The Galactic WN stars. Spectral analyses with line-blanketed model atmospheres versus stellar evolut

  title={The Galactic WN stars. Spectral analyses with line-blanketed model atmospheres versus stellar evolut},
  author={W. R. Hamann and Goetz Graefener and Adriane Liermann},
  journal={Astronomy and Astrophysics},
An infrared light-receiving device includes an optical absorption layer disposed on a principal surface of a substrate and an optical filter disposed on the optical absorption layer, the optical filter including first, second, and third semiconductor regions that are arranged in that order in a direction from the optical absorption layer to the optical filter, each of the first, second, and third semiconductor regions including an n-type InGaAs layer. The optical absorption layer includes a… 

Modelling the optical spectrum of Romano's star

We consider the luminous blue variable (LBV) star V532 in M33, also known as Romano’s star, in two different spectral states: in the optical minimum of 2007/2008 and during a local brightening in

Two extremely luminous WN stars in the Galactic center with circumstellar emission from dust and gas

Context. The central region of our Galaxy contains a large population of young massive stars. These stars are concentrated in three large star clusters, as well as being scattered in the field.

The Wolf-Rayet stars in the Large Magellanic Cloud - A comprehensive analysis of the WN class

Context. Massive stars, although being important building blocks of galaxies, are still not fully understood. This especially holds true for Wolf-Rayet (WR) stars with their strong mass loss, whose


We present new results on the chemical composition of the Galactic ring nebula NGC 6888 surrounding the WN6(h) star WR136. The data are based on deep spectroscopical observations taken with the High

TRES survey of variable diffuse interstellar bands

Diffuse interstellar bands (DIBs) are absorption features commonly observed in optical/near-infrared spectra of stars and thought to be associated with polyatomic molecules that comprise a

The radial abundance gradient of oxygen towards the Galactic anti-centre

We present deep optical spectroscopy of eight HII regions located in the anticentre of the Milky Way. The spectra were obtained at the 10.4m GTC and 8.2m VLT. We determined Te([NII]) for all objects

Investigating the origin of the spectral line profiles of the Hot Wolf–Rayet Star WR 2

The hot WN star WR 2 (HD 6327) has been claimed to have many singular characteristics. To explain its unusually rounded and relatively weak emission line profiles, it has been proposed that WR 2 is

Modelling the nebular emission from primeval to present-day star-forming galaxies

We present a new model of the nebular emission from star-forming galaxies in a wide range of chemical compositions, appropriate to interpret observations of galaxies at all cosmic epochs. The model

Dust in the Wolf–Rayet nebula M 1-67

The Wolf-Rayet nebula M1-67 around WR124 is located above the Galactic plane in a region mostly empty of interstellar medium, which makes it the perfect target to study the mass-loss episodes



Optical Spectroscopy of EZ Canis Majoris: Indication for Large-Scale Structures in a Wolf-Rayet Wind

We have carried out optical spectroscopy of the Wolf-Rayet star EZ CMa during 20 consecutive nights in 1995 January in support of the IUE Mega-project. In parallel with this optical spectroscopy, we

The relationship between infrared, optical, and ultraviolet extinction

The parameterized extinction data of Fitzpatrick and Massa (1986, 1988) for the ultraviolet and various sources for the optical and near-infrared are used to derive a meaningful average extinction

Mid-infrared imaging and spectroscopy of the enigmatic cocoon stars in the Quintuplet Cluster

In an attempt to determine the nature of the enigmatic cocoon stars in the Quintuplet Cluster, we have obtained mid-infrared imaging and spectrophotometry of the cluster, using the CAM and SWS

The Treatment of Non-LTE Line Blanketing in Spherically Expanding Outflows

Extensive modifications to the non-LTE radiative transfer code of Hillier have been made in order to improve the spectroscopic analysis of stars with stellar winds. The main improvement to the code

Grids of model spectra for WN stars, ready for use

Grids of model atmospheres for Wolf-Rayet stars of the nitrogen sequence (WN subclass) are presented. The calculations account for the expansion of the atmosphere, non-LTE, clumping, and line

Non-thermal emission in Wolf-Rayet stars: are massive companions required?

We examine the radio spectral indices of 23 Wolf–Rayet (WR) stars to identify the nature of their radio emission. We identify nine systems as non-thermal emitters. In seven of these systems the

Hydrogen in the atmosphere of the evolved WN3 Wolf–Rayet star WR 3: defying an evolutionary paradigm?

WR 3 is the brightest very early-type WN star in the sky. Based on several years of timeresolved spectroscopy and precision photometry on various time-scales, we deduce that WR 3 is most likely a

Correcting for the Effects of Interstellar Extinction

This paper addresses the issue of how best to correct astronomical data for the wavelength‐dependent effects of Galactic interstellar extinction. The main general features of extinction from the IR

NGC 6611: a cluster caught in the act

We have combined optical CCD photometry and spectroscopy with infrared imaging photometry to study the young cluster NGC 6611. We use these data to derive improved values for the reddening law

XMM-Newton high-resolution X-ray spectroscopy of the Wolf-Rayet object WR 25 in the Carina OB1 association

We report the analysis of the first high-resolution X-ray spectra of the Wolf-Rayet (WR) object WR 25 (HD 93162, WN6ha+O4f) obtained with the reflection grating spectrometers (rgs )a nd theeuropean