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Approximated forms of the RII and RIII redistribution matrices are frequently applied to simplify the numerical solution of the radiative transfer problem for polarized radiation, taking partial frequency redistribution (PRD) effects into…

Solar and Stellar Astrophysics · Physics 2023-11-29 Simone Riva , Nuno Guerreiro , Gioele Janett , Diego Rossinelli , Pietro Benedusi , Rolf Krause , Luca Belluzzi

We study the Spectral Energy Distributions, SEDs, (from FUV to MIR bands) of the first sizeable sample of 34 low-luminosity radio galaxies at high redshifts, selected in the COSMOS field. To model the SEDs we use two different…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Ranieri D. Baldi , Marco Chiaberge , Alessandro Capetti , Javier Rodriguez-Zaurin , Susana Deustua , William B. Sparks

Hydrogen emission lines can provide extensive information about star-forming galaxies in both the local and high-redshift Universe. We present a detailed Lyman continuum (LyC), Lyman-alpha (Ly{\alpha}), and Balmer line (H{\alpha} and…

Observations with the JWST in lensed fields have revealed that galaxies at cosmic dawn may concentrate their star formation in highly dense, compact, star clusters. The high columns and low metallicities encountered in their birth…

Astrophysics of Galaxies · Physics 2026-05-15 Shyam H Menon , Aaron Smith

Stellar model atmospheres form the basis for any element abundance determination and hence are crucial ingredients for studies of stellar, galactic and cosmic evolution. With recent observational progress with the advent of 8m-class…

Astrophysics · Physics 2007-05-23 Martin Asplund

We explore the onset of star formation in the early Universe, exploiting the observations of high-redshift Lyman-break galaxies (LBGs) and Lyman alpha emitters (LAEs), in the framework of the galaxy formation scenario elaborated by Granato…

Astrophysics · Physics 2010-11-11 J. Mao , A. Lapi , G. L. Granato , G. de Zotti , L. Danese

We investigate the impact of 3D hydrodynamical model atmospheres of red giant stars at different metallicities on the formation of spectral lines of a number of ions and molecules. We carry out realistic 3D simulations of surface convection…

Astrophysics · Physics 2009-11-13 Remo Collet , Martin Asplund , Regner Trampedach

We investigate the Lyman alpha line transfer in nearby and high redshift starbursting galaxies, where the effect of high optical depths and the role of dust in the scattering medium are expected to be conspicuous and should be treated in a…

Astrophysics · Physics 2009-10-31 Sang-Hyeon Ahn , Hee-Won Lee , Hyung Mok Lee

We have developed a pseudo two-dimensional model of a planetary atmosphere, which takes into account thermochemical kinetics, photochemistry, vertical mixing, and horizontal transport, the latter being modeled as a uniform zonal wind. We…

Earth and Planetary Astrophysics · Physics 2014-05-08 Marcelino Agundez , Vivien Parmentier , Olivia Venot , Franck Hersant , Franck Selsis

The vast majority of star-forming galaxies are surrounded by large reservoirs of gas ejected from the interstellar medium. Ultraviolet absorption and emission lines represent powerful diagnostics to constrain the cool phase of these…

The secondary-to-primary ratios are unique tools to investigate cosmic ray propagation mechanisms. In this work, we use the latest data of deuteron-to-helium~4 ratio and helium~3-to-helium~4 ratio measured by PAMELA combined with other…

High Energy Astrophysical Phenomena · Physics 2018-12-31 Juan Wu , Chen Huan

We analyse the joint distribution of dust attenuation and projected axis ratios, together with galaxy size and surface brightness profile information, to infer lessons on the dust content and star/dust geometry within star-forming galaxies…

We have fit synthetic visibilities from 3-D (CO5BOLD + PHOENIX) and 1-D (PHOENIX, ATLAS 12) model stellar atmospheres of Procyon (F5 IV) to high-precision interferometric data from the VLTI Interferometer (K-band) and from the Mark III…

Astrophysics · Physics 2009-11-13 J. P. Aufdenberg , H. -G. Ludwig , P. Kervella

Context. Although oxygen is an important tracer of Galactic chemical evolution, measurements of its abundance in the atmospheres of the oldest Galactic stars are still scarce and rather imprecise. At the lowest end of the metallicity scale,…

Solar and Stellar Astrophysics · Physics 2015-04-22 V. Dobrovolskas , A. Kučinskas , P. Bonifacio , E. Caffau , H. -G. Ludwig , M. Steffen , M. Spite

The intrinsic strength of the Ly$\alpha$ line in young, star-forming systems makes it a special tool for studying high-redshift galaxies. However, interpreting observations remains challenging due to the complex radiative transfer involved.…

Astrophysics of Galaxies · Physics 2019-06-05 Christoph Behrens , Andrea Pallottini , Andrea Ferrara , Simona Gallerani , Livia Vallini

The measurement of oxygen lines in metal-poor unevolved stars, in particular near-UV OH lines, can provide invaluable information on the properties of the Early Galaxy. Near-UV OH lines constitute an important tool to derive oxygen…

Astrophysics of Galaxies · Physics 2015-05-19 J. I. Gonzalez Hernandez , P. Bonifacio , H. -G. Ludwig , E. Caffau , N. T. Behara , B. Freytag

Mass loss from massive stars located in the part of the Hertzsprung-Russell diagram (HRD) where we find luminous blue variables (LBVs) is profoundly important for stellar evolution yet poorly understood. We use time-dependent…

Solar and Stellar Astrophysics · Physics 2026-03-24 P. Schillemans , J. O. Sundqvist , D. Debnath , L. Delbroek , N. Moens , C. Van der Sijpt

During the recent years significant progress has been made in the modeling of red giant atmospheres with the aid of 3D hydrodynamical model atmosphere codes. In this contribution we provide an overview of selected results obtained in this…

Solar and Stellar Astrophysics · Physics 2013-05-16 A. Kucinskas , H. -G. Ludwig , M. Steffen , V. Dobrovolskas , J. Klevas , D. Prakapavicius , E. Caffau , P. Bonifacio

We combine high resolution hydrodynamical simulations with an intermediate resolution, dark matter only simulation and an analytical model for the growth of ionized regions to estimate the large scale distribution and redshift evolution of…

Cosmology and Nongalactic Astrophysics · Physics 2015-07-15 Tirthankar Roy Choudhury , Ewald Puchwein , Martin G. Haehnelt , James S. Bolton

The significance of the Ly$\alpha$ emission line as a probe of the high-redshift Universe has long been established. Originating mainly in the vicinity of young, massive stars and in association with accretion of large bulks of matter, it…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-17 Peter Laursen