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Neptune Mass Exoplanets

Jeff Valenti

MJupiter / 19 = MNeptune = 17 MEarth

Geoff Marcy (Berkeley) Debra Fischer (Yale)

Andrew Howard (Berkeley) John Johnson (Caltech)

Howard Isaacson (Berkeley) Jason Wright (PSU)

Jay Anderson (STScI) Nikolai Piskunov (Uppsala)

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Key Points

Core-Accretion planet formation scenario

Metal-rich stars have more Jupiter mass planets

Msini sensitivity has steadily improved

Largest Msini in a system constrains models

Measuring [Fe/H] for M dwarfs is hard

Known systems with Msini < MNep are metal poor

Core-Accretion predicts “planet desert” below MNep

Set limits on Msini of undetected planets

Extrapolating mass function to super-Earths

Radial velocities affected by “jitter”

Improving velocity precision with “grand solution”

Host

meta

llicityM

ass

functio

n

3

Core Accretion Planet Formation

Early PhaseSticking andCoagulation

Middle PhaseGravitational

Attraction

Late PhaseGas Sweeping

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Synthetic Spectrum Fits

6223 K5770 K5277 K4744 K

Valenti & Fischer (2005, ApJ, 159, 141)

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Metal rich stars have more Jupiter-mass planets

Core-Accretion!

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Msini sensitivity has steadily improved

Mass ofNeptune

Lowest Massin FV (2005)[K < 30 m/s]

exoplanets.org

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[Fe/H] of host star vs. lowest Msini in system

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[Fe/H] of host star vs. highest Msini in system

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G+M binaries constrain photometric [Fe/H] for M dwarfs

[Fe/H]+0.24

+0.45

+0.28+0.31

+0.21

+0.21Jupiters

Neptunes

Binaries

Johnso

n &

Apps (2

00

9, A

pJ, 6

99

, 933)

IR: Barbara Rojas-Ayala

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Improve [Fe/H] for M dwarfs

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Known systems with Msini < MNep are metal poor

Star Max MsinI [Fe/H]

HD 156668 4.2 +0.05

CoRot-7b 5.0 +0.05

GJ 1214 6.5 ?

HD 1461 8 +0.18

HD 97658 8.2 -0.23

GJ 176 8.3 -0.1

HD 7924 9 -0.15

HD 40307 9.1 -0.31

GJ 674 11.1 -0.3

HD 4308 15 -0.31

GJ 581 15.7 -0.2

HD 69830 18 -0.06

HD 125612 19 0.24

HD 190360 19 0.21

HD 219828 19.8 0.19

Mass ofNeptune

Mean[Fe/H]

is-0.13

Still needto evaluate sample bias

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Current models predict a “planet desert”

Gas GiantsGas Giants

Ice GiantsIce GiantsMass ofNeptune

Snow Line

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Set Limits on Mass of Undetected Planets

Bad Case, N=22

Good Case, N=131

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Dete

ctio

ns

Can

did

ate

sFA

P <

0.0

5

Planets

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Observations Disprove Current Models

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Planetary Mass Function (P < 50 days)H

ow

ard

et a

l. (20

10, S

cien

ce, 3

30

, 6

53

)

HD 179079 – Apparent Uncertainties

Error bars = stddev(vseg-vmean)/√Nseg

M sin i = 27.5 MEarth

Radial velocities affected by “jitter”V

ale

nti e

t al. (2

009, A

pJ, 7

02, 9

89)

Analysis componentStellar component

Plenty of Constraints for Grand Solution

Radial Velocities for GJ 412a

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Key Points

Core-Accretion planet formation scenario

Metal-rich stars have more Jupiter mass planets

Msini sensitivity has steadily improved

Largest Msini in a system constrains models

Measuring [Fe/H] for M dwarfs is hard

Known systems with Msini < MNep are metal poor

Core-Accretion predicts “planet desert” below MNep

Set limits on Msini of undetected planets

Extrapolating mass function to super-Earths

Radial velocities affected by “jitter”

Improving velocity precision with “grand solution”

Host

meta

llicityM

ass

functio

n