Article
Astronomy & Astrophysics
A. Amayo, G. Delgado-Inglada, G. Stasinska
Summary: New ionization correction factors (ICFs) for carbon, nitrogen, neon, sulfur, chlorine, and argon in giant Hii regions were provided in this study. The ICFs were computed using representative photoionization models from a large initial grid, and were used to calculate abundances of nitrogen, neon, sulfur, and argon in samples. Oxygen depletion into dust grains at a rate increasing with metallicity was found, and the discussion on possible depletion of sulfur and argon requires consideration of recent Type Ia Supernova yields, which are uncertain.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
F. Mannucci, F. Belfiore, M. Curti, G. Cresci, R. Maiolino, A. Marasco, A. Marconi, M. Mingozzi, G. Tozzi, A. Amiri
Summary: The diffuse ionized gas has an impact on the nebular emission of galaxies, but the effect may be lower than previously assumed, and aperture effects play a significant role in observed differences. Correction may be needed in observed data to recover the genuine contribution from H II regions, and this has implications for measuring metallicity using strong-line methods.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Fabian Scheuermann, Kathryn Kreckel, Ashley T. Barnes, Francesco Belfiore, Brent Groves, Stephen Hannon, Janice C. Lee, Rebecca Minsley, Erik Rosolowsky, Frank Bigiel, Guillermo A. Blanc, Mederic Boquien, Daniel A. Dale, Sinan Deger, Oleg Egorov, Eric Emsellem, Simon C. O. Glover, Kathryn Grasha, Hamid Hassani, Sarah M. R. Jeffreson, Ralf S. Klessen, J. M. Diederik Kruijssen, Kirsten L. Larson, Adam K. Leroy, Laura A. Lopez, Hsi-An Pan, Patricia Sanchez-Blazquez, Francesco Santoro, Eva Schinnerer, David A. Thilker, Bradley C. Whitmore, Elizabeth J. Watkins, Thomas G. Williams
Summary: Connecting the gas in H II regions to the underlying ionizing radiation source helps us understand stellar feedback and the evolution of H II regions. Using PHANGS-MUSE, we detect and measure physical properties of nearly 24,000 H II regions across 19 galaxies. By analyzing associations with ionizing sources, we find correlations between association ages and various properties, suggesting an evolutionary sequence. We also observe correlations with local metallicity variations, indicating preferential star formation in metal-rich areas.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
J. E. Mendez-Delgado, C. Esteban, J. Garcia-Rojas, K. Z. Arellano-Cordova, K. Kreckel, V Gomez-Llanos, O. Egorov, M. Peimbert, M. Orte-Garcia
Summary: We have conducted a study based on the DEep Spectra of Ionized REgions Data base (DESIRED). This database comprises 190 high signal-to-noise ratio optical spectra of H II regions and other photoionized nebulae, in which about 29,380 emission lines are found. Our analysis reveals that the electron density (-n(e)-) of the objects is underestimated when only [S II]λ 6731/λ 6716 and/or [O II]λ 3726/λ 3729 are used as density indicators due to the non-linear density dependence. This underestimation has implications for the analysis of infrared fine structure lines and the resulting ionic abundances.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Estrella Florido, Almudena Zurita, Enrique Perez-Montero
Summary: This study uses a sample of 536 H ii regions in nearby spiral galaxies to obtain new empirical calibrations of several strong-line indices to estimate nitrogen-to-oxygen abundance ratio. The study shows strong correlations between all indices and log (N/O) based on T-e, even stronger than with 12 + log (O/H). N2O2 is the most strongly correlated index, and a second-order polynomial provides the best fit to the log (N/O)-N2O2 relation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
J. M. Pittard, M. M. Kupilas, C. J. Wareing
Summary: We investigate the resolution dependence of H II regions expanding past their Stromgren spheres. We find that if the Stromgren radius is resolved with certain conditions, the structure, size, and radial momentum of the regions at a given time are in good agreement with analytical expectations. Otherwise, the radial momentum may be over- or underestimated by factors up to 10 or more. Our work is significant for understanding the amount of radial momentum and the relative importance of ionizing feedback from massive stars in numerical simulations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Lidia M. Oskinova, Daniel Schaerer
Summary: This study investigates the sources powering nebular He II emission in star-forming galaxies, and finds that soft X-ray radiation produced by hot gas can explain He II ionization. The temperature of hot gas is lower and the production rate of He II ionizing photons is higher in low-metallicity galaxies compared to high-metallicity galaxies. Ensembles of star clusters up to 10-20 million years old in galaxies can generate enough soft X-rays to induce nebular He II emission. Observations of the low-metallicity galaxy I Zw 18 suggest that its He II nebula is powered by a hot superbubble. Soft X-rays from hot superbubbles are among the dominant sources of He II ionizing flux in low-metallicity star-forming galaxies.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
S. Zamora, Angeles Diaz, Elena Terlevich, Vital Fernandez
