The Power Spectrum of Turbulence in NGC 1333: Outflows or Large-Scale Driving? (2009)
Padoan, Paolo, Juvela, Mika, Kritsuk, Alexei G., Norman, Michael L.
Is the turbulence in cluster-forming regions internally driven by stellar outflows or the consequence of a large-scale turbulent cascade? We address this question by studying the turbulent energy...
The IMF of stellar clusters: effects of accretion and feedback (2009)
Dib, Sami, Shadmehri, Mohsen, Padoan, Paolo, G., Maheswar, Ojha, D. K., Khajenabi, Fazeleh
(abridged) We develop a model which describes the coevolution of the mass function of dense cores and of the IMF in a protocluster clump. In the model, cores injected in the clump evolve under the...
Simulating Supersonic Turbulence in Magnetized Molecular Clouds (2009)
Kritsuk, Alexei G., Ustyugov, Sergey D., Norman, Michael L., Padoan, Paolo
We present results of large-scale three-dimensional simulations of weakly magnetized supersonic turbulence at grid resolutions up to 1024^3 cells. Our numerical experiments are carried out with the...
Lunttila, Tuomas, Padoan, Paolo, Juvela, Mika, Nordlund, Åke
Recent measurements of the Zeeman effect in dark-cloud cores provide important tests for theories of cloud dynamics and prestellar core formation. In this Letter we report results of simulated Zeeman...
The Star Formation Rate of Supersonic MHD Turbulence (2009)
This work revisits the star formation rate (SFR) model of Krumholz and McKee, extends it to the case of a magnetized medium, and verifies it with a set of numerical simulations of driven, supersonic,...
Bridging the Gap Between Stars and Planets: The Formation and Early Evolution of Brown Dwarfs (2009)
Mohanty, Subhanjoy, Burgasser, Adam, Chabrier, Gilles, Padoan, Paolo, Hennebelle, Patrick, Pascucci, Ilaria, ...
This White Paper, submitted to the National Academy of Sciences' Astro2010 Decadal Review Committee, focuses on 2 central themes in the study of young brown dwarfs -- their formation mechanism and...
Simulations of Supersonic Turbulence in Molecular Clouds: Evidence for a New Universality (2009)
Kritsuk, Alexei G., Ustyugov, Sergey D., Norman, Michael L., Padoan, Paolo
We use three-dimensional simulations to study the statistics of supersonic turbulence in molecular clouds. Our numerical experiments describe driven turbulent flows with an isothermal equation of...
Dissipative Structures in Supersonic Turbulence (2008)
Pan, Liubin, Padoan, Paolo, Kritsuk, Alexei G.
We show that density-weighted moments of the dissipation rate, $\epsilon_l$, averaged over a scale $l$, in supersonic turbulence can be successfully explained by the She and L\'ev\^eque model [Phys....
The Temperature of Interstellar Clouds from Turbulent Heating (2008)
To evaluate the effect of turbulent heating in the thermal balance of interstellar clouds, we develop an extension of the log-Poisson intermittency model to supersonic turbulence. The model depends...
The Super-Alfv\'enic Model of Molecular Clouds: Predictions for Zeeman Splitting Measurements (2008)
Lunttila, Tuomas, Padoan, Paolo, Juvela, Mika, Nordlund, Åke
We present synthetic OH Zeeman splitting measurements of a super-Alfvenic model of molecular clouds. We select dense cores from synthetic 13CO maps computed from the largest simulation to date of...
Scaling Laws and Intermittency in Highly Compressible Turbulence (2007)
Kritsuk, Alexei G., Padoan, Paolo, Wagner, Rick, Norman, Michael L.
We use large-scale three-dimensional simulations of supersonic Euler turbulence to study the physics of a highly compressible cascade. Our numerical experiments describe non-magnetized driven...
The Statistics of Supersonic Isothermal Turbulence (2007)
Kritsuk, Alexei G., Norman, Michael L., Padoan, Paolo, Wagner, Rick
We present results of large-scale three-dimensional simulations of supersonic Euler turbulence with the piecewise parabolic method and multiple grid resolutions up to 2048^3 points. Our numerical...
Padoan, Paolo, Nordlund, AAke, Kritsuk, Alexei G., Norman, Michael L., Li, Pak Shing
The Padoan and Nordlund model of the stellar initial mass function (IMF) is derived from low order statistics of supersonic turbulence, neglecting gravity (e.g. gravitational fragmentation, accretion...
The Power Spectrum of Supersonic Turbulence in Perseus (2006)
Padoan, Paolo, Juvela, Mika, Kritsuk, Alexei, Norman, Michael L.
