Micrometric measures and orbits of southern visual double stars

525 measures of 213 visual double stars have been made using the 26.5‐inch (67‐cm) Innes telescope in Johannesburg and the Repsold micrometer between 2008.375 and 2008.419, 2010.608 and 2010.652, and 2013.663 and 2013.712. A comparison with known orbits is made. Revised orbits are presented for WDS 01061–4643 (SLR 1), WDS 12415–4858 (HJ 4539), WDS 16253–4909 (COO 197) and WDS 16425–3705 (R 283). (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

CCD measurements of visual double stars at Calar Alto

342 CCD measurements of relative positions and magnitude differences for 145 visual double stars are presented. Observations were carried out at the 1.23m telescope of the German‐Spanish Astronomical Center at Calar Alto (Spain), all of them in V and R photometric bands.     

Micrometer measurements of visual double stars at Calar Alto

We present 93 micrometer measurements of 55 double stars observed with the 152 cm telescope at the Spanish observatory at Calar Alto (Almeria, Spain).     

Visual double stars in professional spanish astronomy: Past,present and future projects

Summary This poster describes the contribution of professional Spanish astronomy to all aspects of the study of visual double stars (observation, calculation of orbits and development of new methods of calculation), together with projected programmes of visual and interferometer observations.     

Astrometric parameters of visual double stars derived from simulated hipparcos measurements

Summary In the course of the reduction ofHipparcos data the astrometric parameter determination of visual binaries is reduced to the parameter determination of single stars. This approach assumes that the off-set of the binary components with respect to the conventional light point directly measured by the Hipparcos telescope are known on the individual scanning circles. The computer algorithms are outlined, preliminary results based on simulated measurements are discussed. Presented by H.-H. Bernstein.     

Main-sequence magnetic CP stars III. Results of magnetic field measurements

We present the third part of the survey of magnetic parameters of main-sequence magnetic CP stars. We analyze the main definitions and terminology, basic data on the magnetic fields of CP stars (catalogs, the history of the stellar magnetism research, the main observational results obtained over 60 years of studies). We describe the modern views on the properties of magnetic CP stars, i.e. their geometric structure, distribution of field strengths, magnetic field and rotation, magnetic field and energy distribution anomalies, and the evolutionary status of magnetic CP stars. We conclude that the observational data mostly support the theory of the relict origin and evolution of magnetic fields of CP stars.     

Photographic measurements of 320 double stars of POURTEAU remeasured 50 years after their discovery

The position angle and separation of 320 double stars from Pourteau's Catalogue (18^h < α < 19^h) measured on the prints of the Palomar Observatory Sky Survey 50 years after their discovery are given.     

Observations of southern Wolf-Rayet stars

The Wolf-Rayet star HD 90657 is found to be a spectroscopic binary with a WN5+O6 spectrum and a period of 6.456 days. Preliminary orbital elements show an elliptic orbit and a mass ratioM _WR/M _o0.5. Evidence is presented for the Wolf-Rayet atmosphere being accelerated outwards and not being spherically symmetric.Operated under an agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), the Universidad de Buenos Aires and the Comisión Nacional de Estudios Geoheliofísicos.     

Formation rate of triple stars relative to double stars

A series of our and McAlisteret al.'s speckle observations of spectroscopic binaries show that certain fractions of them are triple systems. A typical configuration of those systems is that of two stars separated by about 0.1 AU with a third component in an orbit at a distance about 10 AU from the central stars. These results suggest that the third star was formed from the outer circumstellar envelope after forming the central double.     

Photovisual magnitude differences of double stars

Differences in magnitudes between the components of 874 double stars have been derived from visual estimates on several series of multi-exposure photographic plates. The plates were obtained with long focus refractors primarily for the purpose of determining the relative positions of double stars according to the well-known Hertzsprung method. Except for binaries with magnitude differences less than half a magnitude, plates were taken with objective gratings limiting the effective magnitude differences between the components to half a magnitude. Similar to what has been done in variable star work, it was found possible to estimate the magnitude difference to the nearest tenth from this material by visual inspection, using a seven power eyepiece. The internal mean error of a single estimate of a magnitude is ±0 ^m .064, while the external mean error of a single value in the catalogue based upon an average of three independent determinations is ±0 ^m .054. Comparisons with other photometric series of this type have been made. In particular the photoelectric series by Eggen (1963, 1966) and by Johnson (1953) show close agreements, with no systematic differences. The results will appear inPubl. U.S. Naval Obs., 2nd Series,18, Pt. V.     

On the formation of double stars

From a calculation of Roche densities in visual binaries, it is concluded that the stars in these systems would be tidally unstable at the time of formation if they were formed with their observed separations (semi-major axes). To avoid this difficulty, it is proposed that the visual binaries are formed by the disintegration of small clusters. Binaries formed this way are shown to have some interesting upper limits to their mass ratios. Comments are also made on the differences between the processe of star and planet formation.     

Infrared measurements of faint symbiotic stars

Far infrared IRAS measurements and near infrared observational data of nineteen faint symbiotic stars are presented in this paper. From their flux distributions and the near infrared and far infrared colours an attempt is made to study the type of these stars. The colour temperature, dust temperature and mass-loss rates are estimated from the far infrared flux ratios and compared to those of known S and D type symbiotic stars. Probably nine of them are S type, two of them are D type and three of them are D type symbiotic stars. But it is difficult to suggest the type of five stars from the information available.     

Micrometer measurements of visual double stars made at the Cǒte D'Azur Observatory

We present 196 micrometer measurements of 99 double stars observed with the 50 and 74 cm refractor at the Cǒte D'Azur Observatory (Nice, France).     

New orbits of wide visual double stars

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.     

Edward Schoenfeld: Visual photometry of variable stars. 2. Variable stars

We describe the results of visual photometry of 111 variable stars observed by Schoenfeld in the 19th century. The entire body of data contains brightness curves in tabulated form, as well as certain additional useful information: graphs of changes in brightness of variable stars and identification tables of comparison stars and stars suspected of variation in brightness.     

Distant components in double and multiple stars

Summary A discussion is presented of the IDS, LDS, and Gliese's catalogues, inasmuch as they are relevant to the multiplicity of field stars and the distribution of separations of the companions in binaries and triples. The effect of dissociation of binaries with time is exhibited for a ‘quasi-unbiased’ sample of 106 nearby binaries taken from Gliese's catalogue. There are no binaries as old or older than the Sun with separations larger than 4000 AU, while binaries younger than the Sun may have separations as large as 180000 AU. The rate of this disruption seems too large to be produced by field stars; probably molecular clouds and spiral arms are the most effective agents. It appears that the size of the inner commet cloud cannot be much larger than 2000–4000 AU.