Heavy ion escape from Martian wake enhanced by magnetic reconnection

Abstract How ion escape from the near-Mars space is one of the biggest puzzles for understanding the atmospheric evolution of Mars. Ions in the plasma wake region continuously escape from the unmagnetized planet. Although the average ion escape rate in the wake region is relatively low, observations also have revealed the presence of events that contribute bursty and enhanced ion escape fluxes. Boundary instabilities and magnetic reconnection are suggested to be the candidate mechanisms. However, there is a lack of evaluation of ion escape caused by reconnection and comparison of the two mechanisms under a similar plasma environment. Here, we show an exciting reconnection event in the Martian wake. Two types of flux ropes are observed during the event. One was generated by reconnection, while others were produced by dayside boundary instability and convected to tail. The escape rate of oxygen ions in the reconnection region was estimated to be about 53–72% of the total tailward escape. Furthermore, the escape flux in the flux rope produced by reconnection was over twice that caused by dayside instabilities.

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Planetary magnetic field control of ion escape from weakly magnetized planets

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1819 ◽

2019 ◽

Vol 488 (2) ◽

pp. 2108-2120 ◽

Cited By ~ 12

Author(s):

Hilary Egan ◽

Riku Jarvinen ◽

Yingjuan Ma ◽

David Brain

Keyword(s):

Magnetic Field ◽

Effective Interaction ◽

Three Dimensional ◽

Power Laws ◽

Wind Pressure ◽

Escape Rate ◽

Opening Angle ◽

Plasma Environment ◽

Ion Escape ◽

Planetary Magnetic Field

ABSTRACT Intrinsic magnetic fields have long been thought to shield planets from atmospheric erosion via stellar winds; however, the influence of the plasma environment on atmospheric escape is complex. Here we study the influence of a weak intrinsic dipolar planetary magnetic field on the plasma environment and subsequent ion escape from a Mars-sized planet in a global three-dimensional hybrid simulation. We find that increasing the strength of a planet’s magnetic field enhances ion escape until the magnetic dipole’s standoff distance reaches the induced magnetosphere boundary. After this point increasing the planetary magnetic field begins to inhibit ion escape. This reflects a balance between shielding of the Southern hemisphere from ‘misaligned’ ion pickup forces and trapping of escaping ions by an equatorial plasmasphere. Thus, the planetary magnetic field associated with the peak ion escape rate is critically dependent on the stellar wind pressure. Where possible we have fit power laws for the variation of fundamental parameters (escape rate, escape power, polar cap opening angle, and effective interaction area) with magnetic field, and assessed upper and lower limits for the relationships.

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Stellar influence on heavy ion escape from unmagnetized exoplanets

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz788 ◽

2019 ◽

Vol 486 (1) ◽

pp. 1283-1291 ◽

Cited By ~ 8

Author(s):

Hilary Egan ◽

Riku Jarvinen ◽

David Brain

Keyword(s):

Solar System ◽

Stellar Wind ◽

Extreme Ultraviolet ◽

Dynamic Pressure ◽

Extreme Environments ◽

Heavy Ion ◽

Wind Pressure ◽

Field Orientation ◽

Plasma Environment ◽

Ion Escape

Abstract Planetary habitability is in part determined by the atmospheric evolution of a planet; one key component of such evolution is escape of heavy ions to space. Ion-loss processes are sensitive to the plasma environment of the planet, dictated by the stellar wind and stellar radiation. These conditions are likely to vary from what we observe in our own Solar system when considering a planet in the habitable zone around an M-dwarf. Here, we use a hybrid global plasma model to perform a systematic study of the changing plasma environment and ion escape as a function of stellar input conditions, which are designed to mimic those of potentially habitable planets orbiting M-dwarfs. We begin with a nominal case of a solar wind experienced at Mars today, and incrementally modify the interplanetary magnetic field orientation and strength, dynamic pressure, and Extreme Ultraviolet input. We find that both ion-loss morphology and overall rates vary significantly, and in cases where the stellar wind pressure was increased, the ion loss began to be diffusion or production limited with roughly half of all produced ions being lost. This limit implies that extreme care must be taken when extrapolating loss processes observed in the Solar system to extreme environments.

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The escape of CO2+ and other heavy minor ions from Mars

10.5194/epsc2020-410 ◽

2020 ◽

Author(s):

Lukas Maes ◽

Markus Fraenz ◽

James McFadden ◽

Mehdi Benna

Keyword(s):

