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We present a digital atlas of peculiar, high-luminosity massive stars in the near-infrared region (10 470−11 000 Å) at medium resolution (R 7000). The spectra are centered around He i 10 830 Å, which is formed in the wind of those stars, and is a crucial line to obtain their physical parameters. The instrumental configuration also sampled a rich variety of emission lines of Fe ii, Mg ii, C i, N i, and Pa γ. Secure identifications for most spectral lines are given, based on synthetic atmosphere models calculated by our group. We also propose that two unidentified absorption features have interstellar and/or circumstellar origin. For the strongest one (10 780 Å) an empirical calibration between E(B − V) and equivalent width is provided. The atlas displays the spectra of massive stars organized in four categories, namely Be stars, OBA Iape (or luminous blue variables, LBV candidates and ex/dormant LBVs), OB supergiants and Wolf-Rayet stars. For comparison, the photospheric spectra of non emission-line stars are presented. Selected LBVs were observed in different epochs from 2001 to 2004, and their spectral variability reveals that some stars, such as η Car, AG Car and HR Car, suffered dramatic spectroscopic changes during this time interval.Key words. atlases -stars: emission-line, Be -stars: Wolf-Rayet -stars: winds, outflows -stars: early-type IntroductionIn the last decades tremendous progress has been achieved in understanding how a massive star evolves along the HR diagram. A new scenario of massive star evolution was developed after the models allowed for the effects of rotation in the stellar structure and evolution (Maeder & Meynet 2000b). Also, the physical parameters of massive stars can currently be constrained with the advent of a new generation of fully-blanketed, spherical-symmetric, non-LTE radiative transfer codes (Hubeny & Lanz 1995;Hillier & Miller 1998;Hamann & Koesterke 1998;Pauldrach et al. 2001;Gräfener et al. 2002;Puls et al. 2005). Even for extremely massive objects such as Eta Carinae (Hillier et al. 2001) we now have a much better comprehension of the physical parameters of the central star by analyzing the emerged spectrum.However, the short transitional stages of massive star evolution are still poorly understood. The radiation emitted by the photosphere of these stars interacts with the optically-thick, dense wind, which makes the spectral classification a very challenging task. In addition to the luminosity, effective temperature and surface gravity, several other stellar parameters might change the spectral morphology of these objects, notably the mass-loss rate and the wind terminal velocity. In the discussion Based on observations made at Observatório do Pico dos Dias/LNA (Brazil).Figures 5 to 18 are only available in electronic form at http://www.aanda.org Electronic version of the spectra (fichiers FITS) is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/465/993 on the...
We present a digital atlas of peculiar, high-luminosity massive stars in the near-infrared region (10 470−11 000 Å) at medium resolution (R 7000). The spectra are centered around He i 10 830 Å, which is formed in the wind of those stars, and is a crucial line to obtain their physical parameters. The instrumental configuration also sampled a rich variety of emission lines of Fe ii, Mg ii, C i, N i, and Pa γ. Secure identifications for most spectral lines are given, based on synthetic atmosphere models calculated by our group. We also propose that two unidentified absorption features have interstellar and/or circumstellar origin. For the strongest one (10 780 Å) an empirical calibration between E(B − V) and equivalent width is provided. The atlas displays the spectra of massive stars organized in four categories, namely Be stars, OBA Iape (or luminous blue variables, LBV candidates and ex/dormant LBVs), OB supergiants and Wolf-Rayet stars. For comparison, the photospheric spectra of non emission-line stars are presented. Selected LBVs were observed in different epochs from 2001 to 2004, and their spectral variability reveals that some stars, such as η Car, AG Car and HR Car, suffered dramatic spectroscopic changes during this time interval.Key words. atlases -stars: emission-line, Be -stars: Wolf-Rayet -stars: winds, outflows -stars: early-type IntroductionIn the last decades tremendous progress has been achieved in understanding how a massive star evolves along the HR diagram. A new scenario of massive star evolution was developed after the models allowed for the effects of rotation in the stellar structure and evolution (Maeder & Meynet 2000b). Also, the physical parameters of massive stars can currently be constrained with the advent of a new generation of fully-blanketed, spherical-symmetric, non-LTE radiative transfer codes (Hubeny & Lanz 1995;Hillier & Miller 1998;Hamann & Koesterke 1998;Pauldrach et al. 2001;Gräfener et al. 2002;Puls et al. 2005). Even for extremely massive objects such as Eta Carinae (Hillier et al. 2001) we now have a much better comprehension of the physical parameters of the central star by analyzing the emerged spectrum.However, the short transitional stages of massive star evolution are still poorly understood. The radiation emitted by the photosphere of these stars interacts with the optically-thick, dense wind, which makes the spectral classification a very challenging task. In addition to the luminosity, effective temperature and surface gravity, several other stellar parameters might change the spectral morphology of these objects, notably the mass-loss rate and the wind terminal velocity. In the discussion Based on observations made at Observatório do Pico dos Dias/LNA (Brazil).Figures 5 to 18 are only available in electronic form at http://www.aanda.org Electronic version of the spectra (fichiers FITS) is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/465/993 on the...
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