The energy of waves in the photosphere and lower chromosphere

Beck, C.; Rezaei, Reza; Puschmann, K. G.

doi:10.1051/0004-6361/201220048

Cited by 25 publications

(24 citation statements)

References 90 publications

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“…These lines thus offer an opportunity to extract temperature as a function of height in the solar atmosphere. Shine & Linsky (1974), Rouppe van der Voort (2002), Sheminova et al (2005), Sheminova (2012), and Beck et al (2013) took advantage of this using high-resolution spectra. In an earlier paper (Henriques 2012), we generalised the technique of Shine & Linsky (1974) for use with Ca ii H filtergrams at different locations in the line wing, which were acquired by tilting a 0.11-nm interference filter so as to tune the transmission profile.…”

Section: Introductionmentioning

confidence: 99%

Ca II H sunspot tomography from the photosphere to the chromosphere

Henriques

Kiselman

2013

A&A

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Aims. We aim at gaining insight into the thermal properties of different small-scale structures related to sunspots.Methods. We use filtergrams in the Ca ii H filter at the Swedish 1-m Solar Telescope to study the relationship between fine structure at different heights in a sunspot. Results. The methods for destretching and aligning the different image data work well. The magnetic spine structure in the outer parts of the sunspot penumbra is found to be associated with higher intensities in the Ca ii H wing passbands but with less steep vertical temperature gradients. Dark lanes in a light bridge behave very similarly to dark cores in penumbral filaments. Fibril structures are seen in the line-core images over the umbra and penumbra. Conclusions. The observations add support to the idea that penumbral filaments, light bridges, and umbral dots are caused by similar processes of overturning convection. Observations in the Ca ii H & K wings are a promising observable, complementing others, for testing simulation results for sunspots at high spatial resolution.

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Section: Introductionmentioning

confidence: 99%

Ca II H sunspot tomography from the photosphere to the chromosphere

Henriques

Kiselman

2013

A&A

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“…However, different mechanisms capable for the transfer of energy into upper photospheric layers have still to be confirmed, especially with respect to results showing a lack of total energy flux transported to the chromosphere by acoustic waves (Carlsson et al 2007), although more recent results obtained by Bello pointed out that the acoustic energy flux might have been underestimated in the past due to insufficient spatial resolution. In contrast, Beck et al (2013a) suggested that magnetic heating processes are more important for the chromospheric energy balance than commonly assumed, when they compared photospheric magnetic fields obtained from spectro-polarimteric observations in the Fe i 630.25 nm line of the Polarimetric Littrow Spectrograph (POLIS; Beck et al 2005) with results retrieved after applying a recently developed LTE-inversion strategy (Beck et al 2013b) on POLIS Ca ii H spectra.…”

Section: Introductionmentioning

confidence: 99%

Evidence of quiet-Sun chromospheric activity related to an emerging small-scale magnetic loop

Gömöry

Balthasar

Puschmann

2013

A&A

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Aims. We investigate the temporal evolution of magnetic flux emergence in the quiet-Sun atmosphere close to disk center. Methods. We combined high-resolution SoHO/MDI magnetograms with TRACE observations taken in the 1216 Å channel to analyze the temporal evolution of an emerging small-scale magnetic loop and its traces in the chromosphere. Results. We find signatures of flux emergence very close to the edge of a supergranular network boundary located at disk center. The new emerging flux appeared first in the MDI magnetograms in form of an asymmetric bipolar element, i.e., the patch with negative polarity is roughly twice as weak as the corresponding patch with opposite polarity. The average values of magnetic flux and magnetic flux densities reached 1.6 × 10 18 Mx, −8.5 × 10 17 Mx, and 55 Mx cm −2 , -30 Mx cm −2 , respectively. The spatial distance between the opposite polarity patches of the emerged feature increased from about 2. 5 to 5. 0 during the lifetime of the loop, which was 36 min. A more precise lifetime-estimate of the feature was not possible because of a gap in the temporal sequence of the MDI magnetograms. The chromospheric response to the emerged magnetic dipole occurred ∼9 min later than in the photospheric magnetograms. It consisted of a quasi-periodic sequence of time-localized brightenings visible in the 1216 Å TRACE channel for ∼14 min that were co-spatial with the axis connecting the two patches of opposite magnetic polarity. Conclusions. We identify the observed event as a small-scale magnetic loop emerging at photospheric layers that subsequently rose to the chromosphere. We discuss the possibility that the fluctuations detected in the chromospheric emission probably reflect magneticfield oscillations which propagate to the chromosphere in the form of waves.

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“…We ran the CAlcium Inversion using a Spectral ARchive code (CAISAR, Beck et al 2013bBeck et al ,c, 2015 over the region containing the EB for a visualization of the 3D structure. Figure 10 shows a 3D rendering of the corresponding region in the inversion results.…”

Section: Formation Height Range Of Ebsmentioning

confidence: 99%

Multiwavelength spectropolarimetric observations of an Ellerman bomb

Rezaei

Beck

2015

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Context. Ellerman bombs (EBs) are enhanced emission in the wings of the Hα line in the solar spectrum. Aims. We study the structure of an EB in the photosphere and chromosphere.Methods. We analyze simultaneous observations of four chromospheric lines (Hα, Ca ii H, Ca ii IR 854 nm, and He i 1083 nm) as well as two photospheric lines (Fe i 630 and Si i 1082.7 nm) along with high-cadence 160 and 170 nm ultraviolet (UV) continuum filtergrams. Full Stokes data from the Helioseismic and Magnetic Imager (HMI) are used to trace the temporal evolution of the magnetic structure.Results. We identify the EB by excess emission in the wings of the Hα line, a brightening in the UV continuum, and large emission peaks in the core of the two Ca ii lines. The EB shows a blueshift in all chromospheric lines, while no shifts are observed in the photospheric lines. The blueshift in the chromospheric layer causes very asymmetric emission peaks in the Ca ii H line. The photospheric Si i spectral line shows a shallower line depth at the location of the EB. The UV continuum maps show that the EB was substantially brighter than its surroundings for about 30 min. The continuum contrast of the EB from 170 nm to 1080 nm shows a power-law dependency on the wavelength. The temperature enhancement amounts to 130 K in the low photosphere and 400 K at the temperature minimum level. This temperature excess is also seen in an LTE inversion of the Ca ii spectra. The total thermal and radiative energy content of the EB is about 10 20 J and 10 18 J in the photosphere and chromosphere, respectively. The HMI data hints at a photospheric magnetic flux cancellation as the driver of the EB. Conclusions. Ellerman bombs release the energy in a height range of several pressure scale heights around the temperature minimum such that they affect both the photosphere and the lower chromosphere.

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The energy of waves in the photosphere and lower chromosphere

Cited by 25 publications

References 90 publications

Ca II H sunspot tomography from the photosphere to the chromosphere

Ca II H sunspot tomography from the photosphere to the chromosphere

Evidence of quiet-Sun chromospheric activity related to an emerging small-scale magnetic loop

Multiwavelength spectropolarimetric observations of an Ellerman bomb

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