Radiation-Hydrodynamic Models of X-Ray & EUV Photoevaporating Protoplanetary Discs (2009)
Owen, J. E., Ercolano, B., Clarke, C. J., Alexander, R. D.
(Abridged) We present the first radiation-hydrodynamic model of a protoplanetary disc irradiated with an X-EUV spectrum. In a model where the total ionizing luminosity is divided equally between...
Gas Phase diagnostics of Protoplanetary disk extension (2008)
Ercolano, B., Drake, J. J., Clarke, C. J.
We investigate the potential of using ratios of fine structure and near-infrared forbidden line transitions of atomic carbon to diagnose protoplanetary disk extension. Using results from 2D...
Maximum stellar mass versus cluster membership number revisited (2008)
Maschberger, Th., Clarke, C. J.
We have made a new compilation of observations of maximum stellar mass versus cluster membership number from the literature, which we analyse for consistency with the predictions of a simple random...
Disc evolution and the relationship between $L_{\rm acc}$ and $L_\ast$ in T Tauri stars (2008)
Tilling, I., Clarke, C. J., Pringle, J. E., Tout, C. A.
We investigate the evolution of accretion luminosity $L_{\rm acc}$ and stellar luminosity ${L_\ast}$ in pre-mainsequence stars. We make the assumption that when the star appears as a Class II object,...
Eccentricity growth of planetesimals in a self-gravitating protoplanetary disc (2008)
Britsch, M., Clarke, C. J., Lodato, G.
We investigate the orbital evolution of planetesimals in a self-gravitating circumstellar disc in the size regime ($\sim 1-5000$ km) where the planetesimals behave approximately as test particles in...
Wyatt, M. C., Clarke, C. J., Greaves, J. S.
The probability of a star hosting a planet that is detectable in radial velocity surveys increases Ppl(Z) oc 10^2Z, where Z is metallicity. Core accretion models reproduce this trend, since the...
The formation of extreme mass ratio binary stars: a tribute to Eduardo De lgado Donate (2007)
Eduardo Delgado was due to have presented a poster at this meeting on his latest results on the formation of extreme mass ratio binaries. Tragically, Eduardo was among those killed in a hiking...
Massive stars: Feedback effects in the local universe (2007)
We examine self-consistent parameterizations of the high-mass stellar population and resulting feedback, including mechanical, radiative, and chemical feedback, as we understand them locally. To...
The Photoevaporation of Discs Around Young Stars in Massive Clusters (2007)
We present models in which the photoevaporation of discs around young stars by an external ultraviolet source (as computed by Adams et al 2004) is coupled with the internal viscous evolution of the...
Feedback Processes in Massive Star Formation (2006)
J E. Dale, R G. Edgar, C J. Clarke
Feedback Processes in Massive Star Formation
The $\dot{M} - M$ relationship in pre-main sequence stars (2006)
We examine the recent data and analysis of Natta et al. concerning the accretion rate on to young stars as a function of stellar mass, and conclude that the apparently steep dependence of accretion...
Disk Evolution in Young Binaries: from Observations to Theory (2006)
Clarke, C. J., Prato, L., McCabe, C.
The formation of a binary system surrounded by disks is the most common outcome of stellar formation. Hence studying and understanding the formation and the evolution of binary systems and associated...
The Jeans mass and the origin of the knee in the IMF (2006)
Bonnell, I. A., Clarke, C. J., Bate, M. R.
We use numerical simulations of the fragmentation of a 1000 solar mass molecular cloud and the formation of a stellar cluster to study how the initial conditions for star formation affect the...
Photoevaporation of protoplanetary discs I: hydrodynamic models (2006)
Alexander, R. D., Clarke, C. J., Pringle, J. E.
In this paper we consider the effect of the direct ionizing stellar radiation field on the evolution of protoplanetary discs subject to photoevaporative winds. We suggest that models which combine...
Photoevaporation of protoplanetary discs II: evolutionary models and observable properties (2006)
Alexander, R. D., Clarke, C. J., Pringle, J. E.
We present a new model for protoplanetary disc evolution. This model combines viscous evolution with photoevaporation of the disc, in a manner similar to Clarke, Gendrin & Sotomayor (2001). However...
