Observational Tests of MSF Models during Protostellar Phase

1. Observational Tests of MSF Models during Protostellar Phase Jeremy Lim (ASIAA) • Most multiple systems in place by pre-main-sequence- likely form during protostellar phase - properties of multiple protostellar systems contain clues to formative process (Bate 00)

2. Aligned disks and surrounding core (pseudodisk) Observational Tests of MSF Models during Protostellar Phase Jeremy Lim (ASIAA) • Most multiple systems in place by pre-main-sequence- likely form during protostellar phase - properties of multiple protostellar systems contain clues to formative process (Bate 00)

3. Orbital motions of protostars same as rotation motion of surrounding core (pseudodisk) Observational Tests of MSF Models during Protostellar Phase Jeremy Lim (ASIAA) • Most multiple systems in place by pre-main-sequence- likely form during protostellar phase - properties of multiple protostellar systems contain clues to formative process (Bate 00)

4. Truncated disks Circumbinary gap Observational Tests of MSF Models during Protostellar Phase Jeremy Lim (ASIAA) • Most multiple systems in place by pre-main-sequence- likely form during protostellar phase - properties of multiple protostellar systems contain clues to formative process (Bate 00)

5. Observational Tests of MSF Models during Protostellar Phase Jeremy Lim (ASIAA) • Required measurements - basic parameters of protostellar components (number, separation, mass) - properties of circumstellar disks (size, mass, orientation, rotation) - properties of outflows (orientation, collimation, mass-loss rate) - orbital parameters (period, orbital plane, orbital direction) - properties of surrounding core (size, mass, orientation, rotation) • Challenges - protostars deeply embedded, requiring observations at  ≥ mid-IR - average separation of PMS/MS binaries is ~40 AU (~0”.3 at 140 AU) - measuring above properties require angular resolution <0”.1 (Bate 00)

6. Observational Tests of MSF Models during Protostellar Phase Jeremy Lim (ASIAA) • Required measurements - basic parameters of protostellar components (number, mass, separation) - properties of circumstellar disks (size, mass, orientation, rotation) - properties of outflows (orientation, collimation, mass-loss rate) - orbital parameters (period, orbital plane, orbital direction) - properties of surrounding core (size, mass, orientation, rotation) • Tools - VLA with angular resolution of ~0”.03 (5 AU at 140 pc) at  = 7 mm, tracing ionized gas (outflows) and dust (circumstellar disks) (Lim & Takakuwa 06)

7. Observational Tests of MSF Models during Protostellar Phase Jeremy Lim (ASIAA) • Required measurements - basic parameters of protostellar components (number, mass, separation) - parameters of circumstellar disks (size, mass, orientation, rotation) - parameters of outflows (orientation, collimation, mass-loss rate) - orbital parameters (period, orbital plane, orbital direction) - propertiesof surrounding core (size, mass, orientation, rotation) • Tools - millimeter interferometers with angular resolutions ≥0”.2, tracing dust and molecular gas in surrounding core (Momose et al. 98)

8. Observational Tests of MSF Models during Protostellar Phase Jeremy Lim (ASIAA) • Measured properties of triple protostellar system L1551 IRS5- basic parameters of protostellar components (number, mass, separation) - parameters of circumstellar disks (size, mass, orientation, rotation) - parameters of outflows (orientation, collimation, mass-loss rate) - orbital parameters (period, orbital plane, orbital direction) - parameters of surrounding core (size, mass, orientation, rotation) (Lim & Takakuwa 06) (Momose et al. 98)

9. 20 AU 20 AU L1551 IRS5 • Two previously known components, new third component (Lim & Takakuwa 06) VLA 7-mm at ~5 AU Flux Density (mJy) N 3rd S (Lim & Takakuwa 06)

10. VLA 3.6-cm at ~17 AU 70 AU 20 AU 20 AU (Rodríguez et al. 03) L1551 IRS5 • Base of previously known twin (aligned within 12°4°) bipolar ionized jets VLA 7-mm at ~5 AU Flux Density (mJy) N 3rd S (Lim & Takakuwa 06) (Lim & Takakuwa 06)

