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Silvia Torres-Peimbert Instituto de Astronomía Universidad Nacional Autónoma de México

Nebular kinematics of planetary nebulae as tests of possible differences of distribution of permitted and forbidden emission lines. Silvia Torres-Peimbert Instituto de Astronomía Universidad Nacional Autónoma de México. September 14, 2007. Outline.

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Silvia Torres-Peimbert Instituto de Astronomía Universidad Nacional Autónoma de México

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  1. Nebular kinematics of planetary nebulae as tests of possible differences of distribution of permitted and forbidden emission lines Silvia Torres-Peimbert Instituto de Astronomía Universidad Nacional Autónoma de México September 14, 2007

  2. Outline • Recombination vs. forbidden lines diagnostics • Definitions • T [O III], T (Balmer), T (O II), T (C II) • Temperature variations vs. compositon and temperature variations • Planetary nebulae • HII regions • Our work • Conclusions

  3. Why are abundances important? • Tests for atomic physics computations • The input chemical composition to produce models of nebulae • Constraints on the stellar evolution theory of IMS from those elements affected by stellar evolution • Initial abundances in the ISM for those elements not affected by stellar evolution • Constraints on models of galactic chemical evolution • Constraints on models of the chemical evolution of the universe through the determination of ΔY/ΔZ and the determination of the primordial helium abundance.

  4. To derive abundances from emission lines: We require temperature diagnostics: Forbidden line intensity ratios I(4363)/I(5007) I(5577)/I(6584) Abundance derivations: N(O++) /N(H+) = I(5007)/I(Hbeta) f(Te,Ne) f(Te,Ne) is very sensitive to temperature

  5. There is a problem: • This is a widespread phenomenon: HII regions and PNe • The recombination coeficients are correct • The ratios C/O/N/Ne are the same • There are inclusions of cold high metallicity gas • They are low temperature • The overall gaseous abundance is the expected • The temperature variations are larger than expected • Gas abundance values are those of the recombination lines (higher)

  6. Are there temperature variations? Models predict t2 ~ 0.003 to 0.03, with typical values around 0.01 Observations give values of t2 in the 0.00 to 0.09 range typical values ~ 0.03) ADF (abundance difference factor) = abundances derived from permitted lines / forbidden lines~ 2 to 3 (O, C, N, Ne), If t2 = 0.00 it is possible to reconcile the abundances

  7. Causes for temperature variations • Chemical inhomogeneities • Deposition of mechanical energy • Time dependent ionization • Density variations • Deposition of magnetic energy • Shadowed regions • All of the above

  8. Time dependent ionization • Photoionization fronts heat the gas above the steady state value • Delay before reaching equilibrium • Decreasing stellar ionizing flux, • the outer regions of the nebula become isolated from the stellar radiation field • Will cool first and then recombine • Producing cold partially ionized outer regions (this might be the case in NGC 7009).

  9. Deposition of mechanical energy The following objects are strong X-ray emitters (Guerrero et al. 2005): BD+30 (WR) NGC 40 (WR) NGC 2392 NGC 3242 NGC 6543 (WR) NGC 7009 NGC 7027

  10. Density variations • Extreme density variations are present in most PNe (optical images) • For steady state photoionization models, density variations are generally not included • For time dependent processes, the regions of higher density will reach equilibrium sooner than those of lower density • Also, density variations might affect the temperature determination if using the wrong characteristic density • e.g. the IR determined densities usually are a lower limit to the average density of a typical PNe

  11. Temperature diagnostics: T[O III], etc. T (recombination lines) – O++ , C++, C+++, N++, etc T (He lines) T Balmer continuum Hyung & Aller 1995

  12. Temperature determinations Te Ne Ni dV T0 = Ne Ni dV (Te -T0)2Ne Ni dV t 2 = T02Ne Ni dV Te(4363/5007) =T0 [1 + (90800/T0 -3) t 2/2] Te(Bac/Hb) =T0 (1 – 1.70t 2) Te(He lines) =T0 (1 – kt 2) k~1.8 Te(4649/5007) =f1 (T0 , t 2) Te(4267/1909) = f2(T0 , t2) Peimbert 1967 …

