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This work presents a Bayesian algorithm to fit the recombination and collisionally excited line spectra of gas photoionized by clusters of young stars. The current model consists in fourteen dimensions: two electron temperatures, one…

Astrophysics of Galaxies · Physics 2019-06-05 Vital Fernández , Elena Terlevich , Angeles I. Díaz , Roberto Terlevich

(abridged) Imaging observations are generally affected by a fluctuating background of speckles, a particular problem when detecting faint stellar companions at small angular separations. Knowing the distribution of the speckle intensities…

Astrophysics · Physics 2009-11-13 Michael P. Fitzgerald , James R. Graham

On the basis of the Galactic O-Star Spectroscopic Survey (GOSSS), a detailed systematic investigation of the O Vz stars is presented. The currently used spectral classification criteria are rediscussed, and the Vz phenomenon is recalibrated…

A method is developed for fitting theoretically predicted astronomical spectra to an observed spectrum. Using a hierarchical Bayesian principle, the method takes both systematic and statistical measurement errors into account, which has not…

Astrophysics · Physics 2008-11-26 Z. Shkedy , L. Decin , G. Molenberghs , C. Aerts

Stellar winds govern the angular momentum evolution of solar-like stars throughout their main-sequence lifetime. The efficiency of this process depends on the geometry of the star's magnetic field. There has been a rapid increase recently…

Solar and Stellar Astrophysics · Physics 2016-11-11 Moira Jardine , Aline Vidotto , Victor See

We compare current 1D and multi-dimensional atmosphere modelling approaches for massive stars to understand their strengths and shortcomings. We calculate averaged stratifications from selected 2D calculations for O stars -- corresponding…

Spectroscopic analyses of 7 SMC B-type supergiants and 1 giant have been undertaken using high resolution optical data obtained on the VLT with UVES. FASTWIND, a non-LTE, spherical,line-blanketed model atmosphere code was used to derive…

Astrophysics · Physics 2009-11-10 C. Trundle , D. J. Lennon , J. Puls , P. L. Dufton

Mass-loss rate, $\dot{M}$, is one of the key parameters affecting evolution and observational manifestations of massive stars, and their impact on the ambient medium. Despite its importance, there is a factor of ~100 discrepancy between…

Solar and Stellar Astrophysics · Physics 2015-06-11 V. V. Gvaramadze , N. Langer , J. Mackey

Modern spectroscopic surveys can only target a small fraction of the vast amount of photometrically cataloged sources in wide-field surveys. Here, we report the development of a generative AI method capable of predicting optical galaxy…

The measurement of atmospheric parameters is fundamental for scientific research using stellar spectra. The Chinese Space Station Telescope (CSST), scheduled to be launched in 2024, will provide researchers with hundreds of millions of…

Solar and Stellar Astrophysics · Physics 2024-08-21 JiaRui Rao , HaiLiang Chen , JianPing Xiong , LuQian Wang , YanJun Guo , JiaJia Li , Chao Liu , ZhanWen Han , XueFei Chen

The wind-driving mechanism of asymptotic giant branch (AGB) stars is commonly attributed to a two-step process: first, gas in the stellar atmosphere is levitated by shockwaves caused by stellar pulsation, then accelerated outwards by…

Solar and Stellar Astrophysics · Physics 2018-11-07 S. Liljegren , S. Höfner , B. Freytag , S. Bladh

We introduce a new method to determine the relative contributions of different types of stars to the integrated light of nearby early-type galaxies. As is well known, the surface brightness of these galaxies shows pixel-to-pixel…

Astrophysics of Galaxies · Physics 2015-06-23 Pieter van Dokkum , Charlie Conroy

High resolution spectral models for simple stellar populations (SSP) developed in the past few years have become a standard ingredient in studies of stellar population of galaxies. As more such models become available, it becomes…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Roberto Cid Fernandes , Rosa M. Gonzalez Delgado

Context. Establishing the multiplicity of O-type stars is the first step towards accurately determining their stellar parameters. Moreover, the distribution of the orbital parameters provides observational clues to the way that O-type stars…

Solar and Stellar Astrophysics · Physics 2015-06-12 L. Mahy , G. Rauw , M. De Becker , P. Eenens , C. A. Flores

We analyze STIS spectra in the 1150-1700 Angstrom wavelength range obtained for six early B supergiants in the neighboring galaxy M31. Because of their likely high (nearly solar) abundance, these stars were originally chosen to be directly…

Spectral energy distributions are computed using 2D rotating stellar models and NLTE plane parallel model atmospheres. A rotating, 2D stellar model has been found which matches the observed ultraviolet and visible spectrum of ? Oph. The SED…

Solar and Stellar Astrophysics · Physics 2015-06-04 Robert G. Deupree , Diego Castañeda , Fernando Peña , C. Ian Short

We present an automated procedure that derives simultaneously the effective temperature $T_{eff}$, the surface gravity logg, the metallicity [Fe/H], and the equatorial projected rotational velocity vsini for "normal" A and Am stars. The…

Instrumentation and Methods for Astrophysics · Physics 2016-04-20 M. Gebran , W. Farah , F. Paletou , R. Monier , V. Watson

The impact of FUSE upon the fundamental parameters of OB stars and Wolf-Rayet stars is reviewed. The stellar wind signatures available in the far-UV provide us with important additional diagnostics of effective temperature. Together with…

Astrophysics · Physics 2007-05-23 Paul A. Crowther

Massive stars play a significant role in different branches of astronomy, from shaping the processes of star and planet formation to influencing the evolution and chemical enrichment of the distant universe. Despite their high astrophysical…

Solar and Stellar Astrophysics · Physics 2026-01-14 N. Monsalves , A. Bayo , M. Jaque Arancibia , J. Bodensteiner , A. G. Caneppa , P. Sánchez-Sáez , R. Angeloni

Many Wolf-Rayet (WR) stars have optically thick winds that cloak the hydrostatic layers of the underlying star. In these cases, traditional spectral analysis methods are plagued by degeneracies that make it difficult to constrain parameters…