How Unique Are Nearby Debris

Disks?Alycia Weinberger (DTM/CIW)

Dustiness

Are the disks we resolve “typical” for their ages?

Dustiness for their agesL I

R/L

*

(Spangler et al. 2001)

AU Mic * *HD 107146

*

HD 32297

*HD 141569

*HD 92945

*BD+20 307

*HD 69830

(Rieke et al. 2005)

Stochastic or Steady-State?

Collisions Make Dust

Kenyon & Bromley 2005

Planet building should generate copious dust.

Are These Disks Very Dusty?

Fig 8 of Kenyon & Bromley 2005

Dust content actually observed exceeds this calculation:•Primoridial Material?•More planetesimals?•Recent Collisions?

HD 141569

HD 32297(MMSN)

Composition

Disk Visible / Near-IR Colors

HD 141569A red (V-J; J-K)HR 4796A red (V-J;J-H) Pic neutral-red (B-I)AU Mic neutral -blue (R-H)HD 107146 red (V-I), ?? (V-J)HD 92945 neutral (V-I)

Not Rayleigh Scattering Why?

Color of Silicates

Mid-Infrared Colors

Access to temperature information:

L=8.25L

( Pic)

Mid-infrared imaging

12 m 18 m

Gemini South (T-ReCS); Telesco et al. 2004

What causes the asymmetry to decrease with wavelength?

Silicate Distribution: Spatially Resolved Mid-IR Spectroscopy

Wavelength (m)

Flux D

ensi

ty (

Jy)

8 AU

16 AU

Weinberger et al. 2003, ApJL

Example:

Pic

Continuum Subtracted Spectra

All Silicates Lie Close to the Star --Planet Induced Collisions?

Wavelength

Sili

cate

Lin

e -

Conti

nuum

R=0

R=8 AU

R=16 AU

R> 24 AU

Weinberger et al. 2003

Grain Populations

Only see silicates out to 25 AU

Crystalline silicates centered at star, but small amorphous silicates not!

Okamoto et al. 2004, Nature

Same ellipticity! Same PA!Different sizes!

IceSublimation?

Reflected & Emitted Light

Weinberger et al. 1999Marsh et al. 2002

8 m (contour)PSF (grayscale)

8 m (contour)11.7 m (grayscale)

Disk is same size at 8 & 12 m!PAHs!

N

E

New Mid-Infrared Imaging

Spatially Resolved Spectra

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)

These are all PAHs not Silicates!

Increasing Line Strengths

Central Disk Spectrum

72 AU

48 AU24 AU

Are PAHs being lifted off grains far from the star? Evidence of gooey organics?

Flu

x /

Conti

nu

um

Wavelength (microns)

More typical compositionF

/V

Fv

HD 36112 = MWC 758Luminosity --- Same!Age ------------Same!

But LIR Much Bigger

Crystalline and amorphous silicates

Dustiness for their agesL I

R/L

*

(Spangler et al. 2001)

AU Mic * *HD 107146

*

HD 32297

*HD 141569

*HD 92945

*BD+20 307

Signature of Huge Impact?

CDE1 ForsteriteEnstatiteAmorphous olivine

Amorphous pyroxeneBlackbody

HIP 8920: Small Grains (Song et al. 2005, Weinberger et al 2006)

Silicate Feature -Small Grains

Fnu (

Jy)

Wavelength (microns)

Silicate-less Debris Disk (Jura et al.)

HIP 8920

Reach et al. 2003

Zodi

Hanner et al. 1994

Song et al. 2005

Formation Region

Did the NRDD form in environmentssimilar to the Sun?

Pic Association ( Pic, AU Mic)

Looks Taurus-Like not Orion-Like

Song et al. 2003

TW Hy Association (HR 4796) also fairly spread/sparse

0

100

200

300

400

500

600

700

800

0 0.5 1 1.5 2

B-V

Li

67

08

A E

qu

ivale

nt

Wid

th [

mA

] Pleiades (100 Myr)

NGC 2264 (5 Myr)

TW Hydrae

Eta Chamaeleontis

HD 141569 B and C

HD 141569 Rejected

Possible HD 141569 NewMembers (Kinematic)MA

(~8Myr)

Kinematic and Youth Selection

Galactic Coordinates of Known Associations

-30

-20

-10

0

10

20

30

40

50

60

70

250270290310330350370390410

Upper Scorpius

Centaurus-Lupus

TW Hydrae

Eta Cha

Epsilon Cha

HD 141569

HD 141569 not accepted

HD 141569 23 acceptedl [°]

b [

°]

50 30 10

Galactic Coords of Young Stars

Where Did the Sun Form?

• 60Fe with t1/2 = 1.5 Myr Found in Solar System (Tachibana & Huss 2003)•Truncation of the Kuiper Belt (e.g. Kobayashi, Ida & Tanaka 2005)

•Formation of Ice Giant and Saturn Compositions (Boss, Wetherill & Haghighipour 2002)

•Triggered Star Formation in Ionization Fronts

Evidence for “Orion-Like” Environment:

eCourtesy Jean SchneiderExoplanet Encyclopedia

Ecc. of Exosolar Planets

The 6 Year Future

Spitzer detections of new debris disks Spitzer determinations of disk lifetimes Spitzer mineralogy of dust Ground mid-infrared interferometer

measurements of inner disks and their compositions

SOFIA searches for H2 emission HST and AO imaging of Spitzer detected

disks Detection of disk rotation ( Eri) Detection of planets in disks (ExAO?)

The End

Silicate Spectra (thick)

HD 36112A35-10 Myr

HD 37258A21-10 Myr

UX OriA31-2 Myr

VX CasA01 Myr

Flu

x D

ensi

ty

Wavelength (m)

Recall that the ages are not well known

Roberge et al. 2000, 2002, 2004

Gas : Dust Ratio

AU Mic Beta Pic ISM

Spec. Type M1 A5

L (Lsolar) 0.1 8.7

Mdust (M)0.01

(Liu et al. 2004)

0.04(Dent et al.

2000)

MH2 / Mdust < 4:1 < 3:1 100:1

When Gas:Dust Low and CO/H2 high CometSublimation not primordial gas/dust

A “Real” Debris Disk - Ours!

Our Solar System has only atenuous disk (Zodiacal Cloud)but also has planets [Cassini (1685)]

Zodi: 10-10 Mplanets; 100x IR luminosity

Evidence for planets in debris disks

What do we look for? Dust sculpted dynamically

GapsAsymmetries (e.g. arcs, warps)Clumps

The Kuiper Belt