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: Disks in Star and Planet Formation, Cumberland Lodge, July 1 16 -19, 2001

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 2 16 -19, 2001

b Pic: Main-Sequence Vega Excess Star A Highlight of IRAS 05460 -5104 Neugebauer et al. 1984, Ap. J 278, L 1 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 3 16 -19, 2001

Thermal radiation by cool 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 4 16 -19, 2001

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 5 16 -19, 2001

CO There ul and is CO gas-to-dust in the b Pic mass disk. . . ratio UV Absorption - Detection: Vidal-Madjar et al. 1994, AA 290, 245 Jolly et al. 1998, AA 329, 1028 Roberge et al. 2000, Ap. J 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, L 25 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 6 16 -19, 2001

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 7 16 -19, 2001

Is there Any Widespread Molecular Gas in the b Pic Disk? H 2 in Emission: Thi et al. 2001, Nat 409, 60 ISO-SWS: pure rotational lines, Eu/k > 500 K, A < 10 10 s-1 M(H 2) = 0. 17 MJup H 2 in Absorption: Lecavelier des Etangs et al. 2001, preprint FUSE: electronic transitions, El/k 0 K, A > 10 8 s-1 M(H 2) 3 10 4 MJup (CO/H 2 > 6 10 4) Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 8 16 -19, 2001

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 9 16 -19, 2001

North Slit length = 300 Slit width = 1 Position angle = 30. 75 deg East Kalas & Jewett 1995, AJ 110, 794 Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 10 16 -19, 2001

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 11 16 -19, 2001

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

Sodium D 1/2 lines toward b Pictoris ESO La Silla, Chile 3. 5 m 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 13 16 -19, 2001

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, Ap. J 512, 337) tstar = 10 - 100 Myr (Crifo et al. 1997, AA 320, L 29 Barrado y Navascués et al. 1999, Ap. J 520, L 123) 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 14 16 -19, 2001

Na. D lines: Velocity tracers of the b Pic disk Optically thin line ratio, 2: 1 Dl = 10 - 4 l 0 Mstar 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 15 16 -19, 2001

b Pic - Na. I D 2 (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 16 -19, 2001

Atomic Gas Mass -2 Disk Absorption Line: N(Na) = 6 1010 cm @systemic/stellar velocity -6), then if. EW(Na. D 2) Na/H solar=(2 10 9. 4 mÅ* 17 g-2 16 M(Na) 2 10 N(HI) = 3 10 cm * [M(dust) 2 1027 g] **cf. et al. et 1995, cf. Freudling Vidal-Madjar al. 1986, AA 301, 231: N(HI) 1019325 cm-2 AA 167, Disk Emission Line: EW(Na. D 2) = 0. 72 mÅ (disk) = 8. 8 deg [r 0(Na. D) = 30 AU, H 0(disk) = 4. 6 AU]* 0. 75 , Formation, Resonance Line Scattering in the b *cf. Pic Disk: in Starr and Planet Cumberland Lodge, July Z(x)Disks = 0. 055 x = r/ rmax x 17 16 -19, 2001 rmax = 120 AU

Detected/non-detected Gas in the b Pic Disk in absorption against stellar continuum: Molecular gas: CO Atomic gas: Na I Molecular gas: H 2 in emission from extended regions of the disk: Atomic gas: Na I Atomic gas: H I Molecular gas: CO, CS, Si. O Needs confirmation Molecular gas: H 2 Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 18 16 -19, 2001

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, Ap. J 539, 435 Resonance Line Scattering in the b Pic Disk: Disks in Star and Planet Formation, Cumberland Lodge, July 19 16 -19, 2001

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 20 16 -19, 2001

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, 16 -19, 2001 July 21

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

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

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