Low‐energy neutral atom signatures of magnetopause motion in response to southward Bz

Collier, M. R.; Moore, T. E.; Fok, M.‐C.; Pilkerton, B.; Boardsen, S. A.; Khan, H.

doi:10.1029/2004ja010626

Cited by 28 publications

(43 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The magnetopause can be seen at a subsolar distance of 9 R E , while the bow shock sits at around 11 R E . The charge exchange process has previously been used for magnetopause modeling, using the resultant energetic neutral atom emission from low charge state ions [e.g., Collier et al, 2005;Hosokawa et al, 2008;Ogasawara et al, 2013]. Charge exchange X-ray emission has also been observed at Venus [Dennerl, 2008], Mars [Holmström et al, 2001], and the Moon [Collier et al, 2014].…”

Section: Introductionmentioning

confidence: 99%

Modeling the magnetospheric X‐ray emission from solar wind charge exchange with verification from XMM‐Newton observations

et al. 2016

View full text Add to dashboard Cite

An MHD‐based model of terrestrial solar wind charge exchange (SWCX) is created and compared to 19 case study observations in the 0.5–0.7 keV emission band taken from the European Photon Imaging Cameras on board XMM‐Newton. This model incorporates the Global Unified Magnetosphere‐Ionosphere Coupling Simulation‐4 MHD code and produces an X‐ray emission datacube from O7+ and O8+ emission lines around the Earth using in situ solar wind parameters as the model input. This study details the modeling process and shows that fixing the oxygen abundances to a constant value reduces the variance when comparing to the observations, at the cost of a small accuracy decrease in some cases. Using the ACE oxygen data returns a wide ranging accuracy, providing excellent correlation in a few cases and poor/anticorrelation in others. The sources of error for any user wishing to simulate terrestrial SWCX using an MHD model are described here and include mask position, hydrogen to oxygen ratio in the solar wind, and charge state abundances. A dawn‐dusk asymmetry is also found, similar to the results of empirical modeling. Using constant oxygen parameters, magnitudes approximately double that of the observed count rates are returned. A high accuracy is determined between the model and observations when comparing the count rate difference between enhanced SWCX and quiescent periods.

show abstract

Section: Introductionmentioning

confidence: 99%

Modeling the magnetospheric X‐ray emission from solar wind charge exchange with verification from XMM‐Newton observations

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Furthermore, the energies, composition, flux, and direction of the ENAs arriving at the observing location provide important information concerning the processes occurring at remote magnetospheric locations (Taguchi et al 2004;Collier et al 2005a;Hosokawa et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals

et al. 2018

View full text Add to dashboard Cite

Both heliophysics and planetary physics seek to understand the complex nature of the solar wind's interaction with solar system obstacles like Earth's magnetosphere, the ionospheres of Venus and Mars, and comets. Studies with this objective are frequently conducted with the help of single or multipoint in situ electromagnetic field and particle observations, guided by the predictions of both local and global numerical simulations, and placed in con- text by observations from far and extreme ultraviolet (FUV, EUV), hard X-ray, and energetic neutral atom imagers (ENA). Each proposed interaction mechanism (e.g., steady or transient magnetic reconnection, local or global magnetic reconnection, ion pick-up, or the KelvinHelmholtz instability) generates diagnostic plasma density structures. The significance of each mechanism to the overall interaction (as measured in terms of atmospheric/ionospheric loss at comets, Venus, and Mars or global magnetospheric/ionospheric convection at Earth) remains to be determined but can be evaluated on the basis of how often the density signatures that it generates are observed as a function of solar wind conditions. This paper reviews efforts to image the diagnostic plasma density structures in the soft (low energy, 0.1-2.0 keV) X-rays produced when high charge state solar wind ions exchange electrons with the exospheric neutrals surrounding solar system obstacles. The introduction notes that theory, local, and global simulations predict the characteristics of plasma boundaries such the bow shock and magnetopause (including location, density gradient, and motion) and regions such as the magnetosheath (including density and width) as a function of location, solar wind conditions, and the particular mechanism operating. In situ measurements confirm the existence of time-and spatial-dependent plasma density structures like the bow shock, magnetosheath, and magnetopause/ionopause at Venus, Mars, comets, and the Earth. However, in situ measurements rarely suffice to determine the global extent of these density structures or their global variation as a function of solar wind conditions, except in the form of empirical studies based on observations from many different times and solar wind conditions. Remote sensing observations provide global information about auroral ovals (FUV and hard X-ray), the terrestrial plasmasphere (EUV), and the terrestrial ring current (ENA). ENA instruments with low energy thresholds (∼ 1 keV) have recently been used to obtain important information concerning the magnetosheaths of Venus, Mars, and the Earth. Recent technological developments make these magnetosheaths valuable potential targets for high-cadence wide-field-of-view soft X-ray imagers.Section 2 describes proposed dayside interaction mechanisms, including reconnection, the Kelvin-Helmholtz instability, and other processes in greater detail with an emphasis on the plasma density structures that they generate. It focuses upon the questions that remain as yet unanswered, such as the significanc...

