Showing papers by "Alan P. Boss published in 1993"
TL;DR: In this article, the authors present a theoretical explanation for the origin of binary stars, and detail the reasoning behind this optimistic claim, which is based on the assumption that the mutual orbital revolution of several visual binary star pairs can be explained by a random distribution of single stars.
Abstract: Convincing evidence for the physical association of double stars was produced by William Herschel over 200 years ago. Starting in 1782, Herschel published catalogues of far more double stars than could be accounted for by a random distribution of single stars, and went on to confirm the concept of physical association by discovering the mutual orbital revolution of several visual binary star pairs (see Berry 1898). Laplace produced the first theoretical explanation for the origin of binary stars soon thereafter (in 1796), and the flow of suggestions for binary origins has continued to the present day. Because of the solid body of observational information about binary systems that is now available for use in discriminating between hypotheses of origin, and because of recent theoretical work on the mechanics of the hypotheses, we have made substantial progress in evaluating the possibilities. This chapter will detail the reasoning behind this optimistic claim.
156 citations
TL;DR: In this paper, 3D calculations of the collapse of moderately centrally condensed molecular cloud cores with varied thermal and rotational energies were performed using a newly developed and tested second-order accurate radiative hydrodynamics code.
Abstract: 3D calculations of the collapse of moderately centrally condensed molecular cloud cores with varied thermal and rotational energies are presented. The calculations are carried out using a newly developed and tested second-order accurate radiative hydrodynamics code. Because of the use of a second-order accurate numerical scheme and initial clouds that resemble both observed prolate molecular cloud cores and magnetically supported clouds at the initiation of the dynamic collapse phase, the new models provide a superior estimate of the likelihood of fragmentation as a mechanism for binary star formation.
96 citations
TL;DR: In this article, the structure of a pre-existing solar-mass protostar is assumed to form from the highest angular momentum vestiges of the placental cloud core, and a spatially second-order accurate, axisymmetric, radiative hydrodynamics code has been used to construct three sets of protoplanetary disk models under this assumption.
Abstract: Models of the thermal structure of protoplanetary disks are required for understanding the physics and chemistry of the earliest phases of planet formation. Numerical hydrodynamical models of the protostellar collapse phase have not been evolved far enough in time to be relevant to planet formation, i.e., to a relatively low-mass disk surrounding a protostar. One simplification is to assumed a pre-existing solar-mass protostar, and calculate the structure of just the disk as it forms from the highest angular momentum vestiges of the placental cloud core. A spatially second-order accurate, axisymmetric (two-dimensional), radiative hydrodynamics code has been used to construct three sets of protoplanetary disk models under this assumption
77 citations
TL;DR: In this article, the authors suggest that the source of the shocks possibly responsible for chondrule formation was episodic accretion onto the solar nebula of low-mass clumps (∼10 22 g) of interstellar gas.
64 citations
TL;DR: In this paper, the authors show that mid-infrared dips in T Tauri star spectra may have a more prosaic cause, and may be simply the result of dust grain opacity and the vertical structure of a low-mass circumstellar disk without a gap.
Abstract: Emission at infrared to millimeter wavelengths from the prototypical pre-main-sequence star T Tauri is consistent with the existence of a low-mass circumstellar disk around T Tauri. T Tauri's spectrum can be characterized as flat, but with a significant dip at mid-infrared wavelengths. Mid-infrared dips can result from gaps in the cireumstellar disk, and such gaps are thought to imply the existence of unseen companions which produce the gaps through gravitational effects. We show here that mid-infrared dips in T Tauri star spectra may have a more prosaic cause, and may be simply the result of dust grain opacity and the vertical structure of a low-mass circumstellar disk without a gap.
19 citations
01 Jan 1993
TL;DR: Theoretical models of the collapse of a dense molecular cloud core to form the protosolar nebula that produces the sun and the planet are discussed in this article, using the equations of hydrodynamics, gravitation, and radiative transfer to follow the time evolution of a cloud collapsing under its own selfgravity.
Abstract: Theoretical models are discussed of the collapse of a dense molecular cloud core to form the protosolar nebula that produce the sun and the planet. The theoretical models use the equations of hydrodynamics, gravitation, and radiative transfer to follow the time evolution of a cloud collapsing under its own self-gravity. Both semi-analytical and fully numerical solutions (in two and three spatial dimensions) were calculated by several workers, One challenge is to find a set of initial conditions that will lead to the formation of a suitable protosolar nebula. Detailed results are shown for 2-D models, both with and without turbulent viscosity for redistributing angular momentum, and for 3-D models investigating the strength of gravitational torques associated with nonaxisymmetry produced during the collapse phase.
16 citations