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AMBIPOLAR DIFFUSION AND TURBULENCE IN THE FORMATION AND EVOLUTION OF ROTATING PRESTELLAR CORES.WE PLAN TO INVESTIGATE USING THREE-DIMENSIONAL NUMERICAL SIMULATIONS THE ROLE OF AMBIPOLAR DIFFUSION (AD) DURING PRESTELLAR CORE FORMATION AND THE CORRELATION BETWEEN THE LOCAL MAGNETIC FIELD AND THE CORE ROTATION DIRECTION. IN GMCS FILAMENTS ARE CREATED BY SHOCKS IN THE TURBULENT FLOW UNDER THE INFLUENCE OF MAGNETIC FIELDS WHILE THE ACTUAL ABILITY OF MAGNETIC FIELDS TO AFFECT THIS PROCESS DEPENDS ON THE COUPLING BETWEEN THE PARTIALLY-IONIZED GAS AND THE MAGNETIC FIELD. IN PREVIOUS WORK WE DISCOVERED A TRANSIENT STAGE OF AD DURING COMPRESSION OF MAGNETIZED GAS BY SUPERSONIC TURBULENCE CREATING POST-SHOCK REGIONS WITH RELATIVELY HIGH MASS-TOFLUX RATIO. CORES THAT DEVELOP IN THESE REGIONS WILL BE MAGNETICALLY SUPERCRITICAL AND ABLE TO COLLAPSE GRAVITATIONALLY. WE THEREFORE PROPOSE TO CONDUCT A PARAMETER STUDY USING THREE-DIMENSIONAL SIMULATIONS TO IDENTIFY THE REQUIREMENTS (IN TERMS OF SHOCK STRENGTH IONIZATION LEVEL MAGNETIC FIELD ORIENTATION ETC.) FOR SUPERCRITICAL CORES TO FORM VIA AD. WE WILL ALSO FOLLOW THE EVOLUTION OF THESE PRESTELLAR CORES TO INVESTIGATE CORE ROTATION. OUR PRELIMINARY RESULTS SHOW THAT CORES ACQUIRE ANGULAR MOMENTUM FROM LOCAL TURBULENTFLOWS AND IT IS NOT NECESSARY FOR THE CORE#S ROTATION AXIS TO ALIGN WITH ITS MAGNETIC FIELD. THIS CHARACTERISTIC BEHAVIOR OF THE TURBULENCEACCELERATED MAGNETICALLY-REGULATED STAR FORMATION MODEL IS IN CONTRAST TO THE CLASSICAL QUASI-STATIC SCENARIO AND MIGHT BE IDENTIFIED INOBSERVATIONS. THERE STILL ARE MANY UNCERTAINTIES IN MAKING THESE IDEAS MORE QUANTITATIVE WHICH WE SEEK TO ADDRESS. OUR SIMULATIONS WILL ENCOMPASS SCALES FROM WITHIN GMCS (SEVERAL PC) TO COLLAPSING CORES (HUNDREDS OF AU) TO AVOID ARTIFICIAL INITIAL CONDITIONS ADOPTED IN OTHER STUDIES OF CORE EVOLUTION. WE BELIEVE THIS RIGOROUS STUDY OF AD WILL BRING NEW INSIGHT TO THE THEORY OF STAR FORMATION AND WILLPROVIDE QUANTITATIVE ANSWERS TO QUESTIONS CONCERNING THE EFFICIENCY OF STAR FORMATION AND THE DISK-FORMING ENVIRONMENT.

$58,107FY2014National Aeronautics and Space AdministrationNASA

University Of Maryland, College Park, College Park MD

Investigators

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AMBIPOLAR DIFFUSION AND TURBULENCE IN THE FORMATION AND EVOLUTION OF ROTATING PRESTELLAR CORES.WE PLAN TO INVESTIGATE USING THREE-DIMENSIONAL NUMERICAL SIMULATIONS THE ROLE OF AMBIPOLAR DIFFUSION (AD) DURING PRESTELLAR CORE FORMATION AND THE CORRELATION BETWEEN THE LOCAL MAGNETIC FIELD AND THE CORE ROTATION DIRECTION. IN GMCS FILAMENTS ARE CREATED BY SHOCKS IN THE TURBULENT FLOW UNDER THE INFLUENCE OF MAGNETIC FIELDS WHILE THE ACTUAL ABILITY OF MAGNETIC FIELDS TO AFFECT THIS PROCESS DEPENDS ON THE COUPLING BETWEEN THE PARTIALLY-IONIZED GAS AND THE MAGNETIC FIELD. IN PREVIOUS WORK WE DISCOVERED A TRANSIENT STAGE OF AD DURING COMPRESSION OF MAGNETIZED GAS BY SUPERSONIC TURBULENCE CREATING POST-SHOCK REGIONS WITH RELATIVELY HIGH MASS-TOFLUX RATIO. CORES THAT DEVELOP IN THESE REGIONS WILL BE MAGNETICALLY SUPERCRITICAL AND ABLE TO COLLAPSE GRAVITATIONALLY. WE THEREFORE PROPOSE TO CONDUCT A PARAMETER STUDY USING THREE-DIMENSIONAL SIMULATIONS TO IDENTIFY THE REQUIREMENTS (IN TERMS OF SHOCK STRENGTH IONIZATION LEVEL MAGNETIC FIELD ORIENTATION ETC.) FOR SUPERCRITICAL CORES TO FORM VIA AD. WE WILL ALSO FOLLOW THE EVOLUTION OF THESE PRESTELLAR CORES TO INVESTIGATE CORE ROTATION. OUR PRELIMINARY RESULTS SHOW THAT CORES ACQUIRE ANGULAR MOMENTUM FROM LOCAL TURBULENTFLOWS AND IT IS NOT NECESSARY FOR THE CORE#S ROTATION AXIS TO ALIGN WITH ITS MAGNETIC FIELD. THIS CHARACTERISTIC BEHAVIOR OF THE TURBULENCEACCELERATED MAGNETICALLY-REGULATED STAR FORMATION MODEL IS IN CONTRAST TO THE CLASSICAL QUASI-STATIC SCENARIO AND MIGHT BE IDENTIFIED INOBSERVATIONS. THERE STILL ARE MANY UNCERTAINTIES IN MAKING THESE IDEAS MORE QUANTITATIVE WHICH WE SEEK TO ADDRESS. OUR SIMULATIONS WILL ENCOMPASS SCALES FROM WITHIN GMCS (SEVERAL PC) TO COLLAPSING CORES (HUNDREDS OF AU) TO AVOID ARTIFICIAL INITIAL CONDITIONS ADOPTED IN OTHER STUDIES OF CORE EVOLUTION. WE BELIEVE THIS RIGOROUS STUDY OF AD WILL BRING NEW INSIGHT TO THE THEORY OF STAR FORMATION AND WILLPROVIDE QUANTITATIVE ANSWERS TO QUESTIONS CONCERNING THE EFFICIENCY OF STAR FORMATION AND THE DISK-FORMING ENVIRONMENT. · GrantIndex