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Context. Compact hierarchical systems are important because the effects caused by the dynamical interaction among its members occur ona human timescale. These interactions play a role in the formation of close binaries through Kozai cycles with tides. One such system is ξ Tauri: it has three hierarchical orbits: 7.14 d (eclipsing components Aa, Ab), 145 d (components Aa+Ab, B), and 51 yr (components Aa+Ab+B, C).Aims. We aim to obtain physical properties of the system and to study the dynamical interaction between its components.Methods. Our analysis is based on a large series of spectroscopic photometric (including space-borne) observations and long-baseline optical and infrared spectro-interferometric observations. We used two approaches to infer the system properties: a set of observation-specific models, where all components have elliptical trajectories, and an N -body model, which computes the trajectory of each component by integrating Newton’s equations of motion.Results. The triple subsystem exhibits clear signs of dynamical interaction. The most pronounced are the advance of the apsidal line and eclipse-timing variations. We determined the geometry of all three orbits using both observation-specific and N -body models. The latter correctly accounted for observed effects of the dynamical interaction, predicted cyclic variations of orbital inclinations, and determined the sense of motion of all orbits. Using perturbation theory, we demonstrate that prominent secular and periodic dynamical effects are explainable with a quadrupole interaction. We constrained the basic properties of all components, especially of members of the inner triple subsystem and detected rapid low-amplitude light variations that we attribute to co-rotating surface structures of component B. We also estimated the radius of component B. Properties of component C remain uncertain because of its low relative luminosity. We provide an independent estimate of the distance to the system.Conclusions. The accuracy and consistency of our results make ξ Tau an excellent test bed for models of formation and evolution of hierarchical systems.

The multiple system V505 Sagittarii is composed of at least three stars: a compact eclipsing pair and a distant component, whose orbit is measured directly using speckle interferometry. In order to explain the observed orbit of the third body in V505 Sagittarii and also other observable quantities, namely the minima timings of the eclipsing binary and three different radial velocities (RVs) detected in the spectrum, we thoroughly test a fourth-body hypothesis—a perturbation by a dim, yet-unobserved object. We use an N-body numerical integrator to simulate future and past orbital evolution of three or four components in this system. We construct a suitable χ 2 metric from all available speckle-interferometry, minima-timings, and RV data and we scan a part of a parameter space to get at least some of the possible solutions. In principle, we are able to explain all observable quantities by the presence of a fourth body, but the resulting likelihood of this hypothesis is very low. We also discuss other theoretical explanations of the minima-timing variations. Further observations of the minima timings during the next decade or high-resolution spectroscopic data can significantly constrain the model.

UBV measurements of early-type stars, mostly eclipsing binaries, obtained at La Silla in the years 1990 to 1994 with the ESO 50 cm telescope are presented. Most of these data were already used in our individual studies of several binaries. Now all photometric measurements were reduced again with an advanced technique and are made available electronically. Our data for MY Ser have not yet been published; new light curve is given and solved. The result is that MY Ser is a contact binary, with very large fill-out parameter. Also a light curve and its solution for V1051 Cen are provided, and the problem of the period of V871 Cen is pointed out. Besides binaries (and the comparison and check stars) data for several stars in southern H II regions are included. Extinction and transformation coefficients are given (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Context. In spite of the importance of massive O-type stars for astrophysics, their accurate masses and other fundamental properties are still a matter of debate. Determining them reliably is hampered by various factors (stellar winds and other forms of circumstellar matter), and the agreement of derived properties with the model predictions is far from satisfactory. Careful studies of O-type binaries, especially of those in stellar clusters, are therefore desirable. Aims. Having obtained new series of electronic spectra and UBV photometry of V1007 Sco, we analysed these data in an effort to check whether the observed properties of V1007 Sco indeed disagree with the prediction of stellar evolutionary models. We briefly analysed data for a few other binaries in NGC 6231, too. Methods. Spectral reductions were carried out with the MIDAS program, photometry reduced using the HEC22 program, the orbital elements were derived with the FOTEL program and the final solutions obtained with the program PHOEBE. Results. Our analysis led to an accurate determination of the apsidal advance, u ω = (0.00884 ± 0.00012) deg d −1 , based on a simultaneous solution of all usable radial-velocity and photometric data. This implies an apsidal period of 111.5 years. It is also demonstrated that the orbital inclination must be close to 67 ◦ . We arrived at the following preliminary values for masses and radii: M1 = (29.5 ± 0.4) M� , M2 = (30.1 ± 0.4) M� , R1 = (15.8 ± 0.7) R� ,a ndR2 = (15.3 ± 0.5) R� . These values clearly indicate a log g of about 3.5 [CGS], implying that the stars are giants and not supergiants, as the standard spectral classification criteria indicate.

