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Infall and Outflow

Dive into the early history of star formation through a selective review from pre-1990 to modern times, exploring dense cores in dark clouds, molecular cloud maps, infall phenomena, and outflow statistics. Learn about key discoveries, such as "Skewed CO Profiles" and "Bipolar Outflows," and their implications for star formation theories. Discover the inside-out collapse model and its extensions, setting the stage for advancements in the 1990s. Explore the kinematic evidence and implications of infall processes in star formation.

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Infall and Outflow

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  1. Infall and Outflow

  2. Infall and OutflowEarly History: pre-1990* David J. Wilner (CfA) *an incomplete, selective review Dense Cores in Dark Clouds LXV: A Symposium in Honor of the 65th Birthday of Phi Myers October 22, 2009

  3. Historical Perspective Star Formation Slipher’s “Space Lines” Barnard’s Dark Clouds Bok globules, T Tauri’s Radio Molecular Lines Molecular Cloud Maps Skewed CO Lines Infall and Outflow Myers Cores: next talks 1900 -1918 1940s 1960s 1970s 1980s modern era Red Sox Champions (5x) Babe Ruth sold… Pesky hesitates Impossible Dream Fall Classic Bucky Dent Bill Buckner Curse Reversed!

  4. Radio Molecular Lines • 1960s: discoveries of OH, H2O, NH3 , H2CO • early 1970s: CO and more, but not much star formation • high mass regions too confused, dark clouds too faint • highly supersonic linewidths Goldreich & Kwan 1974 Zuckerman & Evans 1974 Arons & Max 1975

  5. Maps of Linewidths

  6. also TMC2, Ho et al. 1977 1981: “Larson’s Laws” = turbulence

  7. Skewed CO Profiles: Infall? Snell & Loren 1977

  8. infall interpretation? red/blue stats x map behavior x complexity ✓ Loren et al. 1981 Leung & Brown 1977 Phillips et al. 1981

  9. Bipolar Outflows Snell, Loren & Plambeck 1980

  10. Dense Cores: NH3

  11. Dense Cores: Outflows 0/10 “starless” 7/16 w/IRAS

  12. Outflows and Star Formation • not predicted: form a star by losing mass? • angular momentum removal • magneto-centifugal winds • outflow statistics • effectively ubiquitous • timescale = embedded phase • outflow impact • Poutflow > (MDv)core • disperses dense core • plays role in defining star mass Myers et al. 1988

  13. Inside-Out Collapse Shu 1977 • semi-analytic model • self-gravitating isothermal sphere with most unstable equilibrium • unphysical but reasonable initial condition for dense core collapse • many important extensions

  14. Stage Set for 1990s Chandler et al. 1990 • deeply embedded protostellar candidates identified, e.g. B335, and starless cores • “predictive” theory • recognition of bipolar outflows (though evolution not clear) • improving chemical understanding of dense gas tracers • bigger, more sensitive, mm-wave telescopes, esp. IRAM 30 meter • Phil’s systematic approach

  15. END

  16. Implications for Infall Obs r(r) v(r) • kinematic evidence for inside-out collapse is difficult to detect! • emerges from random motions only within few x 0.01 pc for 1 M star • tiny mass with high v • infall simultaneous with much faster outflow • short-lived phenomenon Anglada et al. 1987 Shu 1977

  17. Schematic Star Formation ARAA 1987 25, pp 23-81

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