We test a method of estimating the power spectrum of turbulence in molecular clouds based on the comparison of power spectra of integrated intensity maps and single-velocity-channel maps, suggested...
High Resolution Simulations of Supersonic Turbulence in Molecular Clouds (2006)
Kritsuk, Alexei G., Wagner, Rick, Norman, Michael L., Padoan, Paolo
We present the results of three-dimensional simulations of supersonic Euler turbulence with grid resolutions up to 1024^3 points. Our numerical experiments describe nonmagnetized driven turbulent...
Can We Trust the Dust? Evidence of Dust Segregation in Molecular Clouds (2006)
Padoan, Paolo, Cambresy, Laurent, Juvela, Mika, Kritsuk, Alexei, Langer, William D., Norman, Michael L.
Maps of estimated dust column density in molecular clouds are usually assumed to reliably trace the total gas column density structure. In this work we present results showing a clear discrepancy...
Klein, Richard I., Inutsuka, Shu-ichiro, Padoan, Paolo, Tomisaka, Kohji
Developing a theory of low-mass star formation ($\sim 0.1$ to 3~M$_{\odot}$) remains one of the most elusive and important goals of theoretical astrophysics. The star-formation process is the outcome...
High Resolution Mapping of Interstellar Clouds by Near--IR Scattering (2005)
Padoan, Paolo, Juvela, Mika, Pelkonen, Veli-Matti
We discuss the possibility of mapping interstellar clouds at unprecedentedly high spatial resolution by means of near-IR imaging of their scattered light. We calculate the scattering of the...
Confinement-Driven Spatial Variations in the Cosmic Ray Flux (2005)
Low-energy cosmic rays (CRs) are confined by self-generated MHD waves in the mostly neutral ISM. We show that the CR transport equation can be expressed as a continuity equation for the CR number...
Adaptive Mesh Refinement for Supersonic Molecular Cloud Turbulence (2004)
Kritsuk, Alexei G., Norman, Michael L., Padoan, Paolo
We performed a series of three-dimensional numerical simulations of supersonic homogeneous Euler turbulence with adaptive mesh refinement (AMR) and effective grid resolution up to 1024^3 zones. Our...
The Stellar IMF as a Property of Turbulence (2004)
We propose to interpret the stellar IMF as a property of the turbulence in the star--forming gas. Gravitationally unstable density enhancements in the turbulent flow collapse and form stars. Their...
Brown Dwarfs from Turbulent Fragmentation (2004)
Padoan, Paolo, Kritsuk, Alexei, Norman, Michael, Nordlund, Ake
The origin of brown dwarfs (BDs) is an important component of the theory of star formation, because BDs are approximately as numerous as solar mass stars. It has been suggested that BDs originate...
A Solution to the Protostellar Accretion Problem (2004)
Padoan, Paolo, Kritsuk, Alexei, Norman, Michael L., Nordlund, Ake
Accretion rates of order 10^-8 M_\odot/yr are observed in young protostars of approximately a solar mass with evidence of circumstellar disks. The accretion rate is significantly lower for protostars...
Electron Abundance in Protostellar Cores (2004)
Padoan, Paolo, Willacy, Karen, Langer, William, Juvela, Mika
The determination of the fractional electron abundance, Xe, in protostellar cores relies on observations of molecules, such as DCO+, H13CO+ and CO, and on chemical models to interpret their...
Jimenez, Raul, MacDonald, James, Dunlop, James, Padoan, Paolo, Peacock, John
We present a new set of stellar interior and synthesis models for predicting the integrated emission from stellar populations in star clusters and galaxies of arbitrary age and metallicity. This work...
Padoan, Paolo, Jimenez, Raul, Juvela, Mika, Nordlund, Aake
The magnetic field strength in molecular clouds is a fundamental quantity for theories of star formation. It is estimated by Zeeman splitting measurements in a few dense molecular cores, but its...
Structure Function Scaling in Compressible Super-Alfvenic MHD Turbulence (2003)
Padoan, Paolo, Jimenez, Raul, Nordlund, Aake, Boldyrev, Stanislav
Supersonic turbulent flows of magnetized gas are believed to play an important role in the dynamics of star-forming clouds in galaxies. Understanding statistical properties of such flows is crucial...
Padoan, Paolo, Goodman, Alyssa, Juvela, Mika
We compute the spectral correlation function (SCF) of 13CO J=1--0 maps of molecular cloud complexes. The SCF is a power law over approximately an order of magnitude in spatial separation in every...