Context. Several binaries with masses anomalously small for their observed spectral types have been discussed in the astronomical literature and interpreted as the result of envelope ejection. V379 Cep is one of these objects. Aims. We obtained new series of electronic spectra and UBV photometry of V379 Cep and analysed them in an effort to check whether the conclusion about its anomalous masses may not be premature. Methods. Reduction of new spectra was carried out in the IRAF and SPEFO programs. New photometry was reduced and transformed to the standard system using the HEC22 program. Orbital elements were derived with the FOTEL program and via disentangling with the program KOREL. The final combined solution was obtained with the program PHOEBE. Some initial period searches were carried out using the phase dispersion minimalization technique. Results. We found that the second system of spectral lines seen in the spectra of V379 Cep does not belong to the secondary but to the primary of another binary Ba + Bb (orbital period of 158 d .71 ± 0 d .17), which constitutes a quadruple system with the narrow-lined 99 d .7638 ± 0 d .0006 eclipsing binary Aa + Ab (for which we report probable detection of the secondary and derive improved period and orbital elements). The mutual motion of the two binaries A + B around the common centre of gravity is also observable, and the probable orbital period is (7878 ± 77) days. Our result shows that the components Aa and Ba are somewhat evolved but removes the reported discrepancy of anomalously small masses. Conclusions. We find that V379 Cep is an astrophysically interesting quadruple system for which a future combination of interferometry, spectroscopy, and photometry can provide individual masses of all four bodies.

We obtained new series of electronic spectra and UBV photometry of V379 Cep and analyzed them in an effort to check whether the conclusion about its anomalous masses is not premature. We found that the second system of spectral lines seen in the spectra of V379 Cep does not belong to the secondary but to the primary of another binary Ba+Bb (orbital period of 159d0) which constitutes a quadruple system with the narrow-lined 99d76 eclipsing binary Aa+Ab (for which we report probable detection of the secondary and derive improved period and orbital elements). The mutual motion of the two binaries A+B around the common centre of gravity is also observable and the probable orbital period is some 7878 days. Our result shows that the components Aa and Ba are somewhat evolved but removes the reported discrepancy of anomalously small masses. We find that V379 Cep is an astrophysically interesting quadruple system for which a future combination of interferometry, spectroscopy and photometry can provide individual masses of all four bodies.

Orbital period changes of the eclipsing binaries GO Cyg and GW Cep are explained by the light-time effect for the first time. New minima of the eclipsing binary AR Aur improve the predicted light-time orbit. The light-time orbit with the quadratic ephemeris of the binary matches the new observations of V505 Sgr better than the linear one. As the light-time effect fits in corresponding O − C diagrams of all four systems have been reaching extreme values, the observations of minima times in forthcoming years are highly desirable.

We obtained high-resolution spectroscopy and UBV photometry of the O-type eclipsing binary V1182 Aql. In the spectra lines of a third component were found; the presence of third light is also supported by the solution of the light curves. New masses for both components of the binary were derived: M1 = 31.0 and M2 = 16.6 M☉. These values differ considerably from those given by Bell et al., which were obtained by neglecting the presence of a third body. With Teff ~ 43,000 K the primary component is much hotter than expected for the previously assumed spectral type O8. Its classification has to be revised to O5.5, which makes V1182 Aql probably the earliest eclipsing binary in the Galaxy. The mass of the primary is smaller than suggested by evolutionary models, while the secondary parameters agree with a position close to the zero-age main sequence (ZAMS). The third body, which manifests itself by strong lines in the optical spectrum and by a third light contribution of ~17% as deduced from the light curve solution might be detectable by interferometric measurements.

