - ASÚ 2018 RIV US eng J - Článek v odborném periodiku
Kleint, L. - Heinzel, Petr - Krucker, S.
On the Origin of the Flare Emission in IRIS' SJI 2832 Filter: Balmer Continuum or Spectral Lines?
Astrophysical Journal. Roč. 837, č. 2 (2017), 160/1-160/7. ISSN 0004-637X. E-ISSN 1538-4357
Grant CEP: GA ČR(CZ) GA16-18495S
Institucionální podpora: RVO:67985815
Klíčová slova: Sun * chromosphere * flares
Obor OECD: Astronomy (including astrophysics,space science)
Impakt faktor: 5.551, rok: 2017

Continuum emission dominates the energetics of flares. Filter-based observations, such as the IRIS SJI 2832 filter, show WL-like brightenings during flares, but it is unclear whether the emission arises from real continuum emission or enhanced spectral lines, possibly turning into emission. The difficulty in filter-based observations, contrary to spectral observations, is to determine which processes contribute to the observed brightening during flares. Here we determine the contribution of the Balmer continuum and the spectral line emission to IRIS' SJI 2832 emission by analyzing the appropriate passband in simultaneous IRIS NUV spectra. We find that spectral line emission can contribute up to 100% to the observed slitjaw images (SJI) emission, that the relative contributions usually temporally vary, and that the highest SJI enhancements that are observed are most likely because of the Balmer continuum. We conclude that care should be taken when calling SJI 2832 a continuum filter during flares, because the influence of the lines on the emission can be significant.
Trvalý link: http://hdl.handle.net/11104/0275177