Aperture Synthesis Observations of CO, HCN, and 89GHz Continuum Emission toward NGC 604 in M 33: Sequential Star Formation Induced by Supergiant Hii region - Astrophysics > Astrophysics of GalaxiesReportar como inadecuado




Aperture Synthesis Observations of CO, HCN, and 89GHz Continuum Emission toward NGC 604 in M 33: Sequential Star Formation Induced by Supergiant Hii region - Astrophysics > Astrophysics of Galaxies - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: We present the results from new Nobeyama Millimeter Array observations ofCO1-0, HCN1-0, and 89-GHz continuum emissions toward NGC 604, known as thesupergiant H ii region in a nearby galaxy M 33. Our high spatial resolutionimages of CO emission allowed us to uncover ten individual molecular cloudsthat have masses of 0.8 -7.4 10$^5$M$ {\sun }$ and sizes of 5 - 29 pc,comparable to those of typical Galactic giant molecular clouds GMCs.Moreover, we detected for the first time HCN emission in the two most massiveclouds and 89 GHz continuum emission at the rims of the -H${\alpha}$ shells-.Three out of ten CO clouds are well correlated with the H${\alpha}$ shells bothin spatial and velocity domains, implying an interaction between molecular gasand the expanding H ii region. Furthermore, we estimated star formationefficiencies SFEs for each cloud from the 89-GHz and combination ofH${\alpha}$ and 24-${\mu}$m data, and found that the SFEs decrease withincreasing projected distance measured from the heart of the central OB starcluster in NGC 604, suggesting the radial changes in evolutionary stages of themolecular clouds in course of stellar cluster formation. Our results providefurther support to the picture of sequential star formation in NGC604 initiallyproposed by Tosaki et al. 2007 with the higher spatially resolved molecularclouds, in which an isotropic expansion of the H ii region pushes gases outwardand accumulates them to consecutively form dense molecular clouds, and theninduces massive star formations.



Autor: Rie Miura, Sachiko K. Okumura, Tomoka Tosaki, Yoichi Tamura, Yasutaka Kurono, Nario Kuno, Kouichiro Nakanishi, Seiichi Sakamoto,

Fuente: https://arxiv.org/







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