We present a spectroscopic and photometric analysis of V1331 Aql, an early-type eclipsing binary with a quite short period, i.e. 1.364 d. Radial velocity curves of both components were constructed from high-dispersion spectra of this close early B-type system, which are the first published spectroscopic measurements of this star. The light curve analysis is based on new UBV curves. Absolute dimensions of the binary components are derived. The primary mass M 1 (=10.1 M ○. ) and radius are close to the expected ZAMS values for type B 1 V. The mass of the secondary component M 2 (=5.3 M ○. ) corresponds to B4IV, but the component is hotter than expected for this type. It is oversized and overluminous for such a mass, and in this respect is similar to the secondary components of semi-detached Algol-like systems. However, it does not completely fill its Roche lobe. A revision of the few other known binaries of comparable spectral type and period and a recalculation of the parameters of AI Cru and V Pup suggests that the detached configuration of V1331 Aql is unique among this group.

The massive eclipsing binary system IU Aurigae is re-analyzed in the context of new photometric observations and an improved treatment of its long-term period changes (O–C diagram) derived from new times of minima. The best-fit of the O–C curve reveals that the third component is orbiting around the system with a period of 293.3 days in a highly eccentric orbit ($e = 0.62$). A solution of the most recent UBV light curves obtained during 1997/1998 showed a third light contribution of ≈ 23% and continuation of the orbital plane precession of IU Aurigae. Since the revised mass of the third component deduced from the analysis of the O–C curve of $m_3=14.2$ $M_{\odot}$ would imply a larger fraction of third light than suggested by the value of 23% derived from the light curve analysis, the third body is possibly composed of two components. A q -search test applied to the UBV light curves yields a minimum ${\chi^2}$ value at $q=0.67 \pm 0.02$, which confirms previous photometric and spectroscopic solutions.

New spectroscopic data were obtained for the early-type binaries V337 Aql, V649 Cas, V382 Cyg, and V431 Pup. Their radial velocity curves are presented. These are the rst such data for V337 Aql and V431 Pup. In the case of V382 Cyg, our data conrm previously obtained results. Especially for V649 Cas our radial velocity curve yields important new implications for the component masses: the detection of third body lines, which are blended with the lines of the primary component, solves the problem of the unacceptably small masses formerly deduced for this binary; now we determine masses closer to the values expected for spectral type B 0. V431 Pup is an important object, because it is a new member of the small group of early-type eclipsing binaries with an evolved component. A published light curve of V337 Aql is solved by the MORO code, and system parameters are derived. The period of V649 Cas is found to be variable, and a more accurate period is calculated for V431 Pup.

