Spectroscopic Analysis of the mid-IR excesses of - PowerPoint Presentation

Slide1

Spectroscopic Analysis of the mid-IR excesses of WDs

Jana Bilikova

1

You-

Hua

Chu

1

, Kate Su

2

, Robert Gruendl

1,

et al.

1

U. of Illinois at Urbana-Champaign,

2

U. of Arizona Slide2

Spitzer MIPS 24 μm

Survey of Hot WDsWD Name PN

Teff (kK) F24(mJy) LIR/L*

K1-22 K1-22 141 1.07 3.1 E-5NGC 2438 NGC 2438 114 12.4 4.5 E-4

WD 0103+732 EGB 1 150 2.76 1.3 E-5

WD 0109+111 110 0.27 4.9 E-6WD 0127+581 Sh2-188 102 0.34 2.7 E-5WD 0439+466 Sh2-216 95 0.98 3.7 E-6WD 0726+133 Abell 21 130 0.92 1.6 E-5WD 0950+139 EGB 6 110 11.7 2.6 E-4WD 1342+443 79 0.22 4.0 E-5WD 2226-210 Helix 110 48.0 2.5 E-4Slide3

Spitzer Archival search

Serch for CSPNs with IR excess

60 PNe examined

18

photometry carried out 6 show IR excess: NGC 6804, NGC 7139 NGC 2438, NGC 2346, NGC 6853, NGC 6905Slide4

Mid-IR emission of hot WDsSlide5

Possible Origins of IR Excesses

Collisions of KBOsBinary evolutionCompact nebulosity in born-again PNeSlide6

6

KPNO

Echelle

Spectra

[OIII]

Hα

Abell 30

NGC 2438

EGB 6

EGB 1

H-poor: feature in [OIII] does not show up in H

α

All

[OIII] features show

H

α

counterparts

Can eliminate the

compact H

-poor

nebulosity

scenarioSlide7

Our dust disk model

Optically thinDust grains - silicates/amorphous carbon

- sizes: n(a) ~ a-3.5 - amin set by β=Frad/F

g of 0.5 (Artymowicz & Clampin

1997)

- Qabs from Mie theoryUniform surface density Slide8

WD 0439+466

The closest CSPN Sh2-216D=129 pc (Harris et al. 2007)

8

40’’

5’Slide9

Sh

2-216 model

Teff = 95,000 Klog g = 6.9

M = 0.55 ML = 160 L



(Rauch et al. 2007)amin ~ 40-80 umR ~ 60-100 AUM = 0.001 MearthSlide10

CSPN K1-22

40’’

2’’

HST has resolved a companion at 0.35’’ (~450 AU) from the CSPN (

Ciardullo

1999). D = 1.33 kpc (Ciardullo 1999)Slide11

CSPN K1-22 model

T

eff = 141,000 Klog g = 6.73

M = 0.59 M(Rauch et al. 1999)L = 325 L



(phot)Kurucz model atm.Teff = 5,000 KM0V staramin ~ 250 umR ~ sublim - 40 AUM = 0.002 Mearth

[O IV]

[Ne III]Slide12

WD 0103+732

D

istance = 650 pc (Napiwotzki 2001)Slide13

WD 0103+732 model

T

eff = 147,000 Klog g = 7.34

M = 0.65 M(Napiwotzki 2001)

L = 480 L

 (phot)amin ~ 340 umR ~ 200 - 360 AUM = 0.14 MearthSlide14

Beware!

Detailed spectral shape of the WD matters - model atmospheres have more UV emission 

hotter grains  disk properties - e.g. WD 0103+732: ~480 Lsun, Rin ~ 200 AU ~1000

Lsun, Rin ~ 500 AUDistance matters

-

dist+phot  LWD amin  disk properties - e.g. K1-22: d=1.33 kpc, L~300 Lsun d=3.4 kpc, L~1000 Lsun

More complicatons

Slide15

WD 0950+139 (EGB 6)

Compact emission line source coincident with

the CSPN

(

Fleming,

Liebert, Green 1986) JHK excess (Fulbright & Liebert 1993)HST: A companion 0.18 ‘’ away (Bond 1994)IRAC, MIPS excessFeatureless spectrum

Su et al., in prep.

KPNO echelleSlide16

CSPN NGC 6804

Spitzer MIPS 24 um

Central emission line source

Dust continuum, rising from J band

We also see a silicate feature at 10 um.

Gemini NIRI+MichelleSlide17

ORIGINS

KBO collisionsInner and outer edge (~100 AU)Small dust mass (~0.1 Mearth

)Not too far for collisions (Dong et al.,Bonsor & Wyatt)Post-AGB binariesSome CSPNs are binaries (maybe others hide a companion?)CSPN stage right after post-AGB (do post-AGB binaries evolve into PNe

?)Slide18

Conclusions

Near and mid-IR excess is a good indicator of interesting phenomena

Great variety among IR excesses

Near-IR excess only, mid-IR excess only, both

No emission lines, only emission lines, both

Featureless dust continuum, mineralogical featuresKnown companions, no companionsEach needs to be studied in detail individuallyStellar atmospheric models

Stay tuned!