High Resolution Observations of Orion-KL:Insight into its Chemical Complexity

D. N. FriedelS. L. Widicus Weaver

Liu et al., 2002, ApJ, 576, 255

Traditional view:Complex N and O bearing species are spatially separatedN bearing species originate in hot/dense regionO bearing species originate in diffuse regionO species are created first followed by N species

Background

seds.lpl.arizona.edu/messier/Pics/Jpg/ori_kc.jpg

Observations

CARMA Array B configuration 1.0''x0.9'' beam D configuration 5.0''x4.0'' beam

Molecule Transition (GHz) Eu (K) S2

C2H5CN 102,9-92,8 89.297 28 119.3

HCOOCH3 81,8-71,7 A 89.314 20 21.0

81,8-71,7 E 89.316 20 21.0

(CH3)2O 152,13-151,14 88.7071 117 11.6

(CH3)2CO 9*,8-8*,7 101.4271 27 7.2

9*,9-8*,8 92.7351 24 8.4

SO2 73,5-82,6 97.702 48 2.5

HCOOH 41,4-31,3 86.546 14 7.3

41,3-31,2 93.098 14 7.31 Frequency is for strongest torsional state

3 mm Continuum

Grayscale is NICMOS 2mm continuumContours are 3mm continuumSources of interest are labeled

Methyl Formate [HCOOCH3]

1 velocity componentMultiple emission componentsDouble lobed feature near star k

Ethyl Cyanide [C2H

5CN]

Three main velocity components:Typical Hot Core velocity (3-5 km s-1)

Strongest emissionBlue shifted component

Compact, associated with star nRed shifted component

Near IRc sources dominated by O bearing species

Formic Acid [HCOOH]

Original detection was with 5''x8'' beamUndetected in B array observations

2 velocity componentsTypical CR velocityTypical HC velocity

Distinct O bearing regionsHCOOH only extendedHCOOH not co-spatial with other O species

SO2

Acetone [(CH3)

2CO]

Only peaks where O and N species are co-spatial

Summary

Region is very complexO and N species differentiated into multiple regionsOverlap regions contain acetoneTraditional view is not correct

Majority of O bearing molecules are in compact regions Only formic acid has purely extended component

Much emission from regions where there is no detected continuum Specifically star n