/ftp/cats/aliases/K/./KWL2014



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J/MNRAS/444/757     HII complexes optical and IR emissions   (Khramtsova+, 2014)
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	table1.dat table2.dat table3.dat table4.dat
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Query from: http://vizier.cds.unistra.fr/viz-bin/VizieR?-source=J/MNRAS/444/757
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Beginning of ReadMe : J/MNRAS/444/757 HII complexes optical and IR emissions (Khramtsova+, 2014) ================================================================================ Optical and infrared emission of HII complexes as a clue to the PAH life cycle. Khramtsova M.S., Wiebe D.S., Lozinskaya T.A., Egorov O.V. <Mon. Not. R. Astron. Soc., 444, 757-775 (2014)> =2014MNRAS.444..757K ================================================================================ ADC_Keywords: Galaxies, nearby ; H II regions ; Interstellar medium ; Photometry, infrared ; Spectroscopy Keywords: galaxies: ISM - infrared: galaxies - infrared: ISM Abstract: We present an analysis of optical spectroscopy and infrared aperture photometry of more than 100 HII complexes in nine galaxies. Spectra obtained with the 6-m telescope of Special Astrophysical Observatory of the Russian Academy of Sciences are used along with archival data from Spitzer and several ground-based telescopes to infer a strength of polycyclic aromatic hydrocarbon (PAH) emission, age, properties of the UV radiation field, and metallicity of studied HII complexes. Physical properties (age, radiation field parameters, metallicity) are related to the F_8_/F_24_ ratio used as a proxy for the PAH abundance in order to reveal factors that may influence the PAH evolution in HII complexes. The well-known correlation between the F_8_/F_24_ ratio and metallicity is confirmed in the studied complexes. The infrared flux ratio also correlates with the [Oiii]lambda5007/Hbeta ratio which is often considered as an indicator of the radiation field hardness, but this correlation seems to be a mere reflection of a correlation between [Oiii]lambda5007/Hbeta and metallicity. In separate metallicity bins, the F_8_/F_24_ ratio is found to correlate with an age of an Hii complex, which is estimated from the equivalent width of Hbeta line. The correlation is positive for low-metallicity complexes and negative for high-metallicity complexes. Analysing various mechanisms of PAH formation and destruction in the context of found correlations, we suggest that PAH abundance is likely altered by the UV radiation within HII complexes, but this is not necessarily due to their destruction. If PAHs can also form in Hii complexes due to some processes like aromatization, photodestruction, shattering and sputtering of very small grains, the net F_8_/F_24_ ratio is determined by a balance between all these processes that can be different at different metallicities. Description: Spectroscopic observations of HII complexes in IC 1727 and NGC 7741 galaxies were performed with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS) using the multi-mode SCORPIO focal reducer in the long-slit spectroscopy mode on 22-23 of October, 2011.