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Studies of Star Formation in the Nearby Universe

Studies of Star Formation in the Nearby Universe . Jeff Mangum. NRAO. Extragalactic Star Formation. Multi-transition analysis of molecular excitation within high spatial density (n(H2) > 10^5 cm^-3) and high kinetic temperature ( Tk > 100 K) environments

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Studies of Star Formation in the Nearby Universe

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  1. Studies of Star Formation in the Nearby Universe Jeff Mangum NRAO

  2. Extragalactic Star Formation • Multi-transition analysis of molecular excitation within high spatialdensity (n(H2) > 10^5 cm^-3) and high kinetic temperature (Tk > 100 K) environments • Atomic fine structure transition measurements of the warm neutral and ionized gas Herschel SPIRE apodized FTS spectrum of M82 from Panuzzoetal. (2010). Spatial resolution is 43.4 arcsec. Filled circles show SPIRE fluxes measured within the same beam. Herschel SPIRE spectrum of Arp220 (Rangwalaetal. 2012)

  3. Extragalactic Environmental Analysis • Silicon-bearing species which track shock environments (SiO) • Ions which are chemical tracers of UV emission (HCO+, DCO+) • Isomer species which can be used as diagnostics of heating mechanisms within star formation regions (HCN/HNC, etc.) • More complex symmetric and asymmetric top molecules which can be used as targeted density and temperature probes of dense gas (H2CO, etc.)

  4. Extragalactic Heating Processes HNC + H  HCN + H Ebarrier = 200 K HCN/HNC ratio a sensitive monitor of heating processes PDR model predictions of the HCN and HNC abundances as a function of column density for varying amounts of cosmic ray (zeta) and mechanical (gamma_mech) heating from Meijerinketal. (2010).

  5. Extragalactic Star Formation • H2CO K-doublet excitation used as density monitor • Transition ratios used as density andtemperature probe Mangum etal (2008, 2013)

  6. Extragalactic Star Formation

  7. Extragalactic Star Formation: Spatial Density Mangum etal (2008, 2013) H2CO K-doublet excitation used as density monitor

  8. Extragalactic Star Formation: Kinetic Temperature Mangum & Wootten (1993) H2CO excitation used as kinetic temperature monitor

  9. Star Formation in the Nearby Universe at Band 2 • Trace extragalactic star formation heating processes (HCN/HNC) • Measure spatial density and kinetic temperature (H2CO K-doublets) • Trace UV penetration into dense environments (HCO+, DCO+) • Identify shock environments (SiO)

  10. The National Radio Astronomy Observatory is a facility of the National Science Foundationoperated under cooperative agreement by Associated Universities, Inc. www.nrao.edu • science.nrao.edu

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