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Star & Planet Formation Alyssa A. Goodman Harvard-Smithsonian Center for Astrophysics
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Stellar Mass Number of Stars of each Mass Which Stars form Where, When, and How? Galaxy Star Cluster Molecular Cloud Complex Star-Forming “Globule” Circumstellar Disk Extrasolar System ? ? Dimitar
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Mass Matters
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Orion Constellation Movie
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Stellar Mass Number of Stars of each Mass Which Stars form Where, When, and How? Galaxy Star Cluster Molecular Cloud Complex Star-Forming “Globule” Circumstellar Disk Extrasolar System ? Implications -evolution of galaxy’s gas & stars with time -variety/longevity of extrasolar systems
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Star-Forming Region in Perseus Image by E.E. Barnard, c. 1907 60 light years
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FLAMINGOS J,H,K Composite; Muench et al. 2003 IC348 Brightness & color measurements give information on the mass distribution (“IMF”) of stars, and the DISKS around those stars.
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Stellar Mass Number of Stars of each Mass How many stars of each mass form? Luhman et al. 2003 log (Stellar Mass) log (# stars) “IMF” Initial Mass Function of Stars
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How does the IMF vary with environmental conditions? IC 348: Luhman et al. 2003; Taurus: Briceño et al. 2002 FLAMINGOS J,H,K Composite; Muench et al. 2003
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Key Questions How does the IMF vary with environment? How fast do clouds & stars form? What creates variety in “protoplanetary” disks?
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Science & Technology How Fast Do Clouds & Stars Form? Statistical analysis of large surveys at radio through X-ray wavelengths Comparison with simulations Databases of unprecedented size, and tools for retrieval, analysis & visualization. (SIRTF, COMPLETE, NVO) Simulations with high(er) dynamic range. (More powerful computers) Higher-resolution studies of disks & their environment (now: VLA, mm-interferometers & SMA; coming soon: JWST, ALMA, coming eventually, we hope: SKA) How does the IMF Vary with Environment? Comparative studies of many galactic & extragalactic star forming regions What creates variety in “protoplanetary” disks? Higher-resolution views of disks Statistical study of environmental influence
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Simulated spectral-line map, based on work of Padoan, Nordlund, Juvela, et al. Excerpt from realization used in Padoan, Goodman &Juvela 2003 Simulations as Data Interpretation Data: Censes of Young Stars Radio spectral-line maps of gas motions Thermal-continuum maps of dust emission & photos of dust extinction Dynamic Range >10 4 Simulations: Including effects of gravity, magnetic fields, chemistry, heating & cooling, stars forming, & thermal pressure…but not all at once (yet) Dynamic Range <10 2
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Synthetic Star Forming Regions Stone, Gammie & Ostriker 1999 Driven Turbulence; M K; no gravity Colors: log density Computational volume: 256 3 Dark blue lines: B-field Red : isosurface of passive contaminant after saturation =0.01 =1 T /10 K n H 2 /100 cm -3 B /1.4 G 2 Weak Magnetic Field Strong Magnetic Field
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Simulations Let Us Live Longer Bate, Bonnell & Bromm 2002; c.f. Ostriker, Stone & Gammie 2001 MHD turbulence (another simulation) gives initial conditions 50 M sun, ~1 lyr, n avg =3 x 10 5 ptcls/cc forms ~50 objects T=10 K SPH, no magnetic fields or heating and cooling movie=1.4 free-fall times
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Circumstellar Disks
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Stellar Mass Number of Stars of each Mass Which Stars form Where, When, and How? Galaxy Star Cluster Molecular Cloud Complex Star-Forming “Globule” Circumstellar Disk Extrasolar System ? Implications -evolution of galaxy’s gas & stars with time -variety/longevity of extrasolar systems
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Key Questions How does the IMF vary with environment? How fast do clouds & stars form? What creates variety in “protoplanetary” disks?
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