2. The Structures and Kinematics of Protoclusters James Di Francesco (NRC-HIA) IAU Symposium 221 Sydney, Australia July 23, 2003

3. Defining Protoclusters  Most stars form within clustered environments (e.g., Lada & Lada 2003)  Embedded cluster ages are <10 6 to ~10 6.5 yr, age spreads can be of same order  Protoclusters = embedded clusters of age <10 6 yrs and significant population of extremely embedded objects (PPCs and Class 0 YSOs)

4. Porras, Christopher, Allen, Di Francesco, Megeath, & Myers 2003 Spatial Distribution of Young Stellar Clusters within 1 kpc Serpens NGC 1333 Ophiuchus

5. Structure of Protoclusters  Hierarchical (e.g., NGC 2264) or centrally-condensed? (e.g., IC 348, Trapezium-ONC)  For protoclusters, near-infrared and submillimeter continuum surveys must be considered together to reveal structure

6. Serpens Oph A Associated stellar objects“Associated” stellar objects Eiroa & Casali (1992): K lim = 15.5 Giovannetti et al. (1998): K lim = 16.3 Kaas (1999): K lim = 17.5 Barsony et al. (1997): K lim = 14.0 Allen et al. (2002): H lim = 21.0

7. NGC 1333 Associated stellar objects Aspin, Sandell, & Russell (1994): K lim = 16.2 (also Aspin & Sandell (1997). Lada, Alves, & Lada (1996))

8. NGC 1333 CO 3-2 wing emission Sandell & Knee (2001) Knee & Sandell (2000)

9. Kinematics of Protoclusters  Few, if any, near-IR studies of kinematics of YSOs in nearby protoclusters (note: see poster 1044 by Gustafsson et al.)  Kinematics obtained instead from associated gas, i.e. from molecular lines observed with heterodyne instruments  Choice of molecular tracer crucial; depletion and excitation affect molecular species very differently  N 2 H + very promising; relatively little depletion, 1-0 transition excited at high density, low optical depth

10. Serpens NW Oph A BIMA/FCRAO N 2 H + 1-0 JCMT 850  m Williams & Myers (2000) Testi & Sargent (1998) (also Testi et al. (2000), Olmi & Testi (2002)) Di Francesco, Andre, & Myers (2003) Motte, Andre, & Neri (1998) BIMA/IRAM 30m N 2 H + 1-0 JCMT 850  m

11. N 2 H + 1-0 Central Line Velocities in Oph A Di Francesco, Andre, & Myers (2003) rms = 0.2 km s -1 subsonic

12. NGC 1333 Walsh, Di Francesco, Myers, Bourke, & Wilner (2003) <- poster 1159 Sandell & Knee (2001) BIMA/FCRAO N2H+ 1-0 JCMT 850  m

13. The Near Future: Large, Unbiased Surveys  Recent maps restricted in extent, sensitivity  SIRTF-c2d: Legacy project to map entirety of 5 nearby star-forming molecular clouds, obtain census of YSO populations down to 0.001 L SUN  COMPLETE: project to complement SIRTF-c2d with extensive submillimeter continuum, millimeter line, and infrared extinction maps of Serpens, Ophiuchus, and Perseus (NGC 1333)

14. COMPLETE

16. Conclusions  Recent IR and submm surveys show hierarchical structure of objects within nearby protoclusters  Influence of recent SF on current SF suggested  Kinematic studies of YSO populations are needed  Kinematic studies of dense gas show narrow ranges of velocities where stars are currently forming  New surveys will reveal entire PPC/YSO populations within nearby clouds containing protoclusters