The meteoroid stream of comet Encke at Mercury: Implications for MErcury Surface, Space ENvironment, GEochemistry, and Ranging observations of the exosphere

Christou, Apostolos; Killen, R. M.; Burger, M. H.

doi:10.1002/2015gl065361

Cited by 42 publications

(48 citation statements)

References 47 publications

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“…As noted by Burger et al [], the warm component is enhanced toward the dawn equator, whereas PSD processes should lead to increased levels at noon. The seasonal variation of Ca abundance observed as well as its variation with TAA has been demonstrated to correlate well with the column abundances expected from impact vaporization [ Killen and Hahn , ; Christou et al , ]. However, impacts alone cannot account for the hot calcium observed; the ejected material may be subjected to additional processes, leading to the generation of excited species (e.g., electron impact dissociation or photodissociation).…”

Section: Resultsmentioning

confidence: 71%

Investigating potential sources of Mercury's exospheric Calcium: Photon-stimulated desorption of Calcium Sulfide

Bennett

McLain

Sarantos

et al. 2016

J. Geophys. Res. Planets

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Ground‐based and MErcury Surface, Space ENvironment, GEochemistry, and Ranging observations detected Ca0 and Ca+ in the exosphere of Mercury as well as unexpectedly high levels of sulfur on Mercury's surface. The mineral oldhamite ((Mg,Ca)S) could be a predominant component of the Mercury surface, particularly within the hollows identified within craters, and could therefore serve as a source of the observed exospheric calcium. Laboratory measurements on the photon‐stimulated desorption (PSD) of CaS powder (an analog for oldhamite) at a wavelength of λ = 355 nm have been conducted, utilizing resonance‐enhanced multiphoton ionization time‐of‐flight mass spectrometry to determine the yields and velocity distributions of Ca0. The desorbing Ca0 could be fit using two Maxwell‐Boltzmann components: a 600 (±30) K thermal component and a 1389 (±121) K nonthermal component, the latter accounting for ~25% of the observed signal. Cross sections for PSD using 3.4 eV photons were found to be 1.1 (±0.7) × 10−20 cm2 for Ca0 and 3.2 (±0.9) × 10−24 cm2 for Ca+. Adopting these cross sections, a Monte Carlo model of the release of Ca0 by PSD from the Tyagaraja crater finds the neutral microexosphere created from this process to be substantial even if only 1% CaS is assumed in the hollows. Diffuse reflectance UV‐visible measurements were made on the CaS powder to determine a bandgap, Eg, of 2.81 (±0.14) eV via the Tauc method.

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Section: Resultsmentioning

confidence: 71%

Investigating potential sources of Mercury's exospheric Calcium: Photon-stimulated desorption of Calcium Sulfide

Bennett

McLain

Sarantos

et al. 2016

J. Geophys. Res. Planets

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“…• after perihelion can be attributed to the crossing of Mercury's orbital plane and a Comet 2P/Encke stream (Killen & Hahn 2015;Christou et al 2015). Also, Sun-grazing comets should be further investigated as a possible source (Sprague et al 2007).…”

Section: Discussionmentioning

confidence: 99%

Statistical analysis of the flux of micrometeoroids at Mercury from both cometary and asteroidal components

Borin

Cremonese

Marzari³

2016

A&A

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Context. Meteoroid impacts are an important source of neutral atoms for the exosphere of Mercury. We previously estimated the contribution of meteoroids originating in the asteroid belt for vapor release. In this paper, we concentrate on the cometary component of particles impacting the planet. Comets and asteroids are considered to be the two major sources of interplanetary dust particles in the solar system. The debate about which source contributes most to dust populating the solar system is still ongoing. Aims. In this work, we compute the orbital evolution of dust particles produced by Jupiter-family comets (JFC) via N-body numerical integrations. From our numerical simulations, we compute the fraction of particles hitting Earth and Mercury's surface and the corresponding distribution of impact velocities. According to some authors more than 80% of all the incoming mass of meteoroids entering the Earth's atmosphere is concentrated in the mass range 10 −7 −10 −3 g. In our model, we considered a slightly different range, 10 −9 to 10 −6 g, to include possible uncertainty. Methods. The orbital evolution of dust particles of different sizes is computed with a numerical integration code, which includes the effects of Poynting-Robertson drag, solar wind drag, and planetary perturbations. Results. By comparing the impact frequency of grains evolving either from main belt asteroids or JFC we find that the cometary component is significantly less efficient in releasing dust particles on Mercury than on the Earth. The opposite occurs in the case of dust coming from the main belt with a flux higher at Mercury than on the Earth. This is mostly due to the different dynamical histories of the grains from their release until impact. This may have important implications for the vapor production rate on Mercury. We compare our results with previous estimates given by different authors.

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“…Killen and Hahn (2015) estimated the dust deposition rate on Mercury to be around 440 t per Earth day, though this should probably be reduced to ∼170 t d −1 based on the recent estimate of the dust input to the terrestrial atmosphere (Carrillo-Sánchez et al 2016). Lastly, Christou et al (2015) demonstrated that the annual, repeatable Ca emission excess in Mercury's exosphere could result from the impact of millimeter-sized grains that were ejected from Comet 2P/Encke 10,000-20,000 years ago.…”

Section: Other Terrestrial Planetsmentioning

confidence: 99%

Impacts of Cosmic Dust on Planetary Atmospheres and Surfaces

et al. 2017

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Recent advances in interplanetary dust modelling provide much improved estimates of the fluxes of cosmic dust particles into planetary (and lunar) atmospheres throughout the solar system. Combining the dust particle size and velocity distributions with new chemical ablation models enables the injection rates of individual elements to be predicted as a function of location and time. This information is essential for understanding a variety of atmospheric impacts, including: the formation of layers of metal atoms and ions; meteoric smoke particles and ice cloud nucleation; perturbations to atmospheric gas-phase chemistry; and the effects of the surface deposition of micrometeorites and cosmic spherules. There is discussion of impacts on all the planets, as well as on Pluto, Triton and Titan.

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The meteoroid stream of comet Encke at Mercury: Implications for MErcury Surface, Space ENvironment, GEochemistry, and Ranging observations of the exosphere

Cited by 42 publications

References 47 publications

Investigating potential sources of Mercury's exospheric Calcium: Photon-stimulated desorption of Calcium Sulfide

Investigating potential sources of Mercury's exospheric Calcium: Photon-stimulated desorption of Calcium Sulfide

Statistical analysis of the flux of micrometeoroids at Mercury from both cometary and asteroidal components

Impacts of Cosmic Dust on Planetary Atmospheres and Surfaces

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