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The science requirements on future gravity satellite missions, following from the previous contributions of this issue, are
summarized and visualized in terms of spatial scales, temporal behaviour and accuracy. This summary serves the identification
of four classes of future satellite mission of potential interest: high-altitude monitoring, satellite-to-satellite tracking,
gradiometry, and formation flights. Within each class several variants are defined. The gravity recovery performance of each
of these ideal missions is simulated. Despite some simplifying assumptions, these error simulations result in guidelines as
to which type of mission fulfils which requirements best. 相似文献
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Recent spectroscopic observations of galaxies in the Fornax Cluster reveal nearly unresolved 'star-like' objects with redshifts appropriate to the Fornax Cluster. These objects have intrinsic sizes of ≈100 pc and absolute B -band magnitudes in the range −14< M B <−11.5 mag and lower limits for the central surface brightness μ B ≳23 mag arcsec−2 , and so appear to constitute a new population of ultracompact dwarf galaxies (UCDs). Such compact dwarfs were predicted to form from the amalgamation of stellar superclusters (by Kroupa) , which are rich aggregates of young massive star clusters (YMCs) that can form in collisions between gas-rich galaxies. Here we present the evolution of superclusters in a tidal field. The YMCs merge on a few supercluster crossing times. Superclusters that are initially as concentrated and massive as knot S in the interacting Antennae galaxies evolve to merger objects that are long-lived and show properties comparable to the newly discovered UCDs. Less massive superclusters resembling knot 430 in the Antennae may evolve to ω Cen-type systems. Low-concentration superclusters are disrupted by the tidal field, dispersing their surviving star clusters while the remaining merger objects rapidly evolve into the μ B − M B region populated by low-mass Milky Way dSph satellites. 相似文献
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A. Bragaglia F. R. Ferraro F. Fusi Pecci R. Buonanno C. E. Corsi I. Ferraro G. Iannicola 《Journal of Astrophysics and Astronomy》1987,8(1):57-68
Using a first approximation to the Hubble space telescope point-spread function, the problems concerning observation and reduction
of globular clusters in the Andromeda nebula are analysed through a simulation procedure in order to study the feasibility
of accurate photometry of individual stars in the clusters. 相似文献