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A Molecular Inventory of the L1489 IRS Protoplanetary Disk

Investigating angular momentum redistribution and mass evolution in a transitional protoplanetary disk observed through molecular line surveys. Findings suggest a short-lived phase between embedded and T Tauri stages.

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A Molecular Inventory of the L1489 IRS Protoplanetary Disk

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  1. A Molecular Inventory of the L1489 IRS Protoplanetary Disk Michiel R. Hogerheijde Christian Brinch Leiden Observatory Jes K. Joergensen CfA

  2. Origin of Protoplanetary Disks • It’s the angular momentum, stupid • Initial distribution of angular momentum • E.g., Goodman et al. 1998; Ohashi et al. 1997; Belloche et al. 2002 • Redistribution during collapse • Formation of a viscous disk • Mass, size, evolution with time, accretion shock • E.g., Stahler 1994; Velusamy et al. 2002 Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

  3. L1489 IRS: A Transitional Object? • Compact dust continuum • 2000 AU radius • Density: radial power law with slope 1.8–2.1 • Mass 0.01–0.02 M • Hogerheijde & Sandell 2000; Joergensen et al. 2002 • Neighboring prestellar core SCUBA 850 and 450 µm observations from Hogerheijde & Sandell (2000) Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

  4. L1489 IRS: A Transitional Object? • Single-dish HCO+ lines • infall • Interferometer HCO+ image • Rotation • Hogerheijde (2001) • CO 4.5 µm absorption lines • Inward motions continue to within 0.1 AU from star • Boogert et al. (2002) Hogerheijde (2001) Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

  5. L1489 IRS: A Transitional Object? HCO+ 3–2 @ 1.1mm BIMA 2000 • Single-dish HCO+ lines • infall • Interferometer HCO+ image • Rotation • Hogerheijde (2001) • CO 4.5 µm absorption lines • Inward motions continue to within 0.1 AU from star • Boogert et al. (2002) Hogerheijde (2001) Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

  6. L1489 IRS: A Transitional Object? • NICMOS scattered light suggests flared disk • Padgett et al. (1998) • Simple model • Flared disk • 10% infall, 90% rotation • Hogerheijde (2001) • Transitional, short-lived (2x104 yr) stage between embedded and T Tauri phase? NICMOS image from Padgett et al. (1998) Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

  7. Molecular Line Survey • Single-dish molecular line measurements • JCMT, IRAM 30m, and Onsala 20m: 14”–38” = 2000–5500 AU • C17O 1–0, 2–1, 3–2 • C18O 1–0, 2–1, 3–2 • CS 2–1, 5–4, 7–6 • C34S 2–1, 5–4 • HCO+ 1–0, 3–2, 4–3 • H13CO+ 1–0, 3–2 • CN 1–0, 3–2 • HCN 1–0, 4–3 • H13CN 1–0 • HNC 4–3 • Aims • More realistic model • Chemical inventory Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

  8. Modeling Approach • Physical model: density • Flattened Plummer sphere • Consistent with SCUBA data • p=1.8 (Joergensen et al. 2002) • (Joergensen et al. 2002) Brinch, Hogerheijde, & Joergensen (in prep) Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

  9. Modeling Approach • Physical model: density • Flattened Plummer sphere • Consistent with SCUBA data • p=1.8 (Joergensen et al. 2002) • f>0 Brinch, Hogerheijde, & Joergensen (in prep) Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

  10. Modeling Approach V • Velocity field • Rotation V √M* r-0.5 • Infall Vr √M* r-0.5 • Parameterize V-field by • |V|√M* r-0.5 • tg()=Vr/V  Vr V Brinch, Hogerheijde, & Joergensen (in prep) Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

  11. Modeling Approach • 2 minimization of synthetic single-dish spectra • Gridded physical model + (constant) abundances • Molecular excitation using Monte Carlo approach • Synthetic spectra, convolved to appropriate resolution • 4+n free parameters • Flattening parameter f • Inclination i • Stellar mass M* • Velocity field direction angle  • Molecular Abundances Xi Brinch, Hogerheijde, & Joergensen (in prep) Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

  12. Results Brinch, Hogerheijde, & Joergensen (in prep) Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

  13. Results Brinch, Hogerheijde, & Joergensen (in prep) Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

  14. Results Brinch, Hogerheijde, & Joergensen (in prep) Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

  15. Results • Preliminary values • Stellar mass 1.1 M • Flattening parameter f=3.0 • Equivalent with h/R=0.35 • Inclination 70˚ • Velocity field angle =18˚ • Inspiral time approximately 105 yr • Significant fraction of embedded life time Brinch, Hogerheijde, & Joergensen (in prep) Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

  16. Results • Abundances • C18O 4x10-7 (-> 12CO 2x10-4 no depletion) • CS 8x10-9 • SO 8x10-9 • H2CO 1x10-9 • HCO+ 4x10-8 • HCN 4x10-9 • HNC 2x10-9 • CN 2x10-9 • Dark cloud values; little depletion; HCO+ increased? Brinch, Hogerheijde, & Joergensen (in prep) Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

  17. HCO+ 1–0 Interferometry Observations Model Prediction Surrounding cloud material Brinch, Hogerheijde, & Joergensen (in prep) Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

  18. Enhanced-SMA Predictions SMA CSO JCMT Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

  19. Enhanced-SMA Predictions HCO+ 4–3 at 0.3” (40 AU) Brinch, Hogerheijde, & Joergensen (in prep) Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

  20. A break in the V-field at 300 AU HCO+ 4–3 at 0.3” (40 AU) Brinch, Hogerheijde, & Joergensen (in prep) Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

  21. Conclusion • L1489 IRS • Disklike rotating and infalling structure • Lifetime 105 yr, significant fraction of embedded phase • Chemical abundances • No evidence for depletion • HCO+ enhanced • Further high-resolution observations with, e.g., enhanced-SMA • Breaks in the velocity field on scales of T Tauri disks • Changes in the chemistry on scales of T Tauri disks Submillimeter Astronomy in the Era of the SMA • June 13–16 2005 • Cambridge MA

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