The Cycling of Material Between the Solar Corona and Chromosphere

Guerreiro, Nuno; Hansteen, V. H.; Pontieu, Bart De

doi:10.1088/0004-637x/769/1/47

Cited by 18 publications

(29 citation statements)

References 32 publications

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“…On the other hand, in contrast to what was speculated by Guerreiro et al (2013), we find no evidence for rapid heating to coronal temperatures shortly before the cooling phase sets in. Two minutes prior to t = 5000 s, the vast majority of the corks (i.e., 85%) already exist at temperatures above 100 000 K, while 4% are within the same temperature interval, whereas only 11% have lower temperature.…”

Section: Temperature Evolution Of Transition Region Corkscontrasting

confidence: 99%

“…Similar numbers are found for various other timesteps, suggesting a fast cooling process for the transition region corks once they reach the T = 100 000 K temperature range. Our results are in agreement with those of Guerreiro et al (2013) who injected a tracer fluid filling the volume between 20 000 K and 300 000 K into the Bifrost simulations. After two minutes of solar time, they found that 95% of the material has left this region, about 70% of which has cooled to chromospheric temperatures, while 25% of the material was heated to higher upper transition region or coronal temperatures.…”

Section: Temperature Evolution Of Transition Region Corkssupporting

confidence: 91%

“…Following a similar approach as Guerreiro et al (2013), we investigated the temperature evolution of corks at transition region temperatures in more detail by following all corks in the temperature range log(T /[K]) = [4.9, 5.1] over time for several minutes. Because our cork-based approach allows for both backward and forward tracing, we can thus also draw conclusions on the situation prior to an observed state.…”

Section: Temperature Evolution Of Transition Region Corksmentioning

confidence: 99%

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Disentangling flows in the solar transition region

Zacharias

Hansteen

Leenaarts

et al. 2018

A&A

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Context. The measured average velocities in solar and stellar spectral lines formed at transition region temperatures have been difficult to interpret. The dominant redshifts observed in the lower transition region naturally leads to the question of how the upper layers of the solar (and stellar) atmosphere can be maintained. Likewise, no ready explanation has been made for the average blueshifts often found in upper transition region lines. However, realistic three-dimensional radiation magnetohydrodynamics (3D rMHD) models of the solar atmosphere are able to reproduce the observed dominant line shifts and may thus hold the key to resolve these issues. Aims. These new 3D rMHD simulations aim to shed light on how mass flows between the chromosphere and corona and on how the coronal mass is maintained. These simulations give new insights into the coupling of various atmospheric layers and the origin of Doppler shifts in the solar transition region and corona. Methods. The passive tracer particles, so-called corks, allow the tracking of parcels of plasma over time and thus the study of changes in plasma temperature and velocity not only locally, but also in a co-moving frame. By following the trajectories of the corks, we can investigate mass and energy flows and understand the composition of the observed velocities.Results. Our findings show that most of the transition region mass is cooling. The preponderance of transition region redshifts in the model can be explained by the higher percentage of downflowing mass in the lower and middle transition region. The average upflows in the upper transition region can be explained by a combination of both stronger upflows than downflows and a higher percentage of upflowing mass. Conclusions. Corks are shown to be an essential tool in 3D rMHD models in order to study mass and energy flows. We have shown that most transition region plasma is cooling after having been heated slowly to upper transition region temperatures several minutes before. Downward propagating pressure disturbances are identified as one of the main mechanisms responsible for the observed redshifts at transition region temperatures.

