New and revised parameters for several southern OB binaries

Abstract

Using ESO FEROS archive spectra of several southern OB-type binaries, we derived periods for three SB2 spectroscopic binaries, HD 97166, HD 115455, and HD 123590, and two SB1 systems, HD 130298 and HD 163892. It was also possible to use new FEROS spectra to improve the parameters of the known binaries, KX Vel and HD 167263. For KX Vel, we determined a dynamic mass of the primary of 16.8 M , while the evolutionary model suggests a higher value of 20.2 M . We derived an improved period for HD 167263, and in its spectra, we recognized contributions of both of its interferometric components.

Chemical abundances of fast-rotating massive stars

“…In the context of this work, we redetermined the RVs of the FEROS spectra used by Mayer et al and complemented the set of RV values thanks to another FEROS spectrum, three CORALIE, and two FIES spectra (Table A.1). Our RVs appear systematically lower by ∼10 km s −1 than those reported by Mayer et al (2014). This difference is not surprising as they used Gaussian fits of individual lines to derive their values, which can differ from correlation results by about 10 km s −1 , depending on the chosen rest wavelength of the fitted lines.…”

“…C.7); this orbital solution was computed with an eccentricity fixed to zero after it was found to be compatible with this value within the error bars. This orbital solution is in good agreement with the solution of Mayer et al (2014) within the error bars, except for the primary systemic velocity (V γ, pri = +2.8 vs. -3.1 km s −1 ).…”

“…This difference is not surprising as they used Gaussian fits of individual lines to derive their values, which can differ from correlation results by about 10 km s −1 , depending on the chosen rest wavelength of the fitted lines. It may further be noted that lowering by 10 km s −1 the primary systemic velocity V γ, pri given by Mayer et al (2014) yields a value more consistent with the average RV of the Sgr OB1 members that they quote (∼−10 km s −1 ). Such a change in the orbital solution, however, implies that two out of the three RV measurements of Feast & Thackeray (1963) and the Stickland & Lloyd (2001) measurement do not fit well the RV curve anymore; but these RVs were measured on photographic plates, hence have a larger error than ours based on high-resolution échelle spectra.…”

“…It has long been recognised as an SB1 system (Feast et al 1957;Conti et al 1977), as recently confirmed by Stickland & Lloyd (2001) and the OWN Survey (Barbá et al 2010;Sota et al 2014). An orbital solution for the SB1 was presented by Mayer et al (2014) who found a 7.8 d period. In the context of this work, we redetermined the RVs of the FEROS spectra used by Mayer et al and complemented the set of RV values thanks to another FEROS spectrum, three CORALIE, and two FIES spectra (Table A.1).…”

A new method for an objective,χ2-based spectroscopic analysis of early-type stars

“…The spectroscopic distance d = 960 +240 −200 pc lies well within the 99%-uncertainty range of the parallax, Π −1 = 1000 +2300 −0500 pc. Finally, the spectroscopically deduced effective surface ratio A eff,s /A eff,p = 0.218 +0.003+0.014 −0.002−0.011 agrees well with the squared ratio of the evolutionary-track radii, (R ,s /R ,p ) 2 = 0.13 +0.41 −0.04 , and is further consistent with the photometric light curve (Mayer et al 2014). The elemental abundances of the system are in line with the single stars except for the relatively low helium, nitrogen, and oxygen content (see Table 5).…”