Tafalla / Caselli Cores to Clusters

Star Formation with Next Generation Telescopes
1. Auflage 2008
ISBN: 978-0-387-26357-1
Verlag: Springer-Verlag
Format: PDF
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, 222 Seiten

It was with pleasure that CAUP became for three days the core to the cloud of star formation experts all over the world. Close to the celebration of its 15th anniversary – therefore still in the early stages of institutional evolution – we are proud of our multiple activities in Astronomy: a productive research centre, classi?ed as “Institution of excellence” within the Portuguese research units, but also an “Institution of Public Utility” as recognised by the Government. Fifteen years ago we choose to play a role not only in research, as expected from any research centre but also in the training of the future astronomers and the promotion of science and scienti?c culture. This choice is clearly stated in our by-laws and also in the multiple activities we have carried out since. Along the years we have organized on a regular basis international Workshops similar to “Cores to Clusters”. Sometimes we have chosen to organize int- national conferences of a larger size. On other occasions the choice has been for smaller and more informal discussion meetings. Or even doctoral schools with very different objectives. In common all those meetings have always had, besides the formal registered participants, a group of informal participants, our undergraduate students of Astronomy, so eager to be in touch with the real world.

Autoren/Hrsg.

Tafalla, M.

Caselli, P.

Inhaltsverzeichnis

1;Contents;7
2;Foreword;12
3;I REVIEW ARTICLES;15
3.1;PHYSICAL PROPERTIES OF PRESTELLAR CORES;16
3.1.1;Introduction;16
3.1.2;Basic Ideas;17
3.1.3;Determining Physical Parameters of Star Forming Regions;20
3.1.4;Mass determinations;21
3.1.5;Temperatures;21
3.1.6;Densities;23
3.1.7;Magnetic Field and Ionization Degree;24
3.1.8;Future Prospects;25
3.1.9;Acknowledgments;25
3.1.10;References;25
3.2;IMPULSIVELY TRIGGERED STAR FORMATION;28
3.2.1;Introduction;28
3.2.2;Fragmentation of a shock-compressed layer;29
3.2.3;Larson’s scaling relations and the clump mass spectrum;30
3.2.4;The critical pressure for rapid star formation;32
3.2.5;The minimum mass for star formation;33
3.2.6;The fragmentation of shells swept up by expanding nebulae;36
3.2.7;Pre-existing cores subjected to a sudden increase in external pressure;37
3.2.8;Forming free-floating brown dwarves and planetary-mass objects by photo-erosion;38
3.2.9;Forming low-mass companions and free-.oating objects in interactions between protostellar discs;39
3.2.10;Conclusions;40
3.2.11;Acknowledgments;40
3.2.12;References;41
3.3;STARLESS CORES;44
3.3.1;Introduction;44
3.3.2;“Classical” studies of starless cores;45
3.3.3;Starless cores studies in the 1990s;46
3.3.4;The internal structure of the l1498 and L1517B cores;48
3.3.5;Density;50
3.3.6;Turbulence;52
3.3.7;Molecular composition;53
3.3.8;Tracing core evolution with molecular freeze out;55
3.3.9;L1521E: the youngest starless core?;57
3.3.10;Acknowledgments;58
3.3.11;References;58
3.4;CHEMICAL PROCESSES IN STAR FORMING REGIONS;60
3.4.1;Introduction;60
3.4.2;Basic concepts in astrochemistry;61
3.4.3;Gas–phase chemistry;62
3.4.4;Surface chemistry;64
3.4.5;References;74
3.5;PROTOSTELLAR JETS: A HIGH ANGULAR RESOLUTION PERSPECTIVE;80
3.5.1;Introduction;80
3.5.2;Properties of stellar jets;82
3.5.3;High angular resolution observations;84
3.5.4;Optical, NIR and Sub-mm Interferometry;87
3.5.5;Conclusions: universality of the accretion/ejection engine;88
3.5.6;Acknowledgments;89
3.5.7;References;89
3.6;NON-ISOTHERMAL GRAVOTURBULENT FRAGMENTATION;90
3.6.1;Introduction;91
3.6.2;Thermal properties of star-forming clouds;92
3.6.3;Numerical Approach;93
3.6.4;Dependency of the Characteristic Mass;94
3.6.5;Summary;96
3.6.6;Acknowledgments;98
3.6.7;References;98
3.7;THE BIRTH OF MASSIVE STARS AND STAR CLUSTERS;100
3.7.1;Introduction;100
3.7.2;Overview of physical properties;101
3.7.3;Setting up initial conditions for star cluster formation;102
