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Galactic Science:
Star and Planet Formation
Michael Liu
Andrea Ghez, Tom Greene, Lynne Hillenbrand, Jessica
Lu, Bruce Macintosh, Stan Metchev,
Nevin Weinberg
Keck SSC meeting, June 2006
Galactic Science:
Key Science Cases
1. Extrasolar Planets (Liu, Macintosh)
2. Debris Disks (Metchev, Liu)
3. Protostars (Hillenbrand, Greene)
4. Galactic Center (Weinberg, Ghez, Lu)
M. Liu (IfA/Hawaii)
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AO is critical for star/planet formation
There are/will be numerous wide-field surveys of
the sky for finding young stars of various ages:
IRAS, Hipparcos, Chandra, Spitzer, JCMT/SCUBA-2,
Pan-STARRS, etc.
Follow-up observations of the relevant physical
scales are <1 arcsec:
angular resolution & high contrast are critical
M. Liu (IfA/Hawaii)
NGC 1333: 34’x26’
Spitzer/IRAC 3
Why do we need NGAO?
• Very high-contrast near-IR imaging
directly image planets and debris disks
• Large sky coverage
study stars over a very wide range of masses & ages
• Multi-band optical and IR wavelengths
determine properties & evolution of circumstellar material
M. Liu (IfA/Hawaii)
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Obligatory star & planet formation slide
M. Liu (IfA/Hawaii)
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Obligatory star & planet formation slide
M. Liu (IfA/Hawaii)
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Resolving the protostellar environment
=
+
Disk+Envelope Density
Temperature Dist.
Use observed
integrated-light SEDs +
high resolution images
to study the evolution of
the youngest stars.
M. Liu (IfA/Hawaii)
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NGAO optical imaging of protostars
• Simulated I-band (scattered light) image of a
protostar with a massive envelope & disk at 1 kpc
Model image
HST ACS/HRC
Keck NGAO
(70 AU resolution)
(25 AU resolution)
NGAO provides highest angular resolution of any filled-aperture
telescope (and complementary to ALMA for this science).
M. Liu (IfA/Hawaii)
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Obligatory star & planet formation slide
M. Liu (IfA/Hawaii)
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Debris Disks: Extrasolar analogs to
the asteroid & Kuiper Belt
Keck NGS: H-band
Resolved disks are a
goldmine for studying:
• structure
• composition
• evolution
• low-mass planets
100’s of these known from integrated light,
but only ~12 resolved to date (2 by AO).
M. Liu (IfA/Hawaii)
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Debris disks studies with NGAO
simulated 3-hour H-band integration
of massive Kuiper Belt in the Pleiades (120 Myr, 130 pc)
Solar system model
Undetectable
Neptune with 1:1
resonant dust ring
High Strehl NGAO
Keck AO today
NGAO could image many (10s-100s)
analogs to the young solar system,
study other Kuiper Belts & low-mass planets
M. Liu (IfA/Hawaii)
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Obligatory star & planet formation slide
M. Liu (IfA/Hawaii)
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Planets around VLM stars & brown dwarfs
~25 MJup
~5 MJup?
Chauvin et al (2005): VLT AO (IR WFS)
• Direct imaging and
spectroscopy of planets
easier around low-mass
stars and brown dwarfs.
• Study objects with SEDs
& atmospheres similar to
“regular” exoplanets, but
perhaps with diff origin.
• High contrast LGS +
IR tiptilt needed.
M. Liu (IfA/Hawaii)
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NGAO: Planet detection sensitivity
• Very high contrast in near-IR enables imaging of Jovianmass planets around low-mass stars and brown dwarfs.
• This can only be
done by NGAO.
The stars are too
optically faint for ExAO
systems (I<8-9).
• A unique avenue
for testing planet
formation models,
by using a wide
range of stellar
host mass.
M. Liu (IfA/Hawaii)
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NGAO opens a unique realm for
high contrast studies for a broad range
of science programs.
AO system
Contrast
Extreme AO
v.bright stars only
107–108
Keck NGAO
105–106
many targets
M. Liu (IfA/Hawaii)
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Why do we need NGAO?
• Very high-contrast near-IR imaging
directly image planets and debris disks
• Large sky coverage
study stars over a very wide range of masses & ages
• Multi-band optical and IR wavelengths
determine properties & evolution of circumstellar material
M. Liu (IfA/Hawaii)
16
The End
M. Liu (IfA/Hawaii)
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