Soft X‐ray and ENA Imaging of the Earth's Dayside Magnetosphere

Connor, H. K.; Sibeck, D. G.; Collier, M. R.; Baliukin, Igor; Branduardi‐Raymont, G.; Brandt, P. C.; Buzulukova, N.; Collado‐Vega, Y. M.; Escoubet, C. P.; Fok, M. C. H.; Hsieh, S. W.; Jung, Jaewoong; Kameda, Shingo; Küntz, K. D.; Porter, F. S.; Sembay, S.; Sun, Tianran; Walsh, Brian M.

doi:10.1029/2020ja028816

Cited by 34 publications

(69 citation statements)

References 144 publications

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“…The large density discrepancy between the XMM of our result and that of the IBEX studies still exists, partly due to the inherent difference between the two datasets and partly due to the different density derivation techniques used. For example, the ENA observations are very sensitive to plasma velocity distributions (Connor et al., 2021). For accurate neutral density estimation, a realistic magnetosheath model and sophisticated analysis of the magnetosheath ion flux that moves toward the IBEX detector are necessary.…”

Section: Discussionmentioning

confidence: 99%

“…(2001, 2008); see also Connor et al. (2012, 2014, 2015, 2016, 2021), Cramer et al. (2017), Ferdousi and Raeder (2016), Ferdousi et al.…”

Section: Data and Modelmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

“…Tracking magnetopause reconnection on a global scale has been particularly challenging due to the lack of possibly simultaneous observations covering wide spatial regions of the magnetopause. Recently, soft X-ray imaging of the Earth's dayside system has been suggested as an innovative way to visualize the dayside magnetopause motion and thus infer the dayside reconnection mode (Connor et al, 2021).A small portion of the solar wind plasma consists of highly charged ions, like O 7+ and O 8+ . The Earth's exosphere is the outermost layer of the atmosphere composed of mostly hydrogen atoms.…”

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confidence: 99%

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Solar Minimum Exospheric Neutral Density Near the Subsolar Magnetopause Estimated From the XMM Soft X‐Ray Observations on 12 November 2008

et al. 2022

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The Earth's magnetosheath and cusps emit soft X‐rays due to the charge exchange between highly charged solar wind ions and exospheric hydrogen atoms. The Lunar Environment Heliospheric X‐ray Imager and Solar wind Magnetosphere Ionosphere Link Explorer missions are scheduled to image the Earth's dayside magnetosphere system in soft X‐rays to investigate global‐scale magnetopause reconnection modes under varying solar wind conditions. The exospheric neutral hydrogen density distribution, especially the value of this density at the subsolar magnetopause is of particular interest for understanding X‐ray emissions near this boundary. This paper estimates the exospheric density during solar minimum using the X‐ray Multimirror Mission (XMM) astrophysics observatory. We selected an event on 12 November 2008 from the XMM data archive, which detects soft X‐rays of magnetosheath origin while solar wind and interplanetary magnetic field conditions are relatively constant. During the event the location of the magnetopause was measured in situ by the THEMIS mission, thus the location of the solar wind ions responsible for the magnetosheath emission is well constrained by observation. We estimated the exospheric density using the Open Geospace Global Circulation Model (OpenGGCM) and a spherically symmetric exosphere model. The ratio of the magnetosheath plasma flux between the OpenGGCM model and the THEMIS, was nearly 1, which means the magnetohydrodynamic model reasonably reproduces the magnetosheath plasma conditions. The OpenGGCM magnetosheath parameters were used to deconvolve soft X‐rays of exospheric origin from the XMM signal. The lower‐limit of the exospheric density of this solar minimum event is 36.8 ± 11.7 cm−3 at 10 RE subsolar location.

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Section: Discussionmentioning

confidence: 99%

“…(2001, 2008); see also Connor et al. (2012, 2014, 2015, 2016, 2021), Cramer et al. (2017), Ferdousi and Raeder (2016), Ferdousi et al.…”

Section: Data and Modelmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Solar Minimum Exospheric Neutral Density Near the Subsolar Magnetopause Estimated From the XMM Soft X‐Ray Observations on 12 November 2008

et al. 2022

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“…Soft X-ray imagers on these spacecrafts will observe motion of the Earths magnetosheath and cusps in soft X-ray with a primary goal of understanding the magnetopause reconnection modes under various solar wind conditions. Soft X-ray is emitted due to interaction between the exospheric neutrals and the highly charged solar wind ions like O 7+ and O 8+ (Sibeck et al, 2018;Connor et al, 2021). Neutral density is a key parameter that controls the strength of soft X-ray sig-https://doi.org/10.5194/angeo-2021-36 Preprint.…”

