Speckle observations with PISCO in Merate: XIII. Astrometric measurements of visual binaries in 2012, and new orbits for ADS 10786 BC, 12144, 12515, 16314 and 16539

We present relative astrometric measurements of visual binaries, made in 2012 with the speckle camera PISCO at the 102‐cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our observing list contains orbital couples as well as binaries whose motion is still uncertain. We obtained 355 new measurements of 344 visual binary stars, with angular separations in the range 0′.14–6′.9, and an average accuracy of 0.′02. The mean error on the position angles is 0°.5. Most of the position angles were determined without the usual 180° ambiguity with the application of triple‐correlation techniques and/or by inspection of the long integration files. We also present new revised orbits for ADS 10786 BC, 12144, 12515, 16314, and 16539, partly derived from PISCO observations. The corresponding estimated values for the masses of those systems are compatible with the spectral types. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Speckle observations with PISCO in Merate (Italy): XIV. Astrometric measurements of visual binaries in 2013 and new orbits for ADS 1097, 5871, 7203, 7775, 9378, 9578, and 11186

We present relative astrometric measurements of visual binaries made in 2013 with the speckle camera PISCO at the 102‐cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our observing list contains orbital couples as well as binaries whose motion is still uncertain. We obtained 134 new measurements of 129 visual binary stars, with angular separations in the range 0.≈23–5 and an average accuracy of 0.≈01. The mean error on the position angles is 0.°5. Most of the position angles were determined without the usual 180° ambiguity with the application of triple‐correlation techniques and/or by inspection of the long integration files. We also present new revised orbits for ADS 1097, 5871, 7203, 7775, 9378, 9578, and 11186, partly derived from PISCO observations. The corresponding estimated values for the masses of those systems are compatible with the spectral types. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Speckle observations with PISCO in Merate: VI. Astrometric measurements of visual binaries in 2006

We present relative astrometric measurements of visual binaries made during the second semester of 2006, with the speckle camera PISCO at the 102 cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our sample contains orbital couples as well as binaries whose motion is still uncertain. We obtained 175 new measurements of 169 objects, with angular separations in the range 0″.1–4″.2, and an average accuracy of 0″.01. The mean error on the position angles is 0°.6. Most of the position angles could be determined without the usual 180° ambiguity with the application of triplecorrelation techniques and/or by inspection of the long integration files.We also present the new orbits we have computed for ADS 11479, 11584 and 16538, for which our measurements lead to large residuals and/or for which the revision was justified by the significant number of observations made since the last orbit computation (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Speckle observations with PISCO in Merate: X. Astrometric measurements of visual binaries in 2009

We present relative astrometric measurements of visual binaries, made in 2009 with the speckle camera PISCO at the 102 cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our observing list contains orbital couples as well as binaries whose motion is still uncertain. We obtained 345 new measurements of 259 objects, with angular separations in the range 0.″18–4.″6, and an average accuracy of 0.″011. The mean error on the position angles is 0.°6. Most of the position angles were determined without the usual 180° ambiguity with the application of triple‐correlation techniques and/or by inspection of the long integration files. We have found a possible new close component for ADS 2377, which would be a new quadruple star system. We also present new revised orbits for ADS 8035, 9982, 11484, and MLR 198, partly derived from those observations, and infer estimated values for the masses of those systems that are compatible with the spectral types (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Speckle observations with PISCO in Merate: VIII. Astrometric measurements of visual binaries in 2007 and new orbits of the multiple system Zeta Aqr

We present relative astrometric measurements of visual binaries made during the second semester of 2007, with the speckle camera PISCO at the 102 cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our sample contains orbital couples as well as binaries whose motion is still uncertain. We obtained 283 new measurements of 279 objects, with angular separations in the range 0″.17–4″.4, and an average accuracy of 0″.014. The mean error on the position angles is 0°.6. Most of the position angles were determined without the usual 180° ambiguity with the application of triple‐correlation techniques and/or by inspection of the long integration files. We also present the new orbit we have computed for Zeta Aqr AB (ADS 15971), for which our measurements lead to large residuals with the previously computed orbit. We were also able to compute the elements of the perturbation orbit Bb‐P caused by an invisible companion, whose mass is estimated at 0.7 M_⊙ (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Speckle observations with PISCO in Merate – VII. Astrometric measurements of visual binaries in 2007

