New orbits of wide visual double stars

© 2017, Pleiades Publishing, Inc.Based on photographic and CCD observations with the Pulkovo 26-inch refractor, radial velocity measurements with the 1.5-m RTT-150 telescope (TUBITAK National Observatory, Turkey), and highly accurate observations published in the WDS catalog, we have obtained the orbits of ten wide visual double stars by the apparent motion parameter method. The orientation of the orbits in the Galactic coordinate system has been determined. For the outer pair of the multiple star HIP 12780 we have calculated a family of orbits with a minimum period P = 4634 yr. Two equivalent solutions with the same period have been obtained for the stars HIP 50 (P = 949 yr) and HIP 66195 (P = 3237 yr). We have unambiguously determined the orbits of six stars: HIP 12777 (P = 3327 yr), HIP 15058 (P = 420 yr), HIP 33287 (P = 1090 yr), HIP 48429 (P = 1066 yr), HIP 69751 (P = 957 yr), and HIP 73846 (P = 1348 yr). The orbit of HIP 55068 is orientated perpendicularly to the plane of the sky, P >1000 yr. The star HIP 48429 is suspected to have an invisible companion

Criteria for the stability of triple systems and their application to observations of multiple stars

Criteria for stability of triple systems are studied and compared with the results of numerical simulations obtained for model triple systems and observed multiple stars. The results for the stability analyses using two new criteria-those of Aarseth and of Valtonen et al.-agree with the simulation results in 98% of cases. Thus, these criteria can be used to analyze the stability of systems for which direct modeling of their dynamical evolution is difficult (for example, because not all orbital parameters for their subsystems are known). The last published version of the "Multiple-Star Catalog" of Tokovinin is analyzed to search for systems that may be unstable according to the two new criteria. More detailed studies are carried out for the HD 284419 (T Tau) system. The parameters of the apparent motion method is used to obtain new orbital solutions for this system. The regions of dynamical stability of the system as functions of the orbital parameters are estimated. It is not possible to determine a unique solution for the orbit with the available data; for periods shorter than 300 yr and longer than 5500 yr, the probability of decay of the system on time scales less than 107 yr is high. This conclusion is supported by the application of the stability criteria, as well as direct modeling of the system's dynamical evolution. © Pleiades Publishing, Ltd., 2010

An old nearby quadruple system Gliese 225.2

We discovered a new component E in the nearby multiple system Gliese 225.2, making it quadruple. We derive a preliminary 24-yr astrometric orbit of this new sub-system C,E and a slightly improved orbit of the 68-yr pair A,B. The orientations of the A,B and C,E orbits indicate that they may be close to coplanarity. The orbit of AB,CE is rather wide and does not allow to determine its curvature reliably. Thus, the 390 yr orbit computed by Baize (1980, Inf. Circ. IAU Comm., 26(80)) was premature. The infrared colors and magnitudes of components A, B, and C match standard values for dwarfs of spectral types K5V, M0V, and K4V, respectively. The new component E, 3 magnitudes below the Main Sequence, has an anomalously blue color index. We estimate its mass as roughly 0.2 solar from the astrometric orbit, although there remains some inconsistency in the data hinting on a higher mass or on the existence of additional components in the system. Large space velocities indicate that Gliese 225.2 belongs to the thick Galactic disk and is not young. This quadruple system survived for a long time and should be dynamically stable. © ESO 2005

Gliese 225.2: An old (stable?) quadruplet

We discovered with adaptive optics a new component E in the nearby multiple system Gliese 225.2, making it quadruple. We derive a preliminary 24-yr astrometric orbit of this new sub-system C,E and a slightly improved orbit of the 68-yr pair A,B. The orientations of the A,B and C,E orbits indicate that they may be close to coplanarity. The 390-yr orbit of AB,CE computed by Baize (1980) was premature, the period is much longer. Large space velocities indicate that Gliese 225.2 belongs to the thick galactic disk and is not young. This quadruple system survived for a long time and should be dynamically stable. © 2008 Springer-Verlag Berlin Heidelberg

Physical parameters and dynamical properties of the multiple system ι UMa (ADS 7114)

