Accounts of Chemical Research, Volume 43, Issue 6, Page 826-836, June 15, 2010. [...]
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Publication year: 2009 This note discusses the stability of collinear equilibrium points around a rotating system composed of two masses rigidly connected by a massless rod in the case where the centripetal force outweighs the gravitational force. It is found that a stable region appears at L1 when the ratio of gravitational to centripetal acceleration is less than 0.125, and that there is always no stable area at L2 and L3; the result is applied to the fast rotating asteroid [...] Publication year: 2009 To try to understand the dynamical and collisional evolution of the Hungaria asteroids we have built a large catalog of accurate synthetic proper elements. Using the distribution of the Hungaria, in the spaces of proper elements and of proper frequencies, we can study the dynamical boundaries and the internal structure of the Hungaria region, both within a purely gravitational model and also showing the signature of the non-gravitational effects. We find a complex interaction between secular resonances, mean motion resonances, chaotic behavior and Yarkovsky-driven drift in semimajor axis. We also find a rare occurrence of large scale instabilities, leading [...] Publication year: 2009 The shaking of Mercury’s orbit by the planets forces librations in longitude in addition to those at harmonics of the orbital period that have been used to detect Mercury’s molten core. We extend the analytical formulation of Peale et al. (2009) in order to provide a convenient means of determining the amplitudes and phases of the forced librations without resorting to numerical calculations. We derive an explicit relation between the amplitude of each forced libration and the moment of inertia parameter (B-A)/Cm. Far from resonance with the free libration period, the libration amplitudes are directly proportional to (B-A)/Cm. Librations [...] Publication year: 2009 Multiple impact basins formed on the Moon about 3.8 Gyr ago in what is known as the lunar cataclysm or late heavy bombardment. Many workers currently interpret the lunar cataclysm as an impact spike primarily caused by main-belt asteroids destabilized by delayed planetary migration. We show that morphologically fresh (class 1) craters on the lunar highlands were mostly formed during the brief tail of the cataclysm, as they have absolute crater number density similar to that of the Orientale basin and ejecta blanket. The connection between class 1 craters and the cataclysm is supported by the similarity of their [...] Publication year: 2010 Publication year: 2009 Particulate organic matter (POM) is a mixture of living POM (organisms) and non-living POM (detritus). Since the majority of amino acids in organisms are comprised of proteins, and since the particulate combined amino acids (PCAAs) liberated by the acid hydrolysis of POM is the largest constituent of POM, PCAAs may be a mixture of proteins in organisms and their degradation products in detritus. However, the early stage of degradation and chemical alteration of proteins and the processes by which proteins in organisms are transferred to detrital PCAAs have not been well documented. Here we use gel chromatography (SDS-PAGE: sodium [...] Author(s): K. L. Luhman, P. R. Allen, C. Espaillat, L. Hartmann, and N. Calvet Publication year: 2009 Thanks to its location at low latitude and close to the terminator in the outbound view of Mercury obtained during MESSENGER’s first flyby, the Beagle Rupes lobate scarp on Mercury has been particularly clearly imaged. This enables us to interpret it as a component of a linked fault system, consisting of a frontal scarp terminated by transpressive lateral ramps. The terrain bounded by these surface manifestations of faulting is the hanging-wall block of a thrust sheet and must be underlain by a basal decollement (a detachment horizon) constituting the fault zone at depth. The decollement must extend a minimum [...] Publication year: 2009 Scattering and absorption of sunlight by aerosols are integral to understanding the radiative balance of any planetary atmosphere covered in a haze, such as Titan and possibly the early Earth. One key optical parameter of an aerosol is its refractive index. We have simulated both Titan and early Earth organic haze aerosols in the laboratory and measured the real and imaginary portion of their refractive index at λ = 532 nm using cavity ringdown aerosol extinction spectroscopy. This novel technique allows analysis on freely-floating particles minutes after formation. For our Titan analog particles, we find a real refractive index [...] |
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