We present relative astrometric measurements of visual binaries made during the first semester of 2007, with the Pupil Interferometry Speckle camera and COronagraph (PISCO) at the 102-cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our sample contains orbital couples as well as binaries whose motion is still uncertain. We obtained 226 new measurements of 214 objects, with angular separations in the range 0.15–4.5 arcsec, and an average accuracy of 0.013 arcsec. The mean error on the position angles is     . Most of the position angles could be determined without the usual 180° ambiguity with the application of triple-correlation techniques and/or by inspection of the long integration files. We also present the new orbits we have computed for ADS 7871, 7982 and 8128, for which our measurements lead to large residuals and/or for which the revision is justified by the significant number of observations made since the publication of the previous orbit.     

Speckle observations with PISCO in Merate – II. Astrometric measurements of visual binaries in 2004

We present relative astrometric measurements of visual binaries taken during the second semester of 2004 with the Pupil Interferometry Speckle camera and Coronagraph (PISCO) at the 1-m Zeiss telescope of the Brera Astronomical Observatory, in Merate, Italy. We performed 207 new observations of 194 objects with angular separations in the range 0.1–4.0 arcsec and an accuracy better than ∼0.01 arcsec. Our sample contains orbital couples as well as binaries whose motion is still uncertain. Our purpose is to improve the accuracy of the orbits and constrain the masses of the components.
Those measurements show that the orbit of ADS 15115 needs to be revised; we propose a new orbit for this object.     

Speckle observations with PISCO in Merate – V. Astrometric measurements of visual binaries in 2006

We present relative astrometric measurements of visual binaries made during the first semester of 2006, with the Pupil Interferometry Speckle camera and COronagraph at the 102-cm Zeiss telescope of the Brera Astronomical Observatory, in Merate. Our sample contains orbital couples as well as binaries whose motion is still uncertain. We obtained 217 new measurements of 194 objects, with angular separations in the range 0.1–4.2 arcsec, and an average accuracy of 0.01 arcsec. The mean error on the position angles is 05. About half of those angles could be determined without the usual 180° ambiguity by the application of triple-correlation techniques. We also present a revised orbit for ADS 277 for which the previously published orbit resulted in a large residual from our measurements.     

The orbit of the visual binary ADS 8630 (γ Vir)

We present a new orbit for the visual binary ADS 8630 = γ Vir. Although it is one of the first visual double stars discovered, its orbital elements were still poorly known. Indeed the very high eccentricity of the orbit and the difficulty of observing the pair at periastron passage in 1836 has meant that it is only now that sufficient measures of the recent close approach in 2005 have allowed an orbital analysis which predicts the angular motion to an acceptable degree of accuracy. We present a series of 35 speckle measurements of ADS 8630 obtained with PISCO in Merate between 2004 and 2006. Those measures have been crucial for determining the new orbital elements since they cover an arc of 130 degrees in the apparent orbit and include the periastron passage of 2005. The masses of the individual F0V components of the binary are found to be 1.40 M_⊙ with an accuracy of about 3%. We also investigate in detail the possibility of the presence of a third body in the system, that was proposed by other authors. The high‐angular resolution infra‐red image of γ Vir that we obtained in June 2006 with the LuckyCam instrument on the ESO NTT shows the absence of any companion as faint as a M0V star at a distance larger than 0.4″. Combined with the analysis of the residuals of our orbit, the values found for the masses of the individual components and the radial velocity measurements, this observation rules out the presence in the system of a third companion with a mass larger than 0.3 M_⊙. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Preliminary orbital elements of six visual binary stars

Preliminary new orbital elements were computed for the visual binary stars A 1 ‐ ADS 1345, A 2629 ‐ ADS 3610, BU 560 ‐ ADS 4371, STF 3115 ‐ ADS 4376, STF 1426 AB ‐ ADS 7730 and STF 2437 ‐ ADS 11956. Using Straizys and Kuriliene's data, we derived new formulae for computing dynamical parallaxes for luminosity classes IV and V. The values found for those systems are in agreement with the Hipparcos parallaxes and the corresponding systemic masses are consistent with the spectral types. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Observations of double stars at Pulkovo with 65 cm Zeiss refractor

