How Unique Are Nearby Debris Disks? Alycia Weinberger (DTM/CIW)
Transcript of How Unique Are Nearby Debris Disks? Alycia Weinberger (DTM/CIW)
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