V746 Cas is known to be a triple system composed of a close binary with an alternatively reported period of either 25d:4 or 27d:8 and a distant third component in a 170 yr (62 000 d) orbit. The object was also reported to exhibit multiperiodic light variations with periods from 0d: 83 to 2d: 50, on the basis of which it was classified as a slowly pulsating B star. Interest in further investigation of this system was raised by the recent detection of a variable magnetic field. Analysing spectra from four instruments, earlier published radial velocities, and several sets of photometric observations, we arrived at the following conclusions: (1) The optical spectrum is dominated by the lines of the B-type primary (Teff 1 16 500(100)K), contributing 70% of the light in the optical region, and a slightly cooler B tertiary (Teff 3 13 620(150)K). The lines of the low-mass secondary are below our detection threshold; we estimate that it could be a normal A or F star. (2) We resolved the ambiguity in the value of the inner binary period and arrived at a linear ephemeris of Tsuper: conj: = HJD 2 443 838:78(81) + 25d:41569(42) × E. (3) The intensity of the magnetic field undergoes a sinusoidal variation in phase with one of the known photometric periods, namely 2d:503867(19), which we identify with the rotational period of the tertiary. (4) The second dominant photometric 1d: 0649524(40) period is tentatively identified with the rotational period of the broad-lined B-type primary, but this interpretation is much less certain and needs further verification. (5) If our interpretation of photometric periods is confirmed, the classification of the object as a slowly pulsating B star should be revised. (6) Applying an N-body model to different types of available observational data, we can constrain the orbital inclination of the inner orbit to 60° < i1 < 85° even in the absence of binary eclipses, and we estimate the probable properties of the triple system and its components., 250015 GA15-02112S Univerzita Karlova v Praze: GA17-00871S, Acknowledgements. We profited from the use of 13 echelle spectra from the Bernard Lyot telescope, made publicly available via the Polar Base web service and Geneva 7-C photometry made available via HELAS service, to which we were kindly directed by C. Aerts. P. Mathias kindly provided us with old archival DAT tapes with the original Aurelie spectra of ten B stars and some advice about their content and structure. The spectra were reconstructed from the tapes with the help of R. Vesely. H. Bozic, K. Hon^ková, and D. Vršnjak kindly obtained some of the calibrated UBV observations of V746 Cas and its comparison stars for us. We acknowledge the use of the public versions of programs FOTEL and KOREL, written by P. Hadrava and PHOEBE 1.0 written by A. Prša. The research of P.H., M.B., P.M., and J.N. was supported by the grant P209/10/0715 of the Czech Science Foundation. J.N. and P.H. were also supported by the grants GA15-02112S of the Czech Science Foundation and No. 250015 of the Grant Agency of the Charles University in Prague. Research of D.K. was supported by a grant GA17-00871S of the Czech Science Foundation. Our thanks are due to M. Wolf, who obtained one Ond^ejov spectrum used here and who provided a few useful comments to this paper. A persistent but constructive criticism by an anonymous referee helped us to re-think the whole study, present our arguments and analyses more clearly and convincingly, and to improve the layout of the text and figures as well. The use of the NASA/ADS bibliographical service and SIMBAD electronic database are gratefully acknowledged.

V505 Mon is an early type eclipsing binary (usually classified as B5 Ib), in which only spectral lines of the primary component are visible. The radial velocity curve provides f(m) = 4.6 M⊙, suggesting that the secondary, invisible component is more massive. We have found evidence that this star is hidden from view by the disk detected during the primary eclipse. The structure of the disk can be characterized by a central ionization zone surrounded by the neutral outer parts. The profiles of the CII 1335/6 doublet lines were used to derive the rotational velocity of the disk as well as the velocity of the stream from the primary component to the disk. The masses of the components, deduced from the fractional size of the disk, are M1 = 1 M⊙ and M2 = 6.1 M⊙. Due to the low mass of the primary component its supergiant nature can be ruled out. Additional matter of a cloudy nature is present in the system and both components are embedded in an extended atmosphere. V505 Mon seems to be a prototype of the whole group of similar early-type binaries, in which the more massive component is hidden by a circumstellar medium, most likely a disk. Probable members are V742 Cas, V1362 Cyg, V2174 Cyg, V447 Sct and FY Vel with orbital periods between 33 and 225 days. Emission in Ha is always present, but there are no emissions in IUE spectra, so these binaries are distinct from the W Ser type. The evolutionary state of the members of this group is not yet understood.

New spectra of the eclipsing binary V505 Mon (usually classied as B5 Ib) were obtained in the optical and UV regions. Only spectral lines of one component are visible, with K =9 3 km s 1 .A ccording to arguments based on the extent of the disk the mass ratio might be about 0.30. The star with the visible spectral lines would then have a mass of 2.3, the other component of 7.7 M, i.e. their supergiant nature can be ruled out. The distance to the system appears to be about 1 kpc. Together with published photometric data, the spectroscopy provides clear evidence for the presence of a disk around the secondary component. The proles of the C ii 1335/6 doublet lines are used to derive the rotational velocity of the disk. The structure of the disk can be characterized by a central ionized zone surrounded by neutral outer parts. Additional matter of cloudy nature has to be present, and both components are embedded in an extended atmosphere. Abundance of carbon was found to be very low. Similarity with some other non-eclipsing binaries is discussed.

