여 아란 Long-lived transition disk systems

The process of star formation (Source:SpitzerScienceCenter) Transition disks are Best for studying Planet Formation

Evidence of Inner hole/gap ? Clearing process due to planet formation The dynamical interaction of the disk with embedded planets (Skrutskie et al. 1990; Calvet et al. 2002) Evaporation by high-energy photons (Hollenbach et al. 1994; Clarke et al. 2001; Gorti & Hollenbach 2009) Brown et al. 2007, 2009 I. Indirect evidence : SED

Andrews et al II. Semi-direct evidence : dust emission images at 340 GHz Tau ? Sco-OB2 ? Per Oph TauOph Tau Lup Tau Oph Lyo et al CO(2-1)

Hillenbrand 2003 Long-lived transition disk systems ~8My-old η Chamaeleontis young stellar cluster “ Best sites to look for the young planets since core-accretion model for Jovian-mass planets requires timescales of ~10 Myr (Pollack et al. 1996)” ~140pc, 2-3Myr ~20-100pc, 8-10Myr

Southern Cross Eta Cha Cluster Eta Cha HD RS Cha Mamajek et al. 1999

Lyo et al. 2004a 1. Confirm their young age

Lyo et al. 2004b 2. Examine their spectral types : T FeH NaI KI TiO CaH

Lyo et al. 2004b Test Evolutionary models

3. Circumstellar disk study a) photometric study : disk fraction = 0.60 ± 0.13 L-band from 0.6m South Pole Infrared Explorer (SPIREX) telescope Lyo et al. 2003

Lawson et al b) Spectroscopic study : Accretion disk fraction = 0.27

4) Examine the disk structure : SED Disk fraction ~50% Gautier et al Sicilia-Aguilar et al. 2009

5) Direct Imaging : ALMA Submillimter continuum at 345GHz + molecular lines HD : 1.9±0.3 M Θ, R in = 140AU Casassus et al. 2013, Nature

An old disk still capable of forming a planetary system Bergin et al. 2013, Nature TW Hya : M disk ~ 0.05 M Θ