The resonance lines of Mg II as diagnostics of the upper solar chromosphere
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The resonance lines of Mg II as diagnostics of the upper solar chromosphere

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Published by National Aeronautics and Space Administration, National Technical Information Service, distributor in [Washington, DC, Springfield, Va .
Written in English

Subjects:

  • Solar chromosphere.,
  • Aeronautics -- Research.

Book details:

Edition Notes

Series[NASA contractor report] -- NASA-CR 195084., NASA contractor report -- NASA CR-195084.
ContributionsUnited States. National Aeronautics and Space Administration.
The Physical Object
FormatMicroform
Pagination1 v.
ID Numbers
Open LibraryOL14704642M

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  We carry out a theoretical study of the polarization of the solar Mg II h-k doublet (including its extended wings) and the subordinate ultraviolet (UV) triplet around nm. These lines are of great diagnostic interest, as they encode information on the physical properties of the solar atmosphere from the upper photosphere to the chromosphere-corona transition : T. del Pino Alemán, J. Trujillo Bueno, R. Casini, R. Manso Sainz. Abstract: We carry out a theoretical study of the polarization of the solar Mg II h-k doublet (including its extended wings) and the subordinate UV triplet around nm. These lines are of great diagnostic interest, as they encode information on the physical properties of the solar atmosphere from the upper photosphere to the chromosphere-corona transition region. the diagnostic rich Mg ii lines during flares, with excellent spa-tial and spectral resolution. The Mg ii h & k resonance lines are the 3s 3p transi-tions to the ground state of singly ionised magnesium, from upper levels that are close in energy (3s 2S 1=2 3p 2P 1=2, and 3s 2S 1=2 3p 2P 3=2 respectively). They are optically thick linesFile Size: 3MB. The intensity ratio of the blue and red peaks correlates strongly with the average velocity in the upper chromosphere. We conclude that the Mg II h and k lines are excellent probes of the very upper chromosphere just below the TR, a height regime that is impossible to probe with other spectral lines.

The core of Mg ii k forms in the upper chromosphere, the subordinate lines and the near wings of h and k form in the intermediate chromosphere, whereas the broadband polarization pattern of the h–k wings is sensitive to conditions in the upper photosphere and low chromosphere. The Mg II h&k Resonance Lines -Optically thick resonance lines that form from multiple layers in the atmosphere. k3: Line core, upper chromosphere k2: Emission peaks, mid chromo. k1: Minima, upper photosphere-Previously studied by Feldman, Doscheck, Lemaire and collaborators using balloon borne experiments, Skylab, and OSO The optimum spectral lines that are useful for diagnosing the solar chromosphere and TR are the Mg II h&k lines at and nm and the hydrogen Ly-alpha line at nm, both of them in the near-UV region of the spectrum. Optionally, the nearby Ca II H&K lines at and nm could be added to the setup. Right panel: theoretical V=I pro les due to a 50 G longitudinal eld. In addition to the k line at nm and the h line at nm, we show also the circular polarization signal in the (blended) subordinate line of Mg ii whose lower level is the upper level of the k resonance line (i.e., the line labelled \a").

The Mg ii h and k lines are powerful diagnostics for studying the solar chromosphere. They have become particularly popular with the launch of the Interface Region Imaging Spectrograph (IRIS) satellite, and a number of studies that include these lines have lead to great progress in understanding chromospheric heating, in many cases thanks to the support from 3D MHD simulations. OBSERVED VARIABILITY OF THE SOLAR MgII h SPECTRAL LINE D. Schmit1,2, P. Bryans3, B. De Pontieu1, S. McIntosh3, J. Leenaarts4, and M. Carlsson5 1 Lockheed-Martin Solar and Astrophysics Laboratory, Palo Alto, CA, USA 2 Bay Area Environmental Research Institute, Petaluma, CA, USA 3 High Altitude Observatory, National Center for Atmospheric Research, Boulder, CO, USA. This multiplet consists of three lines: one centered at Å and one line at Å with a weak blend in its blue wing at Å. Therefore, in the observations we see only two lines. The C II resonance lines sample the solar atmosphere from the upper chromosphere up to the transition region. The bulk of the radiative output of a solar flare is radiated from the chromosphere. We have, until very recently, lacked routine observations of one of the strongest chromospheric lines: the MgII h&k resonance lines. These optically thick lines sample the atmosphere from the upper photosphere to the upper chromosphere and have been shown to be important diagnostics of the atmosphere in the Author: Graham Stewart Kerr, Paulo J. A. Simões, Jiong Qiu, Lyndsay Fletcher.