We present an analysis of the early-type quadruple system QZ Car, consisting of an eclipsing and a non-eclipsing binary. The spectroscopic investigation is based on new high dispersion echelle and CAT/CES spectra of H and He lines. The elements for the orbit of the non-eclipsing pair could be refined. Lines of the brighter component of the eclipsing binary were detected in near-quadrature spectra, while signatures of the fainter component could be identified in only few spectra. Lines of the primary component of the non-eclipsing pair and of both components of the eclipsing pair were found to be variable in position and strength; in particular, the He ii 4686 emission line of the brighter eclipsing component is strongly variable. An ephemeris for the eclipsing binary QZ Car valid at present was derived Prim. Min. = hel. JD . The relative orbit of the two binary constituents of the multiple system is discussed. In contrast to earlier investigations we found radial velocity changes of the systemic velocities of both binaries, which were used -together with an O-C analysis of the expected light-time effect -to derive approximate parameters of the mutual orbit of the two pairs. It is shown that this orbit and the distance to QZ Car can be further refined by minima timing and interferometry.

New times of minimum light were measured for several early-type eclipsing binaries: V337 Aql, V1182 Aql, V1331 Aql, IU Aur, QZ Car and V382 Cyg. The O C diagram for these systems is discussed and new ephemeris is given for AH Cep; observation of AQ Cir is added. It is shown that the scatter of times of minima is several times larger than the measuring errors for most of the binaries studied.

Many early-type main sequence stars are known spectroscopic binaries, while early type spectroscopic binaries with evolved components are rather rare and well-determined masses are available only in some cases. For this reason a program to study stars with suspected variable velocity among early-type evolved stars has been initiated some time ago. In the present paper 54 coude spectra for a sub-group formed of six early-type stars, namely HD 7902, HD 28446, HD 42087, HD 187983, HD 195592 and HD 208501 have been measured and the results of these plates have been presented.

In a previous paper Mayer and Hanna (1991) discussed the process of binary orbit circularization for detached eclipsing binaries. An agreement of observational data with Tassoul's circularization time formula for binaries with masses greater than 2.5 M⊙ was found. In the present paper we also examine orbital circularization in evolved spectroscopic binaries.

Improved orbital and physical parameters of the eccentric O-type system V1007 Sco (P=5.8 days) are presented. UBV light curves obtained over a period of 12 years were analyzed with a Wilson-Devinney-based solution code. Setting off from a set of parameters derived from spectroscopic investigations a consistent photometric solution was achieved. In accordance with the spectroscopic findings the eccentricity was determined as e=0.128 and the apsidal motion with a spectroscopic period of about 150 days was confirmed.

New precise times of minimum light for several early-type eclipsing binaries were obtained at three observatories. The changes of period of the following measured binaries are discussed: V1182 Aql, LY Aur, SZ Cam, FZ CMa, QZ Car, LZ Cen, V606 Cen, AH Cep and TU Mus.

Thanks to its long and rich observational history and rapid apsidal motion, the massive eclipsing binary Y Cyg represents one of the cornestones to critical tests of stellar evolution theory for massive stars. Yet, the determination of the basic physical properties is less accurate than it could be given the existing number of spectral and photometric observations. Our goal is to analyze all these data simultaneously with the new dedicated series of our own spectral and photometric observations from observatories widely separated in longitude. We obtained new series of UBV observations at three observatories separated in local time to obtain complete light curves of Y Cyg for its orbital period close to 3 days. This new photometry was reduced and carefully transformed to the standard UBV system using the HEC22 program. We also obtained new series of red spectra secured at two observatories and re-analyzed earlier obtained blue electronic spectra. Our analyses provide the most accurate so far published value of the apsidal period of 47.805 +/- 0.030 yrs and the following physical elements: M1=17.72+/-0.35$ Msun, M2=17.73+/-0.30 Msun, R1=5.785+/-0.091 Rsun, and R2=5.816+/-0.063 Rsun. The disentangling thus resulted in the masses, which are somewhat higher than all previous determinations and virtually the same for both stars, while the light curve implies a slighly higher radius and luminosity for star 2. The above empirical values imply the logarithm of the internal structure constant log k2 = -1.937. A comparison with Claret's stellar interior models implies an age close to 2 millions yrs for both stars. The claimed accuracy of modern element determination of 1-2 per cent seems still a bit too optimistic and obtaining new high-dispersion and high-resolution spectra is desirable., Comment: 13 pages; accepted for publication in Astronomy and Astrophysics