Lodato, G., Delgado-Donate, E., Clarke, C. J.
In this paper we discuss the nature and the possible formation scenarios of the companion of the brown dwarf 2MASS 1207334-393254. We initially discuss the basic physical properties of this object...
The Differential Lifetimes of Protostellar Gas and Dust Disks (2005)
Takeuchi, Taku, Clarke, C. J., Lin, D. N. C.
We construct a protostellar disk model that takes into account the combined effect of viscous evolution, photoevaporation and the differential radial motion of dust grains and gas. For T Tauri disks,...
Photoionising feedback in star cluster formation (2005)
Dale, J. E., Bonnell, I. A., Clarke, C. J., Bate, M. R.
We present the first ever hydrodynamic calculations of star cluster formation that incorporate the effect of feedback from ionising radiation. In our simulations, the ionising source forms in the...
Statistical Confirmation of a Stellar Upper Mass Limit (2005)
We derive the expectation value for the maximum stellar mass (m_max) in an ensemble of N stars, as a function of the IMF upper-mass cutoff (m_up) and N. We statistically demonstrate that the upper...
Constraints on the ionizing flux emitted by T Tauri stars (2005)
Alexander, R. D., Clarke, C. J., Pringle, J. E.
We present the results of an analysis of ultraviolet observations of T Tauri Stars (TTS). By analysing emission measures taken from the literature we derive rates of ionizing photons from the...
The effects of X-ray photoionization and heating on the structure of circumstellar discs (2004)
Alexander, R. D., Clarke, C. J., Pringle, J. E.
We present the results of a theoretical study investigating the effects of photoionization and heating by X-rays on discs around low-mass stars. In particular we address the question of whether or...
Massive planets in FU Orionis discs: implications for thermal instability models (2004)
FU Orionis are young stellar objects undergoing episodes of enhanced luminosity, which are generally ascribed to a sudden increase of mass accretion rate in the surrounding protostellar disc. Models...
Kinetic theory viscosity (2004)
We show how the viscous evolution of Keplerian accretion discs can be understood in terms of simple kinetic theory. Although standard physics texts give a simple derivation of momentum transfer in a...
On the properties of young multiple stars (2004)
Delgado-Donate, E. J., Clarke, C. J., Bate, M. R., Hodgkin, S. T.
Abridged/ We present numerical results on the properties of young binary and multiple stellar systems. Our analysis is based on a series of SPH + Nbody simulations of the fragmentation of small...
On the origin of ionising photons emitted by T Tauri stars (2003)
Alexander, R. D., Clarke, C. J., Pringle, J. E.
We address the issue of the production of Lyman continuum photons by T Tauri stars, in an attempt to provide constraints on theoretical models of disc photoionisation. By treating the accretion shock...
The dependence of the sub-stellar IMF on the initial conditions for star formation (2003)
Delgado-Donate, E. J, Clarke, C. J., Bate, M. R.
Abridged: We have undertaken a series of hydrodynamical simulations of multiple star formation in small turbulent molecular clouds. Our goal is to determine the sensitivity of the properties of the...
Are there brown dwarfs in globular clusters? (2003)
Bonnell, I. A., Clarke, C. J., Bate, M. R., McCaughrean, M. J., Pringle, J. E., Zinnecker, H.
We present an analytical method for constraining the substellar initial mass function in globular clusters, based on the observed frequency of transit events. Globular clusters typically have very...
Accretion and Dynamical Interactions in Small-N Star-Forming Clusters: I. N=5 case (2003)
Delgado-Donate, E. J., Clarke, C. J., Bate, M. R.
We present results from high-resolution hydrodynamical simulations which explore the effects of small scale clustering in star-forming regions. A large ensemble of small-N clusters with 5 stellar...
A New Algorithm for Radiative Feedback and its Application to the Formation of Massive Stars (2002)
We have developed a simplified method of treating the radiative acceleration of dusty flows. This method retains the sharp impulse at the dust destruction radius that is a feature of frequency...
The spatial distribution of star formation within galaxies strongly affects the resulting feedback processes. Previous work has considered the case of a single, concentrated nuclear starburst, and...
