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Direct evidence for kinetic effects associated with solar wind reconnection.

Xu X, Wang Y, Wei F, Feng X, Deng X, Ma Y, Zhou M, Pang Y, Wong HC - Sci Rep (2015)

Bottom Line: Kinetic effects resulting from the two-fluid physics play a crucial role in the fast collisionless reconnection, which is a process to explosively release massive energy stored in magnetic fields in space and astrophysical plasmas.Because of the absence of kinetic effects and substantial heating, whether the reconnections are still ongoing when they are detected in the solar wind remains unknown.The turbulence associated with the exhaust is a kind of background solar wind turbulence, implying that the reconnection generated turbulence has not much developed.

View Article: PubMed Central - PubMed

Affiliation: 1] Institute of Space Science and Technology, Nanchang University, Nanchang 330031, China [2] State Key Laboratory of Space Weather, Chinese Academy of Sciences, Beijing 100190, China [3] Space Science Institute, Macau University of Science and Technology, Macao, China.

ABSTRACT
Kinetic effects resulting from the two-fluid physics play a crucial role in the fast collisionless reconnection, which is a process to explosively release massive energy stored in magnetic fields in space and astrophysical plasmas. In-situ observations in the Earth's magnetosphere provide solid consistence with theoretical models on the point that kinetic effects are required in the collisionless reconnection. However, all the observations associated with solar wind reconnection have been analyzed in the context of magnetohydrodynamics (MHD) although a lot of solar wind reconnection exhausts have been reported. Because of the absence of kinetic effects and substantial heating, whether the reconnections are still ongoing when they are detected in the solar wind remains unknown. Here, by dual-spacecraft observations, we report a solar wind reconnection with clear Hall magnetic fields. Its corresponding Alfvenic electron outflow jet, derived from the decouple between ions and electrons, is identified, showing direct evidence for kinetic effects that dominate the collisionless reconnection. The turbulence associated with the exhaust is a kind of background solar wind turbulence, implying that the reconnection generated turbulence has not much developed.

No MeSH data available.


Related in: MedlinePlus

Illustration of the power spectrum density of the BM component.In the regime below ion cyclotron frequency (0.05 Hz marked by the vertical dashed line), the spectral slope is about −5/3. In the regime above ion cyclotron frequency, the spectral slope is −3.08. It is more likely that the turbulence is a kind of background solar wind turbulence.
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f4: Illustration of the power spectrum density of the BM component.In the regime below ion cyclotron frequency (0.05 Hz marked by the vertical dashed line), the spectral slope is about −5/3. In the regime above ion cyclotron frequency, the spectral slope is −3.08. It is more likely that the turbulence is a kind of background solar wind turbulence.

Mentions: The turbulence in the solar wind reconnection could be very complicated, since the reconnection generated turbulence and the background solar wind turbulence would probably mix together. Figure 4 shows the power spectrum density of the BM component. The local ion cyclotron frequency is about 0.05 Hz. Below this frequency, the spectral index is −1.75 (~5/3), while above this frequency, the spectral index is -3.08. Therefore, the turbulence in our data is more likely a kind of background solar wind turbulence. The Hall field mainly supported by the central electron jet in our data is basically maintained though it is disturbed near the edge of the exhaust, while the Hall field shown in Eastwood et al.31 is very turbulent and no corresponding central jet can be identified. The reason for this may be that the turbulence generated by reconnection in this event is not much developed. As a result, the central part of the exhaust is minimally affected by the background solar wind turbulence while the near edge portion of plasma could be disturbed. However, as pointed by Browning and Lazarian36, the couple between microscale kinetic effects and macroscale turbulence generated by reconnection remains an open question.


Direct evidence for kinetic effects associated with solar wind reconnection.

Xu X, Wang Y, Wei F, Feng X, Deng X, Ma Y, Zhou M, Pang Y, Wong HC - Sci Rep (2015)

Illustration of the power spectrum density of the BM component.In the regime below ion cyclotron frequency (0.05 Hz marked by the vertical dashed line), the spectral slope is about −5/3. In the regime above ion cyclotron frequency, the spectral slope is −3.08. It is more likely that the turbulence is a kind of background solar wind turbulence.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4308709&req=5

f4: Illustration of the power spectrum density of the BM component.In the regime below ion cyclotron frequency (0.05 Hz marked by the vertical dashed line), the spectral slope is about −5/3. In the regime above ion cyclotron frequency, the spectral slope is −3.08. It is more likely that the turbulence is a kind of background solar wind turbulence.
Mentions: The turbulence in the solar wind reconnection could be very complicated, since the reconnection generated turbulence and the background solar wind turbulence would probably mix together. Figure 4 shows the power spectrum density of the BM component. The local ion cyclotron frequency is about 0.05 Hz. Below this frequency, the spectral index is −1.75 (~5/3), while above this frequency, the spectral index is -3.08. Therefore, the turbulence in our data is more likely a kind of background solar wind turbulence. The Hall field mainly supported by the central electron jet in our data is basically maintained though it is disturbed near the edge of the exhaust, while the Hall field shown in Eastwood et al.31 is very turbulent and no corresponding central jet can be identified. The reason for this may be that the turbulence generated by reconnection in this event is not much developed. As a result, the central part of the exhaust is minimally affected by the background solar wind turbulence while the near edge portion of plasma could be disturbed. However, as pointed by Browning and Lazarian36, the couple between microscale kinetic effects and macroscale turbulence generated by reconnection remains an open question.

Bottom Line: Kinetic effects resulting from the two-fluid physics play a crucial role in the fast collisionless reconnection, which is a process to explosively release massive energy stored in magnetic fields in space and astrophysical plasmas.Because of the absence of kinetic effects and substantial heating, whether the reconnections are still ongoing when they are detected in the solar wind remains unknown.The turbulence associated with the exhaust is a kind of background solar wind turbulence, implying that the reconnection generated turbulence has not much developed.

View Article: PubMed Central - PubMed

Affiliation: 1] Institute of Space Science and Technology, Nanchang University, Nanchang 330031, China [2] State Key Laboratory of Space Weather, Chinese Academy of Sciences, Beijing 100190, China [3] Space Science Institute, Macau University of Science and Technology, Macao, China.

ABSTRACT
Kinetic effects resulting from the two-fluid physics play a crucial role in the fast collisionless reconnection, which is a process to explosively release massive energy stored in magnetic fields in space and astrophysical plasmas. In-situ observations in the Earth's magnetosphere provide solid consistence with theoretical models on the point that kinetic effects are required in the collisionless reconnection. However, all the observations associated with solar wind reconnection have been analyzed in the context of magnetohydrodynamics (MHD) although a lot of solar wind reconnection exhausts have been reported. Because of the absence of kinetic effects and substantial heating, whether the reconnections are still ongoing when they are detected in the solar wind remains unknown. Here, by dual-spacecraft observations, we report a solar wind reconnection with clear Hall magnetic fields. Its corresponding Alfvenic electron outflow jet, derived from the decouple between ions and electrons, is identified, showing direct evidence for kinetic effects that dominate the collisionless reconnection. The turbulence associated with the exhaust is a kind of background solar wind turbulence, implying that the reconnection generated turbulence has not much developed.

No MeSH data available.


Related in: MedlinePlus