Temporal variations of geocoronal and heliospheric X‐ray emission associated with the solar wind interaction with neutrals

Cravens, T. E.; Robertson, I. P.; Snowden, S. L.

doi:10.1029/2000ja000461

Cited by 166 publications

(252 citation statements)

References 37 publications

Supporting

Mentioning

244

Contrasting

Order By: Relevance

“…The last comparison was a simple r −3 model with a 25 cm −3 number density at a distance of 10 R E [Cravens et al, 2001]. The results of each comparison show very minor differences in shape and magnitude, certainly not enough for the Hodges model to be the cause of the variations between the modeled and observed light curves.…”

Section: 1002/2015ja022292mentioning

confidence: 99%

“…We use 2 h time resolution, O/H ratio, and oxygen charge state abundance data from the ACE spacecraft, timeshifted to the bow shock in the same way as the OMNI data. [Cravens et al, 2001;Robertson and Cravens, 2003].…”

Section: Calculatingmentioning

confidence: 99%

“…The electron can be captured in an excited state and transition to lower energy states via photon emission, which in the cases of X-ray photons is detectable by X-ray telescopes [e.g., Cravens et al, 2001;Henley and Shelton, 2008]. X-ray charge exchange is a nonthermal emission, which was first detected in Röntgen satellite (ROSAT) observations of comets, when the solar wind interacted with the neutral gas outflow [Lisse et al, 1996;Cravens, 1997].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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: 1002/2015ja022292mentioning

confidence: 99%

Section: Calculatingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

“…This signal level has generally been attributed to emission associated with the Local Hot Bubble. , Cravens et al (2001) and Robertson and Cravens (2003) have assessed the potential level of contamination to the ROSAT All Sky Survey by solar wind charge exchange in the slow and fast winds. Robertson and Cravens (2003) found that 0.1 to 1.0 keV X-rays produced in the heliosphere by the steady slow and fast winds could account for ∼ 1/2 of the soft X-rays in the Galactic plane and a smaller fraction of the high latitude locallymade soft X-rays.…”

Section: Solar Wind Charge Exchange (Swcx)mentioning

confidence: 99%

The trouble with the Local Bubble

Welsh

Shelton

2009

Astrophys Space Sci

View full text Add to dashboard Cite

The model of a Local Hot Bubble has been widely accepted as providing a framework that can explain the ubiquitous presence of the soft X-ray background diffuse emission. We summarize the current knowledge on this local interstellar region, paying particular reference to observations that sample emission from the presumed local million degree K hot plasma. However, we have listed numerous observations that are seemingly in conflict with the concept of a hot Local Bubble. In particular, the discovery of solar wind charge exchange that can generate an appreciable soft X-ray background signal within the heliosphere, has led to a reassessment of the generally accepted model that requires a hot local plasma.In order to explain the majority of observations of the local plasma, we forward two new speculative models that describe the physical state of the local interstellar gas. One possible scenario is similar to the present widely accepted model of the Local Hot Bubble, except that it accounts for only 50% of the soft X-ray emission currently detected in the galactic plane, has a lower thermal pressure than previously thought, and its hot plasma is not as hot as previously believed. Although such a model can solve several difficulties with the traditional hot Local Bubble model, a heating mechanism for the dimmer and cooler gas remains to be found. The second possible explanation is that of the 'Hot Top' model, in which the Local Cavity is an old su-B.Y. Welsh ( ) Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720, USA e-mail: bwelsh@ssl.berkeley.edu R.L. Shelton Department of Physics and Astronomy, University of Georgia, Athens, GA 30602, USA pernova remnant in which no (or very little) million degree local plasma is presently required. Instead, the cavity is now thought to be filled with partially ionized cloudlets of temperature ∼ 7000 K that are surrounded by lower density envelopes of photo-ionized gas of temperature ∼ 20,000 K. Although this new scenario provides a natural explanation for many of the observations that were in conflict with the Local Hot Bubble model, we cannot (as yet) provide a satisfactory explanation or the emission levels observed in the B and Be ultra-soft X-ray bands.

show abstract

“…The terrestrial exospheric hydrogen density, which exceeds the average density of the solar wind at the magnetopause, drops off rapidly and continuously with distance from Earth. Figure 1 shows the correlation between the solar wind flux observed by NASA's Interplanetary Monitoring Platform 8 (IMP 8) spacecraft and the ROSAT soft X-ray flux, illustrating not only the presence of this signal but also its exceptional correlation with local solar wind conditions, its high count rate even when observing perpendicular to the most intense emission at the nose of the magnetopause (because of ROSAT's operational constraints), and its almost immediate response to rapid variations in the solar wind [Cravens et al, 2001] …”

Section: Detecting Soft X-raysmentioning

confidence: 99%

Astrophysics Noise: A Space Weather Signal

et al. 2010

View full text Add to dashboard Cite

Imagine the accuracy of terrestrial weather forecasts if society relied on only a handful of isolated weather stations to supply all the input to meteorological models. Yet that is precisely the daunting situation faced by space weather forecasters, who seek to predict when and how ejections of plasma from the Sun will interact with the Earth's magnetosphere. These interactions can damage spacecraft electronics, produce spurious global positioning and navigation readings, interfere with radio communications, and disrupt electrical power line grids on the ground. Though modern society increasingly relies on satellite technology and electrical conveniences, only a handful of operating heliophysics missions supply the bulk of space weather model inputs.

show abstract

Temporal variations of geocoronal and heliospheric X‐ray emission associated with the solar wind interaction with neutrals

Cited by 166 publications

References 37 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

The trouble with the Local Bubble

Astrophysics Noise: A Space Weather Signal

Contact Info

Product

Resources

About