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Resonance Line Scattering in the b Pic Disk

Resonance Line Scattering in the b Pic Disk. Göran Olofsson + René Liseau + Alexis Brandeker Stockholm Observatory, Sweden. Resonance Line Scattering in the b Pic Disk. Discovery of extended and velocity tracing atomic gas. …what disk ?.

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Resonance Line Scattering in the b Pic Disk

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  1. Resonance Line Scattering in the b Pic Disk Göran Olofsson + René Liseau + Alexis Brandeker Stockholm Observatory, Sweden Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  2. Resonance Line Scattering in the b Pic Disk Discovery of extended and velocity tracing atomic gas …what disk ? Göran Olofsson + René Liseau + Alexis Brandeker Stockholm Observatory, Sweden Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  3. b Pic: Main-Sequence Vega Excess Star A Highlight of IRAS 05460-5104 Neugebauer et al. 1984, ApJ 278, L1 Backman & Paresce 1993, PPIII, 1253 Disk (in scattered visual light): Smith & Terrile 1984, Sci. 226, 1421 Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  4. Thermal radiation bycool b Pic dust disk:Tave 100 K (inner 450 AU) JCMT-SCUBA 850 mm Holland et al. 1998, Nat 392, 788 Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  5. Accompanying Molecular Emission ? ...mm/submm search for rotational lines - advantage: heterodyne technique permits very high spectral resolution R >> 3105 (Dv << 1 km s-1) disk kinematics from line profiles (see: Anne Dutrey’s talk @ this conference) - disadvantage: single dish telescopes provide only low spatial resolution Dq  1 (Dxb Pic  20 AU) little detail in maps/images (southern hemisphere) Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  6. CO ul and gas-to-dust mass ratio There is CO in the b Pic disk... UV Absorption - Detection: Vidal-Madjar et al. 1994, AA 290, 245 Jolly et al. 1998, AA 329, 1028 Roberge et al. 2000, ApJ 538, 904 N(CO) = 61014 cm-2,Tex = 20 - 50 K mm Emission - Upper Limit: Savoldini & Galletta 1994, AA 285, 467 Dent et al. 1995, MNRAS 277, L25 Liseau & Artymowicz 1998, AA 334, 935 …but in a confined region along the line of sight toward the star Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  7. Grains must be replenished…and so must any Gas Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  8. Is there Any Widespread Molecular Gas in the b Pic Disk? H2 in Emission: Thi et al. 2001, Nat 409, 60 ISO-SWS: pure rotational lines, Eu/k > 500 K, A < 1010 s-1 M(H2) = 0.17 MJup H2 in Absorption: Lecavelier des Etangs et al. 2001, preprint FUSE: electronic transitions, El/k  0 K, A > 108 s-1 M(H2)  3104 MJup (CO/H2 > 6 104) Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  9. Spectrum of bright star and faint disk Is there Any Widespread Atomic Gas in the Disk? Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  10. North Slit length = 300 Slit width = 1 Position angle = 30.75deg East Kalas & Jewett 1995, AJ 110, 794 Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  11. North Check with slit perpendicular* East  and with  Pic Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  12. An Ancient Experiment James E. Keeler 1895 A spectroscopic proof of the meteoric constitution of Saturn’s rings ApJ 1,416-427 Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  13. Sodium D1/2 lines toward b Pictoris ESO La Silla, Chile 3.5m NTT EMMI + long slit (R  60000) nb filter - cross disperser, optimised blaze Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  14. b Pic: Model parameters M =1.8 Mo R = 1.9 Ro Teff/log g/ Z/Zo = 8000 K/4.5/0.0 (NEXTGEN model atmospheres, Hauschildt et al. 1999, ApJ 512, 337) tstar = 10 - 100 Myr (Crifo et al. 1997, AA 320, L29 Barrado y Navascués et al. 1999, ApJ 520, L123) Mdust 0.5 M (Chini et al. 1991, AA 252, 220) idisk = 88.7 deg Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  15. NaD lines: Velocity tracers of the b Pic disk Optically thin line ratio, 2:1 Dl = 10- 4l0Mstar r -1/2 cos i sin f ± dlnon-grav (Å) Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  16. b Pic - NaI D2 (5892 Å) Normalised line profiles 0.27 pxl-1 (5 AU pxl-1) 0.035 Å pxl-1 (2 km s-1) Observations: histogram Model: smooth solid line Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  17. Atomic Gas Mass N(Na) = 61010 cm-2 if Na/H solar (210-6), then N(HI) = 31016 cm-2 * *cf. Freudling et al. 1995, AA 301, 231: N(HI)  1019 cm-2 Disk Absorption Line: @systemic/stellar velocity EW(NaD2) = 9.4 mÅ*  M(Na) 21017 g [M(dust) 21027 g] *cf. Vidal-Madjar et al. 1986, AA 167, 325 Disk Emission Line: EW(NaD2) = 0.72 mÅ  (disk) = 8.8 deg [r0(NaD) = 30 AU, H0(disk) = 4.6 AU]* *cf. Z(x) = 0.055 rmax x0.75 , x = r/ rmax rmax =120 AU Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  18. Detected/non-detected Gas in the b Pic Disk in absorption against stellar continuum:  Molecular gas: CO  Atomic gas: Na I  Molecular gas: H2 in emission from extended regions of the disk:  Atomic gas: Na I  Atomic gas: H I  Molecular gas: CO, CS, SiO  Molecular gas: H2 Needs confirmation Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  19. b Pic Disk: Radial Intensity Profiles Resonantly Scattered Lines and Dust Scattered Light reveal similar spatial distributions indicates coexistence? indicates common origin? …but scattering phase functions… Dust profiles from Heap et al. 2000, ApJ 539, 435 Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  20. Sense of Disk Rotation North Away from us East Toward us Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  21. Conclusions • Line emission from neutral sodium is detected far out in the b Pic disk, to at least 140 AU. • This emission originates mainly from resonantly scattered stellar photons by Na atoms throughout the disk, with central absorption. • Mass estimates of the neutral atomic gas indicate that the gas-to-dust mass ratio is probably very much smaller than typical ISM values. • The observed velocities are well fit by Keplerian rotation. • This rotation is clockwise (SW: toward us, NE: away from us). • Potentially, these lines are optimal tracers of the velocity fields in debris disks and open up the possibility of observational dynamical studies. Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  22. The End ? Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  23. Future Plans b Pic: Na I at higher spatial and spectral resolution spectral. mapping at different PAs spectral line survey (Mg II, Ca II, K I , O I…) Other Vega xs stars: as above (in both hemispheres) IF resonance lines common feature, then dynamical investigations - including planetary disturbences Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

  24. The Final End ! …FOR NOW Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 16-19, 2001

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