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961.
Ken O’Hara-Dhand Richard L. S. Taylor Ian James Smalley David H. Krinsley Claudio Vita-Finzi 《Central European Journal of Geosciences》2010,2(1):45-51
Impact between windblown quartz grains as a source of desert dust is consistent with laboratory abrasion experiments and has received some field confirmation in the Negev. The suggestion is that an important process on Mars now gains support from laboratory studies; even though their geochemical interpretation is controversial, they show that dust generation by impact is tenable even for quartz. A simple mechanism for small dust production from sand seas is proposed; internal stresses can be mobilized by impact energy. A speculative mechanism (the andesite scenario) is proposed for fine particle production by particle impact on Mars. The internal stress range in terrestrial sand grains may vary, depending on the nature of the source rock, and this may influence particle production by impact processes. 相似文献
962.
963.
Ian C. LYON 《Meteoritics & planetary science》2005,40(7):981-987
Abstract— This paper describes the use of matrix‐assisted laser desorption and ionization (MALDI) to measure the mass distribution of nanodiamonds extracted from meteorites. The techniques used to prepare and mass analyze nanodiamond samples from the Murchison (CM2) and Allende (CV3) meteorites are described. The mass spectra of nanodiamonds (peaking at between 1 times 104‐1.5 times 104 Daltons) are compared with size distributions obtained by point‐counting transmission electron microscopy (TEM) images obtained elsewhere and reasonable agreement is found. The implications of the ability to produce and mass analyze a beam of nanodiamonds are explored. 相似文献
964.
Matt Hilton Chris Collins Roberto De Propris Ivan K. Baldry Carlton M. Baugh Joss Bland-Hawthorn Terry Bridges Russell Cannon Shaun Cole Matthew Colless Warrick J. Couch Gavin B. Dalton Simon P. Driver George Efstathiou Richard S. Ellis Carlos S. Frenk Karl Glazebrook Carole A. Jackson Ofer Lahav Ian Lewis Stuart Lumsden Steve J. Maddox Darren Madgwick Peder Norberg John A. Peacock Bruce A. Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2005,363(2):661-674
965.
966.
C. Halliday † Roger L. Davies Harald Kuntschner M. Birkinshaw Ralf Bender R.P. Saglia Glenn Baggley 《Monthly notices of the Royal Astronomical Society》2001,326(2):473-489
The shape of the line-of-sight velocity distribution (LOSVD) is measured for a sample of 14 elliptical galaxies, predominantly low-luminosity ellipticals. The sample is dominated by galaxies in the Virgo cluster but also contains ellipticals in nearby groups and low-density environments. The parametrization of the LOSVD given by Gerhard and van der Marel & Franx is adopted, which measures the asymmetrical and symmetrical deviations of the LOSVD from a Gaussian by the amplitudes h 3 and h 4 of the Gauss–Hermite series. Rotation, velocity dispersion, h 3 and h 4 are determined as a function of radius for both major and minor axes. Non-Gaussian LOSVDs are found for all galaxies along the major axes. Deviations from a Gaussian LOSVD along the minor axis are of much lower amplitude if present at all. Central decreases in velocity dispersion are found for three galaxies. Two galaxies have kinematically decoupled cores: NGC 4458 and the well-known case of NGC 3608. 相似文献
967.
968.
969.
R. J. Ivison Ian Smail Misty Bentz J. A. Stevens K. Menéndez-Delmestre S. C. Chapman A. W. Blain 《Monthly notices of the Royal Astronomical Society》2005,362(2):535-541
We have investigated the rest-frame optical and far-infrared properties of a sample of extremely bright candidate Lyman-break galaxies (LBGs) identified in the Sloan Digital Sky Survey. Their high ultraviolet luminosities and lack of strong ultraviolet emission lines are suggestive of massive starbursts, although it is possible that they are more typical luminosity LBGs which have been highly magnified by strong gravitational lensing. Alternatively, they may be an unusual class of weak-lined quasars. If the ultraviolet and submillimetre (submm) properties of these objects mirror those of less luminous, starburst LBGs, then they should have detectable rest-frame far-infrared emission. However, our submm photometry fails to detect such emission, indicating that these systems are not merely scaled-up (either intrinsically or as a result of lensing) examples of typical LBGs. In addition we have searched for the morphological signatures of strong lensing, using high-resolution, near-infrared imaging, but we find none. Instead, near-infrared spectroscopy reveals that these systems are, in fact, a rare class of broad absorption line quasars. 相似文献
970.
Ian M. Matley 《The Professional geographer》1970,22(6):311-316