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The disk of AB Aurigae

The disk of AB Aurigae. Dmitry Semenov (MPIA, Heidelberg, Germany). Yaroslav Pavluchenko (INASAN, Moscow, Russia). Katharina Schreyer (AIU, Jena, Germany). Thomas Henning (MPIA, Heidelberg, Germany).

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The disk of AB Aurigae

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  1. The disk of AB Aurigae Dmitry Semenov (MPIA, Heidelberg, Germany) Yaroslav Pavluchenko (INASAN, Moscow, Russia) Katharina Schreyer (AIU, Jena, Germany) Thomas Henning (MPIA, Heidelberg, Germany) Kees Dullemond (MPA, Garching, Germany) Aurore Bacmann (Observatoire de Bordeaux, France) Ringberg April 15

  2. The disk of AB Aurigae Chemical modeling Dmitry Semenov Observations Aurore Bacmann (Observatoire de Bordeaux, France) Katharina Schreyer (AIU Jena) (MPIA Heidelberg) Radiative transfer Lines: Yaroslav Pavluchenko (INASAN, Moscow, Russia) Continuum: Kees Dullemond (MPA, Garching, Germany) Ringberg April 15

  3. Outline • Motivation • General Properties • Observations & Results • a) IRAM 30m & b) PdBI • The Model of the AB Aurigae system • Chemical modeling • Line radiative transfer simulations • Modeling results • Conclusions 3/18

  4. Motivation • Why AB Aurigae ? • One of the best-studied Herbig Ae(/Be) stars: A0 Ve+sh • D = 144 +23 pc, M = 2.4 ± 0.2 M8, age = 2−5 Myr • (e.g. van den Ancker et al. 1997, Manning & Sargent 1997, Grady et al. 1999, • deWarf et al. 2003, Fukagawa et al. 2004) • circumstellar structure: • compact disk (Rdisk≈ 450 pc, Mdisk≈ 0.02 M8, • i,f poorly defined) • (Mannings & Sargent 1997, Henning et al. 1998) • + extended, low-density envelope • (R > 1000 pc, optically thin, AV = 0.5m • internal structure + extent not well determined)   -17 well suitable object to study the chemistry of the disk

  5. R-band image, University of Hawaii 2.2m telescope (Grady et al. 1999) AB Aur: General Properties The envelope IRAS 60μm  HST visual image (Grady et al. 1999) •  extended asymmetrical • nebulosity, • inhomogeneous • spherical • envelope, • Renvelope≈ • 1300 AU ( = 10″) • i< 45o •  IRAS 60μm map  Renvelope = 4’ ≈ 35 000 AU • SED Modeling (Miroshnichenko et al. 1999) Renvelope ≈ 5000 AU N E 10″

  6. AB Aurigae: General Properties - The disk 13CO (10) OVRO Main velocities Subaru H-band image (Fukagawa et al. 2004): mass supply from the envelope contributes to the spiral instability 4.5 5 5.5 6 6.5 vLSR (km s-1) 5″ 5 0 -5 arcsec (Mannings & Sargent, 1997, OVRO) Keplerianrotation, a/b  110 AU / 450 AU  i  76o 8″ 8″ HST image (Grady et al. 1999)

  7. DCO+ 21 HCN 10 HNC 10 AB Aur - Our observational results: IRAM 30m Observations: • 2000-2001 • beamsizes: 10″ − 30″ Results: • detected species: • HCO+, CS, • CO, C18O, • HCN, HNC, • ~3: SiO, • H2CO, CN, • DCO+ CS 54 CO 21 C18O 21 CS 21 0 5 10 0 5 10 0 5 10 0 5 10 HCO+ 10 HCO+ 32 Tmb[K] 0 10 20 -10 0 10 20 0 5 10 -5 0 5 10 15 SiO 21 H2CO 31,221,1 CN 10  non-detections N2H+, CH3CN, HDCO, C2H, SO, SO2 0 5 10 0 5 10 0 5 10 0 5 10 vLSR[km/s] 7/18

  8. 4.5 5.5 6.5 vLSR (km s-1) C2H 10 3/2-1/2 F=2-1 AB Aur - Our observational results: PdB Interferometer sum HCO+J=1-0 Beam 6.5″ x 5″ Observations: 2002, beams ~ 5″ x 7″ Main velocities Results: HCO+ map, ~3: 34SO, SO2, HCN, C2H, … HST image: Grady et al. 1999 34SO 3221 SO2 73,582,6 S[Jy] HCN 10 velocity [km/s]

  9. SED AB Aurigae The model of the AB Aur system (Dullemond & Dominik, 2004) • 2D continuum radiative transfer code  passive flared disk model • low-density cones have the open angle  • shadowed part of the envelope is denser and cooler R 9/18

