Debris disks

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Debris disks

• Basic properties
• Observational methods constraints
• Why debris?
• Structures

Alexis Brandeker, Lecture 6 in star formation
mini-course
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Discovery of debris disks
From Backman Parece 1993, PPIII, 1253
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Discovery of debris disks
From Backman Parece 1993, PPIII, 1253
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First disk spatially resolvedb Pictoris
Discovery image by Smith Terrile 1984 (Sci.
226, 1421)
500 AU
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Properties

• Large (up to 1000 AU) dusty disks found around
  young main-sequence stars 10 Myr 1 Gyr
• Dust disk mass M 10-3 to a few MEarth.
• Essentially free of gas
• Cold typically 30 300 K
• Dominating dust emission from ?m to mm sized
  grains

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The fabulous four at 850m
3.2 pc
7.7 pc
7.7 pc
20 pc
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b Pictoris in scattered light
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ZAMS
20 Myr
30 Myr
Barrado y Navascués 1999
50 Myr
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Why debris?
From Artymowicz 1997, AR 25175
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? ? Frad/Fgrav
? 1
0.51
2.2
0.1
0.3
0.4
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Top view
Orbit of Pluto-mass parent body before breakup
Side view
?
Elapsed time 21 years
Florida Dynamics Group
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Top view
Side view
?
Elapsed time 569 years
Florida Dynamics Group
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Subaru/COMICS
(Y.Okamoto et al. 2004)
Total (magenta) 0.1mm amorphous olivine
(green) 2mm amorphous olivine (red) Crystalline
forsterite (blue) Power-law continuum (cyan)
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Dust disk lifetimes
From Haisch, Lada Lada 2001, ApJ, 553, 153
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What about gas?
Energy diagram of H 2
Pollack et al. 1993
Total mass
30.0
Energy K
20.0
Core mass
10.0
Gas mass
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mm/submm observations

• Liseau Artymowicz 1998, AA 335, 935

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Edge-on ? absorption!
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Gas in emission

• Sodium D1/2 lines toward b Pictoris

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Dynamical studies...

• Stellar structure
• M(1.750.1)Mo
• Gas dynamics
• Mdyn(1.400.05)Mo

Discrepancy probably due to radiation pressure!
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HR 4796A
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b Pictoris in scattered light
NE
SW
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NE
SW
24.3 ?m
FWHM
5 arcsec
18.3 ?m
100 AU
11.7 ?m
Gemini south / T-ReCS
Telesco et al. 2005
pixel
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1.2 mm (SEST/SIMBA)
Liseau et al. 2003
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Asymmetris in gas disk
VLT / UVES (Brandeker et al. 2004)
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Evolution young vs. old debris
Credit M. Liu
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StarStrider
AU