Magnetic Fields and Star Formation : Theory Versus Observations

Magnetic Fields play a key role in the physics of star formation on all scales: from the formation of the large complexes of molecular clouds to the formation of solar-like planetary systems. The plasma physics involved is non-linear and very complex, which requires the development of large numerical codes. An additional difficulty is that the detection and study of magnetic fields is not easy from an observational point of view, and therefore theoretical models cannot easily be constrained.

In the week from April 21st to 25th in 2003, a meeting was held on the Campus of the Universidad Complutense de Madrid (Spain) to join theoretical and observational efforts to address these issues. The objective was to define a set of relevant problems for the physics of star formation that can be properly addressed with the current or near-future instruments.

This book summarizes the results of this intensive week of work. The book is written in a comprehensive manner and reviews our current knowledge of the subject. It also represents an updated account of the ideas and thoughts of the scientists working in the field of Star Formation. The contributions are presented in six chapters which correspond to the six fundamental issues (sessions) on which the discussion was focused during the workshop: the physics of turbulence in the Interstellar Medium (ISM), the formation of structure in the ISM, the formation of stars within dense cores of molecular gas, the physics of accretion disks, the physics of outflows and their interaction with the ISM, and the interaction between the stellar magnetosphere and accretion disk.

Each chapter starts with a comprehensive summary written by one of the editors, which includes input from the contributions as well as the editor's own thoughts on the subject. For all these reasons the book is well-suited as a primer to introduce graduate students in the richness of this field of research.

Preface. 1: Turbulence in the ISM.- Turbulence in the ISM. Overview; M. Heyer, E. Zweibel. Theory: A review of the theory of incompressible MHD turbulence; B. Chandran.- Basic properties of compressible MHD turbulence: implications for molecular cloud; A. Lazarian, J. Cho.-Magnetic flux transport in the ISM through turbulent ambipolar diffusion; F. Heitsch, et al. High resolution simulations of nonhelical MHD turbulence; N.E.L. Haugen, et al. Scaling relations of supersonic turbulence in molecular clouds; S. Boldyrev, et al. Hydrodynamical simulations of molecular dynamics in supersonic turbulent flow; G. Pavlovski, et al. Observations: Observational magnetodynamics. 21 years of HI Zeeman splitting measurements... and more; C. Heiles. Structure of molecular clouds; E. Falgarone, et al. The tiny-scale atomic structure: gas cloudlets or scintillation phenomenon? S. Stanimirovic, et al. The relation between the turbulent widths of emission lines from HII regions and the luminosities of the regions; J. Beckman, M. Relano. BIMA and JCMT spectropolarimetric observations of the CO J=2-1 line towards Orion KL/Irc2; J.M. Girart, et al. The measurement of the orientation of the magnetic field in molecular clouds; M. Houde, et al. 2: Formation of Structure and Fragmentation.- Formation of structure and fragmentation. Overview; E. Vazquez-Semandi. Theory: Turbulent Fragmentation and Star Formation; J. Ballesteros-Paredes. MHD simulations of the ISM: The importance of the galactic magnetic field on the ISM "phases"; M.A. D'Avillez, D. Breitschwerdt. Comments on turbulent star formation; R. Klessen. Observations: Magnetic fields in molecular clouds; R. Crutcher. Evolution of magnetic fields in Bok globules: observations vs. theory; S. Wolf. High resolution studies of the ion and neutral spectra as a probe of the magnetic field structure; S.P. Lai. 3: From Cores to Stars.- From cores to stars. Overview; R. Rebolo. Theory: From molecular cores to stars and brown dwarfs; M.R. Bate. Contraction and fragmentation of magnetized rotating clouds and formation of binary systems; K. Tomisaka, et al. Star formation and the Hall effect; M. Wardle. Observations: Submillimeter observations of protostellar cores: probing the initial conditions for protostellar collapse; P. Andre, et al. The substellar population in the young Sigma Orionis cluster: spatial distribution; V.J.S. Bejar, et al. On the internal structure of starless cores. Physical and chemical properties of L1498 and L1517B; M. Tafalla, et al. 4: Accretion Disks.- Accretion disks. Overview; M. Tagger. Theory: Turbulence in accretion disks; J.F. Hawley. Coronae & outflows from helical dynamos, compatibility with the MRI and application to protostellar disks; E. Blackman, J.C. Tan. Observations:- Observation of disks; A. Dutrey. On the alignment of T Tauri stars with the local magnetic field in the Taurus molecular cloud complex; F. Menard, G. Duchene. Polarization in the young cluster NGC 6611: circumstellar, interstellar, or both? P. Bastien, et al. 5: Jets and Large Scale Outflows.- Jets and large scale outflows. Overview; R. Pudritz. Theory: Self-collimated stationary disc winds; J. Ferreira, F. Casse. Outflows from dynamo-active protostellar accretion discs; B. von Rekowski, et al. H2 diagnostic of magnetic molecular shocks in bipolar outflows; S. Cabrit, et al. Observations: The magnetic environment of young stellar objects; A. Chrysostomou, et al.- A collimated stellar wind emanating from a massive protostar; G. Garay, et al.- 6: Interaction Disk-stellar Magnetosphere.- Interaction disk-stellar magnetosphere. Overview; A.I. Gomez de Castro.- Theory: Magnetic interaction between stars and accretion disks; D. Uzdensky.- The emergence of magnetic field into stellar atmospheres; F. Moreno-Insertis. Magnetic star-disk interaction in classical T Tauri stars; M. Kueker, et al. The temperature and ionization of T Tauri microjets; D. O'Brien, et al. Observations: Observations of magnetic fields on T Tauri stars; J. Valenti, C. Johns-Krull. X-ray activity and accretion in young stellar objects; T. Preibisch. The origin of jets from young stars: MHD disk wind models confronted to observations; C. Dougados, et al. Testing the models for jet generation with HST observations; F. Bacciotti, et al. Time dependent magnetospheric accretion in T Tauri stars; J. Bouvier, et al. Classical T Tauri stars and substellar analogs. Classification based on empirical criteria; D. Barrado y Navascues, et al. Clues to substellar formation: rotation and the low-mass end of the initial mass function; M.R. Zapatero Osorio, et al. On the nature of transport in fusion plasmas; C. Hidalgo.