Results 1 to 10 of about 13,144 (210)
Reservoir for Comet Material: Circumstellar Grains [PDF]
Space Science Reviews, 2007 Primitive meteorites and interplanetary dust particles contain small quantities of dust grains with highly anomalous isotopic compositions. These grains formed in the winds of evolved stars and in the ejecta of stellar explosions, i.e., they represent a sample of circumstellar grains that can be analyzed with high precision in the laboratory.
Peter Hoppe
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Composite grains: Application to circumstellar dust
Atti della Accademia Peloritana dei Pericolanti : Classe di Scienze Fisiche, Matematiche e Naturali, 2011 Using the discrete dipole approximation (DDA) we calculate the absorption efficiency of the composite grain, made up of a host silicate spheroid and inclusions of graphite, in the spectral region 5.0-25.0μm.
D. B. Vaidya, R. Gupta
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Circumstellar grains and the intrinsic polarization of starlight
Astrophysical Journal, 1975 Twenty-five long-period variable stars exhibiting intrinsic variable polarization have been monitored over the range 3.5-11 microns for several cycles. No conclusive evidence for gross changes in amount of circumstellar grains has been found. Thus circumstellar infrared emission is attributed to the total abundance of grains surrounding the star ...
W J Forrest, F C Gillett, W A Stein
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On the Composition of Circumstellar Grains
Astrophysical Journal, 1969 Circumstellar grain compositions of stars with various O to C abundance ratios, calculating molecular equilibrium of condensates and gaseous compounds in stellar ...
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n-Alkanes formed by methyl-methylene addition as a source of meteoritic aliphatics [PDF]
Communications ChemistryAliphatics prevail in asteroids, comets, meteorites and other bodies in our solar system. They are also found in the interstellar and circumstellar media both in gas-phase and in dust grains.
P. Merino +16 more
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Inefficient Growth of SiOx Grains: Implications for Circumstellar Outflows
Astrophysical Journal Letters, 2022 Abstract To explain observations of abundant circumstellar dust and high stellar wind velocity, most models simply postulate the efficient nucleation and growth of silicate dust particles. Here, we report measurement of the SiO–(SiOx)n grain sticking coefficient in a microgravity sounding rocket experiment, indicating very inefficient (0.
Yuki Kimura +2 more
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Large dust grains in the inner region of circumstellar disks [PDF]
Astronomy and Astrophysics, 2006 CONTEXT: Simple geometrical ring models account well for near-infrared interferometric observations of dusty disks surrounding pre-main sequence stars of intermediate mass. Such models demonstrate that the dust distribution in these disks has an inner hole and puffed-up inner edge consistent with theoretical expectations.
A Isella, L Testi, A Natta
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Presolar He and Ne Isotopes in Single Circumstellar SiC Grains
Astrophysical Journal, 2007 Noble gas isotopes in presolar silicon carbide (SiC) dust grains from primitive meteorites provide, together with major element isotopic compositions, insight into the nucleosynthetic output of different types of evolved stars >4.5 Gyr ago. We report here new results from helium and neon isotopic analyses of single presolar SiC grains with sizes ...
Philipp R Heck +2 more
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Extinction and abundance properties of Alpha Scorpii circumstellar grains
Astrophysical Journal, 1987 The UV extinction and element depletions in the circumstellar envelope Alpha Sco are investigated using IUE, Copernicus, and AS data of Alpha Sco B which can be seen in absorption through the cool-star envelope. The circumstellar reddening, depletions, and spectral extinction toward Alpha Sco B are estimated.
J P Swings
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Scattering and Absorption by Aligned Grains in Circumstellar Environments
Astrophysical Journal, 2002 We present radiative transfer calculations showing the polarization effects of scattering and absorption by aligned grains. The grain model consists of a size distribution of oblate or spinning prolate particles with varying degrees of alignment. To develop an understanding of the radiative transfer effects, we begin with the simple case of a spherical
Barbara A Whitney, Michael J Wolff
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