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AT20G compact HII region Survey: Spitzer character of the sources in the MIR

AT20G compact HII region Survey: Spitzer character of the sources in the MIR. Martin Cohen, University of California/Berkeley “Hyper Compact HII regions” Workshop 8 September 2010. Outline. What is the relationship betweenMIR/radio? Radio - ionized gas; MIR - PAHs in PDRs

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AT20G compact HII region Survey: Spitzer character of the sources in the MIR

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  1. AT20G compact HII region Survey: Spitzer character of the sources in the MIR Martin Cohen, University of California/Berkeley “Hyper Compact HII regions” Workshop8 September 2010

  2. Outline • What is the relationship betweenMIR/radio? • Radio - ionized gas; MIR - PAHs in PDRs • Matched-resolution (MOST) 843MHz & (MSX) 8.3m Galactic Plane images Cohen & Green ratio: F(8.3m)/S(843MHz) • Thermal radio emission: median:25±5 • AT20G sources have at least three classes of MIR counterpart Cohen & Green 2001, MNRAS, 325, 531 Cohen et al. 2007, MNRAS, 374, 979

  3. Extragalactic MIR countperparts 8m absent or faint; 24 m well detected and planetary nebulae

  4. GLIMPSE Benjamin et al. 2003 PASP, 115, 953 45" 1983 1996 2004 19" b±1.1 1.7"

  5. MSX 8.3m Resolution & sensitivity changes: MSXSpitzer IRAC for HII regions IRAC 8.0m 19GHz; 15” beam

  6. Radio (black) ionized gas; IR (white) hydrocarbon molecules in the PDR Mid-IR: MSX 8.3m Far-IR emission from dust heated by the star How are MIR and radio related? Radio: MOST 843MHz Radio

  7. MIR morphology of HII regions 4.5 5.8 8.0m234 Compact Ultra-compact Cometary Compact Compact HII Compact

  8. Samples of the AT20G UCHII regions Almost no MIR UC regions are found. Mostly small groups or pairs of compact and diffuse HII. IRAC false colours separate UC white (dust) emission from compact and diffuse yellow (PAHs) MIR/Radio = 42

  9. An IRAC color-color plane Emphasizes PNe & HII regions dH H F(8.3m)/S(843MHz) Diffuse HII:median:25 PNe median: 5 UC HII median:42 HII compact: median: 140 (very small set) P

  10. Radio-MIR comparisons of groups (1) 1235-6302 1555-5243

  11. Radio-MIR comparisons of groups (2) 1547-5448 H2? 1609-5154

  12. Hyper & Ultra compact MIR countperparts G301 H G323 H G309 H G330 H G307 U G332 U G302 U G328 U

  13. Optical extinction along lines of sight • Use deep silicate absorptions at 10,18 m

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