Modeling the structure chemistry and appearance of protoplanetary

Modeling the structure, chemistry and appearance of protoplanetary disks Molecular Hydrogen Emission from Protoplanetary Disks Hideko Nomura (Kobe Univ. ), Tom Millar (UMIST)

§ 1 Introduction

Obs. of Protoplanetary Disks SED of TTS + disk Central Star Disk (Chiang & Goldreich 1997) CTTS 106 yr WTTS 107 yr (Andre et al. 1994)

Observations of H 2 Line Emission MIR GG Tau, GO Tau, Lk. Ca 15 J=2 -0, J=3 -1 by ISO (Thi et al. 2001) NIR GG Tau, TW Hya, Lk. Ca 15, Do. Ar 25 (v, J)=(1, 3)-(0, 1) by NOAO (Bary et al. 2003) UV TW Hya 146 Lyman-band H 2 lines by HST, FUSE (Herczeg et al. 2002)

H 2 Transition Lines (Shull & Beckwith 1982) UV pumping continuous fluorescence (UV) UV pumping UV fluorescent line emission Infrared quandrapolar cascades H+H collisional Collisional process excitation, level populations de-excitation v=0 radiative UV radiation field cascade (IR) Temperature profile

Irradiation from Central Star Disk Irradiation from central star H 2 level transitions via UV pumping Heat gas & dust (Chiang & Goldreich 1997) in disks Radiative transfer process Global physical disk structure (gas & dust temperature, and density profiles)

§ 2 Disk Model

Gas Density & Temperature Hydrostatic equilibrium in z-direction z ★ x cs 2=2 k. T/mmp W(x)=1. 4 x 10 -7 s-1(x/1 AU)-3/2 (M*=0. 5 Ms ) ・ Macc=10 -8 Ms/yr (=const. ) Thermal equilibrium (Gpe+Lgr-Lline=0) Gpe : Grain photoelectric heating by FUV Lline : Cooling by OI, CII & CO line excitation Lgr : Energy exchange by collisions between gas and dust particles

Dust Temperature Local radiative equi. (abs. =reemission) Heating sources: (A) viscous heating at equatorial plane (B)(B) radiation from central star 2 D radiative transfer equation Short characteristic method in spherical coordinate (Dullemond & Turoulla 2000)

UV Radiation from Central Star UV excess Stellar blackbody (T*=4000 K) + Thermal bremsstrahlung (Tbr=2. 5 x 104 K) TW Hya (Costa et al. 2000)

Resulting Temperature Profile with UV excess R=0. 1 AU without UV excess R=0. 1 AU 10 AU Disk surface heated up by photoelectric heating Midplane & Outer disk (without UV excess) gas temp. = dust temp.

§ 3 H 2 Level Populations

H 2 Level Populations Statistical Equilibrium H+H UV Rform, l blm bml u, B 1 Su+ , C 1 Pu UV H+H Rdiss, l m, X 1 Sg+ Aml Clm Cml l, X 1 Sg+ Em>El

Resulting Level Populations with UV excess without UV excess R=0. 1 AU 10 AU v=0 v=1 v=2 v=3 v=4 10 AU with UV excess or Inner disk (hot) : LTE collisional process, nupper: large Outer disk without UV excess (cold) : non-LTE UV pump. & cascade, nupper: small

§ 4 Resulting H 2 Line Emission Observer Iul IR with UV excess: Tgas: n u: Iul: Sul [erg/cm-2/s] v=1 -0 S(1) (@2. 12 mm) Obs. (Bary et al. ’ 03) with UVe without UVe (1. 0 - 15) x 10 -15 9. 3 x 10 -15 3. 3 x 10 -18 UV with UV excess: UV: e. g. , v=1 -7 R(3) (@1489. 6 A) n u: Iul: [erg/cm-2/s] Obs. (Herczeg with UVe without et al. ’ 02) UVe + Lya UVe 4. 8 x 10 -14 1. 4 x 10 -14 1. 3 x 10 -16 4. 0 x 10 -22

§ 5 Discussion

Dustless Disk Model Planet formation Dustless disk model SED Conserv. of dust mass & dust size growth amount of small dust Dustless disk : no infrared excess

Resulting Temperature Profile with UV excess Dusty R=0. 1 AU Dustless R=0. 1 AU 10 AU Dustless (ndust/ngas: small) grain photoelectric heating Tgas

Resulting Level Populations Dusty with UV excess Dustless R=0. 1 AU v=0 10 AU v=1 v=2 R=0. 1 AU v=3 v=4 v=0 v=1 v=2 v=3 v=4 10 AU Outer region of dustless disk (cold) : non-LTE UV pump. & cascade nupper: large UV radiation fields dust absorption

Resulting H 2 Line Emission v=1 -0 S(1) (@2. 12 mm): Obs. (Bary et al. ’ 03) Dusty (1. 0 - 15) x 10 -15 9. 3 x 10 -15 [erg/cm-2/s] Dustless 6. 5 x 10 -16 S(0) (@28. 2 mm), S(1) (@17. 0 mm): Obs. (Thi et al. ’ 01) Dusty Dustless S(0) (2. 5 – 5. 7) x 10 -14 4. 2 x 10 -17 9. 3 x 10 -17 S(1) (2. 8 – 8. 1) x 10 -14 8. 5 x 10 -16 5. 0 x 10 -16 UV (@900 A-2900 A) Obs. (Herczeg et al. ’ 02) Dusty Dustless (1. 2 - 73) x 10 -15 3. 8 x 10 -15 1. 2 x 10 -14 Obs. possibility to detect H 2 emission from dustless disks in NIR & UV

§ 6 Summary UV excess + Radiative transfer process Gas & dust temperature, density profiles Gas temperature@disk surface: ~2, 000 K Grain photoelectric heating H 2 level populations : LTE, nupper: large Strong NIR H 2 lines : consistent with obs. collisional excitation (hot gas) Strong UV H 2 lines : consistent with obs. pumping by Lya emission H 2 emission from dustless disks