Some results of the photographic observations of double stars with 65 cm refractor of Pulkovo observatory are presented. We use the apparent motion parameters (AMP) method which allows to determine the orbits and to carry out the dynamical investigation of wide binaries on the basis of a short arc of their orbital motion. We have determined more than 40 orbits for wide pairs and also the sum of masses and in some cases—the mass-ratio of components. The references to our works and the basic results of observations are contained in Kisselev et al. [2004. Catalogue of relative positions of visual double stars made on the observations with 26^″ refractor of Pulkovo observatory. Strassbourg, I/297]. We apply two ways of revealing the hidden mass of our stars, namely: revealing of possible perturbations from comparison of observational and calculated positions using differences O-C (for instance, perturbations in the orbital motion of ADS 15571) and also by means of comparison of the sum of the masses obtained by us and the sum of the masses obtained by means of the mass-luminosity relation. An excess of masses of about 1-3 solar masses is detected for binaries: ADS 497, ADS 8450 and ADS 10329 by means of last method.The estimations of the masses for some binaries are discussed. Also we justify the necessity of precise parallaxes and relative radial velocities of stars, which could be measured by space telescopes such as the GAIA as the additional parameters for determination of orbits of binaries.     

Relative astrometric and photometric measurements of visual binaries made with the Nice 76‐cm refractor in 2008

We present relative astrometric and photometric measurements of visual binaries made in 2008, with the 76‐cm refractor of Côte d'Azur Observatory. Our observing list contains orbital couples as well as binaries whose motion is still uncertain. Three different techniques were used for obtaining measurements: Lucky imaging, speckle interferometry and the Direct Vector Autocorrelation method. We obtained 2420 new measurements of the relative position of 2225 objects, with angular separations in the range 0″.07‐11″.5, and an average accuracy of 0″.02. The mean error on the position angles is 0°.6. We managed to observe faint systems (m_V ≈ 12) with large magnitude difference (up to Δm_V ≈ 5). We have thus been able to measure many systems containing red dwarf stars that had been poorly monitored since their discovery. We also measured the difference of magnitude of the two components of 376 objects with an estimated error of 0.1 mag. Finally, we provide a list of 33 newly discovered components of multiple or binary systems, which is a significant complement to our GII catalog (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Relative astrometry and near‐infrared differential photometry of nearby southern orbital binaries with adaptive optics

We present relative astrometry and differential photometry measurements for a sample of nearby southern orbital binaries making use of the technique of Adaptive Optics. The observations were made in December 2000, with the ADONIS camera mounted at the 3.6‐m ESO telescope from La Silla Observatory, equipped with the broad‐band near‐infrared filters (J ‐, H ‐, K ‐passbands). Our sample contains stars which do not fit very well the empirical mean mass‐luminosity relation (according to our previous study), but for which accurate parallaxes (determined by the Hipparcos satellite) and high‐quality orbits were available thanks to many previous efforts. We derived accurate positions and J, H, K magnitudes of the individual components of those binaries. The individual stellar components have near‐infrared colour indices well grouped in those plots and are comparable to standard single stars. The data reduction procedure used for deriving those results is described in detail. It is based on a least‐squares fit of Moffat‐Lorentz profiles in direct imaging for well‐resolved systems and on Fourier analysis for very close pairs. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Eight new and three recalculated orbits for binaries

In this paper new orbital elements are given for eleven binaries. For eight of them, WDS 00003–4417 = I 1477, WDS 00106–7313 = I 43 AB, WDS 00366+5609 = A 914, WDS 00519–4343 = I 47, WDS 01315+1521 = BU 506, WDS 01577+4434 = A 1526, WDS 08144–4550 = FIN 113 AB and WDS 08291–4756 = FIN 315 Aa‐Ab, the orbital elements are calculated for the first time. For three of them, WDS 04422+2257 = MCA 16 Aa‐Ab, WDS 08275–5501 = FIN 116 and WDS 14567–6247 = FIN 372, the orbital elements are recalculated. One of the eleven binaries, MCA 16 Aa‐Ab, was discovered by McAlister in 1980 by speckle interferometry and four pairs were discovered by Finsen between 1929 and 1960. For these five pairs, all measured separations are less than 0″.4 and most of the observations were done by using the interferometric techniques. The orbital periods calculated here are between 39 and 270 years. The remaining six pairs were discovered between 1878 and 1926 and most of the observations are visual. They have longer orbital periods, between 384 and 1637 years. In addition to the orbital elements the masses, dynamical parallaxes, absolute magnitudes and ephemerides for the next five years are also given in this paper (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Eclipsing binaries in the MOST satellite fields

