The Lifetime of Dust Disks Lynne Hillenbrand Caltech

The Lifetime of Dust Disks Lynne Hillenbrand. . . Caltech

Star and planet formation/evolution 10 105 yr Disk/wind Lstar 104 yr Planet building 107 yr 109 yr 1 Planetary system 100 AU Main 8, 000 sequ ence 5, 000 Cloud collapse 2, 000 Tstar (K) [Beckwith & Sargent 1996]

Before/during/after protostellar collapse [04302+2247] [B 68] [Padgett et al. ] [ONC “proplyd”] [Alves, Lada] [Mc. Caughrean et al. ; Stauffer et al. ]

Not so much later: Debris disks

What is the difference between “primordial” and “debris” disks? Primordial [Dullemond and Pontoppidian] Debris

Spitzer legacy science: The formation and evolution of planetary systems 3 Myr – 3 Gyr DEBRIS DIKS ice giant formation Characterize transition from primordial to debris dust disks. • Growth of gas giant planets: Constrain time scale for gas disk dissipation. • Mature solar system evolution: Examine diversity of planetary systems based on debris disks. POST ACCRETION • Birth of planetary embryos:

Evolution of our own dust disk in time [D. Backman analytic model] Mass in small grains Spectral energy distribution

Circumstellar disk and SED NIR 0. 1 MID 1. 0 FIR 10. 0 – 40. 0 sub- m 100 AU In an observed SED, each wavelength traces a distinct temperature, and different temperatures correspond to different radii in disk (cooler at larger radii). Temperature 1 10 100

Young (< 30 Myr) disks NIR – MID 0. 1 – <1. 0 AU A Spitzer instrument to detect these disks: IRAC (3. 6 m, 4. 5 m, 8. 0 m)

Warm disks MIR FIR 10. 0 – 40. 0 A Spitzer instrument to detect these disks: IRS (10 – 35 m)

Cold outer disks FIR ~20 – 100 AU A Spitzer Instrument to detect these disks: MIPS (24 – 160 m)

Constraints on planet-formation time scales Inner disk dissipation Data suggest <3– 10 Myr as maximum accretion disk lifetime. *Typical* lifetime for material at <0. 1 AU is <3 Myr. Mid-disk dissipation Maximum disk lifetime for terrestrial planet material at 1 AU is also <10 Myr. Compare with meteoritic evidence suggesting Earth formed in <10 Myr with moon-forming impact occurring at 30 Myr. Outer disk dissipation and re-generation Primordial disk lifetimes as yet unconstrained. Debris disk lifetimes consistent with expectations from self-sustaining collisional cascade.