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Title: Synthetic observations of wave propagation in a sunspot umbra

Spectropolarimetric temporal series from Fe I λ6301.5 Å and Ca II infrared triplet lines are obtained by applying the Stokes synthesis code NICOLE to a numerical simulation of wave propagation in a sunspot umbra from MANCHA code. The analysis of the phase difference between Doppler velocity and intensity core oscillations of the Fe I λ6301.5 Å line reveals that variations in the intensity are produced by opacity fluctuations rather than intrinsic temperature oscillations, except for frequencies between 5 and 6.5 mHz. On the other hand, the photospheric magnetic field retrieved from the weak field approximation provides the intrinsic magnetic field oscillations associated to wave propagation. Our results suggest that this is due to the low magnetic field gradient of our sunspot model. The Stokes parameters of the chromospheric Ca II infrared triplet lines show striking variations as shock waves travel through the formation height of the lines, including emission self-reversals in the line core and highly abnormal Stokes V profiles. Magnetic field oscillations inferred from the Ca II infrared lines using the weak field approximation appear to be related with the magnetic field strength variation between the photosphere and the chromosphere.
Authors:
 [1] ; ;  [2]
  1. NorthWest Research Associates, Colorado Research Associates, Boulder, CO 80301 (United States)
  2. Instituto de Astrofísica de Canarias, C/Vía Láctea, s/n, E-38205 La Laguna, Tenerife (Spain)
Publication Date:
OSTI Identifier:
22370359
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 795; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; APPROXIMATIONS; CALCIUM; CHROMOSPHERE; COMPUTERIZED SIMULATION; EMISSION; FLUCTUATIONS; IRON; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; OPACITY; OSCILLATIONS; PHOTOSPHERE; STOKES PARAMETERS; SUN; SUNSPOTS; SYNTHESIS; VELOCITY; WAVE PROPAGATION