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991.
Earth, Moon, and Planets - 相似文献
992.
Through a combination of aerobraking (drag deceleration) and ablation, meteoroids which enter planetary atmospheres may be slowed sufficiently to soft-land as meteorites. Results of an earlier study suggest that the current 6 mbar atmosphere of Mars is sufficient to aerobrake significant numbers of small (<10 kg) asteroidal-type meteoroids into survivable, low-velocity (<500 m s−1) impacts with the planet's surface. Since rates of meteorite production depend upon the density of Mars's atmosphere, they must also change as the martian climate changes. However, to date, martian meteorite production has received relatively little attention in the literature Here we expand upon our previous work to study martian meteorite production rates and how they depend upon variations of the martian atmosphere, and to estimate the ranges of mass, velocity and entry-angle that produce meteorites. We find that even the current atmosphere of Mars is sufficient to soft-land significant fractions of incident stony and iron objects, and that these fractions increase dramatically for denser martian atmospheres. Therefore, like impact cratering, meteorite populations may preserve evidence of past martian climates. 相似文献
993.
John D. Bunton 《Experimental Astronomy》2004,17(1-3):251-259
When the SKA was proposed, a major technical obstacle to its feasibility was the cost of the correlator. Significant advances made in correlator design since then are described. These advances have made SKA correlator possible within reasonable cost constrains. At the same time performance issues with the proposed FX architecture have been addressed. 相似文献
994.
A set of well-measured, {low-z}, type Ia supernovae from the Calán/Tololo SNe data sets is used to determine benchmark parameters
in our hydrodynamics-based, light-curve model. The light-curve data fit fairly well in B, V, and R passbands but not as well
in the I passband. The fitting procedure, extracted best-fit model parameters, and their connection to type Ia SN parameters
are presented. Our benchmarked light-curve model represents an alternative to empirical template methods for the analysis
of light-curve data. 相似文献
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D. Heath Jones Will Saunders Matthew Colless Mike A. Read Quentin A. Parker Fred G. Watson Lachlan A. Campbell Daniel Burkey Thomas Mauch Lesa Moore Malcolm Hartley Paul Cass Dionne James Ken Russell Kristin Fiegert John Dawe John Huchra Tom Jarrett Ofer Lahav John Lucey Gary A. Mamon Dominique Proust Elaine M. Sadler Ken-ichi Wakamatsu 《Monthly notices of the Royal Astronomical Society》2004,355(3):747-763
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