catching planets in formation with gmt

Alycia J. Weinberger -

Carnegie DTM

Catching Planets in Formation with 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?

SP

EC

IME

NS

PE

CIM

EN

Weinberger - 10/4/2010

Nearby Star Forming Regions

Good News: Most are in the South Bad News: All are >100 pc away

Ophiuchus -24 120 pc ≤1 Myr Lupus -38 100 pc ≤ 1 Myr Corona Aust -37 170 pc ≤ 1 Myr Chamaeleon -77 170 pc 2.5 Myr Upper Sco -30 140 pc 5 Myr

4 AU at 150 pc = 27 mas (separate “inner” and “outer” Solar System)

Diffraction limit (/D) of GMT at 1.6 m is 13 mas


106

yrs107

yrs108

yrs109

yrs

CAI /ChondruleFormation

Moonforming

Impact (30+ Myr)

Current age of the Sun:

4.5x109 yrs.

Late Heavy Bombardment

(600 Myr)

Star-formation to solid formation

Massive, gas-rich disk

Planetesimal dominated disk

Dust / planet dominated disk

Gas RemovalGiant planets

form

Terrestrial planets

form

Planetary Formation Timescales

Astronomer’s t0

Alycia Weinberger 2009


• Substantial mismatch between predicted and observed distribution of exoplanets.

• Major uncertainties:• How do gas-giant planets form.• How much do planets migrate.• Are there many habitable (water, etc) planets.

•Need to extend observational phase space:• Probe lower masses.• Detect very young planets.• Determine composition.

Main Questions


Disks: How to make, compose and possibly destroy planets


Watching planet formation

335 yr

339 yr

346 yr

If planets form by gravitational instability (Boss 1997), spiral arms in disk may be observable in scattered light.

Need high contrast in near-infrared: 10-7 to 10-9

Synergy with ALMA

(Jang-Condell & Boss 2007)

10 mas 30 mas


Where is ice line / where is the water?

Giant planets may form more efficiently outside the ice-line

Water-rich planetesimals from outside the ice-line may deliver water to dry inner planets

Salyk et al. 2008, ApJLNIRSPEC, R~25,000


Imaging Ices

(Inoue et al. 2008)

Imaging of scattering from water ice in disks

mJy/sq.arcsec

(Honda et al. 2009)

HD 142527


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 mas for GMT)

Requires S/N>100 on continuum and resolving line kinematically

Need aperture for low line flux sources: detections are 10-16 - 10-17 W/m2

Need excellent calibration in high continuum/line sources

QuickTime™ and a decompressor

are needed to see this picture.

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]


Observing planets in disks

(Jang-Condell & Kuchner 2010)

It should be possible to detect planets forming in the outer parts of classical T Tauri star disks


Effect of Companions?

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)


Spatially resolved disk kinematics

AO allows disk rotation curves Combined constraint of

kinematics and size Consider the relevant

scales GMT DL at 5 m = 0.04 Closest sites of ongoing

star formation - 150 pc; GMT probes 6 AU (about where Jupiter formed)



Goto et al. 2006, ApJ, 652, 758Subaru IRCS+AO, Tint=20 min, R~20K

When do planets form?When does gas in inner disk disappear?


Spatially Resolved Spectra of Emission

Te

rre

stri

al 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


Young Planets Themselves: Where they are and what they are made of


Free Floaters

•How many stars/brown dwarfs are there?•Do they have disks?•Is the disk lifetime the same as for stars?

Example: OphiuchusSize: ~7 X 7 Deg (cloud core plus extended region) GMACS FOV: 8 x 18’ NIRMOS FOV:5.5 x 5.5’

IMACS limiting magnitude I~21.5, S/N=30, in 4 hr @ R~2000

10-4 Lsun or 3- 5MJ

15% too faint (>21.5) for IMACS

IMACS 12x12’ (Gully-Santiago)


Analogs and Intrinsically Interesting

1 MJ object = 840 K, i.e. T dwarf, with K~19

~1 hr at R~400 with GMT

(Knapp et al. 2004)


Discovery Space for Planet Imaging



Olivier Guyon (U. AZ)


Discovery Space for Young Planets

• Contrast of young giant planet and star ~10-6 makes them easier to image

•“TIGER” instrument is being developed as potential first-light imager.

(Phil Hinz, U. AZ)


Planet Spectroscopy

GMTIFS offset to “planet” location. Use spatial information to correct for scattered light at each wavelength. Preferable to long slit.

McElwain et al. 2008Keck, OSIRIS


Example: Pic Planet (~8 MJup)

•0.’’35 from and 7.7 mag fainter than the star

•“only” need 104 contrast•This is >10 /D for GMT

•L’/M=11.1 mag (in principle can get GMTNIRS spectrum at S/N=100 in 1 hr)

•Molecular composition•Auroral emission (magnetic field)•Variability (rotation, winds)

Quanz et al. 2010


Spectra of Young Exosolar Planets

Tiger

Fomalhaut planet appears dominated by a scattered light disk. Could learnabout both.

(Kalas et al. 2008)


Detecting Planets in Debris Disks

Figure Credit: Chris Stark (U MD)


Uses of 1st Generation Instruments for star and planet formation studies

•GMTNIRS - Probing stellar astrophysics, disk kinematics and disk and even planet composition, radial velocity studies•Tiger - Imaging disks and planets in disks, composition•GMTIFS - Imaging young planets, disks•GMTNIRS / GMACS - Studying free floating planets and brown dwarfs in star forming regions•GCLEF - Debris disk gas, radial velocity studies

GMT will enable many creative projects not envisioned yet and like each generation of large telescope, enable qualitative leaps in measurement ability.


Stellar and Disk Co-Evolution

(Tom Greene)


Embedded protostar with disk

1 100 Log() [m]

Log

(F

lux

Den

sity

)

Flat spectrum and/or “Class I”

Log

(F

lux

Den

sity

)

Class II

Want to learn simultaneously about the star and its disk

1 100 Log() [m]


Stellar Magnetic Fields

Disk 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.


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 of luminosities and gravities (and therefore ages) appear for stars of all types

Most embedded, veiled objects do seem younger than optically revealed ones (White & Hillenbrand 2004)-- need IR


Origin of Isotope Ratios

CO self-shielding: Lyons & Young (2005) suggested that irradiation of our young disk generated our 18O/17O/16O ratios

Need O to be incorporated into water

(R. Smith et al. 2009)


Direct Observations of Circumstellar Disks and origins of the diversity of planetary 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

catching planets in formation with gmt

Documents

young planets

gasgiant planets form

velocity kmsobserving

inner disk

au backgdrainbow

ice line

water ice

disk kinematicsao