Herbig-Haro flows and the birth of low mass stars : proceedings of the 182nd Symposium of the International Astronomical Union, held in Chamonix, France, 20-26 January 1997

Herbig-Haro objects were discovered 50 years ago, and during this half century they have developed from being mysterious small nebulae to be­ coming an important phenomenon in star formation. Indeed, HH flows are now recognized not only as fascinating astrophysical laboratories involving shock physics and chemistry, hydrodynamics and radiation processes, but it has gradually been realized that HH flows hold essential clues to the birth and early evolution of low mass stars. IAU Symposium No. 182 on Herbig-Haro Flows and the Birth of Low Mass Stars were held from January 20 to 24, 1997 in Chamonix in the french alps. A total of 178 researchers from 26 countries met to discuss our present level of understanding of Herbig-Haro flows and their relation to disk accretion events and T Tauri winds and other outflow phenomena like molecular outflows, embedded molecular hydrogen flows and radio jets. The present book contains the manuscripts from the oral contributions of the symposium. The poster papers were printed in a separate volume Low Mass Star Formation - from Infall to Outflow, edited by Fabien Malbet and Alain Castets, which was distributed at the beginning of the meeting. Together these two books document the vigorous state and the scientific appeal which research into Herbig-Haro flows and related issues in star formation enjoys today, observationally as well as theoretically. Front Matter....Pages i-xx Front Matter....Pages 1-1 50 Years of Herbig-Haro Research....Pages 3-18 HST Observations of the L1551 IRS5 Jet....Pages 19-28 Giant Herbig-Haro Flows....Pages 29-38 Herbig-Haro Objects in the Orion Nebula Region....Pages 39-46 Spectroscopic Properties of Herbig-Haro Flows....Pages 47-62 Spectroscopic Signatures of Microjets....Pages 63-72 The Ionization State along the Beam of Herbig-Haro Jets....Pages 73-82 Thermal Radio Jets....Pages 83-92 Molecular Hydrogen Emission in Embedded Flows....Pages 93-102 Turbulent Mixing Layers in Herbig-Haro and Embedded H 2 Jets....Pages 103-110 Far-IR Spectrophotometry of HH Flows with the ISO Long-Wavelength Spectrometer....Pages 111-120 Front Matter....Pages 121-121 Observational Properties of Molecular Outflows....Pages 123-140 The Molecular Outflow and CO Bullets in HH111....Pages 141-152 Shock Chemistry in Bipolar Molecular Outflows....Pages 153-162 Models of Bipolar Molecular Outflows....Pages 163-180 The Physics of Molecular Shocks in YSO Outflows....Pages 181-198 The Physical and Chemical Effects of C-Shocks in Molecular Outflows....Pages 199-212 Herbig-Haro Objects as Searchlights for Dense Cloud Chemistry....Pages 213-222 Front Matter....Pages 223-223 Protostellar X-rays, Jets, and Bipolar Outflows....Pages 225-239 Energetics, Collimation and Propagation of Galactic Protostellar Outflows....Pages 241-258 Front Matter....Pages 223-223 Numerical Simulations of Jets from Accretion Disks....Pages 259-274 Asymptotic Structure of Rotating MHD Winds and Its Relation to Wind Boundary Conditions....Pages 275-290 Hydrodynamic Collimation of YSO Jets....Pages 291-302 The Class 0 Outflow Hammered Out?....Pages 303-312 Numerical Simulations of Optical Knots in YSO Outflows....Pages 313-322 Asymmetric Modes of the Kelvin-Helmholtz Instability in Protostellar Jets....Pages 323-333 Kelvin-Helmholtz Instabilities and the Emission Knots in Herbig-Haro Jets....Pages 335-342 On the Energetics and Momentum Distribution of Bow Shocks and Colliding Winds....Pages 343-352 Front Matter....Pages 353-353 Hubble Space Telescope Imaging of the Disks and Jets of Taurus Young Stellar Objects....Pages 355-364 Disks and Outflows as Seen from the IRAM Interferometer....Pages 365-380 NMA Imaging of Envelopes and Disks Around Low Mass Protostars and T Tauri Stars....Pages 381-390 The Observational Evidence for Accretion....Pages 391-405 The Radiative Impact of FU Orionis Outbursts on Protostellar Envelopes....Pages 407-416 Properties of the Winds of T Tauri Stars....Pages 417-432 Magnetospherically Mediated Accretion in Classical T Tauri Stars....Pages 433-442 Jets, Disk Winds, and Warm Disk Coronae in Classical T Tauri Stars....Pages 443-454 Thermal Structure of Magnetic Funnel Flows....Pages 455-463 Magnetic Fields of T Tauri Stars....Pages 465-474 Evidence for Magnetic Fields in the Outflow from T Tau S....Pages 475-480 Front Matter....Pages 481-481 The Evolution of Flows and Protostars....Pages 483-494 Front Matter....Pages 481-481 Circumstellar Molecular Envelopes....Pages 495-506 Millimeter Interferometry of Class 0 Sources: Rotation and Infall towards L1448N....Pages 507-514 Water Masers toward Low-Luminosity Young Stellar Objects....Pages 515-524 Massive Star Formation: Observational Constraints....Pages 525-536 Low-Mass Versus High-Mass Star Formation....Pages 537-549 Orion Proplyds and the Eagle’s Eggs....Pages 551-560 Two-Wind Interaction Models of the Proplyds in the Orion Nebula....Pages 561-570 Conference Summary....Pages 571-586 Back Matter....Pages 587-597

In addition to being fascinating astrophysical laboratories in their own right, Herbig-Haro flows have in recent years emerged as key phenomena in our attempts to understand the complex and violent processes that govern the birth of low mass stars.
This book provides an up-to-date overview of the major advances which the study of Herbig-Haro jets has enjoyed in the last few years. On the observational side, Hubble Space Telescope images have revealed the intricate details of the shock structures in these supersonic flows, millimeter interferometry and infrared imaging can now probe the detailed structure of the molecular component of deeply embedded jets, and sub-millimeter and radio continuum maps now enable us to study the near environment of the optically invisible driving sources of jets. On the theoretical side, detailed numerical and analytical magnetohydrodynamic models have now reached a level of sophistication that allows realistic comparison with observations and insights into the jet formation mechanisms.
Similarly detailed observational and theoretical studies of the disks and winds of T Tauri stars are now gradually being linked to the Herbig-Haro flows, providing a first glimpse of how stars can be born by both accreting and ejecting infalling material.

Proceedings of the 182nd Symposium of the International Astronomical Union, held in Chamonix, France, 20-26 January 1997