  13. The formulation is a first approximation to describe possible temperature distributions a) Temperature inhomogeneities

  14. The formulation is a first approximation to describe possible temperature distributions a) Temperature inhomogeneities Other options b) Temperature & density inhomogeneities

  15. Planetary nebulae

  16. M2-36 M1-42 Temperatures M2-36 Bac = 5,900K [OIII] = 8,400K M1-42 Bac = 5,360K [OIII] = 9,200K Liu et al. 2001

  17. Orion Nebula I(4649) / I(Hb) = 1.2 x 10-4 Esteban et al. 1997

  18. T(Balmer continuum) vs. T[O III] Liu & Danziger 1993

  19. N(C++) from recombination lines vs. N(C++) from collisionally excited lines CII 4267 line C III] 1909 line Peimbert, et al. 1995

  20. N(O++) vs. Balmer temperature Recombination/collisionally excited ratios (log ADF) vs. [O III] – Balmer Temperatures Liu et al. 2001

  21. Chemical homogeneity diagnostics When all helium is He+ and all oxygen is O++, it can be shown that: • If t2(Balmer , [O III]) ≈ t2(He I , [O III]) ≈ t2(O II, [O III]) ≈ t2(C II, [C III]) chemically homogeneous • If t2(Balmer , [O III]) <t2(He I , [O III]) ≈ t2(O II, [O III]) ≈ t2(C II, [C III]) chemically inhomogeneous

  22. Evidence for chemically homogeneous PNe: • For well observed objects: t2 values derived from T(Balmer) and T([O III]) are similar to those derived from T(He I) and T([O III]), T(C II) and T([O III]), and T(O II) and T([O III]). • The carbon evolution of the Galaxy. • For NGC 5307 and NGC 5315 the radial velocities and the FWHM of the O II and [O III] lines are the same.

  23. Chemically inhomogeneous nebulae are based on: • The IR lines yield lower abundances than the RL. • High density H-poor knots in A30 and A78. -- They were expelled later and at higher velocities than the main body of the nebula. -- The photospheric abundances of these stars are H-poor. • About 10% of the CSPNe and of the white dwarfs in the Sloan sample are H-poor.

  24. NGC 5882 Integral field spectroscopy Tsamis et al. 2007

  25. NGC 6153 Temperature and abundance 4959 and 4649 Tsamis et al. 2007

  26. NGC 6153. ADF radial profile Tsamis et al. 2007

  27. NGC 5882 T[O III] = 9160 T(rec) = 2400 Tsamis et al. 2007

  28. 2-phase composition in PNe: • Cold inclusions • H-poor • of a few % mass • C/O, Ne/O • Ejecta from stars • Planetary bodies

  29. NGC 6543: Temperature determinations • T(Bac) = 7100 ± 1000, Kingsburgh et al. 1996 • T(Bac) = 6800 ± 400, Zhang et al. 2004 • T(He II) = 5730 ± 1000, Zhang et al. 2005, based on 3 He I lines T(He II) 6800 ± 400 Georgiev et al. 2007

  30. NGC 6543: Atmospheric Model Orange: pure He model Blue: their best model Green: observations Georgiev, et al. 2007

  31. NGC 6543: Stellar and nebular abundances • In units of 12 + Log N(X)/N(H). Georgiev, et al. 2007

  32. HII regions

  33. Orion NebulaSmall scale structures and t 2 [O III] 5007 image O´Dell et al. 2003

  34. Orion Nebula – [O III] temperature T[4363/5007] columnar values for each pixel O´Dell et al. 2003

  35. Orion Nebula: Noise vs. true temperature variations The face of the nebula is mottled with small scale variations in TC with angular dimensions of about 10” (~0.02 pc) and amplitudes of 400 K O´Dell et al. 2003