Mass Spectra ◽

Heavy Ion ◽

Escape Rate ◽

Neutral Gas ◽

Peak Fitting ◽

Ion Escape ◽

Fitting Method ◽

Static Data ◽

Martian Ionosphere ◽

Ion Species

Next to its main constituent O2+, the Martian ionosphere consists of several other ion species, like CO2+, O+, CO+, HCO+, N2+, etc. The ionospheric escape is dominated by O2+ and O+ ions, and as a result the escape of these species is well studied. The other, minor ion species are more difficult to measure in the escaping plasma, because their contribution is typically obscured in the mass spectra of ion instruments by the more abundant O2+ peak. In this study we use data from the SupraThermal And Thermal Ion Composition instrument (STATIC) on board MAVEN to investigate the escape of these ions. We use a peak-fitting method to separate the contribution of several ion species, including O2+, CO2+, O+ and ions with a mass between 28-30 AMU. Our method is validated against Neutral Gas and Ion Mass Spectrometer (NGIMS), also onboard MAVEN, and results in the ionosphere agree qualitatively very well. We apply this method to STATIC data from January 2016 until May 2019 to perform a statistical study examining the escape of low energy (<100 eV) heavy (>=16 AMU) ions throughout the Martian magnetosphere and its surrounding. We find that CO2+ ions do escape through the tail but at a very limited rate, namely at less than 1% of the O2+ escape rate. Ions with a mass between 28-30 AMU, however, are found to constitute a significant part of the ionospheric outflow, with an escape rate 30% of the O2+ rate and 15% of the total heavy ion escape.

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Flux Rope Acceleration and Enhanced Magnetic Reconnection Rate

10.2172/813604 ◽

2003 ◽

Author(s):

C.Z. Cheng ◽

Y. Ren ◽

G.S. Choe ◽

Y.-J. Moon

Keyword(s):

Magnetic Reconnection ◽

Flux Rope ◽

Reconnection Rate

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Electron flat-top distributions around the magnetic reconnection region

Journal of Geophysical Research Atmospheres ◽

10.1029/2007ja012461 ◽

2008 ◽

Vol 113 (A1) ◽

pp. n/a-n/a ◽

Cited By ~ 60

Author(s):

Y. Asano ◽

R. Nakamura ◽

I. Shinohara ◽

M. Fujimoto ◽

T. Takada ◽

...

Keyword(s):

Magnetic Reconnection ◽

Reconnection Region

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Formation of coronal rain triggered by impulsive heating associated with magnetic reconnection

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936253 ◽

2019 ◽

Vol 630 ◽

pp. A123 ◽

Cited By ~ 5

Author(s):

P. Kohutova ◽

E. Verwichte ◽

C. Froment

Keyword(s):

Magnetic Reconnection ◽

Thermal Instability ◽

Flux Rope ◽

Coronal Loops ◽

Rain Event ◽

Subsequent Formation ◽

Standard Models ◽

Field Lines ◽

Impulsive Heating ◽

Coronal Rain

Context. Coronal rain consists of cool plasma condensations formed in coronal loops as a result of thermal instability. The standard models of coronal rain formation assume that the heating is quasi-steady and localised at the coronal loop footpoints. Aims. We present an observation of magnetic reconnection in the corona and the associated impulsive heating triggering formation of coronal rain condensations. Methods. We analyse combined SDO/AIA and IRIS observations of a coronal rain event following a reconnection between threads of a low-lying prominence flux rope and surrounding coronal field lines. Results. The reconnection of the twisted flux rope and open field lines leads to a release of magnetic twist. Evolution of the emission of one of the coronal loops involved in the reconnection process in different AIA bandpasses suggests that the loop becomes thermally unstable and is subject to the formation of coronal rain condensations following the reconnection and that the associated heating is localised in the upper part of the loop leg. Conclusions. In addition to the standard models of thermally unstable coronal loops with heating localised exclusively in the footpoints, thermal instability and subsequent formation of condensations can be triggered by the impulsive heating associated with magnetic reconnection occurring anywhere along a magnetic field line.

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MMS Observation of Secondary Magnetic Reconnection Beside Ion‐Scale Flux Rope at the Magnetopause

Geophysical Research Letters ◽

10.1029/2020gl089075 ◽

2020 ◽

Vol 47 (16) ◽

Author(s):

X.‐C. Dong ◽

M. W. Dunlop ◽

T.‐Y. Wang ◽

K. J. Trattner ◽

C. T. Russell ◽

...

Keyword(s):

Magnetic Reconnection ◽

Flux Rope

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Solar activities observed with the New Vacuum Solar Telescope

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316000235 ◽

2015 ◽

Vol 11 (S320) ◽

pp. 315-320

Author(s):

Shuhong Yang ◽

Jun Zhang

Keyword(s):

Magnetic Reconnection ◽

Flux Rope ◽

Observational Evidence ◽

Small Scale ◽

Solar Telescope ◽

New Name ◽

Direct Observations ◽

Filament Activation ◽

First Time

AbstractBased on the New Vacuum Solar Telescope observations, some new results about the solar activities are obtained. (1) In the Hα line, a flux rope tracked by filament activation is detected for the first time. There may exist some mild heating during the filament activation. (2) The direct observations illustrate the mechanism of confined flares, i.e., the flares are triggered by magnetic reconnection between the emerging loops and the pre-existing loops and prevented from being eruptive by the overlying loops. (3) The solid observational evidence of magnetic reconnection between two sets of small-scale loops is reported. The successive slow reconnection changes the conditions around the reconnection area and leads to the rapid reconnection. (4) An ensemble of oscillating bright features rooted in a light bridge is observed and given a new name, light wall. The light wall oscillations may be due to the leakage of p-modes from below the photosphere.

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