3.7.4;How do stars form within clusters?;104
3.7.5;Formation of Cores;104
3.7.6;Accretion to Stars;105
3.7.7;Assumptions and Predictions of the McKee-Tan Model;106
3.7.8;Observational Evidence for Massive Star Formation from Cores and Accretion Disks;108
3.7.9;The timescale of star cluster formation;110
3.7.10;How does feedback affect the formation process?;111
3.7.11;Feedback in Individual Cores;111
3.7.12;Feedback during Star Cluster Formation;112
3.7.13;Feedback on GMCs;113
3.7.14;Acknowledgments;113
3.7.15;References;114
3.8;PRECURSORS OF UCHII REGIONS AND THE EVOLUTION OF MASSIVE OUTFLOWS;118
3.8.1;Precursors of UCHii regions;118
3.8.2;High-Mass Protostellar Objects (HMPOs);119
3.8.3;High-Mass Starless Cores (HMSCs);123
3.8.4;Massive molecular out.ows: an evolutionary scenario;124
3.8.5;Summary of observational constraints;124
3.8.6;A potential evolutionary scenario;127
3.8.7;Discussion and potential caveats;129
3.8.8;References;130
3.9;OBSERVATIONS OF ACCRETION ONTO HIGH MASS STARS;134
3.9.1;Introduction;134
3.9.2;Observations;137
3.9.3;The Accretion Flow;137
3.9.4;A simple model of the accretion .ow;140
3.9.5;Implications for star formation by accretion;142
3.9.6;References;142
3.10;DISKS AROUND MASSIVE (PROTO)STARS;144
3.10.1;The dividing line between high- and low-mass stars;144
3.10.2;Possible scenarios for high-mass star formation;145
3.10.3;Evidence for disks in massive (proto)stars;146
3.10.4;Disks traced by maser lines;146
3.10.5;Disks traced by continuum emission;147
3.10.6;Disks traced by thermal line emission;148
3.10.7;Conclusions;151
3.10.8;References;152
3.11;EMBEDDED CLUSTERS;154
3.11.1;Introduction;154
3.11.2;Importance of Embedded Clusters;155
3.11.3;Global Properties of Embedded Clusters;158
3.11.4;Embedded Cluster Mass Function;158
3.11.5;Embedded Cluster Birthrate and Survival;159
3.11.6;Role of Embedded Clusters in Understanding Star and Planet Formation;161
3.11.7;Protoplanetary, Circumstellar Disks;162
3.11.8;Acknowledgments;164
3.11.9;References;165
3.12;MASSIVE PROTOSTARS AND SMALL PROTOCLUSTERS;167
3.12.1;Massive Protostars;167
3.12.2;Clustering around candidate precursors to massive stars;168
3.12.3;NIR counterparts to candidate massive protostars;170
3.12.4;H2 emission around massive protostars;172
3.12.5;Scenario for massive star formation;173
3.12.6;Small proto-clusters;174
3.12.7;FutureWork;176
3.12.8;Acknowledgments;177
3.12.9;References;177
3.13;PRE-MAIN-SEQUENCE EVOLUTIONAND BROWNDWARFS BEYOND THE SOLAR VICINITY.;179
3.13.1;Introduction;179
3.13.2;Observations;181
3.13.3;Results;181
3.13.4;The luminosity and mass functions;184
3.13.5;Summary and .nal remarks;187
3.13.6;Acknowledgments;188
3.13.7;References;188
3.14;BROWN DWARFS;189
3.14.1;Introduction;189
3.14.2;Brown dwarfs and new Spectral types;191
3.14.3;Companions to stars;192
3.14.4;Searches in star clusters and young stellar associations: the brown dwarf mass function;192
3.14.5;Multiplicity;194
3.14.6;Formation mechanisms;195
3.14.7;Acknowledgments;196
3.14.8;References;196
4;II CONTRIBUTED POSTER ARTICLES;200
4.1;REVEALING THE STRUCTURE OF LUPINE DARKNESS: FROM CORES TO CLUSTERS;201
4.1.1;Abstract;201
4.1.2;Introduction;201
4.1.3;Observations and Data Reduction;202
4.1.4;Results;202
4.1.5;Analysis and Discussion;204
4.1.6;Acknowledgments;206
4.1.7;References;206
4.2;INFRARED STUDY OF THE SOUTHERN GALACTIC STAR FORMING REGION ASSOCIATED WITH IRAS 10049-5657;207
4.2.1;Introduction;207
4.2.2;Observations;207
4.2.3;Results and discussion;208
4.2.4;Radiative transfer modelling;210
4.2.5;Summary;211
4.2.6;References;212
4.3;STUDYING PROTOSTELLAR JETS THROUGH A COMBINED INFRARED/OPTICAL SPECTRAL ANALYSIS;213
4.3.1;Introduction;214
4.3.2;Variation of the physical parameters along the jet;214
4.3.3;Depletion of refractory species and presence of dust in the jet beam;215
4.3.4;Mass flux estimates and their implications;216
4.3.5;References;218
4.3.6;Introduction;219
4.3.7;Observations and data reduction;220
4.3.8;Results;220
4.3.9;Acknowledgments;221
4.3.10;References;222
4.3.11;Index;225