Related papers: Investigation of CygOB2 #11 (O5 Ifc) by modeling i…

We present the results of modeling of the spectrum of the brightest stars belonging to the Cyg OB2 association - #7 (O3If*) and #11 (O5Ifc). #7 is one of the hottest stars in our Galaxy, while #11 belongs to the spectral class Ofc, which…

We examine the feasibility of using medium resolution spectra for determining the parameters of atmospheres of hot stars by means of numerical simulations. We chose the star Cyg OB2 No7 as a test object and obtained its spectrum…

Elemental abundances of carbon, nitrogen, oxygen, magnesium, aluminum, and silicon are presented for a sample of twelve rapidly rotating OB star (v sin i > 60 km s^-1) members of the Cep OB2, Cyg OB3 and Cyg OB7 associations. The abundances…

Aims. Having established the binary status of nineteen O-type stars located in four Cygnus OB associations, we now determine their fundamental parameters to constrain their properties and their evolutionary status. We also investigate their…

Cygnus OB2 is a rich OB association in the Galaxy which has experienced intense star formation in the last 20-25 Myr. Its stellar population shows a correlation between age and Galactic longitude. Exploring the chemical composition of its…

We have analyzed six OB supergiants and one giant covering spectral types from O3 to B1 in the Galactic OB association Cyg OB2 by means of an updated version of FASTWIND (SAntolaya-Rey, Puls, Herrero, 1997, A&A 323, 348) that includes an…

Fundamental parameters and the carbon, nitrogen and oxygen abundances are determined for 22 B-type stars with distances up to 600 pc and slow rotation (vsini up to 66 km/s). The stars are selected according to their effective temperatures…

On the basis of an extensive new spectroscopic survey of Galactic O stars, we introduce the Ofc category, which consists of normal spectra with C III \lambda\lambda4647-4650-4652 emission lines of comparable intensity to those of the Of…

We aim to constrain the properties and evolutionary status of early and mid-spectral type supergiants (from O4 to O7.5). These posses the highest mass-loss rates among the O stars, and exhibit conspicuous wind profiles. Using the non-LTE…

Aiming to explore weak spectral features of stellar and interstellar origin we used the NES echelle spectrograph of the 6-m telescope to obtain high-resolution spectra for 13 hot O3 - B4 stars in the Cyg OB2 association, including a high…

We have computed a grid of hydrostatic spherical COMARCS models for C stars covering metallicities from [Z/H]=0 to -2 and values of the carbon excess [C-O] from 6.41 to 9.15, plus some temperature sequences, where the amount of oxygen and…

Following a brief exposition of the morphological process, two examples of its application in contemporary astronomy are presented. The first comprises a major digital, blue-violet spectral classification program on Galactic O stars, that…

We present the results of investigation of five stars, originally classified as dwarfs, belonging to Cyg OB2 association, their stellar and wind properties. Using both TLUSTY and CMFGEN codes we derived effective temperatures, surface…

The compact association Cygnus OB2 is known to contain a large population of massive stars, but its total mass is currently a matter of debate. While recent surveys have uncovered large numbers of OB stars in the area around Cyg OB2,…

Cyg OB2 is one of the most massive associations of O-type stars in our Galaxy. Despite the large interstellar reddening towards Cyg OB2, many studies, spanning a wide range of wavelengths, have been conducted to more clearly understand this…

We have compiled a significantly updated and comprehensive census of massive stars in the nearby Cygnus OB2 association by gathering and homogenising data from across the literature. The census contains 169 primary OB stars, including 52…

Cygnus OB2 provides a unique insight into the high-mass stellar content in one of the largest groups of young massive stars in our Galaxy. Although several studies of its massive population have been carried out over the last decades, an…

The blue hypergiant Cyg OB2-12 (B3Ia+) is a representative member of the class of very massive stars in a poorly understood evolutionary stage. We obtained its high-resolution X-ray spectrum using Chandra observatory. PoWR model atmospheres…

Massive stars are the key agents of feedback. Consequently, quantitative analysis of massive stars are required to understand how the feedback of these objects shapes/ creates the large scale structures of the ISM. The giant HII region N206…

We provide an observational view of evolutionary models in the Hertzsprung--Russell diagram, on the main sequence. For that we computed evolutionary models with the code STAREVOL for 15 < M/Msun < 100. We subsequently calculated atmosphere…