  36. Chemically inhomogeneous H II regions: Pros • NGC 5253 -- N excess Sanchez-Lopez et al.(2007). - from the O II and C II recombination lines - t 2 values of 0.052 and 0.072, - the excess N is due to pollution by massive WR stars • 30 Dor -- Tsamis and Pequignot (2005) - chemically inhomogeneous model of 30 Doradus - reproduces the observed line intensities of the forbidden and permitted O, C, and N lines

  37. Chemically inhomogeneous H II regions : Objections • The model of Tsamis & Pequinot - Excess abundance of O x 8 - Excess C x 14 - Models of chemical evolution of irregular galaxies (Carigi, et al. ) Carbon: 64% due to IMS, 36% to massive stars Nitrogen: ~80% is due to IMS Oxygen: 100% massive stars • The ratios C/N/O do not fit • The small dispersion in abundances of H II regions in irregular galaxies and in the abundance gradient in our galaxy are against this idea

  38. Chemically inhomogeneous H II regions(2 phase model): Implications • 30 Dor A. • Peimbert give: 12 + log O/H = 8.45, • Tsamis & Pequinot give 8.33 for t2 = 0.000 and 8.54 for t2 = 0.033 • Therefore the TP model is closer to the abundances given by the O II lines than to those given by the [O III] lines and the T[O III] temperature

  39. Overall situation 2/2 • PNe with strong X-ray emission show large t2 (BD + 30, NGC 40, NGC 2392, NGC 3242, NGC 6543, NGC 7009, NGC 7027) • Objects with large velocity dispersions also show large t2 (NGC 2392, NGC 2371-2, NGC 2818, NGC 6302, and Hu 1-2) • Galactic chemical evolution models indicate that most of the carbon of the galaxy has been produced by intermediate mass stars. Consistent with C/H derived from recombination lines • Future: Compare stellar abundances with nebular abundances Determine accurate density and temperature diagnostics

  40. Overall situation1 / 2 • Most PNe show temperature variations larger than predicted by photoionized chemically homogeneous models • High quality observations are needed to show if a given nebula is chemically homogeneous or not • The comparison of T(He I) with T(Balmer) is important. (For nebulae where practically all He is He+) • A small fraction of PNe show chemical inhomogeneities that can produce large temperature variations • Only about 10% of the central stars of PNe and of the white dwarf samples are H-poor

  41. Our work Anabel Arrieta** Leonid Georgiev* Michel Richer* * Instituto de Astronomía, Universidad Nacional Autónoma de México ** Universidad Iberoamericana, México

  42. a b Our data: Echelle spectra from 2.1-m at San Pedro Mártir

  43. NGC 7009-a (along major axis) Position-velocity diagrams ordered by excitation potential

  44. 4363 4649 4662 4649/4363 4662/ 4363 4662/4649 NGC 7009-a (along major axis) Oxygen lines Ratio of oxygen lines (min, max, rms) 4649/4363     0.56, 1.3 ,  0.14 4662/4363     0.58, 1.27,  0.12 4662/4649     0.78, 1.37, 0.08

  45. NGC 7009-b (along minor axis) Position-velocity diagrams ordered by excitation potential

  46. 4363 4649 4662 NGC 7009-b (along minor axis) Oxygen lines Ratio of oxygen lines (min, max, rms) 4649/4363     0.78  1.14   0.06 4662/4363     0.71  1.19   0.07 4662/4649     0.70  1.29   0.08

  47. a b

  48. NGC6543-a Position-velocity diagrams Ordered by excitation potential

  49. 4363 4649 4662 NGC 6543-a Oxygen lines Ratio of oxygen lines (min, max, rms) 4649/4363      0.62   1.17   0.08 4662/4363      0.55   1.35   0.11 4662/4649     0.55   1.61   0.13

  50. NGC 6543-b Position-velocity diagrams Ordered by excitation potential Same as previous, but for slit b

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