Transcript E. van Dishoeck

Exo-planets: ground-based
• How common are giant planets? What is the
distribution of their orbits?
– 3.6m HARPS: long-term radial velocity monitoring of
large samples to 1 m/s => Saturns out to ~5 AU
– VLT-AO/OWL: Direct imaging of giant planets;
complement to JWST NIRCAM/MIRI direct detection
– VLTI (10 mas)/ALMA (100 mas): astrometry => >10
MEarth out to large AU; complement to GAIA, which
can observe much larger sample but for shorter period
Ewine van Dishoeck, ESO-ESA coordination meeting, September 15 2003, Garcching
Planetary search methods
Perryman 2000
Planetary search methods
- HARPS 1 m/s => > Saturn out to 5 AU with 10 yr monitoring
- VLTI 10 mas => > 10 MEarth in terrestrial planet forming zone
Perryman 2000
Giant planets (cont’d)
• How do giant planets affect terrestrial planet
formation? Inward migration, ejection of
remnant planetesimals, pumping up of i,e
– Link ground-based giant planet systems with space-based
searches for Earth-like planets?
• Free-floating/isolated exo-planets and brown
dwarfs => formation from disk or fragmenting
cloud?
– VLT/JWST searches in/near star-forming regions (younger
objects have larger luminosities)
Giant planets (cont’d)
• Planetary atmospheres: composition =>
thermal properties, mass, age
– VLT, OWL => high-res spectra; complements
JWST NIR, MIRI spectrophotometry and
low-res spectra
Ground-based spectrum of nearest T dwarf
Need space to observe critical H2O and CH4 bands
Scholz et al. 2003
Model exo-planetary atmospheres
Note change in mid-infrared spectral features with age
Based on Burrows et al. 1997
Exo-earths with OWL
• Sun is ~1010 times brighter than Earth at VIS
– concentrate light as much as possible
– make separation as large as possible
 both D and Strehl must be very large
• OWL would see
– Earth-like planets in HZ out to 30pc
– cold Jupiters out to Pleiades (120pc) and beyond
– hot Jupiters further out (but resolution)
 D=100m just enough for this (sensitivity  D4 ! )
• Spectroscopy
– Exo-biospheres?
Gilmozzi 2003
Solar system @10 pc
OWL 100m
J Band
80% Strehl
104 sec
0.4’’ seeing
O.1’’
Jupiter @5AU
Earth @1AU
Gilmozzi 2003
Why are exo-planetary systems
different from our own?
Theory
Simulation G. Bryden
The answer lies in
the past, during
the time when the
star and its
planets are being
assembled
Need spatially resolved images
at mid-IR and mm
Formation of planetary systems
Massive gas-rich disks
Planet building
phase
Tenuous debris disks
M(gas + dust)=0.01 Msun
t=few Myr
gas + dust interstellar
M(dust)<1 Mearth
t>10 Myr
dust produced in situ
- Time scale for gas and dust dissipation? => Jovian
planet formation timescale
- Time scale for dust settling and grain growth?
- Planet formation mechanism: core accretion vs.
disk instability
- Physical structure disks (T, n, v, ….)?
- Chemical evolution gas + dust
Synergy ground-based facilities
Dutrey et al. 2000
Example: Vega debris disk
Dust trapped in resonances due to unseen planet with few MJup?
Simulation
PdB 1mm data
What ALMA and
JWST are expected
to see…
Wilner et al.
2002
star
Synergy between ground and space
• SIRTF/Herschel/submm bolometer arrays will detect (largely
unresolved) mid- and far-infrared excesses around hundreds of stars
of different age, luminosity, evolution stage, …
• ALMA and JWST-MIRI will have the sensitivity to detect and image
dust in disks down to lunar masses at subarcsec resolution (down to
1 AU) out to distances of 300 pc
• VLTI-MIDI will be able to image the hot dust within few AU in
brightest systems
• Herschel will provide peak luminosity and spectral energy
distribution
• Complete spectroscopy 1 mm to 3 mm of both gas and dust by
combined VLT/JWST/Herschel/ALMA data in brighter systems
• GAIA essential to obtain accurate distances for analysis and statistics
Disks around brown dwarfs
Example of synergy between facilities
Herschel
Disk
BD
VLT
ALMA
10s
1hr
Natta & Testi 2001
-Brown dwarf with VLT
-Peak disk luminosity with Herschel (unresolved except in nearest objects)
-Mass + image cold dust and gas with ALMA
-Image warm gas with VLTI
Pathways to life?
Based on Ehrenfreund & Charnley 2000
Search for building blocks of pre-biotic molecules
Links between disks and comets
- Pre-biotic gas-phase molecules in disks with ALMA
- Ices in disks with VLT/JWST/OWL
- Silicates, organic refractory material with VLT/JWST/OWL
Silicates in disk: mid-IR
CO ice in disk: IR
Organics in protostars: mm
Malfait et al. 1998
Thi et al 2002
Cazaux et al. 2003
ALMA and JWST: perfect complement
• 0.3 - 7 mm
• 0.015 – few arcsec
• Thousands of lines
by hundreds of gasphase molecules
• CO as cold mass
tracer
• Cold dust (10-100 K)
• 1 - 28 mm
• 0.03 – 1 arcsec
• Major gas and solidstate species; PAHs;
atomic lines
• Direct observation
(warm) H2
• Warm dust (60-1000 K)