Digital home business is a large potential market for which ACEMIND European collaborative project intends to provide a set of consistent solutions to enhance the local network management in home and small enterprises. These networks are typically constituted by some tens of devices connected to each other via a set of wired and wireless technologies. The deployment of such networks has been intensive in Europe in the last decade and will continue in the future. However common end-users still suffer from complicated installation, operation or maintenance. Recent progress has been made to integrate heterogeneous connectivity into a single network. A proof of concept has been shown thanks to European collaborative project OMEGA and the hybrid network demonstrator has led to an IEEE standard and available commercial products. The goal of ACEMIND project is to enrich this initial concept with new features and services such as energy efficiency, packets load balancing or anomaly detection. Another target is to integrate future products using new transmission technologies. Then, using a unique userfriendly GUI (Graphical User Interface), it will be possible to monitor and manage the home network with a large range of services such as energy optimization, UHD TV or wellness.

New physical elements of the early B-type eclipsing binary V346 Cen are derived using the HARPS spectra downloaded from the ESO archive and also numerous photometric observations from various sources. A model of the observed times of primary and secondary minima that fits them best is a combination of the apsidal motion and an abrupt decrease in the orbital period from 6322123 to 6321843 (shortening by 24 s), which occurred somewhere around JD 2 439 000. Assumption of a secularly decreasing orbital period provides a significantly worse fit. Local times of minima and the final solution of the light curve were obtained with the program PHOEBE. Radial velocities of both binary components, free of line blending, were derived via 2D cross-correlation with a program built on the principles of the program TODCOR. The oxygen lines in the secondary spectra are weaker than those in the model spectra of solar chemical composition. Using the component spectra disentangled with the program KOREL, we find that both components rotate considerably faster than would correspond to the synchronization at periastron. The apside rotation known from earlier studies is confirmed and compared to the theoretical value.

The long-period (P = 27.1 years) peculiar eclipsing binary e Aur, which has recently completed its two year-long primary eclipse, has perplexed astronomers for over a century. The eclipse arises from the transit of a huge, cool and opaque, disk across the face of the F0 Iab star. One of the principal problems with understanding this binary is that the very small parallax of p = (1.53 ± 1.29) mas, implying a distance range of d ∼ (0.4−4.0) kpc, returned by a revised reduction of the Hipparcos satellite observations, is so uncertain that it precludes a trustworthy estimate of the luminosities and masses of the binary components. A reliable distance determination would help solve the nature of this binary and distinguish between competing models. A new approach is discussed here: we estimate the distance to e Aur from the calibration of reddening and interstellar-medium gas absorption in the direction of the system. The distance to e Aur is estimated from its measured E(B −V) and the strength of the diffuse interstellar band 6613.56 A. Spectroscopy and UBV photometry of several B- and A-type stars (

For years, δ Orionis was considered a normal binary with an 09.5 II primary exhibiting apsidal-line advance. However, radial-velocity curves of both binary components have been derived from the IUE and optical spectra using the cross-correlation technique, and surprisingly low masses of 11.2 and 5.6 M ⊙ were found. We obtained new spectra in the red spectral region and new UBV photometry. Using all published photometry and radial velocities, we deduced more accurate orbital and apsidal line periods. The main result of this paper is to show that the observed line spectra of δ Orionis are composed of the lines of the O9.5 II primary and a similarly hot tertiary, while the lines of a cooler B-type secondary are too faint to be detected in the available spectra. The character of the light curve (low-amplitude partial eclipses and a non-negligible scatter of the data) does not allow for a unique light-curve solution. Nevertheless, we show that the assumption of normal primary-component mass and radius corresponding to the 09.5 II classification (25 M ⊙ , 16-17 R ⊙ ) leads to consistent parameters for the system.

The triple systems display several interesting effects; and are also important for understanding the origin and evolution of binaries. Namely mutual inclination of two orbits, changes of observed inclination, and problems with the third light will be discussed in this contribution.

