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The Birth of Stars and Planets in the Orion Nebula

The Birth of Stars and Planets in the Orion Nebula. K. Smith (STScI). Orion (the hunter). Why Orion?. Closest massive star forming region (450pc) (there are closer low mass star forming regions) Relatively young (1Myr) Now believed that our Sun started life in such an environment.

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The Birth of Stars and Planets in the Orion Nebula

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  1. The Birth of Stars and Planets in the Orion Nebula K. Smith (STScI)

  2. Orion (the hunter)

  3. Why Orion? • Closest massive star forming region (450pc) (there are closer low mass star forming regions) • Relatively young (1Myr) • Now believed that our Sun started life in such an environment

  4. Giant molecular clouds Found throughout galactic plane Are the sites of star formation Dame et al

  5. Star formation…

  6. Stars form in clusters and groups Pleiades NGC 1850, LMC NGC 346, SMC

  7. Orion + CO

  8. NGC 2022 NGC 1741 Witch Head Nebula Rosette Nebula Barnard loop Orion and surroundings in the visible

  9. …and in the far-infrared IRAS 100 micron image

  10. Stellar density in Taurus vs. Orion 14.6´ × 15.1´ @140pc = 0.59pc ×0.61pc 7´ × 7´ @450pc = 0.91pc ×0.91pc

  11. Massive stars Disperse the cloud Ionise the gas May disrupt low mass star disks Burn out quickly

  12. NGC2024 Horsehead NGC1977 NGC1976 M42 Hot stars, ionized gasand dusty nebulae trace star formation

  13. Massive stars Disperse the cloud Ionise the gas May disrupt low mass star disks Burn out quickly Low mass stars Have disks and accrete material for several million years Launch jets Form planetary systems

  14. Planetary system Cloud collapse Disk/wind Low-mass binary 107 yr 109 yr 104 yr 105 yr The current paradigm (Low Mass Objects)

  15. 1000 AU 13CO 2-1 4.4-5.8 km s-1 Sargent & Beckwith 1987, Ap. J., 323, 294. HST images of disks provided "proof" Disk / jet “standard” model SII 6717 Å 3.5m Calar Alto e.g. Lin et al, 1994, Ap. J., 435, 821. XZ Tau HL Tau HH 30 HH 30 5000 AU Ray et al. 1996, Ap. J., 468, L103. Mundt et al. 1990, A&A, 232, 37.

  16. Disks in the IR (NICMOS/HST)

  17. HK Tau B Adaptive optics on Keck C. Koresko, Ap.J.Lett. 1998

  18. Jets

  19. Jets from binaries

  20. Treasury program PI : M. Robberto 104 HST orbits, parallel ACS +WFPC2 +NIC3 • ACS: B (420s), V (385s), I (385s), z (385s), Ha (340s) • WFPC-2: U (2400s), B (80s), I (10s), Ha (400s) • NIC-3: J (5256s), H (4192s) 2 Orientations • 100° (35 orbits, Fall 2004) • 280° (69 orbits, Spring 2005) Precise tiling pattern allows for full coverage with ACS and WFPC2

  21. Mapping strategy

  22. Mapping strategy Fall campaign on 2-Mass

  23. Mapping strategy On ESO Optical Image On 2MASS JHK Color

  24. Motivation Apart from pretty picture, what do we learn? IMF - the distribution of masses Binary properties HR diagram - test models of stellar evolution Reaction of disks to different environments

  25. For every massive star (>10Msol)… there are many hundreds of lower mass stars Hillenbrand & Carpenter, 2000

  26. The HR diagram Hillenbrand 1997

  27. PSF subtraction reveals close binary companions Companion is 0.45" from the primary, flux ratio ~6 mag I band Original images, visits 49, 4a, 4c final drizzled

  28. Disks in the Orion environment

  29. 114-426: giant dark silhouette disk

  30. Superheated surface layer with small grains produces infrared. “Black” interior produces millimeter-wave emission. IR emission from Disks Chiang & Goldreich 1997, Ap. J., 490, 368.

  31. The cluster core

  32. The core region

  33. Proplyds 206-446 182-413 Section of the Orion Nebula 183-405 114-426 400 AU 2000 AU O’Dell & Wen 1992, Ap.J., 387, 229; McCaughrean & O’Dell 1996, AJ, 108, 1382.

  34. Disk evaporation

  35. Disk evaporation 6 – 13.6 eV UV photons

  36. Disk evaporation 6 – 13.6 eV UV photons

  37. Disk evaporation 6 – 13.6 eV UV photons

  38. Disk evaporation 6 – 13.6 eV UV photons

  39. Disk evaporation > 13.6 eV photons 6 – 13.6 eV UV photons

  40. Disk evaporation > 13.6 eV photons 6 – 13.6 eV UV photons

  41. Disk evaporation Stellar wind > 13.6 eV photons 6 – 13.6 eV UV photons

  42. Disk evaporation Stellar wind > 13.6 eV photons > 13.6 eV photons 6 – 13.6 eV UV photons 6 – 13.6 eV UV photons Disks are evaporated by FUV photons

  43. Animation showing HH502 motion between Aug 2002 and Nov 2004 (2.25 yr)

  44. To sum up… The treasury programme is the widest and deepest survey yet made of the Orion nebula cluster The main goals; Determine the IMF for low mass stars in Orion Obtain a precise HR diagram to test models Observe disks in a ‘hostile’ environment - believed to be similar to the birth environment of the Sun

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