Star Formation and the Initial Mass Function (2002)
Supersonic turbulence fragments the interstellar medium into dense sheets, filaments, cores and large low density voids. The turbulence is driven on large scales, probably predominantly by...
Structure Function Scaling of a 2MASS Extinction Map of Taurus (2002)
Padoan, Paolo, Cambresy, Laurent, Langer, William
We compute the structure function scaling of a 2MASS extinction map of the Taurus molecular cloud complex. The scaling exponents of the structure functions of the extinction map follow the Boldyrev's...
Structure Function Scaling in the Taurus and Perseus Molecular Cloud Complexes (2002)
Padoan, Paolo, Boldyrev, Stanislav, Langer, William, Nordlund, AAke
We compute the structure function scaling of the integrated intensity images of two J=1-0 13CO maps of Taurus and Perseus. The scaling exponents of the structure functions follow the velocity scaling...
Supersonic turbulence and structure of interstellar molecular clouds (2002)
Boldyrev, Stanislav, Nordlund, Aake, Padoan, Paolo
The interstellar medium (ISM) provides a unique laboratory for highly supersonic, driven hydrodynamics turbulence. We present a theory of such turbulence, confirm it by numerical simulations, and use...
Scaling relations of supersonic turbulence in star-forming molecular clouds (2001)
Boldyrev, Stanislav, Nordlund, Aake, Padoan, Paolo
We present a direct numerical and analytical study of driven supersonic MHD turbulence that is believed to govern the dynamics of star-forming molecular clouds. We describe statistical properties of...
Theoretical Models of Polarized Dust Emission from Protostellar Cores (2001)
Padoan, Paolo, Goodman, Alyssa, Draine, Bruce, Juvela, Mika, Nordlund, AAke, Rognvaldsson, Ornolfur Einar
We model the polarized thermal dust emission from protostellar cores that are assembled by super-sonic turbulent flows in molecular clouds. Self-gravitating cores are selected from a three...
A New Method to Measure and Map the Gas Scale-Height of Disk Galaxies (2001)
Padoan, Paolo, Kim, Sungeun, Goodman, Alyssa
We propose a new method to measure and map the gas scale height of nearby disk galaxies. This method is applied successfully to the Australia Telescope Compact Array interferometric HI survey of the...
The Stellar IMF from Turbulent Fragmentation (2000)
The morphology and kinematics of molecular clouds (MCs) are best explained as the consequence of super--sonic turbulence. Super--sonic turbulence fragments MCs into dense sheets, filaments and cores...
Turbulent Fragmentation and the Initial Conditions for Star Formation (2000)
Padoan, Paolo, Nordlund, AAke, Rognvaldsson, Ornolfur Einar, Goodman, Alyssa
Super-sonic turbulence fragments molecular clouds (MC) into a very complex density field with density contrasts of several orders of magnitude. A fraction of the gas is locked into dense and...
The Turbulent Shock Origin of Proto--Stellar Cores (2000)
Padoan, Paolo, Juvela, Mika, Goodman, Alyssa A., Nordlund, AAke
The fragmentation of molecular clouds (MC) into protostellar cores is a central aspect of the process of star formation. Because of the turbulent nature of super-sonic motions in MCs, it has been...
The Effects of Noise and Sampling on the Spectral Correlation Function (2000)
Padoan, Paolo, Rosolowsky, Erik W., Goodman, Alyssa A.
The effects of noise and sampling on the ``Spectral Correlation Function'' (SCF) introduced by Rosolowsky et al. 1999 are studied using observational data, numerical simulations of...
Primordial Proto-Galaxies (1999)
Padoan, Paolo, Jimenez, Raul, Dunlop, James
The first stars to form in protogalaxies must have primordial chemical composition. We refer to a protogalaxy that is forming stars of primordial composition, or very low metallicity ($Z\le 0.01...
Proto-Galactic Starbursts at High Redshift (1999)
Jimenez, Raul, Padoan, Paolo, Dunlop, James, Bowen, David, Juvela, Mika, Matteucci, Francesca
We have computed the evolving ultraviolet-millimeter spectral energy distribution (SED) produced by proto-galactic starbursts at high redshift, incorporating the chemical evolution of the...
Ambipolar Drift Heating in Turbulent Molecular Clouds (1999)
Although thermal pressure is unimportant dynamically in most molecular gas, the temperature is an important diagnostic of dynamical processes and physical conditions. This is the first of two papers...
