ObservationaObservational l Constraints Constraints on the on the Formation Formation and and Properties Properties of Giant of Giant PlanetsPlanets

Jeff Valenti

Orbital Properties of Planets

Observed Planet-Metallicity Relationship Two competing planet formation theories We measured lots of stellar abundances Higher metallicity stars have more detected planets!

Not caused by accretion of rocky debris

Timescale for Building Gas Giant Planets Our HST detection of hot H2

Characterizing Transiting Planets My HST program to observe an evaporating exosphere JWST spectra of atmospheric absorption and emission

Road Map for the Talk

Planet DiscoveryPLANET consortium

SWEEPS, XO

N2K, Ge

Planets Migrate!http://exoplanets.org/a_hist.gif

“Snow Line”

Pile-up at P=3 days

Disk is Truncated by Stellar Magnetosphere

Shu et al. (1994)

Milky Way & CookiesMonday, April 3

Two Theories of Planet Formation

Metals : 0.1 nm

Dust : 1 nm – 1 mm

Planetesimals : 1 mm – 1 km

Cores : 1 km – 1 Mm

Planets : 1 Mm – 0.1 Gm

Core-AccretionCore-Accretion

GravitationalGravitationalInstabilityInstability

crit nH

Do Metals Matter ?

Do Metals Matter ?

SME - “Spectroscopy Made Easy” Valenti & Piskunov (1996, A&AS, 118, 595) Publicly available

Radiative transfer code [with Nikolai Piskunov] LTE, Feautrier solver, Adaptive λ grid, C++ Chemical equilibrium for over 150 molecules (NextGen EOS)

Fit observed spectrum with synthetic spectrum Use precise atomic data from solar spectrum fit Interpolate Kurucz atmospheres in Teff, logg, and [M/H] Calculate synthetic intensities across the stellar surface

Integrate over stellar surface: rotation and RT macroturbulence

Non-linear least squares solver (Levenberg-Marquardt) Free parameters: log(gf), Teff, logg, [M/H], etc.

Spectroscopic Analysis Tool

Determining Spectroscopic Properties

Segment #1

Segment #2

Valenti & Fischer (2005)

Stellar Macroturbulence

Valenti & Fischer (2005)

Isochrone Analysis

1040 Stars

T, L, Fe,

M, R, age

Spectroscopic Properties of Cool Stars

Valenti & Fischer (2005, ApJS, 159, 141) 1807 observed spectra (6 CPU months) 1040 nearby dwarfs and subgiants N2K: 410 Keck + 400 Subaru + 270 Magellan spectra analyzed

Properties based on fitting spectra Effective temperature (1%) Surface gravity (15%) Rotational velocity (0.5 km/s) Abundances: Na, Si, Ti, Fe, Ni (5-10%)

Properties based on matching evolutionary models Stellar mass (15%) Radius (3%) Age constraints

Metals in Full Sample and Stars with Planets

Quadratic Dependence on Stellar Metals

p = (10 [Fe/H])

= ( N(Fe) M)

= (4.5 ± 0.8) % = (1.8 ± 0.3)

N(Fe) M

Increasing metals by 40% doubles the number of stars with planets

Fischer & Valenti (2005)

Dependence on Stellar Mass? Fischer & Valenti (2005)

Cooler Stars

Metallicity bias…

Does Accretion Cause Planet-Metallicity Relationship?

6500 6000 5500 5000TEFF (K)

0.0

-0.2

-0.4

-0.6

0.2

0.4

0.6

[M/H]

Stars withPlanets

Pinsonneault, De Poy, & Coffee (2001)

1 M

Subgiants with and without Planets

6500 6000 5500 5000TEFF (K)

4.0

6.0

8.0

2.0

0.0

M bol

Planets

Subgiants

Subgiant Test – No Diluted Enrichment

6500 6000 5500 5000TEFF (K)

4500

-0.2

-0.6

0.2

0.6

[Fe/H]

Subgiants with planets are still metal rich

[Fe/H]=0.15

Velocity Precision vs. Metallicity

Line Depths NOT Proportional to Abundance

Strong Lines are Saturated

Metals Do Not Affect Migration Stopping Point

Stars with Distant Planets Seem To Be Metal Rich

3% of Keck sample has long period

planets

Statistics are improving where giant planets form.

Next Step: Detection Limits for Each Star

Adapted from Cumming(2004, MNRAS, 354, 1165)P < 4 yr

K > 30

m/s

30 m/s

N=15

N=30

p=99%p=50%

FV05

Classical Core-Accretion Model Is Slow

Phase ICore formation

via rapid accretionof planetesimalsin “feeding zone”

Phase IIEnvelope formation viagradual gas accretion

Phase IIIGiant planet formationvia rapid gas accretion

Pollack et al. (1996)

IsolationMass

Core Only

Core +Envelope

Dust Near a Star Dissipates Quickly

Haisch, Lada, & Lada (2001)

Warm dust only lasts “a

few Myr”

How long does the gas last?

Hot Inner Edge(s) of Disks

Akeson et al. (2006)

RY TauSU Aur

Molecular Hydrogen in Accretion Disks

Herczeg et al.(2002; 2004; 2005)

Ly- Pumped Fluorescence of Hot H2Herczeg et al. (2004)

Ly- Pumped Fluorescence of Hot H2Herczeg et al. (2004)

Find planets that transit bright (V<12) stars Absorption by planetary atmosphere during transit Thermal emission in and out of secondary eclipse 1) HD209458b, 2) TrES-1, 3) HD189733b, 4) HD149026b

N2K Survey Fischer (SFSU), Laughlin (UCSC), Valenti (STScI), … Surveying the “next 2000” stars, V<10.5 (14,000 candidates)

Constructed metal-rich sample using photometric indexes

“Three strikes and you’re out!” - focus on short periods

So far: 410 Keck + 400 Subaru + 270 Magellan stars So far: 7 planets announced + 3 in press + 36 candidates

So far: 1 new transiting planet!

Comparative Planetology

“N2K” Discovers Its First Transiting Planet!

Subaru & Keck– 0.5 0.0 0.5

Orbital Phase

– 40

0

40

Velocity (m/s)

HD 149026

Sato et al. (2006)

Diversity of Planets - Formation vs. Evolution

Bouchy et al. (2005)Evaporating

Exosphere Program 10718

Evaporating Exospheres

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Vidal Madjar et al. (2003)

Planetary Transits with JWST/NIRSpec

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Brown (1991)

R=3000

Planetary Eclipses with JWST/NIRSpec

Spitzer

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R=3000

Key Results Spectroscopic Properties of Cool Stars (SPOCS)

1040 solar-type stars in Keck, Lick, AAT planet search programs

Analyzing another 2000 stars in N2K program

Quantified Planet-Metallicity Relationship Increasing metals by 40% doubles the number of stars with planets

Not due to preferential accretion of metals onto star Inconsistent with gravitational instability (migration?) Fundamental constraint on all formation models

HST and JWST will characterize disks and atmospheres Use fluoresced H2 to study gas in protoplanetary disks Measure extent of planetary exosphere during transit Obtain atmospheric absorption spectra during transit Measure thermal emission spectra in/out of secondary eclipse