We analyze the physical parameters, orbital elements, and dynamic stability of the multiple system ι UMa (HD 76644 = ADS 7114). We have used the positions from the WDS catalog and our own observations on the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences and the 1.5-m Russian-Turkish Telescope (Antalya, Turkey). We have obtained more precise orbital parameters of the subsystems, and spectral types, absolute magnitudes, and masses of the components. The primary has Sp = F0 V-IV, M = 1.7 ± 0.1M ⊙, T eff = 7260 ± 70 K, and log g = 4.30 ± 0.07. The companion in the close Aa subsystem is most likely a white dwarf with a mass of approximately 1.0 ± 0. 3M ⊙. The spectral types and masses of the components in the BC subsystem are M3V, M4V and 0.35 ± 0.05M ⊙, 0.30 ± 0.05M ⊙, respectively. The total mass is 3.4 ± 0.4M ⊙. The Aa subsystem probably has an orbital period of 4470 d = 12.2 y and an eccentricity of approximately 0.6. The outer subsystem seems to have a period of approximately 2084 yrs and an eccentricity of approximately 0.9. We have carried out simulations using the stability criteria and shown that for all possible variations in the component parameters, the multiple system is unstable on a time scale of less than 10 6 years with a probability exceeding 0.98. Possible reasons for this instability are discussed. © 2012 Pleiades Publishing, Ltd

Multicolour CCD Measurements of Visual Double and Multiple Stars. III

Recent CCD observations were performed in the period 1998-2004 for a large sample of visual double and multiple stars selected from the Hipparcos Catalogue and/or from the Gliese Catalogue of Nearby Stars. Accurate astrometric and photometric data allowing to characterize the individual components are provided. These data are confronted to Hipparcos data or to data from an older epoch in order to assess the nature of the observed systems. We simultaneously apply a Moffat-Lorentz profile with a similar shape to all detected components and adjust the profile parameters from which we obtain the relative astrometric position (epoch, position angle, angular separation) as well as differential multi-colour photometry (filters (B)VRI). We thus acquired recent data for 71 visual systems of which 6 are orbital binaries, 27 are nearby and 30 are multiple systems. In three cases, the systems remained unresolved. 23 new components were detected and measured. Two new visual double stars of intermediate separation were also found. The estimated accuracies in relative position are 0.04 deg and 0.01" respectively, while those in differential photometry are of the order of 0.01-0.02 mag in general. The nature of the association of 55 systems is evaluated. New basic binary properties are derived for 20 bound systems. Component colours and masses are provided for two orbital binaries.Comment: 7 pages, 2 Postscript figures, 1 appendix, 1 annex containing 3 tables. Appendix A and Tables~4-6 are only available in electronic form. Astronomy and Astrophysics, in press (2006

The multiple system ADS 9626: A quadruple star or an encounter of two binaries?

© 2014, Pleiades Publishing, Ltd. The parameters of the quadruple system ADS 9626 (µ Boo) are analyzed. The system consists of two double stars: the Aa pair with an angular separation of ρ = 0.08″ and the BC pair with an angular separation of ρ = 2.2″, separated by ρ = 107″ and having the same parallaxes and proper motions. Position observations with the Pulkovo 26″ refractor have yielded from direct astrometric measurements the difference in the apparent magnitudes and the component-mass ratio for the BC subsystem: Δm = 0.59 ± 0.06, M(B)/M(C) = 1.18 ± 0.02. Spectroscopy with the Russian-Turkish 1.5-m telescope has yielded the radial velocities and physical parameters of the Aa, B, and C components. Speckle-interferometric observations with the 6-m telescope of the Special Astrophysical Observatory have provided the first measurements of the magnitude difference in the close Aa subsystem: Δm = 0.46 ± 0.03 (λ = 5500 Å) and Δm = 0.41 ± 0.03 (λ = 8000 Å). The new observations are consistent with the known orbits, which were used to find the radial velocities for the centers of mass of the inner subsystems. Themotion of the outer pair, Aa-BC, is studied using the apparent motion parameters (AMP) method. It is not possible to derive an elliptical orbit for this pair; the elements of a hyperbolic orbit have been estimated. The difference of the heavy-element abundances for the Aa and BC subsystems of 0.5 dex confirms that these pairs have a different origin. This suggests that we are observing here a close encounter of two binary stars

Physical parameters and dynamical properties of the multiple star o and

An analysis of the physical characteristics, orbital parameters, and dynamical stability of the multiple Be star HD 217675 (o And) is presented. Observations on the 6-m SAO and 1.5-m RTT telescopes are used to refine the orbital parameters of the subsystems. The spectral types, absolute magnitudes, and masses of the components are estimated. The total mass of the system is 18 ± 2 M⊙. It is shown that the configuration of the system is 2 + 2, where one of the subsystems is a spectral binary with a period of 33 d and the outer pair has a period of 117 yr. The parameters of the second inner subsystem are uncertain, making it difficult to draw firm conclusions about the stability of this multiple star. © 2010 Pleiades Publishing, Ltd