Summary: This article presents a method to calculate extinction corrections based on weaker lines of He I and applies it to the study of the 30 Doradus nebula. The comparison between helium and hydrogen determinations of c(H beta) yields compatible results within the errors, and using both sets of lines simultaneously significantly reduces the error in the derivation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Da Eun Kang, Ralf S. Klessen, Victor F. Ksoll, Lynton Ardizzone, Ullrich Koethe, Simon C. O. Glover
Summary: This paper presents a new method using a conditional invertible neural network (cINN) to accurately predict the physical properties of star-forming regions by analyzing degenerate observations. The new network, named Noise-Net, takes into account observational uncertainties during training and outperforms the previous version of the cINN, even under large uncertainties.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
C. Espinosa-Ponce, S. F. Sanchez, C. Morisset, J. K. Barrera-Ballesteros, L. Galbany, R. Garcia-Benito, E. A. D. Lacerda, D. Mast
Summary: This article presents the exploration of the physical properties of H ii regions and their aggregations in the CALIFA survey, and explores their connections with galactic stellar evolution.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
F. Belfiore, F. Santoro, B. Groves, E. Schinnerer, K. Kreckel, S. C. O. Glover, R. S. Klessen, E. Emsellem, G. A. Blanc, E. Congiu, A. T. Barnes, M. Boquien, M. Chevance, D. A. Dale, J. M. Diederik Kruijssen, A. K. Leroy, H-A Pan, I Pessa, A. Schruba, T. G. Williams
Summary: This study investigates the origin of the diffuse ionised gas (DIG) in 19 nearby spiral galaxies using integral field spectroscopy. The results show that leakage radiation from H II regions and emission from hot low-mass evolved stars both contribute to the characteristics of the DIG.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Benjamin Metha, Michele Trenti, Tingjin Chu, Andrew Battisti
Summary: This study introduces the geostatistical technique of universal kriging to reconstruct the complete 2D metallicity distribution of a galaxy from metallicities measured at H ii regions. High-fidelity metallicity maps of the local spiral galaxy NGC 5236 are constructed and significant correlation in the metallicity of H ii regions is found. The predictions of this method outperform interpolation based on metallicity gradients. The kriging method is also applied to predict metallicities in regions dominated by diffuse ionized gas emission, and comparisons with novel ionization corrections show a systematic offset and scatter.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Chamani M. Gunasekera, Xihan Ji, Marios Chatzikos, Renbin Yan, Gary Ferland
Summary: The study investigates the depletion strength's effect on emission lines and thermal balance of the ionized cloud. It also finds that the parameters - metallicity, ionization parameter U, and depletion strength F-* - have mutual effects on the emission-line strengths and thermal balance of the interstellar medium (ISM). Comparing the results to H II regions, the best-fit F-* is approximately 0.5 but may not be suitable for all metallicities.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Maya Skarbinski, Sarah M. R. Jeffreson, Alyssa A. Goodman
Summary: Using the moving-mesh code arepo, we studied the physical drivers of slow molecular cloud mergers in a Milky Way-like galaxy simulation and determined their influence on the mass distribution and star formation efficiency of galactic cloud population. We found that 83% of these mergers occur at a relative velocity below 5 km s(-1) and are associated with large-scale atomic gas flows driven by expanding bubbles of hot, ionized gas caused by supernova explosions and galactic rotation. The major effect of these mergers is to aggregate molecular mass into higher-mass clouds, accounting for over 50% of the molecular mass in clouds with mass M > 2 x 10(6) M-circle dot. These high-mass clouds have higher densities, internal velocity dispersions, and instantaneous star formation efficiencies compared to their unmerged, lower mass precursors. Consequently, the mean instantaneous star formation efficiency in our simulated galaxy with a merger rate of just 1% of clouds per Myr is 25% higher than in a similar population of clouds without mergers.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
M. Valerdi, J. K. Barrera-Ballesteros, S. F. Sanchez, C. Espinosa-Ponce, L. Carigi, A. Mejia-Narvaez
Summary: By calibrating the emission line flux ratio, the study investigates the abundance of helium and explores its variations in different galaxies through a large sample of H II regions. The observed trends suggest a consistency between the change in helium abundance with respect to oxygen abundance and the chemical enrichment with mass/oxygen abundance.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Pushpita Das, Oliver Porth, Anna L. Watts
Summary: NASA's NICER telescope has provided evidence for non-dipolar magnetic field structures in rotation-powered millisecond pulsars. Researchers have used simulations to study the accretion flows onto neutron stars with complex magnetic fields, and found that the location and size of the resulting hotspots depend on the initial stellar field strength and geometry. They also discovered that the disc-connected field lines and pulsar wind play a significant role in spinning down the stars. The results shed light on the variability of hotspots in accreting millisecond pulsars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)