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Identifying Triggered Star Formation with Herschel and SCUBA-2

Larry Morgan (LJMU) Toby Moore (LJMU) David Eden(LJMU) James Urquhart (ATNF) Mark Thompson (University of Hertfordshire) Charles Figura (Wartburg College) Rene Plume(Calgary) Annie Zavagno(Marseille) +HiGal and JPS Teams. Identifying Triggered Star Formation with Herschel and SCUBA-2.

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Identifying Triggered Star Formation with Herschel and SCUBA-2

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  1. Larry Morgan (LJMU) Toby Moore (LJMU) David Eden(LJMU) James Urquhart (ATNF) Mark Thompson (University of Hertfordshire) Charles Figura (Wartburg College) Rene Plume(Calgary) Annie Zavagno(Marseille) +HiGal and JPS Teams Identifying Triggered Star Formation with Herschel and SCUBA-2

  2. Triggered Star-Formation • “A shock front can compress pre-existing dense clumps forcing them to contract and form new stars. The swept-up shell itself may become gravitationally unstable and fragment into new protostars.” • Kirsanova et al. (2008)

  3. 3°x 3° field at l=30 • ∼300 Class 0 YSOs identified • 76 HII regions coincident with high source densities HiGal Science Demonstration Image (Molinari et al. 2010) N49

  4. Zavagno et al. (2010) • 3 colour image of HII region in SDP field • 2nd generation massive stars observed on periphery of ionized region • Seen in 20% of ionized bubbles (Deharveng et al.,2010) Blue - 8 µm, Green - 24 µm, Red - 20 cm, Contours - 870 µm

  5. More Direct Evidence • Herschel/HiGal + SCUBA2/JPS allow SED fitting of large samples for first time • Fits degenerate at shorter wavelengths are well constrained at Herschel/SCUBA2 wavelengths Zavagno et al. (2010) using Robitaille’s SED tool • Parameterisation (Tdust/Lbol/Menv) of 1,000’s of YSOs

  6. Observational Sample

  7. Case Study • SFO 13 - Bright-Rimmed Cloud at edge of W5 HII region • Host to B-star dominated cluster Green - 4.5 µm, Blue - 8.0 µm, Red - 24 µm. White contours - 21 cm, yellow contours - 850 µm

  8. Radio contours inform us on ionized boundary • Spitzer shows us the PDR/transition region • HiGal/JPS quantify the properties of the embedded core • Environmental factors (ionized layer/PDR) can now be compared to protostellar properties themselves

  9. Identifying Triggering • Previous small samples show potential characteristics of triggered regions • Mass functions in probable triggered regions show bias toward massive YSOs • Star forming efficiencies higher in shocked regions (Moore et al., 2007)

  10. Molecular Observations • Measurements of turbulence show distinct population of triggered sources • Potential observational signatures of triggering though currently based on small source no’s

  11. Molecular Maps • Maps allow for detailed comparison with models • Prohibitively time-consuming

  12. Conclusions • JPS and Hi-Gal projects likely to observe 1,000s of intermediate to high-mass protostars in all stages of development • JPS, Hi-Gal, GLIMPSE, MIPSGAL + molecular followups provide complete census of star forming cores/clumps and relationship to environment • Using newly established techniques a great number of star forming clumps and cores can be identified and classified • Estimated 10-15% of YSOs are related to triggered formation, this will result in 100s of triggered YSOs in upcoming surveys • Good for modelling and observation

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