The growth of H II regions around massive stars: the role of metallicity and dust

Abstract

Gas metallicity $Z$ and the related dust-to-gas ratio $f_{\text{d}}$ can influence the growth of HII regions via metal line cooling and UV absorption. We model these effects in star-forming regions containing massive stars. We compute stellar feedback from photoionization and radiation pressure (RP) using Monte Carlo radiative transfer coupled with hydrodynamics, including stellar and diffuse radiation fields. We follow a $10^5$ M${}_{\odot }$ turbulent cloud with $Z/$Z${}_{\odot }$ = 2, 1, 0.5, 0.1 and $f_{\text{d}}=0.01Z/$Z${}_{\odot }$ with a cluster-sink particle method for star formation. The models evolve for at least 1.5 Myr under feedback. Lower $Z$ results in higher temperatures and therefore larger HII regions. For $Z\ge$Z${}_{\odot }$, radiation pressure $P_{\text{rad}}$ can dominate locally over the gas pressure $P_{\text{gas}}$ in the inner half-parsec around sink particles. Globally, the ratio of $P_{\text{rad}}/P_{\text{gas}}$ is around 1 (2 Z${}_{\odot }$), 0.3 (Z${}_{\odot }$), 0.1 (0.5 Z${}_{\odot }$), and 0.03 (0.1 Z${}_{\odot }$). In the solar model, excluding RP results in an ionized volume several times smaller than the fiducial model with both mechanisms. Excluding RP and UV attenuation by dust results in a larger ionized volume than the fiducial case. That is, UV absorption hinders growth more than RP helps it. The radial expansion velocity of ionized gas reaches $+$15 km/s outwards, while neutral gas has inward velocities for most of the runtime, except for 0.1 Z${}_{\odot }$ which exceeds $+$4 km/s. $Z$ and $f_{\text{d}}$ do not significantly alter the star formation efficiency, rate, or cluster half-mass radius, with the exception of 0.1 Z${}_{\odot }$ due to the earlier expulsion of neutral gas.

13 pages, 9 figures, accepted for publication in MNRAS

References in corpus (24)

• Array Programming with NumPy
• Dust Masses, PAH Abundances, and Starlight Intensities in the SINGS Galaxy Sample
• Modeling Collapse and Accretion in Turbulent Gas Clouds: Implementation and Comparison of Sink Particles in AMR and SPH
• Radiation-Hydrodynamic Simulations of Collapse and Fragmentation in Massive Protostellar Cores
• The Effects of Radiative Transfer on Low-Mass Star Formation
• The Importance of Radiative Feedback for the Stellar Initial Mass Function
• Before the first supernova: combined effects of HII regions and winds on molecular clouds
• The statistical properties of stars and their dependence on metallicity
• Which feedback mechanisms dominate in the high-pressure environment of the Central Molecular Zone?
• Star cluster formation and cloud dispersal by radiative feedback: dependence on metallicity and compactness
• Radiation-hydrodynamical simulations of massive star formation using Monte Carlo radiative transfer: I. Algorithms and numerical methods
• Dust dynamics and evolution in expanding HII regions. I. Radiative drift of neutral and charged grains
• Simulating radiative feedback and star cluster formation in GMCs: II. Mass dependence of cloud destruction and cluster properties
• Radiation-hydrodynamical simulations of massive star formation using Monte Carlo radiative transfer II. The formation of a 25 solar-mass star
• The roles of stellar feedback and galactic environment in star forming molecular clouds
• Young massive star cluster formation in the Galactic Centre is driven by global gravitational collapse of high-mass molecular clouds
• Structure and Expansion Law of HII Regions in structured Molecular Clouds
• A new hybrid radiative transfer method for massive star formation
• Massive star feedback in clusters: variation of the FUV interstellar radiation field in time and space
• The role of collision speed, cloud density, and turbulence in the formation of young massive clusters via cloud-cloud collisions
• Photoionising feedback in spiral arm molecular clouds
• The effect of radiation pressure on spatial distribution of dust inside HII regions
• Radiation hydrodynamics simulations of the evolution of the diffuse ionized gas in disc galaxies
• Photoionization feedback in turbulent molecular clouds

Cited by in corpus (26)

• A JWST/NIRSpec Exploration of the Connection between Ionization Parameter, Electron Density, and Star-Formation-Rate Surface Density in z=2.7-6.3 Galaxies
• Radiation hydrodynamics simulations of massive star cluster formation in giant molecular clouds
• The impact of pre-supernova feedback and its dependence on environment
• The evolution of protoplanetary discs in star formation and feedback simulations
• Stellar feedback in M83 as observed with MUSE -- II. Analysis of the HII region population: ionisation budget and pre-SN feedback
• The formation of massive stellar clusters in converging galactic flows with photoionisation
• Massive star cluster formation I. High star formation efficiency while resolving feedback of individual stars
• Chemulator: Fast, accurate thermochemistry for dynamical models through emulation
• The formation of clusters and OB associations in different density spiral arm environments
• Stellar winds and photoionization in a spiral arm
• Deep diving off the `Cosmic Cliffs': previously hidden outflows in NGC 3324 revealed by JWST
• Far and extreme UV radiation feedback in molecular clouds and its influence on the mass and size of star clusters
• Star cluster formation and feedback in different environments of a Milky Way-like galaxy
• The evolution of circumstellar discs in the Galactic Centre: an application to the G-clouds
• Linking stellar populations to HII regions across nearby galaxies. II. Infrared Reprocessed and UV Direct Radiation Pressure in HII Regions
• The role of previous generations of stars in triggering star formation and driving gas dynamics
• Bringing Stellar Evolution & Feedback Together: Summary of proposals from the Lorentz Center Workshop, 2022
• Investigating the ultraviolet and infrared radiation through the turbulent life of molecular clouds
• The formation of globular clusters with top-heavy initial mass functions
• An APEX search for carbon emission from NGC 1977 proplyds
• Simulations of pre-supernova feedback in spherical clouds
• Pre-supernova stellar feedback in nearby starburst dwarf galaxies
• Dust-Evacuated Zones Near Massive Stars: Consequences of Dust Dynamics on Star-forming Regions
• Thermal Pressures in the Interstellar Medium away from Stellar Environments
• Using simultaneous mass accretion and external photoevaporation rates for d203-504 to constrain disc evolution processes
• Grouped star formation: converting sink particles to stars in hydrodynamical simulations