Evolved Protoplanetary Disks: The Multiwavelength Picture Aurora Sicilia-Aguilar Th. Henning, J. Bouwman, A. Juhász, V. Roccatagliata, C. Dullemond, L. Hartmann, D. Watson Max-Planck-Institut für Astronomie Tübingen, March Tr 37, MIPS 24  m

Multiwavelength data: a journey through Tr 37 Optical: 660 nm, T~5000 K Near-IR: T~600 K 3.6, 5.8, 8.0  m IRAC Mid-IR: T~150 K 24  m MIPS CO(1-0), T~20 K 2.6mm FCRAO Sicilia-Aguilar et al AJ 128, 805 Sicilia-Aguilar et al. 2006, ApJ 638, 897 Patel et al. 1998, ApJ 507, 241

Multiwavelength view of a protoplanetary disk Geometrically thin, optically thick disk Inner gaseous disk Optically thin disk atmosphere IR excess UV excess H  emission M sun /yr ~ 10 M J / Myr Flux Log( /  m) V (km/s) /  m Flux (Jy) Silicate feature Pre-MS Star ~1-10 Myr ~0.1-3 M sun H2H2 Chromospheric accretion Solar-type star ~ AU (0.7-2” in Taurus) ~0.01 M sun

Observing disk evolution with time ~ 10 Myr ~1 Myr V(km/s) log( /  m) HH HH HH Typical CTTS Flattened, accreting disk Non-accreting TO Sicilia-Aguilar et al. 2006, AJ 132, 2135; SA+ in prep ? But: All these objects have the same age!

The trend: Parallel dust and accretion evolution Sicilia-Aguilar et al. 2006, ApJ 638, 897 Sicilia-Aguilar et al. 2006, AJ 132, 2135 Sicilia-Aguilar et al. in prep. IR excesses disappear, accretion decreases Same age, same mass, disk/no disk: Initial conditions? Binaries? (Bouwman et al. 2006, ApJ 653, 57) Solar type stars Non-accreting “transition” objects

Transition objects (TO): On the way to planets? Accreting TO: grain coagulation/planet formation. Despite the age difference (1-2 vs. 4 Myr), they have the same dM/dt in Taurus and in Tr 37, ~10 -9 M A /yr (Najita et al. 2008; SA in prep.). Non-accreting TO: grain coagulation/planet formation… or photoevaporation? TW Hya: accreting TO with a planet Setiawan et al (Nature 451, 38) Other ways of producing inner holes: Binaries (e.g. CoKu Tau/4; Ireland & Kraus 2008)

Time evolution and stellar mass: “Transition” disks? Disk morphology/SEDs are different for M stars and solar-type stars. Flattened disks/”TO” seem more common for M-type stars. Are those “TO”/”evolved” disks really “in transition”? Sicilia-Aguilar et al. 2008, ApJ,687, 1145 M0-M8 objects Taurus, IC 348, 25 Ori data from Kenyon & Hartmann 1995; Hartmann et al. 2005; Briceño et al. 1998, 2007; Luhman et al. 2003; Hernández et al Solar-type objects

Witnessing dust settling? 3 Myr-old K4.5 star : average grain size 3  m 9 Myr-old K4.5 star : average grain size 0.1  m Sicilia-Aguilar et al ApJ 659, 1637 Grain growth/crystallization happens very early in the disk lifetime. Appropriate disk models are required (Bouwman et al. 2008; Juhász et al )

What do the SED/silicate tell? There is a general trend of IR excess & accretion evolution, but… Grain processing (growth to ~  m, crystallization) must happen very early (<1 Myr). Multiple parameters play a role: binaries, disk/star mass, turbulence, environment Large individual variations: the key to understand disk evolution? log( /  m) log( /  m) log( F / erg cm -2 s -1 ) Which cluster is older ? 8 Myr 1 Myr

Summary and future Multiwavelength studies of clusters are required to trace the timescales and processes in disk dissipation. Accretion and IR excesses evolve in parallel, but… … individual objects are VERY different: key to disk dispersal? Mass, binarity, environment, and initial conditions may affect disk evolution. Future: Herschel, JWST, ALMA,…