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We investigate the size--density relation in extragalactic HII regions, with the aim of understanding the role of dust and different physical conditions in the ionized medium. First, we compiled several observational data sets for Galactic…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 L. K. Hunt , H. Hirashita

Atomic ionised regions with strong continuum emission are often associated with regions of high-mass star formation and low-frequency (<2GHz) observations of these regions are needed to help build star formation models. The region toward…

Astrophysics of Galaxies · Physics 2021-12-08 Chenoa D. Tremblay , Tyler L. Bourke , James A. Green , John M. Dickey , O. Ivy Wong , Tim J. Galvin

Observing giant HII regions at fine spatial scales uncovers detailed structures and reveals variations in ionization, abundance, and dynamical properties of ionized gas and the effect of stellar feedback. Using emission line data of M33…

A number of very small isolated HII regions have been discovered at projected distances up to 30 kpc from their nearest galaxy. These HII regions appear as tiny emission line objects in narrow band images obtained by the NOAO Survey for…

We present results of numerical simulations carried out with a 2D radiation hydrodynamics code in order to study the impact of massive stars on their surrounding interstellar medium. This first paper deals with the evolution of the…

Astrophysics · Physics 2009-11-10 Tim Freyer , Gerhard Hensler , Harold W. Yorke

We study the Intra-Halo Stellar Component (IHSC) of Milky Way-mass systems up to galaxy clusters in the Horizon-AGN cosmological hydrodynamical simulation. We identify the IHSC using an improved phase-space galaxy finder algorithm which…

The GMRT observations of the HI 21~cm-line emission from 13~nearby dwarf star-forming galaxies are presented. The ranges of star formation rates and stellar masses of the sample galaxies are 0.03 -- 1.7~$M_\odot~{\rm yr}^{-1}$ and 0.04 --…

Astrophysics of Galaxies · Physics 2020-09-09 Sumit Jaiswal , Amitesh Omar

Observations of infrared fine-structure lines provide direct information on the metallicity and ionization structure of HII regions and indirectly on the hardness of the radiation field ionizing these nebulae. We have analyzed a sample of…

The aim of this study is to investigate systematic chemical differentiation of molecules in regions of high mass star formation. We observed five prominent sites of high mass star formation in HCN, HNC, HCO+, their isotopes, C18O, C34S and…

Astrophysics of Galaxies · Physics 2010-11-02 I. Zinchenko , P. Caselli , L. Pirogov

To investigate the process of star formation triggered by the expansion of an HII region, we present a multi-wavelength analysis of the Galactic HII region RCW 120 and its surroundings. The collect and collapse model predicts that the layer…

This Discussion session focused on star formation within galactic scales. We attempt to identify the dominant physical processes and parameters that characterize star formation, and to identify key questions that illuminate these phenomena.…

Astrophysics · Physics 2007-05-23 M. S. Oey , C. Munoz-Tunon

Stars form in dense, dusty clumps of molecular clouds, but little is known about their origin and evolution. In particular, the relationship between the mass distribution of these clumps (also known as the "clump mass function", or CMF) and…

Abridged. Low-metallicity star-forming dwarf galaxies are prime targets to understand the chemical enrichment of the interstellar medium. The HI region provides important constraints on the dispersal and mixing of heavy elements released by…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Vianney Lebouteiller , Sara Heap , Ivan Hubeny , Daniel Kunth

We present adaptive optics assisted integral field spectroscopy of nine Halpha-selected galaxies at z=0.84--2.23 selected from the HiZELS narrow-band survey. Our observations map the star-formation and kinematics of these representative…

Cosmology and Nongalactic Astrophysics · Physics 2012-11-12 Mark Swinbank , Ian Smail , David Sobral , Tom Theuns , Philip Best , Jim Geach

We present a spatially-resolved (~3 pc pix$^{-1}$) analysis of the distribution, kinematics, and excitation of warm H2 gas in the nuclear starburst region of M83. Our JWST/MIRI IFU spectroscopy reveals a clumpy reservoir of warm H2 (> 200…

Within the framework of the Herschel M 33 extended survey HerM33es we study the Spectral Energy Distribution (SED) of a set of HII regions in M 33 as a function of the morphology. We present a catalogue of 119 HII regions morphologically…

We propose that a significant fraction of the ultracompact HII regions found in massive star-forming clouds are the result of the interaction of the wind and ionizing radiation from a young massive star with the clumpy molecular cloud gas…

Astrophysics · Physics 2015-06-24 J. E. Dyson , R. J. R. Williams , M. P. Redman

Observations show that star formation is an inefficient and slow process. This result can be attributed to the injection of energy and momentum by stars that prevents free-fall collapse of molecular clouds. The mechanism of this stellar…

Solar and Stellar Astrophysics · Physics 2015-05-19 Laura A. Lopez , Mark R. Krumholz , Alberto D. Bolatto , J. Xavier Prochaska , Enrico Ramirez-Ruiz

Many ultracompact HII regions exhibit a cometary morphology in radio continuum emission. In such regions, a young massive star is probably ablating, through its ultraviolet radiation, the molecular cloud clump that spawned it. On one side…

Astrophysics of Galaxies · Physics 2015-06-18 Nathaniel Roth , Steven W. Stahler , Eric Keto

We present the results of a study of young unresolved stellar groupings (clusters, OB associations, and their complexes) associated with HII regions, based on the coupling of spectroscopic, photometric and H{\alpha} spectrophotometric…

Astrophysics of Galaxies · Physics 2023-07-13 A. S. Gusev , F. Sakhibov , O. V. Egorov , V. S. Kostiuk , E. V. Shimanovskaya