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Recent radio surveys have revealed pulsars with dispersion and scattering delays induced by ionized gas that are larger than the rest of the observed pulsar population, in some cases with electron column densities (or dispersion measures;…

Astrophysics of Galaxies · Physics 2024-08-05 S. K. Ocker , L. D. Anderson , T. J. W. Lazio , J. M. Cordes , V. Ravi

Massive stars and their associated ionized (HII) regions could play a key role in the formation and evolution of filaments that host star formation. However, the properties of filaments that interact with H regions are still poorly known.…

Over the last years a new generation of model atmosphere codes, which include the effects of metal line-blanketing of millions of spectral lines in NLTE, has been used to re-determine the properties of massive stars through quantitative…

Astrophysics · Physics 2007-05-23 R. -P. Kudritzki , M. A. Urbaneja

We present new accurate measurements of the physical properties of a statistically significant sample of 103 galaxies at z~2 using near-infrared spectroscopy taken as part of the 3D-HST survey. We derive redshifts, metallicities and star…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-09 F. Cullen , M. Cirasuolo , R. J. McLure , J. S. Dunlop

We develop a time-dependent theory to investigate electron dynamics and photoionization processes of diatomic molecules interacting with strong laser fields including electron-electron correlation effects. We combine the recently formulated…

Chemical Physics · Physics 2016-02-02 Henrik R. Larsson , Sebastian Bauch , Lasse Kragh Sørensen , Michael Bonitz

We present mid-infrared ISO-SWS observations of the fine-structure emissions lines [NeII]12.8, [NeIII]15.6, [NeIII]36, [ArII]6.9, [ArIII]8.9, [SIII]18.7, [SIII]33.5, [SIV]10.5, and the recombination lines Br_alpha and Br_beta, in a sample…

Astrophysics · Physics 2009-11-07 Uriel Giveon , Amiel Sternberg , Dieter Lutz , Helmut Feuchtgruber , Adi Pauldrach

In this paper we discuss some results concerning the abundance discrepancy problem in the context of H II regions. We discuss the behavior of the abundance discrepancy factor (ADF) for different objects and ions. There are evidences that…

Astrophysics of Galaxies · Physics 2016-12-13 C. Esteban , L. Toribio San Cipriano , J. García-Rojas

The metallicity structure of the Milky Way disk stems from the chemodynamical evolutionary history of the Galaxy. We use the National Radio Astronomy Observatory Karl G. Jansky Very Large Array to observe ~8-10 GHz hydrogen radio…

Astrophysics of Galaxies · Physics 2020-01-08 Trey V. Wenger , Dana S. Balser , L. D. Anderson , T. M. Bania

The spatial distribution of metals reflects, and can be used to constrain, the processes of chemical enrichment and mixing. Using PHANGS-MUSE optical integral field spectroscopy, we measure the gas phase oxygen abundances (metallicities)…

{We explored the {softness parameter} in the infrared, whose main purpose is the characterisation of the hardness of the incident ionising radiation in emission-line nebulae. This parameter is obtained from the combination of mid-infrared…

Line ratios in "fir" triplets of helium-like ions have proven to be a powerful diagnostic of conditions in X-ray emitting gas surrounding massive stars. Recent observations indicate that these ratios can be variable with time. The possible…

Solar and Stellar Astrophysics · Physics 2015-06-04 K. T. Hole , R. Ignace

We quantify the correlations between gas-phase and stellar metallicities and global properties of galaxies, such as stellar mass, halo mass, age and gas fraction, in the Evolution and Assembly of GaLaxies and their Environments (EAGLE)…

Astrophysics of Galaxies · Physics 2017-11-08 María Emilia De Rossi , Richard G. Bower , Andreea S. Font , Joop Schaye , Tom Theuns

We study the presence of low intensity high velocity components, which we have termed wing features in the integrated Halpha emission line profiles of the HII region populations of the spiral barred galaxies NGC 1530, NGC 3359 and NGC 6951.…

Astrophysics · Physics 2009-11-10 M. Relano , J. E. Beckman

Reliable nebular emission line diagnostics are essential for accurately inferring the physical properties (e.g. electron temperature, density, pressure, and metallicity) of H II regions from spectra. When interpreting spectra, it is typical…

Astrophysics of Galaxies · Physics 2026-02-06 Larrance Xing , Nicholas Choustikov , Harley Katz , Alex J. Cameron

Using broadband photometry from the Hubble Space Telescope in combination with Very Large Telescope narrowband Halpha observations of the nearby spiral galaxy NGC 300, we explore a method for estimating the escape fractions of…

Solar and Stellar Astrophysics · Physics 2016-08-03 Florian Niederhofer , Michael Hilker , Nate Bastian , Barbara Ercolano

Deriving physical parameters from integrated galaxy spectra is paramount to interpret the cosmic evolution of star formation, chemical enrichment, and energetic sources. We develop modeling techniques to characterize the ionized gas…

We study the ionization equilibrium of Fe using photoionization models that incorporate improved values for the ionization and recombination cross-sections and the charge-exchange rates for the Fe ions. The previously available…

Astrophysics · Physics 2007-05-23 M. Rodriguez , R. H. Rubin

We measured the oxygen abundances of the warm (T$\sim 10^{4}K$) phase of gas in seven early-type galaxies through long-slit observations. A template spectra was constructed from galaxies void of warm gas and subtracted from the…

Cosmology and Nongalactic Astrophysics · Physics 2011-02-11 Alex E. Athey , Joel N. Bregman

We have compiled a sample of 26 metal-poor galaxies with 12 + log(O/H) < 8.1 with both infrared continuum and 1.4 GHz radio continuum data. By comparing to galaxies at higher metallicity, we have investigated the dependence on the…

Astrophysics of Galaxies · Physics 2017-09-06 Jianjie Qiu , Yong Shi , Junzhi Wang , Zhi-Yu Zhang , Luwenjia Zhou

The validity of the emission line luminosity vs. ionised gas velocity dispersion ($L - \sigma$) correlation for HII galaxies (HIIGx), and its potential as an accurate distance estimator are assessed. For a sample of 128 local ($0.02\lesssim…

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