Effect of photoionization energy on the distance distribution between trapped electrons and N,N,N',N'-tetramethyl-p-phenylenediamine cations in organic glasses

Moeckel, H.; Yuen, Josephine; Kevan, Larry

doi:10.1021/j100643a022

Cited by 10 publications

(7 citation statements)

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“…showed that for a single encounter there exists an upper limit of 60% AML in the remaining disc. However, as Pfalzner (2004) and Moeckel & Bally (2006) showed, consecutive encounters can lead to a significant angular momentum transport.…”

Section: Resultsmentioning

confidence: 99%

Cluster-assisted Accretion for Massive Stars

Pfalzner

2006

ApJ

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Gravitational interactions in very young high-density stellar clusters can to some degree change the angular momentum in the circumstellar discs surrounding initially the majority of stars. However, for most stars the cluster environment alters the angular momentum only slightly. For example, in simulations of the Orion Nebula cluster (ONC) encounters reduce the angular momentum of the discs on average at most by 3-5% and in the higher density region of the Trapezium by 15-20% -still a minor loss process. However, in this paper it is demonstrated that the situation is very different if one considers high-mass stars (M * >10 M ⊙ ) only. Assuming an age of 2 Myr for the ONC, their discs have on average a 50-90% lower angular momentum than primordially. This enormous loss in angular momentum in the disc should result in an equivalent increase in accretion, implying that the cluster environment boosts accretion for high-mass stars, thus making them even more massive.

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Section: Resultsmentioning

confidence: 99%

Cluster-assisted Accretion for Massive Stars

Pfalzner

2006

ApJ

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“…Giant planets (or their cores) can migrate due to either planetesimal or gas disk interactions (Kley and Nelson 2012). Hydrodynamic simulations of multiple planets interacting with each other and with a surrounding gas disk (Moeckel et al 2008;Marzari et al 2010;Moeckel and Armitage 2012;Lega et al 2013) show that resonant, tightly packed or well-separated systems can form, but the probabilities for these channels cannot be predicted from first principles. Constraints on the dynamics must currently be derived from comparison of the predicted end states with observed systems.…”

Section: Instabilities In Tightly-packed Sys-temsmentioning

confidence: 99%

The Long-Term Dynamical Evolution of Planetary Systems

Davies¹,

Adams²,

Armitage³

et al. 2014

Protostars and Planets VI

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This chapter concerns the long-term dynamical evolution of planetary systems from both theoretical and observational perspectives. We begin by discussing the planet-planet interactions that take place within our own Solar System. We then describe such interactions in more tightly-packed planetary systems. As planet-planet interactions build up, some systems become dynamically unstable, leading to strong encounters and ultimately either ejections or collisions of planets. After discussing the basic physical processes involved, we consider how these interactions apply to extrasolar planetary systems and explore the constraints provided by observed systems. The presence of a residual planetesimal disc can lead to planetary migration and hence cause instabilities induced by resonance crossing; however, such discs can also stabilise planetary systems. The crowded birth environment of a planetary system can have a significant impact: close encounters and binary companions can act to destabilise systems, or sculpt their properties. In the case of binaries, the Kozai mechanism can place planets on extremely eccentric orbits which may later circularise to produce hot Jupiters.Comment: 23 pages, 10 figures. Refereed review chapter, accepted for publication in Protostars & Planets VI, University of Arizona Press (2014), eds. H.Beuther, C.Dullemond, Th.Henning, R. Klesse

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“…We shall frequently refer to the transverse coordinate ̟ as the impact parameter. Some early results were presented by Moeckel et al (2002).…”

Section: A Hydrodynamical Calculation Of a Wind Colliding With An Impmentioning

confidence: 99%

The Effects of Clumps in Explaining X‐Ray Emission Lines from Hot Stars

Cassinelli

Ignace

Waldron

et al. 2008

Astrophysical Journal

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It is now well established that stellar winds of hot stars are fragmentary and that the X-ray emission from stellar winds has a strong contribution from shocks in winds. Chandra high spectral resolution observations of line profiles of O and B stars have shown numerous properties that had not been expected. Here we suggest explanations by considering the X-rays as arising from bow shocks that occur where the stellar wind impacts on spherical clumps in the winds. We use an accurate and stable numerical hydrodynamical code to obtain steady-state physical conditions for the temperature and density structure in a bow shock. We use these solutions plus analytic approximations to interpret some major X-ray features: the simple power-law distribution of the observed emission measure derived from many hot star X-ray spectra and the wide range of ionization stages that appear to be present in X-ray sources throughout the winds. Also associated with the adiabatic cooling of the gas around a clump is a significant transverse velocity for the hot plasma flow around the clumps, and this can help to understand anomalies associated with observed line widths, and the differences in widths seen in stars with high and low mass-loss rates. The differences between bow shocks and the planar shocks that are often used for hot stars are discussed. We introduce an "on the shock" (OTSh) approximation that is useful for interpreting the X-rays and the consequences of clumps in hot star winds and elsewhere in astronomy.

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Effect of photoionization energy on the distance distribution between trapped electrons and N,N,N',N'-tetramethyl-p-phenylenediamine cations in organic glasses

Cited by 10 publications

References 1 publication

Cluster-assisted Accretion for Massive Stars

Cluster-assisted Accretion for Massive Stars

The Long-Term Dynamical Evolution of Planetary Systems

The Effects of Clumps in Explaining X‐Ray Emission Lines from Hot Stars

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