On the Nature of Soft X-Ray Radiation in Comets

Krasnopolsky, V. A.

doi:10.1006/icar.1997.5722

Cited by 80 publications

(86 citation statements)

References 43 publications

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“…peaks from elastic scattering of solar X-ray photons at 1.50 keV (Fe XXII), 1.85 keV (Si XIII), 2.05 keV (Si XIV), 2.45 keV (S XV), 2.60 keV (S XVI), and 2.88 keV (S XV). Intensities of the cometary SF emission at energies below 0.5 keV agree well with intensity estimations reported by Krasnopolsky (1997) and Krasnopolsky et al (2004). Results on integrated intensity at photon energies above 0.5 keV disagree with those estimations because of an over-estimation of energetic photon intensities in an average solar spectra in Krasnopolsky (1997).…”

Section: Resultssupporting

confidence: 77%

“…Instead, the empirically established proportionality for mass loss rates q dust 1.5q gas is used to estimate the total number of nanoparticles present within the atmosphere (McDonnell et al 1987;Krasnopolsky 1997;Krasnopolsky et al 2004). This relationship has previously been shown to be valid for micron-sized dust particles down to 0.1 μm (Fink & Rubin 2012) and is extrapolated down to nanoparticles for our analysis.…”

Section: Composition Of Cometary Atmospherementioning

confidence: 99%

“…Collisions between highly charged, heavy SW ions, such as C 6+ , N 6+ , O 7+ , O 8+ , Mg 9+ , and Ne 9+ , and neutral cometary particles have been identified as the major source of cometary X-ray photons with energies below 1 keV, as defined by the electron energy levels of such ions (Kharchenko et al 2003). Scattering and fluorescence (SF) of solar X-rays also contribute to the observed X-ray intensities, but their contributions at photon energies below 1 keV have been estimated to be a minor fraction of the total flux of cometary X-rays (Krasnopolsky 1997;Krasnopolsky et al 2004).…”

Section: Introductionmentioning

confidence: 99%

“…The neutral atmospheric gas can be ionized by solar radiation or solar wind (SW) plasma. Neutral atoms and molecules may also be ionized by energetic SW electrons or lose electrons in charge-exchange collisions with SW ions, known as solar wind charge exchange (SWCX; Krasnopolsky 1997;Kharchenko et al 2003;Lisse et al 2004). Collisions between highly charged, heavy SW ions, such as C 6+ , N 6+ , O 7+ , O 8+ , Mg 9+ , and Ne 9+ , and neutral cometary particles have been identified as the major source of cometary X-ray photons with energies below 1 keV, as defined by the electron energy levels of such ions (Kharchenko et al 2003).…”

Section: Introductionmentioning

confidence: 99%

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Cometary emissions induced by scattering and fluorescence of solar X-rays

Snios

Lewkow

Kharchenko

2014

A&A

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To establish the nature of cometary X-ray emissions above 1 keV, detailed modeling of scattering and fluorescence of solar X-rays by a cometary atmosphere is carried out over the 0.3−3.0 keV photon energy range. Computations of the X-ray emissions are performed for different distributions of the cometary neutral gas, dust, and ice grains, with an emphasis placed on nano-sized particles. The calculated emission spectra of energetic photons above 1 keV are compared to cometary observations performed by the Chandra X-ray Observatory, and emission contributions solely from cometary neutral gas are found to be an insufficient X-ray production mechanism. Further comparison between the developed model and observational data also establishes an upper limit on dust and ice nanoparticle density distributions in cometary atmospheres. In addition, similarities in spectral shape above 1 keV observed between cometary emissions, Jovian disk emissions, and scattered solar X-ray spectra during solar flare events are discussed in detail.

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Section: Resultssupporting

confidence: 77%

Section: Composition Of Cometary Atmospherementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cometary emissions induced by scattering and fluorescence of solar X-rays

Snios

Lewkow

Kharchenko

2014

A&A

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“…Alternative x-ray production mechanisms, which ranged from lower-hybrid wave heating, scattering of solar X rays by nano-sized dust grains to electron fluorescence and conversion of the kinetic energy of dust particles to x-rays [9][10][11][12][13], were shown to not be needed to simulate the observed cometary x-ray spectra.…”

Section: Introductionmentioning

confidence: 99%

Laboratory simulation of cometary X-rays using a high-resolution microcalorimeter

Beiersdörfer

Chen

Boyce

et al. 2005

Nuclear Instruments and Methods in Physics Research Section B:

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X-ray emission following charge exchange has been studied on the University of California Lawrence Livermore National Laboratory electron beam ion traps EBIT-I and EBIT-II using a high-resolution microcalorimeter. The measured spectra include the K-shell emission from hydrogenlike and heliumlike C, N, O, and Ne needed for simulations of cometary x-ray emission. A comparison of the spectra produced in the interaction of O 8+ with N 2 and CH 4 is presented that illustrates the dependence of the observed spectrum on the interaction gas.

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Cometary charge exchange diagnostics in UV and X‐ray

et al. 2012

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Since the initial discovery of cometary charge exchange emission, more than 20 comets have been observed with a variety of X-ray and UV observatories. This observational sample offers a broad variety of comets, solar wind environments and observational conditions. It clearly demonstrates that solar wind charge exchange emission provides a wealth of diagnostics, which are visible as spatial, temporal, and spectral emission features. We review the possibilities and limitations of each of those in this contribution.

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On the Nature of Soft X-Ray Radiation in Comets

Cited by 80 publications

References 43 publications

Cometary emissions induced by scattering and fluorescence of solar X-rays

Cometary emissions induced by scattering and fluorescence of solar X-rays

Laboratory simulation of cometary X-rays using a high-resolution microcalorimeter

Cometary charge exchange diagnostics in UV and X‐ray

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