Sixteen new eclipsing binaries have been discovered by the MOST satellite among guide stars used to point its telescope in various fields. Several previously known eclipsing binaries were also observed by MOST with unprecedented quality. Among the objects we discuss in more detail are short‐period eclipsing binaries with eccentric orbits in young open clusters: V578 Mon in NGC 2244 and HD 47934 in NGC 2264. Long nearly‐continuous photometric runs made it possible to discover three long‐period eclipsing binaries with orbits seen almost edge‐on: HD 45972 with P = 28.1 days and two systems (GSC 154 1247 and GSC 2141 526) with P > 25 days. The high precision of the satellite data led to discoveries of binaries with very shallow eclipses (e.g., HD 46180 with A = 0.016 mag, and HD 47934 with A = 0.025 mag). Ground‐based spectroscopy to support the space‐based photometry was used to refine the models of several of the systems (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A direct imaging search for close stellar and sub‐stellar companions to young nearby stars

A total of 28 young nearby stars (ages ≤60 Myr) have been observed in the K_s‐band with the adaptive optics imager Naos‐Conica of the Very Large Telescope at the Paranal Observatory in Chile. Among the targets are ten visual binaries and one triple system at distances between 10 and 130 pc, all previously known. During a first observing epoch a total of 20 faint stellar or sub‐stellar companion‐candidates were detected around seven of the targets. These fields, as well as most of the stellar binaries, were re‐observed with the same instrument during a second epoch, about one year later. We present the astrometric observations of all binaries. Their analysis revealed that all stellar binaries are co‐moving. In two cases (HD 119022 AB and FG Aqr B/C) indications for significant orbital motions were found. However, all sub‐stellar companion candidates turned out to be non‐moving background objects except PZ Tel which is part of this project but whose results were published elsewhere. Detection limits were determined for all targets, and limiting masses were derived adopting three different age values; they turn out to be less than 10 Jupiter masses in most cases, well below the brown dwarf mass range. The fraction of stellar multiplicity and of the sub‐stellar companion occurrence in the star forming regions in Chamaeleon are compared to the statistics of our search, and possible reasons for the observed differences are discussed. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Prospects of high angular resolution measurements of binary stars properties with VLTI

We present a program for observations of spectroscopic binaries with VLTI. The aim of such observations is to obtain high accuracy measurements of stellar parameters, in particular masses, combining the visual orbit with spectroscopic orbital elements. We selected a sample of spectroscopic binaries, including pre-main sequence stars, using the estimated angular nodal separation as a criterion for feasibility. A cross-check with the 4th catalog of measurements of binary stars (Hartkopf, 2001) was carried out and we discuss the statistical properties of the sample. This revised version was published online in July 2006 with corrections to the Cover Date.     

Contribution to the study of composite spectra: XI. Orbital elements of some faint systems

We present the results of a radial‐velocity study of nine new faint SB1 spectroscopic binaries with composite spectra: HD 137975‐6, 177984, HDE 226489, 231613‐4, 255387‐8, 256138‐9, 264997‐8, 276787 and 293041‐2. The observations were made at Haute‐Provence and Cambridge observatories with CORAVEL instruments between 1982 and 2006. From the radial‐velocity measurements of the cool components, we derive the orbital elements of those spectroscopic binaries for the first time. Using all the available data, we propose a model for each system that describes the nature of the individual components, with an estimation of the angular separation and orbital inclination. Finally we discuss the rotation–revolution synchronism of the cool components. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Ephemrides of visual binaries in universal variables

In this paper, universal formulations of the two‐body problem are established for ephemerides of visual binary systems, whatever the type of their orbits may be. A computational algorithm is also given and applied to the binaries ADS 9159, ADS 2959 and ADS 11632 as typical examples of elliptic, parabolic and hyperbolic binaries, respectively.     

Sixty four nights of UBV photometry of early‐type stars at La Sila

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)