Gravitationally Unstable Protoplanetary Disks

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Gravitationally Unstable Protoplanetary Disks

• Kai Cai
• Sept. 17, 2004

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Does GI really occur?

• Toomre Q cs?/?G? lt 1.5 - 1.7 ? Gravitational
  Instabilities (GIs)
• Several class 0/I disks have low Qs
• Why?
• Disks are massive _at_ earlier times
• Disks are smaller _at_ earlier times

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http//sparky.rice.edu/hartigan/images/slides/sl3
9.html
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HH 30
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Environments

• ISOCAM obs. (Gålfalk et al. 2004) 15 new
  YSO candidates in L1551 now 22 YSOs in total
• Extended sources cant distinguish YSOs from
  galaxies or HH objects - deep imaging or spectra
  needed to confirm

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L1551 IRS 5 system
Osorio et al. 2003
Rodríguez et al. 1998
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L1551 IRS 5 is a binary system!

• Class I source
• Orbital proper motions total mass 1.2M?
  period 260 yr, average projected separation 43
  2 AU
• FU Ori characteristics mass piling up onto outer
  disk/CB disk disk Mdot much smaller than 10-4
  M? yr-1

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L1551 IRS 5 Envelope

• SCUBA IRAM large-scale dust thermal emission
  10, 000AU
• Envelope flattened ? Rout / H
• SED fitting Si H2O ice features constraint the
  model parameters
• Mdot determined from model parameters

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L1551 IRS 5 Circumbinary ring/disk

• mm obs. ? dust emission with a scale of 100-400
  AU
• Outer radius envelope centrifugal radius
• Inner radius 3 times the max separation ( 40
  AU)
• Total mass 0.02-0.4M? depending on amax
• May be gravitationally unstable

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L1551 IRS 5 Circumstellar Disks

• 7mm interferometric data (VLA) two compact,
  elongated structures 20AU
• Model ? disk irradiated by the envelope
• Assume the same dust composition as the envelope
• Rd determined from mm flux
• Mdot lower than envelope ? mass pileup _at_ outer
  disk

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Steady-state Accretion Disk model
Hartmann 1998
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Condensations discovered in Northern disk !

• S. Curiel et al., Nature, submitted
• Two condensations discovered at 6AU from
  center
• brightness temperature 1000 K _at_ 7mm
• 7mm multi-epoch data ? trace orbital motions ?
  reasonable M
• Protoplanets? GI-enhanced clumps?

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L1551 IRS 5 Binary Jets

• VLAVLBA 3.5 cm data, 0.1"
• Each component roughly centered 7 mm disk
• Northern jet curved, suggestive of binary
  motion
• Shock interaction between the two outflows

Rodríguez et al. 2003
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L1551 IRS 5 model fit
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X-Rays ? Shocks

• displaced westward from the IRS 5 binary by
  50-100 AU
• Shock v gt 350 km s-1
• Possible mechanisms
• Formed in situ by shocks at the base of the HH
  154 jet
• scattered x-ray escaped from the outflow cavity
  of IRS 5

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SVS 13 (in NGC 1333)
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Looney et al. 2003
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IRAS 043682557 (in L1527)

• Total mass 0.5-2 M?, Menv 0.5 M?
• Two radio sources, projected separation 25AU
• Residual" proper motions
• A compact
  accretion disk
  (R20 AU)
  tidal
  truncation?

Loinard et al. (2002)
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IRAS 16293-2422B

• Rodríguez, Loinard D'Alessio, in prep.
• Current model M 0.8 M?, Md0.4 M?, Rd30 AU
• Mdot1.7X10-6 M? yr-1
• Q0.3 at RRd
• More embedded sources L1448 IRS 3, NGC 1333
  IRAS 2 IRAS 4, VLA 1623,

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Looney et al. 2000
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Flat-spectrum T Tauri stars

• T Tau, HL Tau, DG Tau,
• First studied by Adams et al. (1988)
• Calvet et al. (1994) showed SEDs can be explained
  by dust emission from an infalling envelope
• An later stage than embedded systems

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My Plan

• Consider the gravitational effect of a binary
  companion
• Model one of the circumstellar disks, embedded in
  an envelope
• Thank you!