The Chemical Evolution of the Galaxy with Variable IMFs (1999)
Chiappini, Cristina, Matteucci, Francesca, Padoan, Paolo
In this work we explore the effects of adopting initial mass functions (IMFs) variable in time on the chemical evolution of the Galaxy. In order to do that we adopt a chemical evolution model which...
Super-Sonic Turbulence in the Perseus Molecular Cloud (1999)
Padoan, Paolo, Bally, John, Billawala, Youssef, Juvela, Mika, Nordlund, AAke
We compare the statistical properties of J=1-0 13CO spectra observed in the Perseus Molecular Cloud with synthetic J=1-0 13CO spectra, computed solving the non-LTE radiative transfer problem for a...
A Super-Alfvenic Model of Dark Clouds (1999)
Supersonic random motions are observed in dark clouds and are traditionally interpreted as Alfven waves, but the possibility that these motions are super-Alfvenic has not been ruled out. In this work...
Density PDFs of Super-Sonic Turbulence (1998)
The question of the shape of the density PDF for supersonic turbulence is addressed, using both analytical and numerical methods. For isothermal supersonic turbulence, the PDF is Log-Normal, with a...
Galaxy Formation and Evolution: Low Surface Brightness Galaxies (1998)
Jimenez, Raul, Padoan, Paolo, Matteucci, Francesca, Heavens, Alan
We investigate in detail the hypothesis that low surface brightness galaxies (LSB) differ from ordinary galaxies simply because they form in halos with large spin parameters. We compute star...
Synthetic Molecular Clouds from Supersonic MHD and Non-LTE Radiative Transfer Calculations (1997)
Padoan, Paolo, Juvela, Mika, Bally, John, Nordlund, AAke
The dynamics of molecular clouds is characterized by supersonic random motions in the presence of a magnetic field. We study this situation using numerical solutions of the three-dimensional...
Supersonic Random Flows in the Perseus Molecular Cloud (1997)
Padoan, Paolo, Bally, John, Billawala, Youssef, Juvela, Mika, Nordlund, AAke
We compare the statistical properties of J=1-0 13CO spectra observed in the Perseus Molecular Cloud with synthetic J=1-0 13CO spectra from a 5 pc model cloud. The synthetic spectra are computed...
Supersonic motions in dark clouds are not Alfven waves (1997)
Supersonic random motions are observed in dark clouds and are traditionally interpreted as Alfv\'{e}n waves, but the possibility that these motions are super-Alfvenic has not been ruled out. In this...
A Theoretical Calibration of ^{13}CO LTE Column Density in Molecular Clouds (1997)
Padoan, Paolo, Juvela, Mika, Bally, John, Nordlund, AAke
In this work we use models of molecular clouds (MC), and non-LTE radiative transfer calculations, to obtain a theoretical calibration of the relation between LTE 13CO column density and true column...
The Universality of the Stellar IMF (1997)
Padoan, Paolo, Nordlund, Ake, Jones, Bernard J. T.
We propose that the stellar initial mass function (IMF) is universal in the sense that its functional form arises as a consequence of the statistics of random supersonic flows. A model is developed...
Are Low Surface Brightness Discs Young? (1996)
Padoan, Paolo, Jimenez, Raul, Antonuccio-Delogu, Vincenzo
We reconsider the problem of the age of the stellar discs of late-type Low Surface Brightness (LSB) galaxies by making use of a new IMF recently derived from numerical fluid dynamical simulations...
On star formation in primordial protoglobular clouds (1996)
Padoan, Paolo, Jimenez, Raul, Jones, Bernard
Using a new physical model for star formation (Padoan 1995) we have tested the possibility that globular clusters (GCs) are formed from primordial mass fluctuations, whose mass scale ($10^8$ - $10^9$...
Ages of globular clusters: breaking the age-distance degeneracy with the luminosity function (1996)
We extend our previous method to determine globular cluster ages using the luminosity function (Jimenez \& Padoan 1996). We show that the luminosity function depends on both age and distance modulus...
Padoan, Paolo, Jones, Bernard J. T., Nordlund, AAke
Lada et al. (1994) have described a method for studying the distribution of dust in dark clouds using infrared imaging surveys. In particular they show that the method provides some information about...
A new method to determine Globular Cluster ages (1996)
We present a new method to compute stellar ages in Globular Clusters (GC) that is ten times more precise than the traditional isochrone fitting procedure. The method relies on accurate stellar...
Supersonic Turbulence and the Fragmentation of a Cold Medium (1995)
The role played by velocity fields in the fragmentation of a cold medium and in the formation of protostars is studied. The velocity field is modeled with a compressible turbulent flow. A supersonic...