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The Dust Properties of Galactic H II Regions as seen by Herschel

The Dust Properties of Galactic H II Regions as seen by Herschel. Loren Anderson Laboratoire d'Astrophysique de Marseille Annie Zavagno, Javier Rodon, Lise Deharveng, and the “HOBYS” and “Evolution of Interstellar Dust” consortia

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The Dust Properties of Galactic H II Regions as seen by Herschel

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  1. The Dust Properties of Galactic HII Regions as seen by Herschel Loren Anderson Laboratoire d'Astrophysique de Marseille Annie Zavagno, Javier Rodon, Lise Deharveng, and the “HOBYS” and “Evolution of Interstellar Dust” consortia Special thanks to Helene Roussel for help with data processing

  2. Motivation Dust temperatures/emissivities: → Are necessary for accurate column density & mass calculations → Are much less well-known compared to the gas temperature → Tell us about the dust grain population HII region are unique laboratories with star formation in various stages, all at the same distance from the Sun HII regions with a “bubble” morphology have a well-defined PDRs, simple geometries → Roughly half of all Galactic HII regions have a bubble morphology (Anderson et al. 2010, in prep., from the GBT HII Region Survey)

  3. IRAS Color Temperatures of HII Regions Crowther & Conti 2003, Conti & Crowther 2004 Aperture photometry of UC and “giant” HII regions (those with log(Nly) > 50) Chan & Fich 1995 Aperture photometry of UC and compact HII regions

  4. Dust Temperatures in M17 Povich et al., 2007 Study of M17 with 2MASS, MSX, IRAC, and IRAS from 1 to 100 μm → Interior aperture (R1) peaks near 20μm → Tdust≈ 100 K → PDR apertures (R2 & R3) peak near 60μm → Tdust≈ 40 K SpitzerIRAC 5.8 μm IRAC 4.5μmIRAC 3.6μm

  5. HII Region Sample RCW82: D=2.9 kpc RCW120: D=1.3 kpc W5: D=2.0 kpc Sh104: D=4.0 kpc RCW79: D=4.2 kpc Herschel SPIRE 500 μmHerschel SPIRE 250 μm Herschel PACS 100 μm

  6. HII Region Sample - RCW120 Herschel SPIRE 500 μm Herschel SPIRE 250 μm Herschel PACS 100 μm Spitzer GLIMPSE 8.0 μm see Zavagno et al., 2007, Deharveng et al., 2009, Martins et al., 2010, Zavagno et al., 2010, Anderson et al. 2010

  7. HII Region Sample - Sh104 Herschel SPIRE 500 μmHerschel SPIRE 250 μm Herschel PACS 100 μm see Deharveng et al., 2003, Rodon et al., 2010

  8. HII Region Sample - RCW79 Herschel SPIRE 500 μm Herschel SPIRE 250 μm Herschel PACS 100 μm Spitzer GLIMPSE 8.0 μm see Cohen et al., 2002, Zavagno et al., 2006, Martins et al., 2010

  9. HII Region Sample - RCW82 Herschel SPIRE 500 μm Herschel SPIRE 250 μm Herschel PACS 100 μm Spitzer GLIMPSE 8.0 μm see Pomares et al., 2009, Martins et al., 2010

  10. HII Region Sample - W5 Herschel SPIRE 500 μm Herschel SPIRE 250 μm Herschel PACS 100 μm Spitzer 8.0 μm composite

  11. Dust Temperature Determination RCW120 Anderson et al., 2010 1) Aperture photometry → Get temperature and dust beta values for select regions of interest → Derived temperatures are averages within the aperture → Large-scale distribution of dust temperature values is unknown 2) Temperature Maps → Get spatial distribution of dust temperatures at high angular resolution → The fit quality per aperture (one pixel) is poor compared to that of the aperture photometry → The determination of β from this method is questionable

  12. The β-T Relation Dupac et al., 2003 Desert et al., 2008 Rodon et al., 2010 (Sh104) Anderson et al., 2010 (RCW120)

  13. Aperture Photometry # Along PDRs : 35 (11 are mm-condensations) # Filaments : 26 # UC HII Regions : 5

  14. The β-T Relation RCW82 RCW120 (Anderson et al., 2010) W5 S104 (Rodon et al, 2010) RCW79

  15. The β-T Relation

  16. The β-T Relation Filaments PDR PDR Condensations Entire Field

  17. Derived T and β-values given input T from 10 to 40 K and β=2.5 → For dust spanning a range of temperatures, we cannot derive a false β-T relationship → Derived values are evenly distributed about input β, T Is it Real??? see also Shetty et al., 2009

  18. Dust Temperature Maps RCW82 RCW120 W5 Sh104 RCW79

  19. But, there is a hotter component too.... Herschel SPIRE 250 μmHerschel PACS 100 μm Spitzer MIPS 24 μm NGC 7023-E PDR Abergel et al., 2010 RCW120 Anderson et al., 2010

  20. Conclusions Dust properties: → PDRs: 20-25, β~2 • → Filaments: 15-20, β~2 (~10K, β~3 for IRDCs) • → The “interior” of HII regions coincident with the ionized gas has warmer dust though We find strong evidence for a β-T relation, both for individual HII regions, and also for the entire sample of HII regions • The β-T relation cannot be explained by the effects of noise or calibration uncertainty

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