Chromospheric heating by acoustic waves compared to radiative cooling

Abstract

Acoustic and magnetoacoustic waves are among the possible candidate mechanisms that heat the upper layers of solar atmosphere. A weak chromospheric plage near a large solar pore NOAA 11005 was observed on October 15, 2008 in the lines Fe I 617.3 nm and Ca II 853.2 nm with the Interferometric Bidimemsional Spectrometer (IBIS) attached to the Dunn Solar Telescope. Analyzing the Ca II observations with spatial and temporal resolutions of 0.4" and 52 s, the energy deposited by acoustic waves is compared with that released by radiative losses. The deposited acoustic flux is estimated from power spectra of Doppler oscillations measured in the Ca II line core. The radiative losses are calculated using a grid of seven 1D hydrostatic semi-empirical model atmospheres. The comparison shows that the spatial correlation of maps of radiative losses and acoustic flux is 72 %. In quiet chromosphere, the contribution of acoustic energy flux to radiative losses is small, only of about 15 %. In active areas with photospheric magnetic field strength between 300 G and 1300 G and inclination of 20-60 degrees, the contribution increases from 23 % (chromospheric network) to 54 % (a plage). However, these values have to be considered as lower limits and it might be possible that the acoustic energy flux is the main contributor to the heating of bright chromospheric network and plages.

9 pages, 10 figures. Accepted for publication in The Astrophysical Journal

References in corpus (4)

• Multiwavelength studies of MHD waves in the solar chromosphere: An overview of recent results
• Evidence of Non-Thermal Particles in Coronal Loops Heated Impulsively by Nanoflares
• The solar chromosphere at high resolution with IBIS. I. New insights from the Ca II 854.2 nm line
• Dynamics of the solar atmosphere above a pore with a light bridge

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• IBIS-A: The IBIS data Archive. High resolution observations of the solar photosphere and chromosphere with contextual data
• IRIS observations of chromospheric heating by acoustic waves in solar quiet and active regions
• Constraining the systematics of (acoustic) wave heating estimates in the solar chromosphere
• Radiative losses in the chromosphere during a C-class flare
• A study of the propagation of magnetoacoustic waves in small-scale magnetic fields using solar photospheric and chromospheric Dopplergrams: HMI/SDO and MAST observations
• Chromosphere of the quiet sun -- I. Shock and current-sheet dynamics and heating
• Chromospheric Heating by Acoustic Waves Compared to Radiative Cooling: II -- Revised Grid of Models