The Interacting Early-Type Binary BD +40°4220 (V729 Cyg): Modeling the Colliding Winds Region

in Astrophysical Journal (1999), 517

We present an analysis of an extensive set of spectroscopic observations of the mysterious early-type binary BD +40 deg4220. A new orbital solution is derived from the radial velocities of the absorption ... [more ▼]

We present an analysis of an extensive set of spectroscopic observations of the mysterious early-type binary BD +40 deg4220. A new orbital solution is derived from the radial velocities of the absorption lines. We confirm that the secondary star is highly overluminous for its mass. The absorption lines of both components display phase-locked profile variations, with some of the secondary's lines going into emission between phi=0.20 and phi=0.55. A detailed investigation of the profile variability of the He II lambda4686 emission line reveals that the pattern of variability of this line is very stable. We show that part of the He II lambda4686 emission is produced in the wind interaction region between the stars. Most of the emission lines in the visual spectrum of BD +40 deg4220 display variations that are reminiscent of those observed on the He II lambda4686 line, pointing toward a similar origin. We present numerical simulations of emission-line profiles in a colliding winds binary, showing that an important part of the variability observed in BD +40 deg4220 can be explained by a colliding winds phenomenon. The properties of the wind interaction region can be accounted for if we assume that the secondary star is an evolved object, most probably some kind of Ofpe/WN9 transition star, with a mass loss rate of ~5.5x10^-6 M_solar yr^-1. We finally discuss the fundamental parameters of the binary, concluding that mass transfer must have played a crucial role in the evolution of this system. [less ▲]

New observational results on the colliding wind WR+O binary WR 30a

in Wolf-Rayet Phenomena in Massive Stars and Starburst Galaxies (1999)

Line profile variability in the spectrum of the O(f) supergiant HD 192639

in Astronomy and Astrophysics (1998), 335

We report the results of a medium-resolution spectroscopic investigation of the O(f) supergiant HD 192639. Particular attention is paid to the He {ii}\ lambda 4686 line. This line displays strong profile ... [more ▼]

We report the results of a medium-resolution spectroscopic investigation of the O(f) supergiant HD 192639. Particular attention is paid to the He {ii}\ lambda 4686 line. This line displays strong profile variability on time scales of a few days, changing from a P-Cygni profile with a double-peaked emission component to a pure blue-shifted emission line. It appears that the variability of most of the absorption lines present in our spectra is correlated to the deformation of the He {ii}\ lambda 4686 line and arises probably from a large scale structure in the low-velocity part of the stellar wind rather than from a photospheric phenomenon. We find that the time scale of the variability could be consistent with the estimated rotational period of HD 192639. Based on observations collected at the Observatoire de Haute Provence, France. [less ▲]

The LMC transition star R 84 and the core of the LH 39 OB association.

in Astronomy and Astrophysics (1997), 326

On the basis of sub-arcsecond imaging obtained at the ESO NTT with SUSI and the ESO ADONIS adaptive optics system at the 3.6m telescope, we resolve and study the core components of the LMC OB association ... [more ▼]

On the basis of sub-arcsecond imaging obtained at the ESO NTT with SUSI and the ESO ADONIS adaptive optics system at the 3.6m telescope, we resolve and study the core components of the LMC OB association LH 39. The central star of the association, the rare transition object R 84, is also investigated using CASPEC echelle spectroscopy at the ESO 3.6m telescope. A new, powerful image restoration code that conserves the fluxes allows us to obtain the magnitudes and colors of the components. We bring out some 30 stars in a ~16"x16" area centered on R 84. At a resolution of 0.19"(FWHM), the closest components to R 84 are shown to be stars #21 and #7 lying at 1.1"NW and 1.7"NW respectively of the transition star. The former is possibly a blue star of V=16.7mag and the latter with its V=17.5mag is the reddest star of the field, after R 84. Star #7 turns out to be too faint to correspond to the red M2 supergiant previously reported to contaminate the spectrum of R 84. If the late-type spectrum is due to a line-of-sight supergiant with a luminosity comparable to R 84, it should lie closer than 0.12" to R 84. The transition star shows spectral variability between 1982 and 1991. We also note some slight radial velocity variations of the Of emission lines over timescales of several years. Furthermore, we derive the spectral types of two of the brightest stars of the cluster, using long slit spectra obtained at the NTT telescope equipped with EMMI, and discuss the apparent absence of O type stars in this association. [less ▲]

The WN 11-like Spectrum of HD 5980 during the early Stages of the 1994 Eruption

in Luminous Blue Variables: Massive Stars in Transition (1997)

Not Available

Existence of a short period (3.5-4 hours) in the photometric variability of WR 66.

in Astronomy and Astrophysics (1996), 306

We report here on an independent detection of a short period (~4hours) in the photometric variations of WR66, thus confirming in broad terms the discovery by Antokhin et al.. In addition, we present the ... [more ▼]

We report here on an independent detection of a short period (~4hours) in the photometric variations of WR66, thus confirming in broad terms the discovery by Antokhin et al.. In addition, we present the first spectroscopic variability analysis for this star. A few peculiarities of the spectrum of WR66 are also discussed. Finally, we perform a brief examination of different possible origins of the phenomenon. [less ▲]

Wolf-Rayet stars in the framework of stellar evolution.

Book (1996)

The following topics were dealt with: evolution of massive stars - theory; observational characteristics of Wolf-Rayet stars and related objects; evidences for evolutionary links - transition objects ... [more ▼]

The following topics were dealt with: evolution of massive stars - theory; observational characteristics of Wolf-Rayet stars and related objects; evidences for evolutionary links - transition objects; analysis of the observations - the models and their results; massive stars in starburst. [less ▲]

Line-profile variability and mass-transfer in the early type binary BD+40° 4220

in Liege International Astrophysical Colloquia (1996)

Not Available

Spectropolarimetry of WR66

in Wolf-Rayet stars in the framework of stellar evolution ; 33rd Liege International Astrophysical Coll (1996)

We have carried out spectropolarimetric observations of the Wolf-Rayet star WR66 (WN8) with EFOSC1 mounted on the ESO 3.6m telescope of La Silla. The results indicate a polarization level of about 5 to 6 ... [more ▼]

We have carried out spectropolarimetric observations of the Wolf-Rayet star WR66 (WN8) with EFOSC1 mounted on the ESO 3.6m telescope of La Silla. The results indicate a polarization level of about 5 to 6 % in the continuum which is most probably due to interstellar polarization. [less ▲]

A seven year campaign on WR 22

in Wolf-Rayet Stars: Binaries; Colliding Winds; Evolution. International Astronomical Union. Symposium no. 163 (1995)

Not Available