3. Solar System Formation and Early Evolution: the First 100 Million Years     

Thierry Montmerle  Jean-Charles Augereau  Marc Chaussidon  Mathieu Gounelle  Bernard Marty  Alessandro Morbidelli 《Earth, Moon, and Planets》2006,98(1-4):39-95

The solar system, as we know it today, is about 4.5 billion years old. It is widely believed that it was essentially completed 100 million years after the formation of the Sun, which itself took less than 1 million years, although the exact chronology remains highly uncertain. For instance: which, of the giant planets or the terrestrial planets, formed first, and how? How did they acquire their mass? What was the early evolution of the “primitive solar nebula” (solar nebula for short)? What is its relation with the circumstellar disks that are ubiquitous around young low-mass stars today? Is it possible to define a “time zero” (t ₀), the epoch of the formation of the solar system? Is the solar system exceptional or common? This astronomical chapter focuses on the early stages, which determine in large part the subsequent evolution of the proto-solar system. This evolution is logarithmic, being very fast initially, then gradually slowing down. The chapter is thus divided in three parts: (1) The first million years: the stellar era. The dominant phase is the formation of the Sun in a stellar cluster, via accretion of material from a circumstellar disk, itself fed by a progressively vanishing circumstellar envelope. (2) The first 10 million years: the disk era. The dominant phase is the evolution and progressive disappearance of circumstellar disks around evolved young stars; planets will start to form at this stage. Important constraints on the solar nebula and on planet formation are drawn from the most primitive objects in the solar system, i.e., meteorites. (3) The first 100 million years: the “telluric” era. This phase is dominated by terrestrial (rocky) planet formation and differentiation, and the appearance of oceans and atmospheres.  相似文献   

A test of arm-induced star formation in spiral galaxies from near-infrared and Hα imaging     

Marc S. Seigar  Phil A. James 《Monthly notices of the Royal Astronomical Society》2002,337(3):1113-1117

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Eagle Nebula Pillars: From Models to Observations     

Marc W. Pound  Jave O. Kane  Bruce A. Remington  Dmitri D. Ryutov  Akira Mizuta  Hideaki Takabe 《Astrophysics and Space Science》2005,298(1-2):177-181

Over the past few years, our group has been developing hydrodynamic models to simulate formation of the Eagle Nebula pillars. The true test of any model is, of course, how well it can reproduce the observations. Here, we discuss how we go about testing our models against observations. We describe the process by which we “observe” the model data to create synthetic maps. We show an example of this technique using one of our model runs and compare the resultant synthetic map to the real one.  相似文献   

Galactosynthesis: halo histories, star formation and discs     

Ari Buchalter  Raul Jimenez  Marc Kamionkowski 《Monthly notices of the Royal Astronomical Society》2001,322(1):43-66

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Origin and evolution of the elements: edited by Andrew McWilliam and Michael Rauch     

Marc Rayet 《Meteoritics & planetary science》2005,40(2):331-332

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Fate of dissolved aluminum in the oceans     

Marc Stoffyn  Fred T. Mackenzie 《Marine Chemistry》1982,11(2):105-127

Vertical profiles of dissolved Al in the Atlantic Ocean and Mediterranean Sea are presented. Although dissolved Al appears to be involved in the biochemical cycle of elements, Al does not behave solely as a nutrient within the oceans. Physico-chemical processes (i.e. adsorption and/or chemical precipitation) control the concentration and distribution of Al_aq within the deep waters.A tentative mass balance model of Al_aq in the oceanic system is proposed that takes into account all of the presently known fluxes of Al_aq to and through the oceans. To maintain the deep waters of the ocean at steady state, it is necessary to include in the model, processes that remove Al_aq from these waters. Thus, model calculations support the conclusions drawn from observations that physico-chemical processes remove Al_aq from deep waters. Finally, the proposed model is compatible with the concept that the entire oceanic system is at steady state with respect to dissolved Al.  相似文献   

Planetary Perturbers in Debris Disks     

Kuchner  Marc J. 《Earth, Moon, and Planets》2003,92(1-4):435-445

Neptune dominates the dynamics of the Kuiper Belt. By examining images of debris disks around other stars, we may be able to infer what kinds of planets shape the outer edges of other planetary systems. The last few years have seen a burst of progress in the modeling of azimuthal structures in debris disks created by planetary perturbers; new models incorporate planets on substantially eccentric orbits. I review this recent progress in debris disk dynamics and discuss the Kuiper Belt as a key example.  相似文献   

Constraining dark energy from the abundance of weak gravitational lenses     

Nevin N. Weinberg  Marc Kamionkowski 《Monthly notices of the Royal Astronomical Society》2003,341(1):251-262

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Atmospheric boundary-layer structure observed during a haze event due to forest-fire smoke   总被引：1，自引：0，他引：1  

Markus?PahlowEmail author  Jan?Kleissl  Marc?B.?Parlange 《Boundary-Layer Meteorology》2005,114(1):53-70

During a haze event in Baltimore, U.S.A. from July 6 to 8, 2002, smoke from forest fires in the Québec region (Canada), degraded air quality and impacted upon local climate, decreasing solar radiation and air temperature. The smoke particles in and above the atmospheric boundary layer (ABL) served as a tracer and provided a unique opportunity to investigate the ABL structure, especially entrainment. Elastic backscatter lidar measurements taken during the haze event distinctly reveal the downward sweeps (or wisps) of smoke-laden air from the free atmosphere into the ABL. Visualisations of mechanisms such as dry convection, the entrainment process, detrainment, coherent entrainment structures, and mixing inside the ABL, are presented. Thermals overshooting at the ABL top are shown to create disturbances in the form of gravity waves in the free atmosphere aloft, as evidenced by a corresponding ripple structure at the bottom of the smoke layer. Lidar data, aerosol ground-based measurements and supporting meteorological data are used to link free atmosphere, mixed-layer and ground-level aerosols. During the peak period of the haze event (July 7, 2002), the correlation between time series of elastic backscatter lidar data within the mixed layer and the scattering coefficient from a nephelometer at ground level was found to be high (R=0.96 for z =324 m, and R=0.89 for z=504 m). Ground-level aerosol concentration was at a maximum about 2 h after the smoke layer intersected with the growing ABL, confirming that the wisps do not initially reach the ground.  相似文献   

Vertical distribution of trace elements in the surface waters offshore Nova Scotia     

Marc Stoffyn 《Estuarine, Coastal and Shelf Science》1984,18(4):433-445

Concentrations of the trace elements Fe, Al, Mn, Cu, Cd, Zn and Ni were measured in shallow vertical profiles (maximum depth 500 m) off the Scotian Shelf in the western North Atlantic. The distributions of the trace elements show variations with depth, the most consistent of which are for Fe and Zn. A minimum concentration near the surface followed by an increase with depth is attributed to in situ mechanisms.  相似文献