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Importance of Outer Region of the Disk

The radial distribution of the surface density of a protoplanetary disk around HD 163296: Evidence for the viscous evolution of the disk.

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Importance of Outer Region of the Disk

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  1. The radial distribution of the surface density of a protoplanetary disk around HD 163296: Evidence for the viscous evolution of the disk Jul. 17th 2014 EA ALMA-Science Workshop at JejuEiji Akiyama (NAOJ)CoI: EdwigeChapillon, Daniel Espada, SatokoTakahashi, Itziar de Gregorio-Monsalvo, Pamela Klaassen, Mark Rawlings, Geoffrey Mathews, Yoshimi Kitamura, Antonio Hales, and Masao Saito

  2. Importance of Outer Region of the Disk • How is disk gas cleared ? • How can planets form at a distant from a central star ? Fomalhaut r = 119 AU Kalas et al. 2009

  3. Power Law Disk Model • Power law description in surface densitywasintroduced in the minimum mass solarnebula. (e.g. Kusaka et al. 1970, Weidenschilling 1977, Hayashi et al. 1985)

  4. Discrepancy between Dust & Gas Emission Discrepancy in disk size has emerged between the extent of the dust continuum and molecular gas emission. Dust continuum: smaller size Gas emission: larger size Examples・AB Aur (Pietu et al. 2005) Continuum (2.8, 1.4mm) : 350±30AU12CO(J=2-1) : 1050±10AU ・HD 163296 (Isella et al. 2007) Continuum (0.87-7mm) : 200±15AU12CO(J=3-2) etc : 540±40AUIs the power lawdescriptionreallyappropriate ?

  5. Similarity Solution Disk Model power-law • Surface densityis based on the theory of viscousevolution (Lynden-Bell & Pringle 1974, Hartmann et al. 1998) • Radial temperature distributionSame as power-law disk model y[AU] normalized surface density distance where Σ(r) starts decreasing exponentially log nH2[1/cc] x[AU] power-law similarity Log Σ(r) [g cm-2] similarity y[AU] rout C2 Logr [AU] x[AU]

  6. Examples of Similarity Solution HD163296 10 ALMA SVband7 color: CO(3-2)contour: continuum 8 6 Power Similarity CO(3-2) Vel. [km/s] 4 6 Dec. 2 4 offset [arcsec] 0 2 2 4 R.A. 6 CO(3-2) 10-1 10-0 continuum 2 4 6 8 2 4 6 8 2 4 6 8 velocity [km s-1] 10-2 10-1 CO(3-2) [Jy/beam] continuum [Jy/beam] 10-3 Hughes et al. 2008 10-2 rc = 125 AU 10-4 10-3 10 100 1000r [AU] de Gregorio-Monsalvo et al. 2013

  7. Gallery of ProtoplanetaryDisks (Radio) Andrews et al. 2011 Mathew et al. 2012 Brown et al. 2012 Cieza et al. 2012 Isella et al. 2010

  8. Object Details • HD 163296 is brightHerbigAe star with primordial disk. • Many people have observed and basic properties are well known. • No complex structures → easy to analyze the structure a van denAncker et al. 1998 bMeuus et al. 2001 c van den Ancker, de Winter, & Djie1998 dvan den Ancker et al. 2000 e Isella et al. 2007 log λFλ[erg cm-2s-1μm] log λ[μm] HST Acke & van den Ancker 2004 Wisniewski et al. 1997 No complex structures

  9. Observation Details ALMA SV band 6

  10. Results (ALMA SV band 6) 0th 1st 2nd 12CO(2-1) 13CO(2-1) C18O(2-1) Akiyama et al. submitted

  11. Results (ALMA SV band 6) 0th 1st 2nd 12CO(2-1) 12CO(2-1) 13CO(2-1) C18O(2-1) 13CO(2-1) Flux Density [Jy] Vlsr [km s-1] C18O(2-1) Akiyama et al. submitted

  12. Model Parameters ・Fixed parameters ：The results obtained by other observations applied ・Free parameters ：Best fit parameters are searched ・X（12CO)= 10000 ・Local Thermal Equilibrium (LTE) ・X（12CO) / X（13CO) = 60 ・Hydrostatic Equilibrium ・X（13CO) / X（C18O) = 5 ・Outer radius　　 ：rout (C2)・Temperature　　 ：T100・Surface density：Σ100 (C1)

  13. Model Fit Results 1 CO (2-1) 13CO (2-1) C18O (2-1) PL SS Akiyama et al. submitted 700

  14. Model Fit Results 2 rout = 700AU, p=1.0, θ=45° 12CO(J =1-0) 12CO(J =3-2) 13CO(J =1-0) 13CO(J =3-2) 20 40 0.3 3 15 30 0.15 10 1.5 20 5 Tmb [K] 10 0 0 0 0 -5 20 3 40 0.3 15 30 0.15 10 1.5 20 5 Tmb [K] 10 0 0 0 0 -5 -0.15 -1.5 -10 -10 0 2 4 6 8 10 12Vlsr [km s-1] 0 2 4 6 8 10 12Vlsr [km s-1] 0 2 4 6 8 10 12Vlsr [km s-1] 0 2 4 6 8 10 12Vlsr [km s-1]

  15. Successful Example of SS Model NRO45/ASTE MWC 480 Akiyama et al. 2013 Similarity solutionshows better fit in multi-CO line observation → It supports viscous evolution

  16. Summary HD163296 was selected for its simple disk structure. Similarity solution is based on the theory of viscous evolution.・Surface density tapers off gradually with distance. Similarity solution reproduces the observation ・Verified by ALMA SV (interferometry) and NRO45/ASTE (single dish) data.・Similarity solution model is more suitable than power law for describing disks. → The disk evolves via viscous diffusion

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