The Orientation of Jets Relative to Dust Disks in Radio Galaxies (2002)
Schmitt, H. R., Pringle, J. E., Clarke, C. J., Kinney, A. L.
We use HST broad band images, VLA and VLBI continuum data to study the three dimensional orientation of jets relative to nuclear dust disks in 20 radio galaxies. The comparison between the position...
Testing the Unified Model with an Infrared Selected Sample of Seyferts (2001)
Schmitt, H. R., Ulvestad, J. S., Antonucci, R. R. J., Clarke, C. J., Pringle, J. E., Kinney, A. L.
We present a series of statistical tests using homogeneous data and measurements for a sample of Seyfert galaxies. These galaxies were selected from mostly isotropic properties, their far infrared...
Mechanical Feedback: From stellar wind bubbles to starbursts (2001)
Oey, M. S., Clarke, C. J., Massey, P.
The current understanding of mechanical feedback is reviewed by evaluating the standard, adiabatic model for shell formation and evolution. This model is relevant to phenomena ranging from individual...
Testing the Unified Model with an Infrared Selected Sample of Seyfert Galaxies (2001)
Schmitt, H. R., Antonucci, R. R. J., Ulvestad, J. S., Kinney, A. L., Clarke, C. J., Pringle, J. E.
We present a series of statistical tests done to a sample of 29 Seyfert 1 and 59 Seyfert 2 galaxies selected from mostly isotropic properties, their far infrared fluxes and warm infrared colors. Such...
Accretion in stellar clusters and the IMF (2001)
Bonnell, I. A., Clarke, C. J., Bate, M. R., Pringle, J. E.
We present a simple physical mechanism that can account for the observed stellar mass spectrum for masses $\ms \simgreat 0.5 \solm$. The model depends solely on the competitive accretion that occurs...
Competitive accretion in embedded stellar cluster (2001)
Bonnell, I. A., Bate, M. R., Clarke, C. J., Pringle, J. E.
We investigate the physics of gas accretion in young stellar clusters. Accretion in clusters is a dynamic phenomenon as both the stars and the gas respond to the same gravitational potential....
Observational Implications of Precessing Protostellar Discs and Jets (2000)
Bate, M. R., Bonnell, I. A., Clarke, C. J., Lubow, S. H., Ogilvie, G. I., Pringle, J. E., ...
We consider the dynamics of a protostellar disc in a binary system where the disc is misaligned with the orbital plane of the binary, with the aim of determining the observational consequences for...
Jet directions in Seyfert galaxies (2000)
Kinney, A. L., Schmitt, H. R., Clarke, C. J., Pringle, J. E., Ulvestad, J. S., Antonucci, R. R. J.
We present the study of the relative angle between the accretion disk (or radio jet) and the galaxy disk for a sample of Seyfert galaxies selected from a mostly isotropic property, the 60$\mu$m flux....
Sanna, Ennio, Woodall, Christopher, Watt, N. J., Clarke, C. J., Pittau, M., Leoni, Antonio, ...
Molecular biological techniques have permitted the rapid and sensitive detection of the Mycobacterium paratuberculosis genome in infected tissues, most commonly by polymerase chain reaction...
Direct measurement of the jet geometry in Seyfert galaxies (1999)
Pringle, J. E., Antonucci, R. R. J., Clarke, C. J., Kinney, A. L., Schmitt, H. R., Ulvestad, J. S.
We demonstrate that, by combining optical, radio and X-ray observations of a Seyfert, it is possible to provide a direct measurement of the angle $\beta$ between the direction of the radio jet and...
The kinetics of penetration of grafted polymers into a network (1999)
Geoghegan, M, Clarke, C J, Boue, F, Menelle, A, Russ, T, Bucknall, D G
Accretion Disc Evolution in Single and Binary T Tauri Stars (1998)
Armitage, Philip J., Clarke, C. J., Tout, C. A.
We present theoretical models for the evolution of T Tauri stars surrounded by circumstellar discs. The models include the effects of pre-main-sequence stellar and time dependent disc evolution, and...
