On the apparent line-of-sight alignment of the peak X-ray intensity of the magnetosheath and the tangent to the magnetopause, as viewed by SMILE-SXI
The Soft X-ray Imager (SXI) on board the Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) spacecraft will be able to view the Earth’s magnetosheath in soft X-rays. Simulated images of the X-ray emission visible from the position of SMILE are created for a range of solar wind densities by us...
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| Format: | Article |
| Language: | English |
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Science Press
2024-01-01
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| Series: | Earth and Planetary Physics |
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| Online Access: | http://www.eppcgs.org/article/doi/10.26464/epp2023062?pageType=en |
| _version_ | 1797347723485118464 |
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| author | Andrew Read |
| author_facet | Andrew Read |
| author_sort | Andrew Read |
| collection | DOAJ |
| description | The Soft X-ray Imager (SXI) on board the Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) spacecraft will be able to view the Earth’s magnetosheath in soft X-rays. Simulated images of the X-ray emission visible from the position of SMILE are created for a range of solar wind densities by using 3 years of the SMILE mission orbit, together with models of the expected X-ray emissivity from the Earth’s magnetosheath. Results from global magnetohydrodynamic simulations and a simple model for exospheric neutral densities are used to compare the locations of the lines of sight along which integrated soft X-ray intensities peak with the lines of sight lying tangent to surfaces (defined here to be the magnetopause) along which local soft X-ray intensities peak or exhibit their strongest gradients, or both, for strongly southward interplanetary magnetic field conditions when no depletion or low-latitude boundary layers are expected. Where, in the parameter space of the various times and seasons, orbital phases, solar wind conditions, and magnetopause models, the alignment of the X-ray emission peak with the magnetopause tangent is good, or is not, is presented. The main results are as follows. The spacecraft needs to be positioned well outside the magnetopause; low-altitude times near perigee are not good. In addition, there are seasonal aspects: dayside-apogee orbits are generally very good because the spacecraft travels out sunward at high altitude, but nightside-apogee orbits, behind the Earth, are bad because the spacecraft only rarely leaves the magnetopause. Dusk-apogee and dawn-apogee orbits are intermediate. Dayside-apogee orbits worsen slightly over the first three mission years, whereas nightside-apogee orbits improve slightly. Additionally, many more times of good agreement with the peak-to-tangent hypothesis occur when the solar wind is in a high-density state, as opposed to a low-density state. In a high-density state, the magnetopause is compressed, and the spacecraft is more often a good distance outside the magnetopause. |
| first_indexed | 2024-03-08T11:52:54Z |
| format | Article |
| id | doaj.art-fad40439615c455197b99adbf8656439 |
| institution | Directory Open Access Journal |
| issn | 2096-3955 |
| language | English |
| last_indexed | 2024-03-08T11:52:54Z |
| publishDate | 2024-01-01 |
| publisher | Science Press |
| record_format | Article |
| series | Earth and Planetary Physics |
| spelling | doaj.art-fad40439615c455197b99adbf86564392024-01-24T06:27:11ZengScience PressEarth and Planetary Physics2096-39552024-01-018115517210.26464/epp2023062SI8384-Read-FOn the apparent line-of-sight alignment of the peak X-ray intensity of the magnetosheath and the tangent to the magnetopause, as viewed by SMILE-SXIAndrew Read0Department of Physics & Astronomy, University of Leicester, Leicester, LE1 7RH, UKThe Soft X-ray Imager (SXI) on board the Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) spacecraft will be able to view the Earth’s magnetosheath in soft X-rays. Simulated images of the X-ray emission visible from the position of SMILE are created for a range of solar wind densities by using 3 years of the SMILE mission orbit, together with models of the expected X-ray emissivity from the Earth’s magnetosheath. Results from global magnetohydrodynamic simulations and a simple model for exospheric neutral densities are used to compare the locations of the lines of sight along which integrated soft X-ray intensities peak with the lines of sight lying tangent to surfaces (defined here to be the magnetopause) along which local soft X-ray intensities peak or exhibit their strongest gradients, or both, for strongly southward interplanetary magnetic field conditions when no depletion or low-latitude boundary layers are expected. Where, in the parameter space of the various times and seasons, orbital phases, solar wind conditions, and magnetopause models, the alignment of the X-ray emission peak with the magnetopause tangent is good, or is not, is presented. The main results are as follows. The spacecraft needs to be positioned well outside the magnetopause; low-altitude times near perigee are not good. In addition, there are seasonal aspects: dayside-apogee orbits are generally very good because the spacecraft travels out sunward at high altitude, but nightside-apogee orbits, behind the Earth, are bad because the spacecraft only rarely leaves the magnetopause. Dusk-apogee and dawn-apogee orbits are intermediate. Dayside-apogee orbits worsen slightly over the first three mission years, whereas nightside-apogee orbits improve slightly. Additionally, many more times of good agreement with the peak-to-tangent hypothesis occur when the solar wind is in a high-density state, as opposed to a low-density state. In a high-density state, the magnetopause is compressed, and the spacecraft is more often a good distance outside the magnetopause.http://www.eppcgs.org/article/doi/10.26464/epp2023062?pageType=enx-raysmagnetospheremagnetosheathmagnetopausesolar wind magnetosphere ionosphere link explorer (smile)earthsolar wind charge exchange |
| spellingShingle | Andrew Read On the apparent line-of-sight alignment of the peak X-ray intensity of the magnetosheath and the tangent to the magnetopause, as viewed by SMILE-SXI Earth and Planetary Physics x-rays magnetosphere magnetosheath magnetopause solar wind magnetosphere ionosphere link explorer (smile) earth solar wind charge exchange |
| title | On the apparent line-of-sight alignment of the peak X-ray intensity of the magnetosheath and the tangent to the magnetopause, as viewed by SMILE-SXI |
| title_full | On the apparent line-of-sight alignment of the peak X-ray intensity of the magnetosheath and the tangent to the magnetopause, as viewed by SMILE-SXI |
| title_fullStr | On the apparent line-of-sight alignment of the peak X-ray intensity of the magnetosheath and the tangent to the magnetopause, as viewed by SMILE-SXI |
| title_full_unstemmed | On the apparent line-of-sight alignment of the peak X-ray intensity of the magnetosheath and the tangent to the magnetopause, as viewed by SMILE-SXI |
| title_short | On the apparent line-of-sight alignment of the peak X-ray intensity of the magnetosheath and the tangent to the magnetopause, as viewed by SMILE-SXI |
| title_sort | on the apparent line of sight alignment of the peak x ray intensity of the magnetosheath and the tangent to the magnetopause as viewed by smile sxi |
| topic | x-rays magnetosphere magnetosheath magnetopause solar wind magnetosphere ionosphere link explorer (smile) earth solar wind charge exchange |
| url | http://www.eppcgs.org/article/doi/10.26464/epp2023062?pageType=en |
| work_keys_str_mv | AT andrewread ontheapparentlineofsightalignmentofthepeakxrayintensityofthemagnetosheathandthetangenttothemagnetopauseasviewedbysmilesxi |