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A self-consistent 3D MHD model producing a solar blowout jet

Yajie Chen, Hardi Peter, Damien Przybylski, Lakshmi Pradeep Chitta, Sudip Mandal

TL;DR

The paper addresses how solar blowout jets can form through self-consistent magneto-convective dynamics rather than prescribed surface drivers. It uses a 3D radiation MHD model with the MURaM code to let a twisted flux tube emerge through the photosphere and reconnect with open field, transferring twist via interchange reconnection. The simulation reproduces a standard jet that transitions into a blowout jet with a fast heating front traveling at the local Alfvén speed and a slower mass upflow, matching observed speeds and timing; synthetic emissions in EUV and X-ray channels concur with observations. The results provide a physically grounded mechanism for blowout jets and reveal how near-surface convection-generated magnetic structures can drive energy release and twist transfer to the solar wind base.

Abstract

Context. Solar blowout jets are a distinct subclass of ubiquitous extreme-ultraviolet (EUV) and X-ray coronal jets. Aims. Most existing models of blowout jets prescribe an initial magnetic field configurations and apply ad-hoc changes in the photosphere to trigger the jets. In contrast, we aim for a self-consistent magneto-convective description of the jet initiation. Methods. We employ a 3D radiation magnetohydrodynamic (MHD) model of a solar coronal hole region using the MURaM code. The computational domain extends from the upper convection zone to the lower corona. We synthesize the emission in the extreme UV and X-rays for a direct comparison to observations and examine the evolution of the magnetic field structure of the event. Results. In the simulation a twisted flux tube forms self-consistently, emerges through the surface and interacts with the pre-existing open field. Initially the resulting jet is of the standard type with a narrow spire. The release of the twist into the open field causes a broadening of the jet spire turning the jet into a blowout type. At the same time this creates a fast heating front propagating at the local Alfvén speed. The properties of the modeled jet closely match observations of blowout jets: a slow (180 km/s) mass upflow and a fast (500 km/s) propagating front form, the latter being a signature of the heating front. Also the timing of the jet with respect to the flux emergence and subsequent cancellation matches observations. Conclusions. The near-surface magneto-convection self-consistently generates a twisted flux tube that emerges through the photosphere. The tube then interacts with the pre-existing magnetic field by means of interchange reconnection. This transfers the twist to the open field region and produces a blowout jet that matches the main characteristics of this type of jet found in observations.

A self-consistent 3D MHD model producing a solar blowout jet

TL;DR

The paper addresses how solar blowout jets can form through self-consistent magneto-convective dynamics rather than prescribed surface drivers. It uses a 3D radiation MHD model with the MURaM code to let a twisted flux tube emerge through the photosphere and reconnect with open field, transferring twist via interchange reconnection. The simulation reproduces a standard jet that transitions into a blowout jet with a fast heating front traveling at the local Alfvén speed and a slower mass upflow, matching observed speeds and timing; synthetic emissions in EUV and X-ray channels concur with observations. The results provide a physically grounded mechanism for blowout jets and reveal how near-surface convection-generated magnetic structures can drive energy release and twist transfer to the solar wind base.

Abstract

Context. Solar blowout jets are a distinct subclass of ubiquitous extreme-ultraviolet (EUV) and X-ray coronal jets. Aims. Most existing models of blowout jets prescribe an initial magnetic field configurations and apply ad-hoc changes in the photosphere to trigger the jets. In contrast, we aim for a self-consistent magneto-convective description of the jet initiation. Methods. We employ a 3D radiation magnetohydrodynamic (MHD) model of a solar coronal hole region using the MURaM code. The computational domain extends from the upper convection zone to the lower corona. We synthesize the emission in the extreme UV and X-rays for a direct comparison to observations and examine the evolution of the magnetic field structure of the event. Results. In the simulation a twisted flux tube forms self-consistently, emerges through the surface and interacts with the pre-existing open field. Initially the resulting jet is of the standard type with a narrow spire. The release of the twist into the open field causes a broadening of the jet spire turning the jet into a blowout type. At the same time this creates a fast heating front propagating at the local Alfvén speed. The properties of the modeled jet closely match observations of blowout jets: a slow (180 km/s) mass upflow and a fast (500 km/s) propagating front form, the latter being a signature of the heating front. Also the timing of the jet with respect to the flux emergence and subsequent cancellation matches observations. Conclusions. The near-surface magneto-convection self-consistently generates a twisted flux tube that emerges through the photosphere. The tube then interacts with the pre-existing magnetic field by means of interchange reconnection. This transfers the twist to the open field region and produces a blowout jet that matches the main characteristics of this type of jet found in observations.
Paper Structure (7 sections, 6 figures)

This paper contains 7 sections, 6 figures.

Table of Contents

  1. Introduction
  2. MHD model and methods
  3. Results
  4. Dynamics of the jet
  5. Magnetic origin of the jet
  6. Discussion
  7. Conclusions

Figures (6)

  • Figure 1: Synthesized images of the blowout jet in different passbands. (a) Similar to Fig. \ref{['fig:2imgs']} but around time t${=}1000$ s. (b--c) Similar to (a), but for AIA 304 Å and Hinode/XRT Al-poly passbands at the same time. An animation is available online. See Sect. \ref{['Sect:jet_dynamics']}.
  • Figure 2: Space-time diagrams along the vertical direction. These show the horizontally averaged vertical profile of the respective quantity as a function of time. From top to bottom we display the evolution in EUI 174 Å (a-b), Hinode/XRT (c-d) and in heating rate (e-f). The left column shows the original value of the emissivity (a,c) and heating rate (e), while the right column shows the respective running difference images (with time delay of 10 s) simply to highlight the temporal changes. The dashed lines indicate the apparent speeds of 184 km s$^{-1}$ (a-b) and 504 km s$^{-1}$ (c-f). See Sect. \ref{['Sect:jet_dynamics']}.
  • Figure 3: Magnetic field structure surrounding the jet. The two panels show the situation during the standard- (left) and blowout-jet (right) phases at the same times as in Fig. \ref{['fig:2imgs']}. In each panel the bottom shows a zoom-in of the magnetogram at the respective time. The synthesized EUI 174 Å images integrated along the x- and y- directions are depicted in the vertical slices of each 3D box. The colored lines represent the magnetic field lines in and around the jet. The white arrows point to field lines in the jet spire that become misaligned during the blowout jet phase (right), compared to the more aligned configuration during the standard phase (left). This indicates the untwisting motions that are also visible in the EUI 174 Å images on the vertical slices in the animation showing the temporal evolution. The animation is available online. See Sect. \ref{['Sect:magnetic_field']}.
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