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Register a new userThe Double-Lined Spectroscopic Binary Haro 1-14c
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Authors
M. Simon
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We report detection of the low-mass secondary in the spectroscopic binary Haro 1-14c in the Ophiuchus star forming region. The secondary/primary mass ratio is $0.310pm 0.014$. With an estimated photometric primary mass of 1.2 $M_{odot}$, the secondary mass is $sim 0.4 M_{odot}$ and the projected semi-major axis is $sim 1.5$ AU. The system is well-suited for astrometric mapping of its orbit with the current generation of ground-based IR interferometers. This could yield precision values of the systems component masses and distance.
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R144 is a WN6h star in the 30 Doradus region. It is suspected to be a binary because of its high luminosity and its strong X-ray flux, but no periodicity could be established so far. Here, we present new Xshooter multi-epoch spectroscopy of R144 obtained at the ESO Very Large Telescope (VLT). We detect variability in position and/or shape of all the spectral lines. We measure radial velocity variations with an amplitude larger than 250 km/s in NIV and NV lines. Furthermore, the NIII and NV line Doppler shifts are anti-correlated and the NIV lines show a double-peaked profile on six of our seven epochs. We thus conclude that R144 is a double-lined spectroscopic binary. Possible orbital periods range from 2 to 6 months, although a period up to one year is allowed if the orbit is highly eccentric. We estimate the spectral types of the components to be WN5-6h and WN6-7h, respectively. The high luminosity of the system (log Lbol/Lsun ~ 6.8) suggests a present-day total mass content in the range of about 200 to 300 Msun, depending on the evolutionary stage of the components. This makes R144 the most massive binary identified so far, with a total mass content at birth possibly as large as 400 Msun. We briefly discuss the presence of such a massive object 60 pc away from the R136 cluster core in the context of star formation and stellar dynamics.
We devise a new method for the detection of double-lined binary stars in a sample of the Radial Velocity Experiment (RAVE) survey spectra. The method is both tested against extensive simulations based on synthetic spectra, and compared to direct visual inspection of all RAVE spectra. It is based on the properties and shape of the cross-correlation function, and is able to recover ~80% of all binaries with an orbital period of order 1 day. Systems with periods up to 1 year are still within the detection reach. We have applied the method to 25,850 spectra of the RAVE second data release and found 123 double-lined binary candidates, only eight of which are already marked as binaries in the SIMBAD database. Among the candidates, there are seven that show spectral features consistent with the RS CVn type (solar type with active chromosphere) and seven that might be of W UMa type (over-contact binaries). One star, HD 101167, seems to be a triple system composed of three nearly identical G-type dwarfs. The tested classification method could also be applicable to the data of the upcoming Gaia mission.
Accurate stellar parameters of individual objects in binary systems are essential to constrain the effects of binarity on stellar evolution. These parameters serve as a prerequisite to probing existing and future theoretical evolutionary models. We aim to derive the atmospheric parameters of the 31 SB2s in the TMBM sample. This sample, composed of detached, semi-detached and contact systems with at least one of the components classified as an O star, is an excellent test-bed to study how binarity can impact our knowledge of the evolution of massive stars. 32 epochs of FLAMES/GIRAFFE spectra are analysed using spectral disentangling to construct the individual spectra of 62 components. We apply the CMFGEN atmosphere code to determine their stellar parameters and their He, C and N surface abundances. From these properties, we show that the effects of tides on chemical mixing are limited. Components on longer-period orbits show higher nitrogen enrichment at their surface than those on shorter-period orbits, in contrast to expectations of rotational or tidal mixing, implying that other mechanisms play a role in this process. Components filling their Roche lobe are mass donors. They exhibit higher nitrogen content at their surface and rotate more slowly than their companions. By accreting new material, their companions spin faster and are rejuvenated. Their locations in the N-vsini diagram tend to show that binary products are good candidates to populate the two groups of stars (slowly rotating, nitrogen-enriched and rapidly rotating non-enriched) that cannot be reproduced through single-star population synthesis. This sample is the largest sample of binaries to be studied in such a homogeneous way. The study of these objects gives us strong observational constraints to test theoretical binary evolutionary tracks.
Double-lined spectroscopic binary systems, containing a Wolf-Rayet and a massive O-type star, are key objects for the study of massive star evolution because these kinds of systems allow the determination of fundamental astrophysical parameters of their components. We have performed spectroscopic observations of the star WR 68a as part of a dedicated monitoring program of WR stars to discover new binary systems. We identified spectral lines of the two components of the system and disentangled the spectra. We measured the radial velocities in the separated spectra and determined the orbital solution. We discovered that WR 68a is a double- lined spectroscopic binary with an orbital period of 5.2207 days, very small or null eccentricity, and inclination ranging between 75 and 85 deg. We classified the binary components as WN6 and O5.5-6. The WN star is less massive than the O-type star with minimum masses of 15 +/- 5 Msun and 30 +/- 4 Msun , respectively. The equivalent width of the He II {lambda}4686 emission line shows variations with the orbital phase, presenting a minimum when the WN star is in front of the system. The light curve constructed from available photometric data presents minima in both conjunctions of the system
Multi-color light curves and radial velocities for TYC,1031,1262,1 have been obtained and analyzed. TYC,1031,1262,1 includes a Cepheid with a period of 4.15270$pm$0.00061 days. The orbital period of the system is about 51.2857$pm$0.0174 days. The pulsation period indicates a secular period increase with an amount of 2.46$pm$0.54 min/yr. The observed B, V, and R magnitudes were cleaned for the intrinsic variations of the primary star. The remaining light curves, consisting of eclipses and proximity effects, are obtained and analyzed for orbital parameters. The system consists of two evolved stars, F8II+G6II, with masses of M$_1$=1.640$pm$0.151 {Msun} and M$_2$=0.934$pm$0.109 {Msun} and radii of R$_1$=26.9$pm$0.9 {Rsun} and R$_2$=15.0$pm$0.7 {Rsun}. The pulsating star is almost filling its corresponding Roche lobe which indicates the possibility of mass loss or transfer having taken place. We find an average distance of d=5070$pm$250,pc using the BVR and JHK magnitudes and also the V-band extinction. Kinematic properties and the distance to the galactic plane with an amount of 970 pc indicate that it belongs to the thick-disk population. Most of the observed and calculated parameters of the TYC,1031,1262,1 lead to a classification of an Anomalous Cepheid.
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