  10. T = 100 K T = 35 K The model of the AB Aur system Disk:2D passive disk with vertical temperature gradient, (r) = o·(r / Ro)p, p= −1.5, Mdisk= 3 (± 0.5) 10-2M8, Rin= Ro = 0.7 AU, Rout = 400 AU, vertical hight = 0.3 … 350 AU i= 17˚±3˚, = 80˚ +10˚, Tdisk = 35 ... 1500 K ndisk = 10-24 ... 10-9 g cm-3, Keplerian rotation, Vturb = 0.2 km/s Envelope: Rin = 0 / 400 AU, Rout = 2100 AU,  (r) = o·(r / Rin )p,p =−1.0, low-density cones:  = 25˚,olobe= 9.4 10-20 g cm-3, Tenv = 100 K shadowed torus:olobe= 5.5 10-19 g cm-3,Tenv= 35 K Menv 4 · 10-3 M8, ad = 0.1 μm, AV≈0.5m, Vturb = 0.2 km/s, stationary accretion, V(r)  1 / r (0.2 km/s at r = Rin), dynamical timescale is ~ 107 yrs ad = 0.3 μm −30˚ 400 AU 10/18

  11. AB Aur – Chemical Modeling (Semenov et al., 2004)  a gas-phase chemistry (UMIST95) with a surface reaction set (Hasegawa et al. 1992)  a deuterated chemical network from Bergin et al.1999  self- & mutual-shielding of H2 (Draine & Bertoldi 1996) and CO (Lee et al. 1996)  the 1D slab model to compute UV- and CR-dissociation and ionization rates depending on vertical height  ionization by the decay of radionuclides (disk)  thermal, photo-, and CR-desorption of surface species back in the gas-phase  initial abundances: chemical evolution of a molecular cloud (low-metal set, T = 10 K, n = 2·104 cm-3, time span = 1Myr, Wiebe et al. 2003) 11/18

  12. AB Aur – Chemical Modeling   • Modeling of the chemistry  with reduced chemical network • (in total 560 species made of 13 elements, involved in 5335 reactions) • On the basis of the fractional ionisation, disk  divided into • three layers: • dark dense mid-plane • (chemical network of ~ ten species & reactions) • (ii) intermediate layer • (chemistry of the fractional ionization driven • by the stellar X-rays) • (iii) unshielded low-density surface layer • (photoionisation-recombination processes) Results : 2D-distribution of column densities and molecular abundances for 3 Myr evolutionary time span 12/18

  13. AB Aur - Line radiative transfer (Pavluchenkov & Shustov, 2004) • 2D URAN NLTE code: further development of the public 1D code by Hogerheijde & van der Tak (2000) • solution of the system of radiative transfer equations using the Accelerated –Iteration (ALI) method • the mean intensities are calculated with the Accelerated Monte Carlo algorithm • the same model as obtained by the continuum radiative transfer synthetic line profiles, beam-convolved Results: 13/18

  14. Modeling Results: НСО+(1-0) disk map AB Aurigae 4 3 2 1 0 -1 -2 -3 -4 • Inverse P Cygni profile • a possible evidence for the accretion at distances ~ 600 AU Disk model: R = 400 AU -4 -3 -2 -1 0 1 2 3 4 arcsec 14/18

  15. Modeling Results: НСО+(1-0) disk map AB Aurigae Subaru H-band image disk model Fukagawa et al. 2004 4 3 2 1 0 -1 -2 -3 -4  sub-component structures possibly stem from the spirals -4 -3 -2 -1 0 1 2 3 4 arcsec 15/18

  16. Modeling Results: Estimate of i and  i = 10oi = 15oi= 20o AB Aurigae  inclination angle of the disk  i = 17˚± 3˚ position angle   = 80˚+10˚  = 40o = 80o = 120o −30˚ • 2 1 2 1 2 • arcsec 16/18

  17. AB Aur -Modeling Results: Line profiles of different species Fit for three cases: Left: Middle: Right: Tmb[K] only the disk only the envelope disk + envelope     (J=2−1) 17/18

  18. AB Aurigae - Conclusions • Based on observational data  a suitable model of the AB Aurigae system is acquired  mass, size, geometry and dynamical structure  temperature and density distribution • There is an evidence for the accretion at distances of about 600 AU from the star • It is shown that the IRAM single-dish spectra can be adequately described by the «disk-in-envelope» model • The coupled dynamical, chemical, and radiative transfer simulation is an effective tool to find a consistent model 18/18

  19. AB Aur - Our observations IRAM 30m: 2000-2001, beam sizes 10″ - 30″ detected different transitions of HCO+, CS, CO, C18O, HCN, HNC, ~3: SiO, H2CO, CN, DCO+ non-detections: N2H+, CH3CN, HDCO, C2H, SO, SO2 IRAM Plateau de Bure Interferometer: 2002, synthezied beam sizes 5″×7″ detected HCO+ (& ~ 3: 34SO, SO2, HCN, C2H, …) PdBI 7/19

  20. AB Aurigae - Conclusions • About a dozen molecular spectra as well as the HCO+(1-0) interferometric map of AB Aurigae are acquired • There is an evidence for the accretion at distances of about 600 AU from the star • The mass, size, geometry and dynamical structure of the disk are constrained • The temperature and density distribution of the envelope are estimated • It is shown that the IRAM single-dish spectra can be adequately described by the «disk-in-envelope» model • Further investigations are needed 18/18

