model seds of massive ysos barbara whitney, tom robitaille, remy indebetouw, kenny wood, and jon...

Model SEDs of Massive YSOs

Barbara Whitney, Tom Robitaille, Remy Indebetouw, Kenny

Wood, and Jon Bjorkman

Do we need 2-D, 3-D models?

>100 m: no<100 m: yesExtremely young sources: maybe not (Osorio et al. 1999)

(van der Tak et al. 2000)

Outline• 2-D SED models

– Rotationally flattened envelopes, disks, bipolar cavities

• 3-D SED models– Clumpy molecular clouds

• Model grid and fitter • Focus on NIR/MIR spectra

– Lots of new data in this region (Spitzer)– 1-D models work fine for FIR/submm (Hatchell et

al. 2000, Buether et al. 2002, Mueller et al. 2002, Hatchell & van der Tak 2003, Williams et al. 2005)

Radiative Transfer Models

• Monte Carlo method• 3-D spherical polar grid• Calculates radiative equilibrium of dust

(Bjorkman & Wood 2001)• Non-isotropic scattering + polarization• Output: images + SEDs (+ polarization)• Not included: PAHs, stochastic heating

of small grains, optically thick gas emission

(Whitney et al. 2003a,b, 2004)

2-D YSO Model Geometry• Rotationally-flattened infalling envelope

(Ulrich 1976)• Flared disk• Partially evacuated outflow cavity

L*=40000T*=4000M*=17.5M=10-4

Md=1

Embedded Massive YSO

i Av

0 6

60 53

90 3e4

.

Embedded Massive YSO - No Cavity

i Av

0 45

60 68

90 3e4

L*=40000T*=4000M*=17.5M=10-4

Md=1

.

Massive Star+Disk

i Av

0 0

60 0.1

90 3e3

L*=40000T*=30000M*=17.5Md=0.1

Low-Mass Star + Disk

i Av

0 0

60 0.1

90 3e5

L*=40000T*=4000M*=17.5Md=0.01

Color-color plots (Spitzer IRAC)

o High-mass YSO

o High-mass YSO

X High-mass disk o Low-mass YSO

x Low-mass Disk

Allen et al (2004) disk domain

T*=30000 KT*=4000 KReddening

Vectors:AV=30

Summary of 2-D models

• Central star + disk spectrum contributes to SED, even in young embedded sources in 2-D geometries.

• Massive sources are redder in 3-8 m region than low-mass even for the same envelope Av.

3-D models

• Motivation– UCHII regions: 1-D models of mid-IR

spectra give too deep 10 m absorption for a given FIR flux, and too steeply rising SED in NIR/MIR (Faison et al. 1998, van der Tak et al. 2000)

Model Ingredients

• O star in a molecular cloud

• Use fractal ISM structure, D=2.6 (Elmegreen 1997)

• Average radial density profile is varied from r0 to r-2.5

• Smooth-to-clumpy ratio is varied from 3% to 100%

(Indebetouw et al. 2005)

Courtesy of Remy Indebetouw

IRAC MIPS

Images & SpectraNIR

Color-color plots

Smooth model

200 sightlines from 1 clumpy model

Fits to Data: G5.89-0.39

Best smooth modelBest clumpy modelGrey lines show other sight lines

Mid-IR data: Faison et al. (1998)

G5.89 Model parametersTstar 41000 K

L 2.54x105

Rin 0.0001 pc

Rout 2.5 pc

Menv 50000

Av_ave 131

Smooth/Clumpy 10%

Radial density ave~r0

Fractal dimension 2.6

All the UCHII Observations

Grey lines: G5.89 best model

Mid-IR data: Faison et al. (1998)

3-D Model summary

• UCHII regions may be O-B stars still embedded in their natal molecular clouds but not surrounded by infalling envelopes.

• Bolometric flux of clumpy models varies by a factor of 2 lower and higher than the true luminosity depending of viewing angle

(Indebetouw et al. 2005)

2-D/3-D Model grid + Data fitter

• Motivation: fitting GLIMPSE/2MASS data (7 bands from 1-8 m) of the inner galactic plane. (see Indebetouw talk). GLIMPSE has observed hundreds of massive star formation regions.– 24 m data will be available in the future

(Robitaille et al. 2005)

Grid Parameters (current)Stellar Mass 0.1-40 Msun

Stellar Age 104-107 yrs

Envelope Infall Rate 10-4-10-9 Msun/yr*Mstar

Disk Mass 10-1-10-8 Msun*Mstar

Disk Radius 10-1000 AU

Cavity Size 10-50 degrees

Aperture 1000, 5000, 20000 AU

Viewing Angles 10

1600 models completed in 2 weeks on 8 Mac G5 processors

Model grid: All Embedded YSOs

< 2 Msun2 < Msun < 5 > 5 Msun

All Disk (opaque) Sources

< 2 Msun2 < Msun < 5 > 5 Msun

Disks with Inner holes

Allen et al.Disk domain

All Disk (optically thin) Sources

< 2 Msun2 < Msun < 5 > 5 Msun

Disks with Inner holes

Allen et al.Disk domain

Embedded YSOs - 4 kpc*

< 2 Msun2 < Msun < 5 > 5 Msun

*AssumingGLIMPSEsensitivities

Opaque Disks - 4 kpc

< 2 Msun2 < Msun < 5 > 5 Msun

Inner holes

Allen et al.Disk domain

Optically thin disks - 4 kpc

< 2 Msun2 < Msun < 5 > 5 Msun

Inner holes

Allen et al.Disk domain

All Sources - 4 kpc

Embedded YSOOpaque disksThin disks

High massYSOs; and disks with inner holes

High mass(opaque and thin)Disks with inner holes

Embedded YSOand disks with noinner holes

Embedded YSOsand reddenedDisks

Fitter Description

• Uses linear regression to determine best fit to data

• Convolves models with any desired filter functions

• Distance and extinction range can be specified• Designed to work with large numbers of sources

– Fits 100 sources per second

• Produces statistics on quality and fit parameters

(Robitaille et al. 2005)

Tests on M16

data

Embedded Disk Embedded or disk

Future work• Expand grid

– More variations in model parameters– Add 3-D clumpy models– Use info from recent work (e.g., disks: Beuther et

al. 2004, Beltran et al. 2005 theory: McKee & Tan 2003), this meeting, and models of individual sources

• More testing of Model Fitter• Make grid & fitter publicly accessible with

batch jobs (web access)• RT:

– add PAHs and stochastic heating of small grains– Multiple emission sources