White Dwarfs, Planets, Disks

Marc Kuchner

NASA Goddard Space Flight Center

Laboratory for Exoplanetsand Stellar Astrophysics

Laboratory for Exoplanetsand Stellar Astrophysics

NASA Postdoctoral Program:http://nasa.orau.org/postdoc/

Exoplanet Talks: http://eud.gsfc.nasa.gov/ Marc.Kuchner/exoplanetclub.html

Spitzer Space Telescope

White DwarfBill Reach (IPAC)Ted von Hippel, Don Winget,Mukremin Kilic, Fergal Mullaly(UT Austin)Adam Burrows (U. Arizona)

Wavelength (microns)

White DwarfG29-38

Zuckerman &Becklin 1987

1200 K0.15 Rsun

~40 Jupitermassesby age and T

H

He

CMg

Fe

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log mass (solar masses)

Rad

ius

(Ear

th R

adii)

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White Dwarf

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log mass (solar masses)

Rad

ius

(Ear

th R

adii)

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G29-38b ?

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Jupiter

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DZ

75% 10% 5% 10%

Helium Surface

Hydrogen Surface

No Lines fromSurface!

DQ

DX

Metal, Carbon,Or Unidentified

Carbon andOxygen Core

DA DCDB

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~20% of DAs, including G29-38

Hydrogen Surface with Metals

DAZ

CO core

Teff (K)

Bergeron et al. 2004

DA InstabilityStrip

L

og g

615s

P

ower

23 JUL 1988B-band

24 JUL 1988K-band

Patterson et al. 1991

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Pulsation Timing

(Kleinman et al. 1998) & speckle photometry (Kuchner et al. 1998)

HST/Gemini Photometry

(Debes et al. 2005)

Debes et al. 2005

Log R (AU)

MJu

pite

r

Deuterium Burning Limit

e.g. Debes & Sigurdsson 2002, Jura et al. 2003

Spitzer Space Telescope

White Dwarf

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Jupiter at 5 microns w/ ISO (Encrenaz et al. 1997)

Typical WD ages since formation ofprogenitor are 1.5 - 3.5 109 years.

Planet mass (MJupiter)0 5 10 15

0.3

0.2

0.1

0.0Pla

net/W

D a

t 4.5

mic

rons

109 yr.

3 109 yr.

Spitzer photometry

CIA

Bergeron et al. 1994

Kilic et al. 2006, ApJ, in press

Same Modelsw/ CIA

New Spitzer Photometry

Without the mid IR data:

5400 K, 3.5 Gyr old.

With the mid IR data:

5200 K, 4.5 Gyr old

FJ/FV

F8

m/F

VDZ

All Hydrogen WDs below ~7000 Kshow an 8 micron deficit!

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Galactic Disk:8 +/- 1.5 Gyr

Von Hippel et al., in prep

A New Dusty WD!

Kilic et al. 2005Becklin et al. 2005

Becklin & Zuckerman 1987

Kilic et al., in prepGD 56

Plus 2 more from IRTF and one from Farihi et al makes 5!

Amorphous carbon needed tomatch 1.6 m spectrum

amorphousolivine

forsterite

Reach et al. 2005

C:O ratio 3:11-10RSun

0.01-1000 m grains dn/da a-3.5

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Livio, Pringle & Saffer 1992

H

He

CMg

Fe

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log mass (solar masses)

Rad

ius

(Ear

th R

adii)

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White Dwarf

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C:O ratio in gas 9:1 Roberge et al. in press

11.3 micron C-Hout-of-plane bend

T Tauri Stars -- Spitzer

Geers et al 2005

Particle Plieups Youdin & Chiang 2004

Lodders& Fegley 1997

Wood &Hashimoto1993

Atomic Fraction

SiC

Forsterite

Cohenite

EnstatiteFe

EnstatiteChondrites?

Gas and Graphite

Gaidos 2000Kuchner & Seager 2005

Artist: Lynette Cook

Solar Composition

Kuchner & Seager 2005

Carbon Planet

Kuchner & Seager 2005

Kuchner & Seager 2005

Kuchner & Seager 2005

Tim

e o

f A

rriv

al R

esid

ual

s (

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w/o planets

withnon-interactingplanets

with realplanets

Konacki & Wolzsczan 03

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Cool Hydrogen WDs have mid-IR deficits; the inferred age of theGalactic disk is wrong by ~25%.

Roughly 1/4 DAZ WDs are dusty.

The dust sometimes has silicates----but it may be C rich (e.g. G29-38).

Carbon planets may be common; we can recognize them if they are hot.

Key Points

New Exoplanet Lab at Goddard: come join us as a postdoc or asa speaker!

Wavelength (microns)

Flu

x (m

Jy)

A WD Planet With A Dust Disk

Reach, Von Hippel& Kuchner et al. 2005

Plus one more from Farihi et al. (private comminucation).

That makes 5 dusty DAZs out of 20 DAZs with 8 micronPhotometery.

DAZd ?

New Dusty WDs from IRTF:GD56+GD362(Kilic et al 2006)

GD362 also found byBecklin et al. 2006

The SunGalactic Center

Carigi et al. 2005

Dead Star:White DwarfG 29-38

Solar SystemDust

6 8 10 12 14

Wavelength (microns)

Rel

ativ

e br

ight

ness

Spitzer Sees Ghostof Solar System’sFuture

Marc KuchnerGoddard Space Flight Center

Bill ReachSpitzer Science Center

Ted von HippelUniversity of Texas, Austin

Oppenheimer et al. 2001

Bergeron & Leggett 2002

UltraCool WDs (<4000 K)