  21. AB Aur - Line radiative transfer (Pavluchenkov & Shustov, 2004) • 2D URAN NLTE code: further development of the public 1D code by Hogerheijde & van der Tak (2000) • System of equations including the equation of radiative transfer and statistical equations for the level populations • Mean intensity in every cell is calculated by the accelerated Monte-Carlo technique (AMC) • Level populations are iteratively calculated using the Accelerated Lambda Iteration (ALI) scheme • Global iterations are finished after a requested accuracy in level populations is achieved 13/18

  22. 1. Geometry 2. Integration of transfer equation 1D model 2D model cell boundaries First calculation Second calculation 1 2 3 N ray Back-up integration: 3. Estimation of the error in level populations Grid e er e cell Comparison of the level populations for each cell to estimate Monte-Carlo error

  23. Modeling Results: НСО+(1-0) disk map AB Aurigae Subaru R-band image Fukagawa et al. 2004 4 3 2 1 0 -1 -2 -3 -4  sub-component structures possibly stem from the spirals -4 -3 -2 -1 0 1 2 3 4 arcsec 15/18

  24. Disk Envelope Both Line wings  disk, central peak  envelope 30.01.2004 Friday-seminar talk at AIU Jena HCO+(1-0) [29’’] 24

  25. Beam is smaller  contribution from the disk is larger 30.01.2004 Friday-seminar talk at AIU Jena HCO+(3-2) [9.3’’] Disk Envelope Both 25

  26. Line is optically thick, 30.01.2004 Friday-seminar talk at AIU Jena CO(2-1) [11’’] Disk Envelope Both 26

  27. Line is optically thin, 30.01.2004 Friday-seminar talk at AIU Jena C18O(2-1) [11’’] Disk Envelope Both 27

  28. 30.01.2004 Friday-seminar talk at AIU Jena CS(2-1) [26’’] Disk Envelope Both 28

  29. HCO+(1-0)is optically thin  30.01.2004 Friday-seminar talk at AIU Jena Mass of the disk 21

  30. Dependence on the grain size: • Dependence on the chemical network: • Dependence on the gas-to-dust ratio: ? • Dependence on the disk structure: ? 30.01.2004 Friday-seminar talk at AIU Jena Mass of the disk 22

  31. 30.01.2004 Friday-seminar talk at AIU Jena AB Aurigae: General properties • Star: • Disk: • Envelope: 3

  32. 30.01.2004 Friday-seminar talk at AIU Jena The AB Aurigae system: IR IRAS 60m map radius of the envelope ~ 35000 AU 4

  33. 30.01.2004 Friday-seminar talk at AIU Jena The AB Aurigae system: visual (Grady et al. ApJ, 523, 151, 1999) Scattered light image  extended asymmetrical nebulosity 5

  34. AB Aur: General Properties - The envelope HST K-band image (Grady et al. 1999): inhomogeneous spherical envelope, Rdisk 1300 AU  i < 45o

  35. 30.01.2004 Friday-seminar talk at AIU Jena The AB Aurigae system: 10m The shape of the 10m-silicate band implies that ad<1m(Bouwman et al. A&A, 375, 950, 2001) 8

  36. Results: PdBInterferometer Keplerian rotation, positional angle  90 ?

  37. Gas-phase reaction Desorption Accretion Mantle Grain UV, CR, X-ray Surface reaction 30.01.2004 Friday-seminar talk at AIU Jena Chemical processes in space Grain 15

  38.  = 40o = 80o = 120o Positional angle of the disk  30.01.2004 Friday-seminar talk at AIU Jena Disk positional angle 20

  39. Line wings  disk, central peak  envelope HCO+(1-0) [29’’]

  40. T = 15K T = 25K T = 35K  Envelope temperature (r  800 AU)  35K Temperature of the envelope

  41. 13CO (1-0) OVRO Main velocities 4.5 5 5.5 6 6.5 vLSR (km s-1) 5″ 5 0 -5 arcsec AB Aurigae: General Properties - The disk Subaru H-band image (Fukagawa et al. 2004): mass supply from the envelope contributes to the spiral instability (Mannings & Sargent, 1997) Keplerianrotation, a/b  110 AU / 450 AU  i  76o 8″ 8″ HST image (Grady et al. 1999)

  42. sum HCO+J=1-0 Beam 6.5″ x 5″ HST image: Grady et al. 1999 AB Aur - Our observational results: PdB Interferometer Main velocities 4.5 5 5.5 6 6.5 vLSR (km s-1) Keplerian rotation, position angle  90 ? 34SO 3221 SO2 73,582,6 S[Jy] HCN 10

  43. SED AB Aurigae The model of the AB Aur system (Dullemond & Dominik, 2004) • 2D continuum radiative transfer code  passive flared disk model • low-density cones have the open angle  • shadowed part of the envelope is denser and cooler R 9/18

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