Multi-epoch, high-resolution (R ∼ 50 000) optical spectrosco-py of the O-type (O9 III – IV) star HD 152246 suggests that it is a triple system where a close inner pair (Aa–Ab) with a circular orbit and a period of 6 days is in a 53–d eccentric orbit (e = 0.68) with a third component Ac. The mass ratios for the inner and outer system are 0.10 and 0.96, respectively. The strengths of various He lines classify Aa and Ac as late O-type stars while Ab is invisible in our spectra.

We present the first orbital elements for the massive close binary, HD 101131, one of the brightest objects in the young, open cluster, IC 2944. This system is a double-lined spectroscopic binary in an elliptical orbit with a period of 9.64659 +/- 0.00012 days. It is a young system of unevolved stars (approximately 2 million years old) that are well within their critical Roche surfaces. We use a Doppler tomography algorithm to reconstruct the individual component optical spectra, and we apply well known criteria to arrive at classifications of O6.5 V((f)) and O8.5 V for the primary and secondary, respectively. We compare the reconstructed spectra of the components to single star, spectrum standards to determine a flux ratio of f_2/f_1 = 0.55 +/- 0.08 in the V-band. Both components are rotating faster than synchronously. We estimate the temperatures and luminosities of the components from the observed spectral classifications, composite V magnitude, and cluster distance modulus. The lower limits on the masses derived from the orbital elements and the lack of eclipses are 25 solar masses and 14 solar masses for the primary and secondary, respectively. These limits are consistent with the larger masses estimated from the positions of the stars in the Hertzsprung-Russell diagram and evolutionary tracks for single stars., Comment: 17 pages, 3 figures, submitted to ApJ

Delta Cir is known as an O7.5 III eclipsing and spectroscopic binary with an eccentric orbit. Penny et al. discovered the presence of a third component in the IUE spectra. The eclipsing binary and the third body revolve around a common center of gravity with a period of 1644 days in an eccentric orbit with a semimajor axis of 10 AU. We demonstrate the presence of apsidal-line rotation with a period of ≈141 yr, which is considerably longer than its theoretically predicted value, based on the published radii of the binary components derived from the Hipparchos H p light curve. However, our new solution of the same light curve resulted in smaller radii and better agreement between the observed and predicted period of the apsidal-line advance. There are indications that the third body is a binary. The object was resolved by VLTI using the PIONIER combiner; in 2012 June, the separation was 3.78 mas with magnitude difference in the H region 175. This result means that (assuming a distance of 770 pc) the inclination of the long orbit is 877.

Analyses of multi-epoch, high-resolution (R ~ 50.000) optical spectra of the O-type star HD 152246 (O9 IV according to the most recent classification), complemented by a limited number of earlier published radial velocities, led to the finding that the object is a hierarchical triple system, where a close inner pair (Ba-Bb) with a slightly eccentric orbit (e = 0.11) and a period of 6.0049 days revolves in a 470-day highly eccentric orbit (e = 0.865) with another massive and brighter component A. The mass ratio of the inner system must be low since we were unable to find any traces of the secondary spectrum. The mass ratio A/(Ba+Bb) is 0.89. The outer system has recently been resolved using long-baseline interferometry on three occasions. The interferometry confirms the spectroscopic results and specifies elements of the system. Our orbital solutions, including the combined radial-velocity and interferometric solution indicate an orbital inclination of the outer orbit of 112{\deg} and stellar masses of 20.4 and 22.8 solar masses. We also disentangled the spectra of components A and Ba and compare them to synthetic spectra from two independent programmes, TLUSTY and FASTWIND. In either case, the fit was not satisfactory and we postpone a better determination of the system properties for a future study, after obtaining observations during the periastron passage of the outer orbit (the nearest chance being March 2015). For the moment, we can only conclude that component A is an O9 IV star with v*sin(i) = 210 +\- 10 km/s and effective temperature of 33000 +\- 500 K, while component Ba is an O9 V object with v*sin(i) = 65 +/- 3 km/s and T_eff = 33600 +\- 600 K., Comment: 9 pages, 6 figures, accepted for publication in Astronomy and Astrophysics