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Section: Temperature Evolution Of Transition Region Corkscontrasting

confidence: 99%

Section: Temperature Evolution Of Transition Region Corkssupporting

confidence: 91%

Section: Temperature Evolution Of Transition Region Corksmentioning

confidence: 99%

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Disentangling flows in the solar transition region

Zacharias

Hansteen

Leenaarts

et al. 2018

A&A

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“…IRIS contributes to our understanding by showing us in what form non-radiative energy is transmitted by the chromosphere into the corona. The studies described above help constrain wave-energy fluxes, while imaging of the chromosphere and photosphere combined with modeling constrains the forcing of the field into braids (see, e.g., Cirtain et al, 2013;Guerreiro, Hansteen, and De Pontieu, 2013) and twists by flows. IRIS also sheds light on how and where non-thermal energy is first released.…”

Section: Currents and Reconnectionmentioning

confidence: 99%

The Interface Region Imaging Spectrograph (IRIS)

et al. 2014

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The Interface Region Imaging Spectrograph (IRIS) small explorer spacecraft provides simultaneous spectra and images of the photosphere, chromosphere, transition region, and corona with 0.33 -0.4 arcsec spatial resolution, two-second temporal resolution, and 1 km s −1 velocity resolution over a field-of-view of up to 175 arcsec × 175 arcsec. . IRIS is sensitive to emission from plasma at temperatures between 5000 K and 10 MK and will advance our understanding of the flow of mass and energy through an interface region, formed by the chromosphere and transition region, between the photosphere and corona. This highly structured and dynamic region not only acts as the conduit of all mass and energy feeding into the corona and solar wind, it also requires an order of magnitude more energy to heat than the corona and solar wind combined. The IRIS investigation includes a strong numerical modeling component based on advanced radiative-MHD codes to facilitate interpretation of observations of this complex region. Approximately eight Gbytes of data (after compression) are acquired by B. De Pontieu (B) ·Harvard-Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138, USA

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“…Hansteen et al (2010), for example, studied this mass and energy cycle between the lower atmosphere and the corona and found that both downflows and upflows are present at locations of (strong) magnetic field braiding, leading to redshifts and blueshifts of the order of about 5 km/s (see also e.g. Zacharias et al 2011;Guerreiro et al 2013). Observationally, a multitude of studies have found evidence for the presence of a complex interplay between upflows and downflows in the Transition Region (TR) and lower corona (e.g.…”

Section: Introductionmentioning

confidence: 99%

Chromospheric evaporation and phase mixing of Alfvén waves in coronal loops

Damme

Moortel

Pagano

et al. 2020

A&A

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Context. Phase mixing of Alfvén waves has been studied extensively as a possible coronal heating mechanism but without the full thermodynamic consequences considered self-consistently. It has been argued that in some cases, the thermodynamic feedback of the heating could substantially affect the transverse density gradient and even inhibit the phase mixing process. Aims. In this paper, for the first time, we use MHD simulations with the appropriate thermodynamical terms included to quantify the evaporation following heating by phase mixing of Alfvén waves in a coronal loop and the effect of this evaporation on the transverse density profile. Methods. The numerical simulations were performed using the Lagrangian Remap code Lare2D. We set up a 2D loop model consisting of a field-aligned thermodynamic equilibrium and a cross-field (background) heating profile. A continuous, sinusoidal, high-frequency Alfvén wave driver was implemented. As the Alfvén waves propagate along the field, they undergo phase mixing due to the cross-field density gradient in the coronal part of the loop. We investigated the presence of field-aligned flows, heating from the dissipation of the phase-mixed Alfvén waves, and the subsequent evaporation from the lower atmosphere. Results. We find that phase mixing of Alfvén waves leads to modest heating in the shell regions of the loop and evaporation of chromospheric material into the corona with upflows of the order of only 5-20 m/s. Although the evaporation leads to a mass increase in the shell regions of the loop, the effect on the density gradient and, hence, on the phase mixing process, is insignificant. Conclusions. This paper self-consistently investigates the effect of chromospheric evaporation on the cross-field density gradient and the phase mixing process in a coronal loop. We found that the effects in our particular setup (small amplitude, high frequency waves) are too small to significantly change the density gradient.A&A proofs: manuscript no. CE_PM_final_2 Fig. 1. Contour plots of the temperature (left) and density (right) after the numerical relaxation.

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The Cycling of Material Between the Solar Corona and Chromosphere

Cited by 18 publications

References 32 publications

Disentangling flows in the solar transition region

Disentangling flows in the solar transition region

The Interface Region Imaging Spectrograph (IRIS)

Chromospheric evaporation and phase mixing of Alfvén waves in coronal loops

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