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[1] The possibility of using dolomite as a source tracer for Asian dust was assessed. Samples of potential dust sources were systematically collected from the arid-semiarid areas in north China. Dolomite, of detrital origin, was detected only in samples taken from the regions on the north margin of Tibetan Plateau (NMTP). Thus the NMTP-originated dust can be detected by the presence of detrital dolomite, and applications are performed for the modern dust in Beijing and the ancient dust deposits of loess in north China. Contribution of the NMTP-originated particles to the spring dust in Beijing and the loess in Chinese Loess Plateau and eastern Tibetan Plateau are suggested. However, dolomite cannot be detected in the studied dust-storm dust and the loess in northeast China, indicating their sources other than the NMTP regions.

The Kepler mission has discovered thousands of exoplanets around various stars with different spectral types (M, K, G, and F) and thus different masses and effective temperatures. Previous studies have shown that the planet occurrence rate, in terms of the average number of planets per star, drops with increasing stellar effective temperature (T eff ). In this paper, with the final Kepler Data Release (DR25) catalog, we revisit the relation between stellar effective temperature (as well as mass) and planet occurrence, but in terms of the fraction of stars with planets and the number of planets per planetary system (i.e., planet multiplicity). We find that both the fraction of stars with planets and planet multiplicity decrease with increasing stellar temperature and mass. Specifically, about 75% late-type stars (T eff < 5000 K) have Kepler -like planets with an average planet multiplicity of ∼2.8, while for early-type stars (T eff > 6500 K), this fraction and the average multiplicity fall down to ∼35% and ∼1.8, respectively. The decreasing trend in the fraction of stars with planets is very significant with ∆AIC> 30, though the trend in planet multiplicity is somewhat tentative with ∆AIC∼ 5. Our results also allow us to derive the dispersion of planetary orbital inclinations in relationship with stellar effective temperature. Interestingly, it is found to be similar to the well-known trend between obliquity and stellar temperature, indicating that the two trends might have a common origin.

The Kepler telescope has discovered over 4000 planets (candidates) by searching ∼200,000 stars over a wide range of distance (order of kpc) in our Galaxy. Characterizing the kinematic properties (e.g., Galactic component membership and kinematic age) of these Kepler targets (including the planet candidate hosts) is the first step toward studying Kepler planets in the Galactic context, which will reveal fresh insights into planet formation and evolution. In this paper, the second part of the Planets Across the Space and Time (PAST) series, by combining the data from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and Gaia and then applying the revised kinematic methods from PAST I, we present a catalog of kinematic properties (i.e., Galactic positions, velocities, and the relative membership probabilities among the thin disk, thick disk, Hercules stream, and the halo) as well as other basic stellar parameters for 35,835 Kepler stars. Further analyses of the LAMOST–Gaia–Kepler catalog demonstrate that our derived kinematic age reveals the expected stellar activity-age trend. Furthermore, we find that the fraction of thin (thick) disk stars increases (decreases) with the transiting planet multiplicity (N p = 0, 1, 2 and 3+) and the kinematic age decreases with N p, which could be a consequence of the dynamical evolution of planetary architecture with age. The LAMOST–Gaia–Kepler catalog will be useful for future studies on the correlations between the exoplanet distributions and the stellar Galactic environments as well as ages.

Material sources of the northern deserts and the Loess Plateau in China are always one of the critical focuses in Quaternary and paleoclimate fields. In this paper, the method of Sr-Nd isotope geochemistry is applied to explore the relationship in material source between the Erdos desert and Chinese Loess Plateau. The ε Nd (0) value of the <75 µm silicate fraction between -11.8 and -17.2 is more positive in the west than in the east, and its 87 Sr/ 86 Sr ratio varies from 0.719218 to 0.714824 without similar characteristics in the Erdos desert. In addition, there are Sr-Nd isotopic differences between different grain-size fractions of eolian sand in the Erdos desert. The coarse-grained fractions mainly originated from local parent rock weathering, but the fine-grained fractions were probably affected by the input of foreign materials. Geographical distribution of Sr-Nd isotopes (especially Nd isotopes) of <75 µm silicate fractions indicates that the input of foreign materials into the Erdos desert decreases gradually from its west to east. The ε Nd (0) (0) values of eolian silicate fractions in the western-central Loess Plateau mostly fall in a very narrow range of -9~-11.5, suggesting a uniform source region. However, there is a large Sr isotope variation resulting from different pretreating methods employed by researchers. The ε Nd (0) and 87 Sr/ 86 Sr values of eolian silicate fractions in the eastern Loess Plateau both change markedly. The differences in Sr-Nd isotopes of eolian silicate fractions between the eastern and western-central Loess Plateau indicate that there are different sources for eolian silicate materials in the two sub-areas. Sr-Nd isotopes, especially Nd isotopes of the <75 µm silicate fractions in the Erdos desert are clearly different from those of eolian silicate fractions in the western-central part, but roughly close to those of eolian silicate fractions in the eastern part of the Chinese Loess Plateau, which shows that the Erdos desert was perhaps a main source for the eastern Loess Plateau but not for the western-central Loess Plateau.