The isotope composition of selenium in chondrites constrains the depletion mechanism of volatile elements in solar system materials

Solar nebula processes led to a depletion of volatile elements in different chondrite groups when compared to the bulk chemical composition of the solar system deduced from the Sun's photosphere. For moderately-volatile elements, this depletion primarily correlates with the element condensation temperature and is possibly caused by incomplete condensation from a hot solar nebula, evaporative loss from the precursor dust, and/or inherited from the interstellar medium. Element concentrations and interelement ratios of volatile elements do not provide a clear picture about responsible mechanisms. Here, the abundance and stable isotope composition of the moderately- to highly-volatile element Se are investigated in carbonaceous, ordinary, and enstatite chondrites to constrain the mechanism responsible for the depletion of volatile elements in planetary bodies of the inner solar system and to define a δ(82/78)Se value for the bulk solar system. The δ(82/78)Se of the studied chondrite falls are identical within their measurement uncertainties with a mean of −0.20±0.26‰ (2 s.d., n=14n=14, relative to NIST SRM 3149) despite Se abundance depletions of up to a factor of 2.5 with respect to the CI group. The absence of resolvable Se isotope fractionation rules out a kinetic Rayleigh-type incomplete condensation of Se from the hot solar nebula or partial kinetic evaporative loss on the precursor material and/or the parent bodies. The Se depletion, if acquired during partial condensation or evaporative loss, therefore must have occurred under near equilibrium conditions to prevent measurable isotope fractionation. Alternatively, the depletion and cooling of the nebula could have occurred simultaneously due to the continuous removal of gas and fine particles by the solar wind accompanied by the quantitative condensation of elements from the pre-depleted gas. In this scenario the condensation of elements does not require equilibrium conditions to avoid isotope fractionation. The results further suggest that the processes causing the high variability of Se concentrations and depletions in ordinary and enstatite chondrites did not involve any measurable isotope fractionation. Different degrees of element depletions and isotope fractionations of the moderately-volatile elements Zn, S, and Se in ordinary and enstatite chondrites indicate that their volatility is controlled by the thermal stabilities of their host phases and not by the condensation temperature under canonical nebular conditions.

The tides and kindred phenomena in the solar system; the substance of lectures delivered in 1897 at the Lowell institute, Boston, Massachusetts,

List of "Authorities" at end of each subject.

Other worlds from earth : the future of planetary astronomy : a report of the Planetary Astronomy Committee of the Solar System Exploration Division.

Shipping list no.: 89-402-P.

Comparative planetology and the atmosphere of earth : a report to the Solar System Exploration Division, National Aeronautics and Space Administration /

"November 1989."

Gravity fields of the solar system /

Cover title.

Gravitation: an elementary explanation of the principal perturbations in the solar system.

Mode of access: Internet.

The solar system; a study of recent observations,

"This work grew out of a series of lectures delivered at Columbia university."-Pref.

The description and use of the globes, and the orrery. To which is prefixed, by way of introduction, a brief account of the solar system.

John Harris's work, revised by Joseph Harris. - cf. Dictionary of national biography.

Solar system puzzle kit : an activity for earth and space science /

Grades 5-8.

Concerning the earths in our solar system, which are called planets, and concerning the earths in the starry heaven. Together with an account of their inhabitants, and also of the spirits and angels there : from what has been seen and heard /

Cf. J. Hyde. A bibliography of the works of Emanuel Swedenborg (no. 959).

The new American grammar of the elements of astronomy, on an improved plan: in three books. I. The use of the terrestrial globe in the solution of geographical and astronomical problems. II. The use of the celestial globe in the solution of problems, relative to the sun, planets, and fixed stars. III. The solar system, and the firmament of fixed stars. The whole systematically arranged and scientifically illustrated; with several cuts and engravings; and adapted to the instruction of youth in schools and academies.

Mode of access: Internet.

Astronomical tables and formulæ : together with a variety of problems explanatory of their use and application : to which are prefixed the elements of the solar system /

Problems: p. [217]-264; Appendix, January, 1829: p. [265]-299; Errata: p. [301]-304.

The exploration of the solar system /

Includes bibliography.

Spectroscopic analysis of terrestrial analogues for the interpretation of surface composition of rocky bodies in the solar system. Effects of mineral mixing and particle size. Applications to moon, mars and implications for mercury.

Among the Solar System’s bodies, Moon, Mercury and Mars are at present, or have been in the recent years, object of space missions aimed, among other topics, also at improving our knowledge about surface composition. Between the techniques to detect planet’s mineralogical composition, both from remote and close range platforms, visible and near-infrared reflectance (VNIR) spectroscopy is a powerful tool, because crystal field absorption bands are related to particular transitional metals in well-defined crystal structures, e.g., Fe2+ in M1 and M2 sites of olivine or pyroxene (Burns, 1993). Thanks to the improvements in the spectrometers onboard the recent missions, a more detailed interpretation of the planetary surfaces can now be delineated. However, quantitative interpretation of planetary surface mineralogy could not always be a simple task. In fact, several factors such as the mineral chemistry, the presence of different minerals that absorb in a narrow spectral range, the regolith with a variable particle size range, the space weathering, the atmosphere composition etc., act in unpredictable ways on the reflectance spectra on a planetary surface (Serventi et al., 2014). One method for the interpretation of reflectance spectra of unknown materials involves the study of a number of spectra acquired in the laboratory under different conditions, such as different mineral abundances or different particle sizes, in order to derive empirical trends. This is the methodology that has been followed in this PhD thesis: the single factors previously listed have been analyzed, creating, in the laboratory, a set of terrestrial analogues with well-defined composition and size. The aim of this work is to provide new tools and criteria to improve the knowledge of the composition of planetary surfaces. In particular, mixtures composed with different content and chemistry of plagioclase and mafic minerals have been spectroscopically analyzed at different particle sizes and with different mineral relative percentages. The reflectance spectra of each mixture have been analyzed both qualitatively (using the software ORIGIN®) and quantitatively applying the Modified Gaussian Model (MGM, Sunshine et al., 1990) algorithm. In particular, the spectral parameter variations of each absorption band have been evaluated versus the volumetric FeO% content in the PL phase and versus the PL modal abundance. This delineated calibration curves of composition vs. spectral parameters and allow implementation of spectral libraries. Furthermore, the trends derived from terrestrial analogues here analyzed and from analogues in the literature have been applied for the interpretation of hyperspectral images of both plagioclase-rich (Moon) and plagioclase-poor (Mars) bodies.