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Carlo Felice Manara 1,2 , Massimo Robberto , Nicola Da Rio 3

HST MEASURES OF MASS ACCRETION RATES IN THE ORION NEBULA CLUSTER. Carlo Felice Manara 1,2 , Massimo Robberto , Nicola Da Rio 3 Giuseppe Lodato 1 , HST Orion Treasury Program Team.

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Carlo Felice Manara 1,2 , Massimo Robberto , Nicola Da Rio 3

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  1. HST MEASURES OF MASS ACCRETION RATES IN THE ORION NEBULA CLUSTER Carlo Felice Manara1,2, Massimo Robberto, Nicola Da Rio3 Giuseppe Lodato1, HST OrionTreasuryProgramTeam 1Università degli Studi di Milano (Italy), 2current address: ESO-Garching (Germany), 3current address: ESA (Netherlands)

  2. Fromdusttostars and planets Cloud collapse 104 yr Planetary system Disk formation Low-mass binary 106yr 105 yr 107 yr 109 yr C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  3. Fingerprintsofacctretion T-Tauri star spectra Line emission (Hα) UV Excess Calvet & Gullbring 1998 Gullbring et al. 2000 Muzerolle et al. 2001 C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  4. Magnetosphericaccretion Accretion Shock: UV excess Free-fall region: Line emission Free-fall and accretion shock From Rm to the star matter is in supersonic free-fall. Rm Material crashes on the star generating a shock. Fromtracers and accretionspectrummodels FromTeff and Lstar(HRD) Camenzind 1990 Magnetic field ~103 G Fromevolutionarymodels Frommodels (~5 R*) C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  5. Navier-Stokesequations and solutions The azimuthalcomponentof the Navier-Stokesequationis a diffusive equationof the surface density Σ: With the assumptionthat the viscosityνscaleswith the radiuswith a powerlaw (self-similarsolutions): Itispossibletoobtainanalytically a solution (Lynden-Bell & Pringle,1974) and, for t>> τᵥ, the mass accretion rate Ṁaccdecreaseswithtimewiththispowerlaw: C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  6. Maccevolutionwithage and Mass Calvet et al. 2004, Muzerolle et al. 2003, 2005, Natta et al 2004, 2006, Hartmann et al. 2006, Rigliaco et al. 2011 Hartmann et al. 1998, Robberto et al. 2004, Calvet et al. 2005,2008, Fedele et al. 2010, Sicilia-Aguilar et al. 2010 C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  7. WFPC2 dataset 1643 sources For 1131 of the WFPC2 sourcesTefffrom Da Rio et al. (2011) available. For 897 sources U, B, I band photometryavailable. For 439 sources U, B, I band photometry and Teffavailable. 339 ofthem are used(correctedforredleak no proplyds, binaries, big errors…) C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  8. Method

  9. TwoColorsDiagram UBI Diagram (2CD) with: • Atmosphere Models(Allardet al.2010) • Extinctionlaw(Cardelliet al. 1989) • Accretionspectrum(Calvetet al.98) • 75% opticallythickemission (blackbody at 7000K) • 25% opticallythinemission (HII regionwith n=104 cm-3) + HII region (magnetosphericemission) Teff (K) C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  10. TwoColorsDiagram – AccretionSpectrum Observed 2CD C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  11. TwoColorsDiagram – AccretionSpectrum Observed 2CD C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  12. TwoColorsDiagram – AccretionSpectrum Dereddened 2CD C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  13. TwoColorsDiagram – AccretionSpectrum Calvet & Gullbring 98 C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  14. TwoColorsDiagram – AccretionSpectrum C&G+Magnetosphere C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  15. Derivationof LACC and AV The intersection of the reddening line (red) and the accretion curve (blue) determines simultaneously Lacc and AV. Estimate ofLacc and AVobtainedfor 247 sources. C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  16. LHaestimation C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  17. LACCfromLHa - calibration 204 sources Linear regression – no errors: Linear regression – errors on LACC: C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  18. LACCfromLHa- calibration Linear regression – no errors: Dahm 2008: Linear regression – errors on LACC: Herczeg & Hillenbrand 2008: De Marchi et al. 2010: C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  19. LACCfromLHa Linear regression – no errors: Dahm 2008: 497 sourceswithLaccestimatedfromLHa C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  20. HR Diagram Withevolutionarymodels (e.g. D’Antona & Mazzitelli 1994) derivationofM* and age DerivationofṀaccfor 743 sources (246 with 2CD and 497 fromLHa) C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  21. Results

  22. Final sample C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  23. Lacc vs Lstar Tillinget al. 2008: b = 1.7 ifh = 1.5 and D’Antona & Mazzitelli 1994 models are used. All data: b = 1.76 ± 0.01 2CD data: b = 1.60 ± 0.02 Natta et al. 2006 Clarke & Pringle 2006 Tillinget al. 2008 Ha data: b = 1.77 ± 0.01 C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  24. Macc decreases with time Ṁacc~ t-(1.44±0.02) Hartmannet al., 1998: h=1.5. Se siinterpretal’evoluzione del disco con modelli self similar (h>1)  n~R, i.e. a= costante C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  25. Macc decreases with time h = 1.14±0.02 C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  26. Macc decreases with time h = 1.14±0.02 h = 1.33±0.03 C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  27. Macc decreases with time h = 1.14±0.02 h = 1.33±0.03 h = 1.13±0.12 C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  28. Macc decreases with time h = 1.14±0.02 h = 1.33±0.03 h = 1.13±0.12 h = 0.56±0.08 C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  29. Macc decreases with time h = 1.14±0.02 h = 1.33±0.03 h = 1.13±0.12 h = 0.56±0.08 h ≈ 0 C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  30. Macc increases with Mstar Ṁacc~ M*1.545±0.003 Muzerolleet al., 2003: Ṁacc~ M*2 Natta et al., 2006: Ṁacc~ M*1.8±0.2 Rigliacoet al., 2011: Ṁacc~ M*1.6±0.4 C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  31. Macc increases with Mstar Muzerolleet al., 2003: Ṁacc~ M*2 Natta et al., 2006: Ṁacc~ M*1.8±0.2 Rigliacoet al., 2011: Ṁacc~ M*1.6±0.4 C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  32. Macc spatial distribution C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  33. Conclusion • WederivedLacc in twodifferentways: 2CD and Ha • ObtainedMaccfor 743 sources • Maccvs age: thereis a dependence-> age spread, hintofslowerevolutionforhighermasses • Macc vs M*: big spread, partly due todifferentages C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  34. Future perspective • RefineLaccdetermination (accretionspectrum…) • Macc vs period • Macc vs Mdisk • Macc vs molteplicity (binaries) • Otherregions C.F. Manara, M. Robberto, N. Da Rio et al. – Mass AccretionRatesMeasures in the ONC

  35. Thanks

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