show abstract

“…However, as mentioned in section 1, neutral solar wind also results from solar wind charge exchange (SWCX) with exospheres [e.g., Collier et al, 2005] and this process also occurs at the Moon. If we assume an argon atmosphere with a surface density of n Ar = 10 5 cm À3 , a scale height of H Ar = 40 km and a canonical collision cross section s Ar = 10 À15 cm 2 [Stern, 1999], one can estimate a ratio of neutral solar wind to solar wind flux viewing normal to the surface F NSW /F sw $ n Ar s Ar H Ar = 4 Â 10 À4 .…”

Section: Discussionmentioning

confidence: 99%

“…At Earth, neutral solar wind generated by the charge exchange interaction of solar wind protons with the exosphere has provided remote observations of changes in the location of the magnetosphere and high-latitude reconnection points [e.g., Taguchi et al, 2005Taguchi et al, , 2006Collier et al, 2005]. The difficulty observing neutral solar wind arises from both technical challenges associated with detecting low-energy neutral atoms and the potential high background levels due to stray light that results from looking in a direction close to the Sun.…”

Section: Introductionmentioning

confidence: 99%

Neutral solar wind generated by lunar exospheric dust at the terminator

Collier

Stubbs

2009

J. Geophys. Res.

Self Cite

View full text Add to dashboard Cite

[1] We calculate the flux of neutral solar wind observed on the lunar surface at the terminator due to solar wind protons penetrating exospheric dust grains with (1) radii greater than 0.1 mm and (2) radii greater than 0.01 mm. For grains with radii larger than 0.1 mm, the ratio of the neutral solar wind flux produced by exospheric dust to the incident ionized solar wind flux is estimated to be $10 À4 -10 À3 for solar wind speeds in excess of 800 km s À1 but much lower (<10 À5 ) at average to slow solar wind speeds. However, when the smaller grain sizes are considered, this ratio is estimated to be !10 À5 at all speeds and at speeds in excess of 700 km s À1 reaches $10 À3 . These neutral solar wind fluxes are easily measurable with current low-energy neutral atom instrumentation. Observations of neutral solar wind from the surface of the Moon would provide independent information on the distribution of very small dust grains in the lunar exosphere that would complement and constrain optical measurements at ultraviolet and visible wavelengths.Citation: Collier, M. R., and T. J. Stubbs (2009), Neutral solar wind generated by lunar exospheric dust at the terminator, J. Geophys.

show abstract

Low‐energy neutral atom signatures of magnetopause motion in response to southward B_z

Cited by 28 publications

References 34 publications

Modeling the magnetospheric X‐ray emission from solar wind charge exchange with verification from XMM‐Newton observations

Modeling the magnetospheric X‐ray emission from solar wind charge exchange with verification from XMM‐Newton observations

Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals

Neutral solar wind generated by lunar exospheric dust at the terminator

Contact Info

Product

Resources

About