An analysis of new and published sets of spectroscopic and photometric observations of the astrophysically important eclipsing O+O binary system V1007 Sco in NGC 6231, leads to significantly improved basic physical properties of the system. We arrived at the following preliminary values for masses and radii: M 1 = 28.4 M⊙, M 2 = 29.5 M⊙, R 1 = 15.6 R ⊙, R 2 = 17.1 R⊙. These values clearly indicate log g of about 3.5 [CGS], therefore the stars are Oe giants, not Of supergiants. Similarity to Be stars follows also from the fact that the Balmer and He I emission in the spectra from the year 2000 is much stronger than in the spectra taken several years ago. We also report the discovery of apsidal motion with a period of 132 years. Our solution implies a constant of internal structure essentially in agreement with its theoretical value and with the age of NGC 6231. We suggest that the masses, which still differ from the evolutionary ones, and the observed variable Balmer and He I emission may be related to the fact that both stars come very close to their respective limits of dynamical stability near periastron, and large mass loss from the system is likely.

Analyses of 13 FEROS spectra from the ESO archive and 617 V-band photometric observations from the ASAS3 database allowed us to demonstrate that HD 165246 is a double-lined spectroscopic binary. As an earlier finding revealed, HD 165246 is also an eclipsing system. We were able to derive consistent orbital and light-curve solutions and all basic physical properties of the system. The period of this O8 V + B7 V binary is 4. d 592706 and the semiamplitudes of the radial-velocity curves are K 1 = 55. 5k m s −1 and K 2 = 321 km s −1 . As the mass ratio is small (0.173), the secondary lines cannot be seen directly in the spectra; however the application of spectral disentangling allowed us to detect weak Balmer and He i lines of the secondary component. The primary component rotates with a high projected velocity of v sin i = 243 km s −1 . A combined radial-velocity and light-curve solution led to the component masses and radii expected for the young stars of the given spectral types. Due to the high rotation velocity, the primary component might display changes in surface abundances of some elements. However, we did not find any significant differences with respect to the abundances of slowly rotating stars.

The A-type star HR 6412 = V2368 Oph was used by several investigators as a photometric comparison star for the known eclipsing binary U Oph but was found to be variable by three independent groups, including us. By analysing series of new spectral and photometric observations and a critical compilation of available radial velocities, we were able to find the correct period of light and radial-velocity variations and demonstrate that the object is an eclipsing and double-lined spectroscopic binary moving in a highly eccentric orbit. We derived a linear ephemeris T min.I = HJD (2454294.67 +/- 0.01) + (38.32712 +/- 0.00004)d x E and estimated preliminary basic physical properties of the binary. The dereddened UBV magnitudes and effective temperatures of the primary and secondary, based on our light- and velocity-curve solutions, led to distance estimates that agree with the Hipparcos distance within the errors. We find that the mass ratio must be close to one, but the limited number and wavelength range of our current spectra does not allow a truly precise determination of the binary masses. Nevertheless, our results show convincingly that both binary components are evolved away from the main sequence, which makes this system astrophysically very important. There are only a few similarly evolved A-type stars among known eclipsing binaries. Future systematic observations and careful analyses can provide very stringent tests for the stellar evolutionary theory., Comment: 10 pages, 7 figs, in press 2011 A&A

We analyse new spectra of the multiple system SZ Cambecause previous studies found different values of the primary radial velocity amplitude. The older solutions of light curves also have different ratios of secondary to primary luminosity as inferred from the observed equivalent widths of spectral lines. We therefore reanalyse the light curves of the eclipsing pair. Only the light curve derived by Wesselink has a solution that agrees with the observed equivalent width ratio. The resulting parameters of the binary are discussed. Masses of M 1 = 16.6 and M 2 = 11.9 M ⊙ , and radii R 1 = 9.4 and R 2 = 5.4 R ⊙ are derived. We point out that radial velocities measured with the CCF method can be misleading when the method is applied to multiple systems with complex line blends. New radial velocities are also obtained for the visual component ADS 2984 A (HD 25639).