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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 2 2009 Tr 37, MIPS 24m
Multiwavelength data: a journey through Tr 37 Near-IR: T~600 K 3.6, 5.8, 8.0 m IRAC Optical: 660 nm, T~5000 K Sicilia-Aguilar et al. 2006, ApJ 638, 897 Sicilia-Aguilar et al. 2004 AJ 128, 805 CO(1-0), T~20 K 2.6mm FCRAO Mid-IR: T~150 K 24 m MIPS Sicilia-Aguilar et al. 2006, ApJ 638, 897 Patel et al. 1998, ApJ 507, 241
Multiwavelength view of a protoplanetary disk Silicate feature IR excess Flux (Jy) Geometrically thin, optically thick disk Inner gaseous disk Flux Optically thin disk atmosphere H2 /m Log(/m) ~100-300 AU (0.7-2” in Taurus) ~0.01 Msun Pre-MS Star ~1-10 Myr ~0.1-3 Msun UV excess H emission 10-8 Msun/yr ~ 10 MJ/ Myr Chromospheric accretion Solar-type star Flux V (km/s)
? Observing disk evolution with time H V(km/s) log(/ m) Typical CTTS ~ 10 Myr ~1 Myr H V(km/s) log(/ m) Flattened, accreting disk H But: All these objects have the same age! V(km/s) log(/ m) Non-accreting TO Sicilia-Aguilar et al. 2006, AJ 132, 2135; SA+ in prep
The trend: Parallel dust and accretion evolution • 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 “transition” objects Non-accreting Sicilia-Aguilar et al. 2006, AJ 132, 2135 Sicilia-Aguilar et al. in prep. Sicilia-Aguilar et al. 2006, ApJ 638, 897
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 MA/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. 2008 (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? Solar-type objects M0-M8 objects • 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”? 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. 2007 Sicilia-Aguilar et al. 2008, ApJ,687, 1145
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 • Grain growth/crystallization happens very early in the disk lifetime. • Appropriate disk models are required (Bouwman et al. 2008; Juhász et al. 2009 ) Sicilia-Aguilar et al. 2007 ApJ 659, 1637
What do the SED/silicate tell? 1 Myr log( F / erg cm-2 s-1) 8 Myr log(/ m) log(/ m) • 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? Which cluster is older ?
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 areVERYdifferent: key to disk dispersal? • Mass, binarity, environment, and initial conditions may affect disk evolution. Future: Herschel, JWST, ALMA,…