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  • 1
    Electronic Resource
    Electronic Resource
    Formation of a planet orbiting pulsar 1829–10 from the debris of a supernova explosion (1991)
    [s.l.] : Nature Publishing Group
    Nature 353 (1991), S. 827-829 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Survival of a pre-supernova planet would encounter two main problems. First, and most serious, an orbit of ap = 0.7 AU would place the planet inside the photosphere of any red supergiant likely to become a Type II supernova. Such stars typically have radii of 2-4 AU (ref. 4) for at least several ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/353827a0
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    Paper (German National Licenses)
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  • 2
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    TIDAL AND MAGNETIC INTERACTIONS BETWEEN A HOT JUPITER AND ITS HOST STAR IN THE MAGNETOSPHERIC CAVITY OF A PROTOPLANETARY DISK (2009)
    Institute of Physics
    Details
    Publication Date: 2009-12-23
    Print ISSN: 0004-637X
    Electronic ISSN: 1538-4357
    Topics: Physics
    Published by Institute of Physics
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    PAPER CURRENT
  • 3
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    The Dynamics of Spherical Stellar Systems: II.--Theoretical Models (1963)
    Oxford University Press
    Details
    Publication Date: 1963-06-01
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press on behalf of The Royal Astronomical Society.
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  • 4
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    Formation of a planet orbiting pulsar 1829–10 from the debris of a supernova explosion (1991)
    Springer Nature
    Details
    Publication Date: 1991-10-01
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Springer Nature
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  • 5
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    Formation of a planet orbiting pulsar 1829 - 10 from the debris of a supernova explosion (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: How the 10-earth mass planet in a nearly circular 0.7 AU orbit around PSR1829 - 10 might have been created inside the young SNR is described. It is proposed that the planet formed from a rotationally supported disk of about 0.02 solar mass of heavy elements that fell back from the supernova explosion to an initial radius of about 1000 km. Viscous evolution of the disk then concentrated most of its angular momentum into a small amount of material at the disk's outer extremity: 10 earth masses at 10 exp 13 cm. Here, dust grains that had condensed and precipitated toward the midplane grew through cohesive collisions and gravitational instabilities into 100-km planetesimals which coagulated into the planet on a million-yr time scale. The presence of a more massive and more distant second planet is found to be unlikely.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 353; 827-829
    Format: text
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  • 6
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    Numerical studies of collapsing interstellar clouds (1986)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Numerical simulation of the structure and evolution of interstellar clouds was initiated. Steps were taken toward an integrated treatment of the dynamical, thermal, and chemical processes entering model calculations. A detailed study was made of radiative transfer in molecular lines to allow model predictions to be tested against empirical data. The calculations have successfully reproduced and explained several observed cloud properties, including abundances of complex molecular species and the apparent depletion of CO in dense cores.
    Keywords: ASTROPHYSICS
    Type: NASA-TM-88771 , NAS 1.15:88771
    Format: application/pdf
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  • 7
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    Giant Molecular Cloud Structure and Evolution (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Bodenheimer and Burkert extended earlier calculations of cloud core models to study collapse and fragmentation. The initial condition for an SPH collapse calculation is the density distribution of a Bonnor-Ebert sphere, with near balance between turbulent plus thermal energy and gravitational energy. The main parameter is the turbulent Mach number. For each Mach number several runs are made, each with a different random realization of the initial turbulent velocity field. The turbulence decays on a dynamical time scale, leading the cloud into collapse. The collapse proceeds isothermally until the density has increased to about 10(exp 13) g cm(exp -3). Then heating is included in the dense regions. The nature of the fragmentation is investigated. About 15 different runs have been performed with Mach numbers ranging from 0.3 to 3.5 (the typical value observed in molecular cloud cores is 0.7). The results show a definite trend of increasing multiplicity with increasing Mach number (M), with the number of fragments approximately proportional to (1 + M). In general, this result agrees with that of Fisher, Klein, and McKee who published three cases with an AMR grid code. However our results show that there is a large spread about this curve. For example, for M=0.3 one case resulted in no fragmentation while a second produced three fragments. Thus it is not only the value of M but also the details of the superposition of the various velocity modes that play a critical role in the formation of binaries. Also, the simulations produce a wide range of separations (10-1000 AU) for the multiple systems, in rough agreement with observations. These results are discussed in two conference proceedings.
    Keywords: Astrophysics
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  • 8
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    Evolution of primoridal gas clouds (1986)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The dynamical, chemical, and thermal evolution of zero-metal gas clouds was modeled to study conditions of star formation in the early universe. Numerical results are given for the collapse of spherical clouds of mass 1000 and 50000 solar mass. Cooling by H2 lines and by photons emitted in H + e(-) yields H(-) = h (sup nu) maintains collapse until formation of an equilibrium protostellar core of mass 0.02 solar mass. The cooling by photons produced with H is essential for low mass star formation. If the cloud is fragmented, the evolution of the pieces is similar to that of the parent cloud, but the equilibrium core has larger density and mass.
    Keywords: ASTROPHYSICS
    Type: NASA-CR-176959 , NAS 1.26:176959
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  • 9
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    Formation and Early Evolution of Solar and Extra-Solar Giant Planets (2001)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: This project investigates the origin of giant planets, both in the Solar System and around other stars. It is assumed that the planets form by the core accretion process: small solid particles in a disk surrounding a young star gradually coagulate into objects of a few kilometers in size, known as planetesimals, which then accumulate into solid protoplanetary cores. Once the cores have become large enough, they are able to attract gas from the surrounding disk to form the deep gaseous envelope of the giant planet. Our code simulates giant planet growth in a spherical approximation, and it has been quite successful in addressing a number of basic planetary properties. Further improvements to the code have been made to achieve a more realistic understanding of planetary formation. The computations of the models were based on an earlier version of our code and were stopped at the onset of runaway gas accretion. Now, improved boundary conditions have been incorporated into the code to allow for hydrodynamic inflow of gas and to handle the late stages of evolution when the planet evolves at constant mass. These changes were made to the version of the code that uses a constant accretion rate and to the version that uses a self-consistent method for calculating both the solid and gas accretion rates. The equation of state has been updated to incorporate the detailed tables of Saumon, Chabrier, and Van Horn. The opacities were updated to include the results of Alexander and Ferguson. The outer boundary conditions were modified. During the accretion phase when the planet's radius is between the accretion radius and the tidal radius, we set the outer boundary at a 'modified' accretion radius, which is the point where thermal energy is enough to bring gas to the edge of the Hill sphere.
    Keywords: Astrophysics
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  • 10
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    Protoplanetary Formation and the FU Orionis Outburst (1996)
    In:  CASI
    Details
    Publication Date: 2019-08-16
    Description: The following three publications which reference the above grant from the NASA Origins of Solar Systems program are attached and form the final technical report for this project. The research involved comparisons of the spectral energy distributions of FU Orionis objects with theoretical models and associated studies of the structure of the outbursting accretion disks, as well as related studies on the effects of magnetic fields in disks, which will lead in the future to models of FU Orionis outbursts which include the effects of magnetic fields. The project was renewed under a new grant NAGW-4456, entitled 'Effects of FU Orionis Outbursts on Protoplanetary Disks'. Work now being prepared for publication deals more specifically with the issue of the effects of the outbursts on protoplanetary formation. Models of the spectral energy distribution of FU Orionis stars. A simple model of a buoyant magnetic dynamo in accretion disks and a numerical study of magnetic buoyancy in an accretion disk have been submitted.
    Keywords: Astrophysics
    Type: NASA-CR-202393 , NAS 1.26:202393
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