11. 20 AU 20 AU L1551 IRS5 • Base of previously known twin (aligned within 12°4°) bipolar ionized jets VLA 7-mm at ~5 AU Flux Density (mJy) Jet properties Both jets orthogonal to circumstellar disks (N comp within 8°4°, S comp 13°5°) Both jets collimated ≤3 AU from protostars N jet has 1.3 times intensity (mass-loss rate) of S jet Any jet from 3rd component has <1/4 times intensity (mass-loss rate) of N/S jets N 3rd S (Lim & Takakuwa 06) (Lim & Takakuwa 06)

12. 20 AU L1551 IRS5 • Three circumstellar dust disks (jets subtracted) VLA 7-mm at ~7 AU Flux Density (mJy) Circumstellar Disks properties N and S disks similar sizes of 16.00.7 AU and 17.81.3 AU respectively N and S disks similar inclinations of 59°2° and 58°4° respectively N and S disks comparable PA for major axes of 165°3° and 158°5° respectively N and S disks planes closely aligned 3rd disk size of 81 AU, and PA for major axis of 118°8° 3rd disk smaller/tilted wrt N and S disks N N N 3rd 3rd 3rd S S S (Lim & Takakuwa 06)

13. L1551 IRS5 Angular separation and Postion Angle of S wrt N component • Orbital motion VLA 2-cm at ~17 AU 1983.89 1983.89 1998.41 2002.09 1997.02 1998.41 (Rodriguez et al. 03) VLA 7-mm at ~8 AU VLA 7-mm at ~5 AU 7 mm 1997.02 2002.09 N N 7 mm 2 cm (Rodriguez et al. 03) 2 cm S S (Rodriguez et al. 97) (Lim & Takakuwa 06) (Lim & Takakuwa 06)

14. L1551 IRS5 • Orbital motion VLA 7-mm at ~5 AU Orbital poperties Orbital direction clockwise Can be fit by coplanar (i.e., inclination ~59°) circular orbit –> Dorb=50.21.7 AU, Porb=37779 yr, Mtotal=0.890.26 M Predicted max (largest non-intersecting orbit) disks size of 25.8 0.8 AU (Pichardo et al. 05) (measure 16-18 AU for N/S disks) Coplanar elliptical orbits must have e ≤ 0.3, otherwise predicted max disk size smaller than observed (if near apastron) or predicted circumbinary gap larger than observational constraints (if near periastron) (Lim & Takakuwa 06)

15. NMA C18O(1-0) at 350 AU intensity=gray, velocity=color 1000 AU (Momose et al. 98) L1551 IRS5 • Surrounding molecular core VLA 7-mm at ~5 AU (Lim & Takakuwa 06) N/S disks with inclinations ~59°, major axis at PA≈162°, and clockwise orbital motion Pseudodisk with inclination ~64°, major axis at PA≈ 165°, and clockwise rotation

16. NMA C18O(1-0) at 350 AU intensity=gray, velocity=color 1000 AU (Momose et al. 98) L1551 IRS5 • N/S protostellar components formed via fragmentation of inner region of surrounding core (parent pseudodisk) VLA 7-mm at ~5 AU (Lim & Takakuwa 06) N/S disks with inclinations ~59°, major axis at PA≈162°, and clockwise orbital motion Pseudodisk with inclination ~64°, major axis at PA≈ 165°, and clockwise rotation

17. NMA C18O(1-0) at 350 AU intensity=gray, velocity=color 1000 AU (Momose et al. 98) L1551 IRS5 • 3rd disk is inclined by (at least) ~45° wrt N/S disks - fragmentation, tidal tilting by more massive protostellar component(s) - capture VLA 7-mm at ~5 AU (Lim & Takakuwa 06) N/S disks with inclinations ~59°, major axis at PA≈162°, and clockwise orbital motion Pseudodisk with inclination ~64°, major axis at PA≈ 165°, and clockwise rotation

18. Conclusions • Measured properties of protostellar system L1551 IRS5 - three protostellar components - N/S disks aligned with each other and surrounding pseudodisk - orbital motion of N/S components same direction as pseudodisk rotation - indicate formation via fragmentation in inner region of pseudodisk - 3rd disk not aligned, tilted by protostellar neighbours or captured? (Lim & Takakuwa 06) (Momose et al. 98)