Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：American Astronomical Society  

Abstract

The physical connection between thermal convection in the solar interior and the solar wind remains unclear due to their significant scale separation. Using an extended version of the three-dimensional radiative magnetohydrodynamic code RAMENS, we perform the first comprehensive simulation of the solar wind formation, starting from the wave excitation and the small-scale dynamo below the photosphere. The simulation satisfies various observational constraints as a slow solar wind emanating from the coronal hole boundary. The magnetic energy is persistently released in the simulated corona, showing a hot upward flow at the interface between open and closed fields. To evaluate the energetic contributions from Alfvén wave and interchange reconnection, we develop a new method to quantify the cross-field energy transport in the simulated atmosphere. The measured energy transport from closed coronal loops to open field accounts for approximately half of the total. These findings suggest a significant role of the supergranular-scale interchange reconnection in solar wind formation.

DOI： 10.3847/2041-8213/acdde0

Web of Science

Scopus

Other Link： https://iopscience.iop.org/article/10.3847/2041-8213/acdde0/pdf

Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

Abstract

Chromospheric jets are plausible agents of energy and mass transport in the solar chromosphere, although their driving mechanisms have not yet been elucidated. Magnetic field measurements are key for distinguishing the driving mechanisms of chromospheric jets. We performed a full Stokes synthesis in the infrared range with a realistic radiative magnetohydrodynamics simulation that generated a chromospheric jet to predict spectro-polarimetric observations from the Sunrise Chromospheric Infrared spectro-Polarimeter (SCIP) onboard the SUNRISE III balloon telescope. The jet was launched by the collision between the transition region and an upflow driven by the ascending motion of the twisted magnetic field at the envelope of the flux tube. This motion is consistent with upwardly propagating non-linear Alfvénic waves. The upflow could be detected as continuous Doppler signals in the Ca ii 849.8 nm line at the envelope where the dark line core intensity and strong linear polarisation coexist. The axis of the flux tube was bright in both Fe i 846.8 nm and Ca ii 849.8 nm lines with down- flowing plasma inside it. The structure, time evolution, and Stokes signals predicted in our study will improve the physical interpretation of future spectro-polarimetric observations with SUNRISE III/SCIP.

DOI： 10.1093/mnras/stad1509

Web of Science

Scopus

Publishing type：Research paper (scientific journal)   Publisher：American Astronomical Society  

Abstract

In solving the solar coronal heating problem, it is crucial to comprehend the mechanisms by which energy is conveyed from the photosphere to the corona. Recently, magnetic tornadoes, characterized as coherent, rotating magnetic-field structures extending from the photosphere to the corona, have drawn growing interest as a possible means of efficient energy transfer. Despite its acknowledged importance, the underlying physics of magnetic tornadoes remains elusive. In this study, we conduct a three-dimensional radiative magnetohydrodynamic simulation that encompasses the upper convective layer and extends into the corona, with a view to investigating how magnetic tornadoes are generated and efficiently transfer energy into the corona. We find that a single event of magnetic flux concentration merger on the photosphere gives rise to the formation of a single magnetic tornado. The Poynting flux transferred into the corona is found to be four times greater in the presence of the magnetic tornado, as compared to its absence. This increase is attributed to a reduction in energy loss in the chromosphere, resulting from the weakened magnetic-energy cascade. Based on an evaluation of the fraction of the merging events, our results suggest that magnetic tornadoes contribute approximately 50% of the Poynting flux into the corona in regions where the coronal magnetic-field strength is 10 G. Potentially, the contribution could be even greater in areas with a stronger coronal magnetic field.

DOI： 10.3847/1538-4357/accbb8

Web of Science

Scopus

Other Link： https://iopscience.iop.org/article/10.3847/1538-4357/accbb8/pdf

Publishing type：Research paper (scientific journal)   Publisher：American Astronomical Society  

Abstract

One key aspect of understanding the solar dynamo mechanism and the evolution of solar magnetism is to properly describe the emergence of solar active regions. In this Letter, we describe the Lagrangian photospheric flows dynamics during a simulated flux emergence that produces an active region formed by pores. We analyze the lower photospheric flow organization prior, during and following the rise of an active region, uncovering the repelling and attracting photospheric structures that act as sources and sinks for magnetic element transport. Our results show that around 10 hr before the simulated emergence, considerable global changes are taking place on mesogranular scales indicated by an increase of the number of regions acting as a source to the multiple and scattered emergences of small-scale magnetic flux. At the location of active region’s appearance, the converging flows become weaker and there is an arising of a diverging region 8 hr before the emergence time. Our study also indicates that the strong concentration of magnetic field affects the flow dynamics beyond the area of the actual simulated pores, leading to complex and strongly diverging flows in the neighboring regions. Our findings suggest that the Lagrangian analysis is a powerful tool to describe the changes in the photospheric flows due to magnetic flux emergence.

DOI： 10.3847/2041-8213/acd007

Web of Science

Scopus

Other Link： https://iopscience.iop.org/article/10.3847/2041-8213/acd007/pdf

Language：Japanese   Publisher：The Japanese Society for Artificial Intelligence  

<p>Solar spectral analysis plays an important role in solar physics research to understand the Sun-Earth relationship. Hinode Solar Optical Telescope (Hinode SOT/SP) has been accumulating solar spectro-polarimetry (SP) data for more than 15 years. However, processing this huge amount of high dimensional data is challenging even with the existing computational methods. To this end, we suggest a compressed representation of SP data using a deep learning technique that will be useful for further steps of solar spectral analysis, such as flare prediction, automatic categorization of spectra and detection of anomalous spectra. We built an autoencoder for compressing solar spectra containing Stokes I and V polarization parameters. The encoder converts the input (SP data) into a lower dimensional compressed representation of the spectra, and then decodes it back into the output (reconstruction). We compared performances of the model trained with different errors: standard loss as mean absolute error (mae), and customized loss as sum of weighted mae of Stokes I and V. From the scatter plot of true and reconstruction the model with customized loss function resulted in smaller standard deviations of 0.57-0.7% (continuums) and 2.71-3.16% (line centers) for Stokes I, and 4.79% (left line core) for Stokes V.</p>

DOI： 10.11517/pjsai.jsai2023.0_3xin424

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