Section: Introductionmentioning

confidence: 99%

Terrestrial exospheric dayside H-density profile at 3–15 R_e from UVIS/HDAC and TWINS Lyman-α data combined

Connor

Jung

Nass

et al. 2021

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Abstract. Terrestrial ecliptic dayside observations of the exospheric Lyman-α column intensity between 3–15 Earth radii (Re) by UVIS/HDAC at CASSINI have been analysed to derive the neutral exospheric H-density profile at the Earth's ecliptic dayside in this radial range. The data were measured during CASSINIS's swing by manoeuvre at the Earth on 18 August 1999 and are published by (Werner et al., 2004). In this study the dayside HDAC Lyman-α observations published by (Werner et al., 2004) are compared to calculated Lyman-α intensities based on the 3D H-density model derived from TWINS Lyman-α observations between 2008–2010 (Zoennchen et al., 2015). It was found, that both Lyman-α profiles show a very similar radial dependence in particular between 3–8 Re. Between 3.0–5.5 Re impact distance Lyman-α observations of both TWINS and UVIS/HDAC are existing at the ecliptic dayside. In this overlapping region the cross-calibration of the HDAC profile against the calculated TWINS profile was done, assuming, that the exosphere there was similar for both due to comparable space weather conditions. As result of the cross-calibration the conversion factor between counts/s and Rayleigh fc = 3.285 [counts/s/R] is determined for these HDAC observations. Using this factor the radial H-density profile for the Earths ecliptic dayside was derived from the UVIS/HDAC observations, which constrained the neutral H-density there at 10 Re to a value of 35 cm−3. Furthermore, a faster radial H-density decrease was found at distances above 8 Re (≈ r−3) compared to the lower distances 3–7 Re (≈ r−2.37). This increased loss of neutral H above 8 Re might indicate a higher rate of H ionization in the vicinity of the magnetopause at 9–11 Re (near sub solar point) and beyond, because of increasing charge exchange interactions of exospheric H atoms with solar wind ions outside the magnetosphere.

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Finding Magnetopause Standoff Distance using a Soft X-ray Imager - Part 2: Methods to Analyze 2-D X-ray Images

Samsonov

Sembay

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et al. 2022

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The Earth's magnetosheath and cusps are the sources of soft X-rays. In the accompanying paper (Part 1) and this paper, we discuss the methods of finding the magnetopause position by analyzing the X-ray images. We use the software developed for the Soft X-ray Imager (SXI) on board the forthcoming Solar wind -Magnetosphere -Ionosphere Link Explorer (SMILE) mission. We show how to find the maximum SXI count rate in noisy count maps. We verify the assumption that the maximum of the X-ray emissivity integrated along the Line-of-Sight (Ix ) is tangent to the magnetopause. We consider two cases using two MHD models and apply different methods of magnetospheric masking. Overall, the magnetopause is located close to the maximum Ix gradient or between the maximum Ix gradient and the maximum Ix depending on the method used. But since the angular distance between the maximum Ix gradient and the maximum Ix is relatively small (about 3{degree sign}), the maximum Ix might be used as an indicator of the outer boundary of a wide magnetopause layer usually obtained in MHD simulations.

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Soft X‐ray and ENA Imaging of the Earth's Dayside Magnetosphere

Cited by 34 publications

References 144 publications

Solar Minimum Exospheric Neutral Density Near the Subsolar Magnetopause Estimated From the XMM Soft X‐Ray Observations on 12 November 2008

Solar Minimum Exospheric Neutral Density Near the Subsolar Magnetopause Estimated From the XMM Soft X‐Ray Observations on 12 November 2008

Terrestrial exospheric dayside H-density profile at 3–15 R_e from UVIS/HDAC and TWINS Lyman-α data combined

Finding Magnetopause Standoff Distance using a Soft X-ray Imager - Part 2: Methods to Analyze 2-D X-ray Images

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Soft X‐ray and ENA Imaging of the Earth's Dayside Magnetosphere

Cited by 34 publications

References 144 publications

Solar Minimum Exospheric Neutral Density Near the Subsolar Magnetopause Estimated From the XMM Soft X‐Ray Observations on 12 November 2008

Solar Minimum Exospheric Neutral Density Near the Subsolar Magnetopause Estimated From the XMM Soft X‐Ray Observations on 12 November 2008

Terrestrial exospheric dayside H-density profile at 3–15 Re from UVIS/HDAC and TWINS Lyman-α data combined

Finding Magnetopause Standoff Distance using a Soft X-ray Imager - Part 2: Methods to Analyze 2-D X-ray Images

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Terrestrial exospheric dayside H-density profile at 3–15 R_e from UVIS/HDAC and TWINS Lyman-α data combined