The Size Distribution of Superbubbles in the Interstellar Medium (1998)
We use the standard, adiabatic shell evolution to predict the size distribution N(R) for populations of SN-driven superbubbles in a uniform ISM. We derive N(R) for simple cases of superbubble...
C. J. Clarke, R. J. George, R. W. Bell, R. J. Hobbs
Dryland salinity poses a major threat to agricultural production in the wheatbelt of Western Australia and much time and effort is expended on understanding the mechanisms which cause it and on...
Clarke, C. J., George, R. J., Bell, R. W., Hobbs, R. J.
Dryland salinity poses a major threat to agricultural production in the wheatbelt of Western Australia and much time and effort is expended on understanding the mechanisms which cause it and on...
Clarke, C. J., George, R. J., Bell, R. W., Hobbs, R. J.
Dryland salinity poses a major threat to agricultural production in the wheatbelt of Western Australia and much time and effort is expended on understanding the mechanisms which cause it and on...
On the Form of the HII Region Luminosity Function (1997)
Observed variations in the HII region luminosity function (HII LF) seen in spiral arm vs. interarm regions, and different galactic Hubble type, can be explained simply by evolutionary effects and...
An Investigation into the Geometry of Seyfert Galaxies (1997)
Clarke, C. J., Kinney, A. L., Pringle, J. E.
We present a new method for the statistical investigation into the distributions of the angle beta between the radio axis and the normal to the galactic disk for a sample of Seyfert galaxies. We...
The Superbubble Size Distribution in the Interstellar Medium of Galaxies (1997)
We use the standard, adiabatic shell evolution to predict the size distribution N(R) for populations of OB superbubbles in a uniform ISM. We derive N(R) for simple cases of superbubble creation rate...
The ejection of T Tauri stars from molecular clouds and the fate of circumstellar discs (1996)
Armitage, P. J., Clarke, C. J.
We investigate the evolution of circumstellar discs around T Tauri stars that are ejected from small stellar clusters within molecular clouds. In particular, we study how the interaction that leads...
Magnetic braking of T Tauri stars (1995)
Armitage, P. J., Clarke, C. J.
We construct models for the rotation rates of T Tauri stars whose spin is regulated by magnetic linkage between the star and a surrounding accretion disc. Our models utilise a time-dependent disc...
Energetics of star-disc encounters in the non-linear regime (1995)
Hall, S. M., Clarke, C. J., Pringle, J. E.
We investigate the response of a circumstellar accretion disc to the fly-by of a perturbing mass on a parabolic orbit. The energy and angular momentum transferred during the encounter are calculated...
Magnetically modulated accretion in T Tauri stars (1995)
Clarke, C. J., Armitage, P. J., Smith, K. W., Pringle, J. E.
We examine how accretion on to T Tauri stars may be modulated by a time-dependent `magnetic gate' where the inner edge of the accretion disc is disrupted by a varying stellar field. We show that...
The structure of grafted polystyrene layers in a range of matrix polymers (1995)
Clarke, C J, Jones, R A L, Shull, K R, Edwards, J L, Penfold, J
Kinetics of formation of physically end-adsorbed polymers from the melt (1994)
Clarke, C J, Jones, R A L, Edwards, J L, Clough, A S, Penfold, J
N-Body Simulations of Star-Disc Captures in Globular Clusters (1993)
The presence of protostellar disks can greatly increase the dissipation during close stellar encounters, leading to the formation of a significant population of binaries during the initial collapse...
Dutia, B M, Clarke, C J, Allen, D J, Nash, A A
Murine gammaherpesvirus is a natural rodent pathogen which causes a primary infection in the lungs and establishes a persistent infection in B lymphocytes. During the primary infection, large amounts...
Dutia, B M, Clarke, C J, Allen, D J, Nash, A A
Murine gammaherpesvirus is a natural rodent pathogen which causes a primary infection in the lungs and establishes a persistent infection in B lymphocytes. During the primary infection, large amounts...
Clarke, C J, Wilson, A D, Williams, N A, Stokes, C R
Cholera toxin is widely recognized as a potent stimulator of mucosal IgA responses after oral feeding. However, comparatively little is known of its ability to stimulate cellular responses. This is...