Star and Planet Formation with the GMTastronomy.swin.edu.au/research/conferences/CGMT/... · Alycia...
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Alycia J. Weinberger - Carnegie DTM Star and Planet Formation with the GMT What sets the stellar/substellar mass function and how universal is it? Do all stars form planets and if not, why not? What causes the diversity of planetary systems?
Transcript of Star and Planet Formation with the GMTastronomy.swin.edu.au/research/conferences/CGMT/... · Alycia...
Alycia J. Weinberger - Carnegie DTM
Star and Planet Formationwith the GMT
What sets the stellar/substellar mass function andhow universal is it?Do all stars form planets and if not, why not?What causes the diversity of planetary systems?
Weinberger - 6/14/2010
Nearby Star Forming Regions
Good News: Most are in the South Bad News: All are >100 pc away
Ophiuchus -24δ 120 pc ≤1 Myr Lupus -38δ 100 pc ≤ 1 Myr Corona Aust -37δ 170 pc ≤ 1 Myr Chamaeleon -77δ 170 pc 2.5 Myr Upper Sco -30δ 140 pc 5 Myr
4 AU at 150 pc = 27 mas (separate “inner” and “outer”Solar System)
Diffraction limit (λ/D) of GMT at 1.6 µm is 13 mas
Weinberger - 6/14/2010
106 yrs 107 yrs 108 yrs 109 yrs
CAI /ChondruleFormation
Moonforming
Impact (30+ Myr)
Current age ofthe Sun:
4.5x109 yrs.
Late HeavyBombardment
(600 Myr)
Star-formationto solidformation
Massive,gas-richdisk
Planetesimaldominateddisk Dust / planet
dominated diskGas Removal
Giant planetsform
Terrestrialplanets
form
Planetary Formation Timescales
Astronomer’st0
Alycia Weinberger 2009
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Stellar and Disk Co-Evolution
(Tom Greene)
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Embedded protostar with disk
1 100 Log(λ) [µm]
Log
(Flu
x D
ensi
ty)
Flat spectrum and/or “Class I”
Log
(Flu
x D
ensi
ty)
Class II
Want to learn simultaneously about the star and its disk
1 100 Log(λ) [µm]
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Initial Mass Function and Disks
•How many stars/brown dwarfs arethere?•Do they have disks?•Is the disk lifetime the same as forstars?
Example: OphiuchusSize: ~7 X 7 Deg (cloud core plusextended region) GMACS FOV: 8 x 18’ NIRMOS FOV:5.5 x 5.5’
IMACS limiting magnitudeI~21.5, S/N=30, in 4 hr @ R~2000
10-4 Lsun or 3- 5MJ15% too faint (>21.5) for IMACS
IMACS 12x12’ (Gully-Santiago)
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Initial Mass Function in Star Form. Reg.1 MJ object = 840 K, i.e. T dwarf, with K~19
~1 hr at R~400 with GMT
(Knapp et al. 2004)
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Astrophysics of Young Stars
Log (Teff)
log
g
(Doppmann et al. 2005)
Keck 0.3-2 hr /source a R~18,000
A wide range ofluminosities andgravities (andtherefore ages)appear for stars of alltypes
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Stellar Magnetic FieldsDisk evolution is supposedly magnetically drivenOnly a handful of stars have directly measured fields
(Johns-Krull et al. 2009)
Measure Zeeman splitting (or broadening) of lines such as Ti I.
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Direct Observations of CircumstellarDisks and origins of the diversity ofplanetary systems
Disk Spectroscopy Direct measurement of gas content and
temperature High spectral resolution proxy for spatial
resolution (gas close to the star moves fast) High spatial resolution to resolve the disk directly
(Spectroastrometry) Disk Imaging
Direct measurement of structure Composition from low-resolution spectroscopy of
emitted and scattered light
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Origin of Isotope Ratios
CO self-shielding: Lyons & Young (2005) suggestedthat irradiation of our young disk generated our18O/17O/16O ratios
Need O to be incorporated into water
(R. Smith et al. 2009)
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Where is ice line / where is the water?
Giant planets mayform more efficientlyoutside the ice-line
Water-richplanetesimals fromoutside the ice-linemay deliver water todry inner planets
Salyk et al. 2008, ApJLNIRSPEC, R~25,000
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What are gas densities in planet region?
“Spectroastrometry” Analogous to centroiding to
0.01 pixel Find gas within 1/100 of a
spatial resolution element(~0.3 mas for VLT, 0.1 masfor GMT)
Requires S/N>100 oncontinuum and resolving linekinematically
Need aperture for low lineflux sources: detections are10-16 - 10-17 W/m2
Need excellent calibration inhigh continuum/line sources
Pontoppidan et al. 2008, ApJ, 684, 1323VLT CRIRES+AO, Tint=32 min, R~100K
S/N=280
-30 -20 -10 0 10 20 30 Velocity [km/s]
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Effect ofCompanions?
Disk is transitional•Contains gas
Scattered Light• Large extent (400 AU)• Red visible – near-IR color
HD 141569A
Mid-IR Emission•Compact extent•PAHs
Star: A0, 16.5 L, 5 Myr old
(Weinberger et al. in prep)
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Spatially resolved disk kinematics
AO allows disk rotationcurves Combined constraint of
kinematics and size Consider the relevant
scales GMT DL at 5 µm = 0.″04 Closest sites of ongoing
star formation - 150 pc;GMT probes 6 AU (aboutwhere Jupiter formed) Goto et al. 2006, ApJ, 652, 758
Subaru IRCS+AO, Tint=20 min, R~20K
When do planets form?When does gas in inner diskdisappear?
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Spatially Resolved Spectra of Emission
Terr
estr
ial O
3
Central Disk Spectrum24 AU (0.’’24)
168 AU (1.’’68)
• • •
192 AU (1.92 AU) - Backgd
(Rainbow step every 24 AU)
Weinberger et al. in prep
~1.5 hr at Keck
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Where are the silicates?
•Hidden under carbon? This explains red colortoo.
PAH+SilicatePAH+AmorphousCarbon+BB
Weinberger et al. in prep
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Imaging Ices
(Inoue et al. 2008)
Imaging of scattering from water ice in disks
mJy/sq.arcsec
Honda et al. 2009)
HD 142527
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Watchng planet formation
335 yr
339 yr
346 yr
If planets form bygravitational instability(Boss 1997), spiralarms in disk may beobservable inscattered light.
Need high contrast innear-infrared: 10-7 to10-9
(Jang-Condell & Boss 2007)
10 mas 30 mas
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Observing planets in disks
(Jang-Condell & Kuchner 2010)
It should bepossible todetect planetsforming in theouter parts ofclassical TTauri stardisks
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Planet Spectroscopy
GMTIFS offset to “planet” location. Usespatial information to correct for scatteredlight at each wavelength. Preferable to longslit.
McElwain et al. 2008Keck, OSIRIS
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Spectra of Young Exosolar Planets
Tiger
Fomalhaut planetappearsdominated by ascattered lightdisk. Could learnabout both.
(Kalas et al. 2008)
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Detecting Planets in Debris Disks
Figure Credit: Chris Stark (U MD)
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Uses of 1st Generation Instruments forstar and planet formation studies
•GMTNIRS - Probing stellar astrophysics, disk kinematics and composition•Tiger / ExAOCam - Imaging disks and planets in disks, composition
•GMTIFS - Imaging young planets, disks•GMTNIRS / GMACS - Finding brown dwarfs in star forming regions•GCLEF - Debris disk gas, kinematics
GMT will enable many creative projects not envisioned yetand like each generation of large telescope, enablequalitative leaps in measurement ability.
