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Spicules and their on-disk counterparts - The main driver of solar chromospheric heating? - The GREGOR Fabry-Perot Interferometer @ VTT

Author: Klaus Gerhard Puschmann
Affiliation: Martinstr. 64, 64285 Darmstadt, Germany

Main category: Natural Sciences (Astronomy)

Caption:
Summary of the recent observational discovery suggesting Spicules as the main driver of solar chromospheric heating. Spectra recorded on 4 May 2005 with the GREGOR Fabry-Perot Interferometer (Puschmann et al. 2006, A&A 451, 1151) at the VTT. The Hα line was sampled in 21 steps of 11 pm width with a cadence of 22s. Movie created by Klaus Gerhard Puschmann, Darmstadt, Germany on 27 February 2016.


Further information:
The question how the outer solar atmosphere is heated from solar photospheric temperatures of about 5800K up to solar chromospheric and coronal temperatures of about 20.000K and millions of degrees respectively, still remains without any satisfying answer.

The density in the solar atmosphere drops fast in the photosphere, where the opacity reduces so much that the solar plasma becomes transparent to radiation. Therefore, it seems to be impossible to transfer energy to the outer solar atmosphere by radiation. Different energy transport mechanisms are apparently required.

Spicules are highly dynamic jet-like structures best observed at and beyond the solar limb in chromospheric lines such as Hα (6563 Å), Ca II H (3968.5 Å) and Ca II IR (8542 Å). Provided that spicules possess on-disk counter parts, they could be one of the main drivers for the solar chromospheric heating. Type I spicules might be the result of photospheric acoustic p-mode leakage between granular cells, providing significant energy to the chromosphere. Type II spicules might by the result of magnetic reconnection at photospheric level and be related to Alfvén waves (MHD waves).

The time series of Hα line parameters, resulting from the post-factum application of the Multi-Object Multi-Frame Blind Deconvolution technique (MOMFBD, van Noort, M., Rouppe van der Voort, L., & Löfdahl, M. G. 2005, Sol. Phys., 228, 191) as part of the GREGOR Fabry-Perot Interferometer Data Pipeline iSPOR-DP (imaging Spectropolarimetric Parallel Organized Reconstruction Data Pipeline, Puschmann, K. G. & Beck, C. 2011, A&A, 533, A21) reveal the entire and detailed complexity as well as the overwhelming dynamics of spicules apparently covering the entire solar disk, thus confirming spicules as the potential driver of chromospheric heating, with an expected mass flux larger than 100 times that of the solar wind.


Further Reading: Spicules and their on-disk counterparts - The main driver for solar chromospheric heating? - K. G. Puschmann: arXiv e-print - arXiv:1602.05185 - http://adsabs.harvard.edu/abs/2016arXiv160205185P

Language: English

DOI: requested

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