Heiles meeting, Sep 04

Where is the Atomic Carbon in Ophiuchus

Di Li

Paul Goldsmith

Gary Melnick

and SWAS team

Heiles meeting, Sep 04

Heiles meeting, Sep 04

JCMT 850 Micron

Heiles meeting, Sep 04

Telescopes

Heiles meeting, Sep 04

Mapping Parameters

FCRAO• 44” resolution at 2.6mm

• Beam sampling

SWAS• 4.2’ resolution at 0.6mm

• Nyquist Sampling

Line RMS V t_int Spectra

CO 2.5K 0.4 km/ s 15s 28840

13CO 0.7 0.1 30 26384

C18O 0.5 0.1 60 7631

CI 0.3 0.6 80 1271

Heiles meeting, Sep 04

CO Raw Data

Heiles meeting, Sep 04

Temperature Structure

Heiles meeting, Sep 04

Dust Radiative Transfer

Heiles meeting, Sep 04

UV, Opacity, and Temperature

Schematic Model of Orion

Heiles meeting, Sep 04

Column Density

• Optically Thin Tracer• CI and C18O 1-0

• Modest Optical Depth• 13CO

uTkE

utotal gZeNN Bu /)]/([ Tx and LTE will give thecorrection factor, Z.

dVTAhc

kN R

ul

Bu 3

28

hTk

e

e

RBTk

h

Tk

h

xB

xB

)1/(1

)1/(1ln

)1(

1ln

163

02

3

xBTkh

ul

u

eA

VN

Heiles meeting, Sep 04

Heiles meeting, Sep 04

Opacity Effects

Heiles meeting, Sep 04

The “Norm” of CI and CO in Ophiuchus

Heiles meeting, Sep 04

13CO Column Density

Heiles meeting, Sep 04

Cloud Structures: the Rho Oph Clouds

Heiles meeting, Sep 04

Turbulence

Heiles meeting, Sep 04

Opacity Correction

2ln

})]1/(2ln[

ln{0

0

e

Heiles meeting, Sep 04

Clump and Inter-Clump Structure

Heiles meeting, Sep 04

3D Model Fit

Model; Vmic=0.2 km/s; f_b = 0.35

n(H2)

Cm-3

[CI]/

[H2]

[13CO]/

[H2]

VmacKm/s

Clump 4x104 1x10-6 2x10-6 0.72

Inter-clump

2x103 10-4 10-6 1.5

Clump 5x103 0.57

Inter-clump

1.5x103

r = 0.5 pc

off

se

t

Heiles meeting, Sep 04

Fit to the Center Position

Heiles meeting, Sep 04

Fitting Results to the Center Position

Heiles meeting, Sep 04

The Fit to the Offset Position

Heiles meeting, Sep 04

CI and HI in Dark Clouds

Across One Cloud From Cloud to Cloud

Heiles meeting, Sep 04

Summary

• Ophiuchus Clouds are low mass star forming clouds in enhanced UV fields.

• The distribution and abundance of CI cannot be explained by UV field alone.

• The statistics of CO, CI, and HINSA turbulence suggest different origin of atomic CI and cold atomic hydrogen in molecular clouds.

• Clump-Interclump structure is a straightforward model to provide good fit to both CO and CI spectra through 3d radiative transfer.

• GALFA, combined with large scale millimeter surveys, would provide a unprecedented opportunity to study the distribution, kinematics, and correlation between atomic hydrogen and molecules in nearby star forming clouds. Particularly, whether UV is import in regulating HINSA abundance.