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We present MUSE integral field data of two HII region complexes in the Large Magellanic Cloud (LMC), N44 and N180. Both regions consist of a main superbubble and a number of smaller, more compact HII regions that formed on the edge of the…

Astrophysics of Galaxies · Physics 2018-10-17 A. F. McLeod , J. E. Dale , C. J. Evans , A. Ginsburg , J. M. D. Kruijssen , E. W. Pellegrini , S. K. Ramsay , L. Testi

Optical and infrared emission lines from HII regions are an important diagnostic used to study galaxies, but interpretation of these lines requires significant modeling of both the internal structure and dynamical evolution of the emitting…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Silvia Verdolini , Sherry C. C. Yeh , Mark R. Krumholz , Christopher D. Matzner , Alexander G. G. M. Tielens

We present the results of radiation-magnetohydrodynamic simulations of the expansion of HII regions and surrounding photodissociation regions in turbulent, magnetised, molecular clouds on scales of up to 4 parsecs, including the effects of…

Astrophysics of Galaxies · Physics 2015-05-27 S. J. Arthur , W. J. Henney , G. Mellema , F. De Colle , E. Vázquez-Semadeni

Using numerical simulations of galactic disks resolving scales from ~1 to several hundred pc, we investigate dynamical properties of the multiphase ISM with turbulence driven by star formation feedback. We focus on HII region effects by…

Astrophysics · Physics 2011-02-11 H. Koyama , E. C. Ostriker

We study the dependence of the physical and observable properties of the CGM on its halo mass. We analyse 22 simulations from the Auriga suite of high resolution cosmological `zoom-in' simulations at $z=0$ with halo masses…

Astrophysics of Galaxies · Physics 2024-09-10 Andrew W. S. Cook , Freeke van de Voort , Rüdiger Pakmor , Robert J. J. Grand

We study the role of atomic hydrogen (HI) in regulating size growth of local galaxies. The size of a galaxy, $D_{\rm r,~25}$, is characterized by the diameter at which the $r-$band surface brightness reaches $\mu_{\rm r}=25.0~\rm…

Astrophysics of Galaxies · Physics 2021-12-15 Zhizheng Pan , Jing Wang , Xianzhong Zheng , Xu Kong

It is possible that the properties of HII regions during reionization depend sensitively on many poorly constrained quantities (the nature of the ionizing sources, the clumpiness of the gas in the IGM, the degree to which photo-ionizing…

The size-velocity dispersion ($\sigma$) relation, while well established for giant HII regions, remains uncertain for their smaller counterparts (physical radii R < 20 pc). Thanks to the LAMOST MRS-N dataset's large sky coverage and high…

The dynamical evolution of HII regions with and without stellar motion in dense, structured molecular clouds is studied. Clouds are modeled in hydrostatic equilibrium, with gaussian central cores and external halos that obey r**-2 and r**-3…

Astrophysics · Physics 2011-02-11 Jose Franco , Guillermo Garcia-Segura , Stan Kurtz

To aid in the physical interpretation of planetary radii constrained through observations of transiting planets, or eventually direct detections, we compute model radii of pure hydrogen-helium, water, rock, and iron planets, along with…

Astrophysics · Physics 2010-04-06 Jonathan J. Fortney , Mark S. Marley , Jason W. Barnes

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

Resolution of nearby giant HII regions into their stellar and nebular constituents provides fundamental insights for interpreting more distant and powerful starburst activity. The following summarizes recent advances in our understanding of…

Astrophysics · Physics 2007-05-23 William H. Waller

To advance our understanding of massive star formation, it is essential to perform a comprehensive suite of simulations that explore the relevant parameter space and include enough physics to enable a comparison with observational data. We…

Astrophysics of Galaxies · Physics 2025-11-19 Birka Zimmermann , Stefanie Walch , Seamus D. Clarke , Richard Wünsch , Andre Klepitko

(Abridged) From a new H alpha mosaic image of the complete disc of the spiral galaxy M100, a catalogue is composed listing 1948 individual HII regions. I give details of the data collection and reduction procedure, and of the production of…

Astrophysics · Physics 2009-10-30 J. H. Knapen

Context. Measuring star formation at a local scale is important to constrain star formation laws. Yet, it is not clear whether and how the measure of star formation is affected by the spatial scale at which a galaxy is observed. Aims. We…

Cosmic reionization progresses as HII regions form around sources of ionizing radiation. Their average size grows continuously until they percolate and complete reionization. We demonstrate how this typical growth can be calculated around…

Astrophysics · Physics 2009-11-13 Marcelo A. Alvarez , Tom Abel

We present general properties of ionized hydrogen (HII) bubbles and their growth based on a state-of-the-art large-scale (100 Mpc/h) cosmological radiative transfer simulation. The simulation resolves all halos with atomic cooling at the…

Astrophysics · Physics 2009-11-13 Min-Su Shin , Hy Trac , Renyue Cen

Spatially resolved studies of star forming regions show that the assumption of spherical geometry is not realistic in most cases, with a major complication posed by the gas being ionised by multiple non-centrally located stars or star…

Astrophysics · Physics 2009-06-23 B. Ercolano , N. Bastian , G. Stasinska

We present radiation-magnetohydrodynamic simulations aimed at studying evolutionary properties of H\,{\normalsize II} regions in turbulent, magnetised, and collapsing molecular clouds formed by converging flows in the warm neutral medium.…

Two continuum subtracted H-alpha HST frames of M101 are used to determine the positions, angular sizes and absolute fluxes of 237 HII regions using a semi-automated technique. From these we have constructed the luminosity and diameter…

Astrophysics · Physics 2016-08-30 P. O. Pleuss , C. H. Heller , K. J. Fricke