The results of 2033 intensified CCD observations of double stars, made with the 26 inch refractor of the U.S. Naval Observatory, are presented. Each observation of a system represents a combination of over 2000 short-exposure images. These observations are averaged into 1297 mean relative positions and range in separation from 0.54" to 58.96", with a mean separation of 14.99". This is the 14th in this series of papers and covers the period 2007 January 17 through 2007 December 31. The first two resolutions of closer companions to previously known wider pairs are also presented.
Results of 2433 intensified CCD observations of double stars, made with the 26 inch refractor of the U.S. Naval Observatory, are presented. Each observation of a system represents a combination of over 2000 short-exposure images. These observations are averaged into 1013 mean relative positions and range in separation from 0.96" to 58.05", with a mean separation of 13.50". This paper is the 15th in the series of papers and covers the period 2008 January 3 through 2008 December 21.
The results of 1031 speckle-interferometric observations of double stars, made with the 26 inch refractor of the U.S. Naval Observatory, are presented. Each speckle-interferometric observation of a system represents a combination of over two thousand short-exposure images. These observations are averaged into 457 mean relative positions and range in separation from 0.15" to 16.94", with a median separation of 3.03". The range in V-band magnitudes for the primary (secondary) of observed targets is 3.1-12.9 (3.2-13.3).
The results of 3362 intensified CCD observations of double stars, made with the 26 inch refractor of the U.S. Naval Observatory, are presented. Each observation of a system represents a combination of over 2000 short-exposure images. These observations are averaged into 1970 mean relative positions and range in separation from 0.78" to 72.17", with a mean separation of 14.76". This is the 17th in this series of papers and covers the period 2010 January 6 through December 20. Also presented are 10 pairs that are resolved for the first time.
Results are presented of 4222 intensified CCD observations of double stars, made with the 26 inch refractor of the U.S. Naval Observatory in 2013 and 2014. These observations are averaged into 2335 mean relative positions and range in separation from 0.53'' to 83.90'', with a median separation of 11.42''. This is the 20th in this series of papers and covers the period 2013 January 4 through 2014 December 18. Also presented are 13 pairs which are measured for the first time, 12 pairs which appear to be lost, linear elements for 17 pairs, and orbital elements for five additional pairs. Finally, we investigated apparent systematic residuals to earlier measures in this series, and modify scale factors for closer pairs observed between 1990 and the present.
The results of 2408 intensified CCD observations of double stars, made with the 26 inch refractor of the U.S. Naval Observatory, are presented. Each observation of a system represents a combination of over 2000 short-exposure images. These observations are averaged into 1602 mean relative positions and range in separation from 1.94'' to 107.41'', with a median separation of 11.96''. This is the twenty-first in this series of papers and covers the period from 2015 January 13 through 2015 December 19. Significant instrumentation changes are reported in this paper.
The results of speckle interferometric measurements of binary and multiple stars conducted in 2008 and 2009 at the Blanco and SOAR 4m telescopes in Chile are presented. A total of 1898 measurements of 1189 resolved pairs or sub-systems and 394 observations of 285 un-resolved targets are listed. We resolved for the first time 48 new pairs, 21 of which are new sub-systems in close visual multiple stars.
We present a high-angular resolution survey for the search of binary and multiple stars in the Galactic open cluster Melotte 111. Combining our own speckle-interferometric observations with data taken from the literature, we found a ratio of the number of single to multiple stars to be 29:8:0:0:0:1 for the most probable members, indicating a multiplicity fraction for this cluster of 25.6%+/-2%. We also observed field stars in the vicinity of the cluster and estimated a ratio of multiplicities of 286:17:1:0:0:0:1 (between one and seven companions), equivalent to a multiplicity fraction of 5.9%+/-3%. We showed that the cumulative distribution of separations for our sample stars is in agreement with Opik's law.
We present the results of speckle interferometry of a sample of 117 chemically peculiar stars with global magnetic fields. The observations were made in December 2009 at the BTA with a spatial resolution of about 0.02 arcseconds in the visual spectral region. Twenty-nine stars were resolved into individual components, 14 of them for the first time (HD965, HD5797, HD8855, HD10783, HD16605, HD21699, HD35502, HD51418, HD64486, HD79158, HD103498, HD108651, HD213918, HD293764). In twelve cases a companion turned out to be 2-4 magnitudes fainter than the main component - a magnetic star. Young hot Bp stars HD35502 and HD213918 are exceptions, since their companions are fainter by about 1 magnitude. In all cases, the linear distance from a star to its companion at the epoch of observations in the picture plane exceeded 10^9^km. Eighty-eight magnetic CP stars revealed no secondary components within our study. Thus, the fraction of speckle interferometric binaries in our sample amounts to 25%.
We present the results of speckle interferometric observations of 156 stars possessing global magnetic fields, carried out with the 6-m BTA telescope of the Special Astrophysical Observatory. Virtually all stars were observed between 2010 and 2012. Thirty-four stars were resolved into individual components (31 double and 3 triple), of which 14 binary systems (BD+41 43, HD2887, HD30466, HD36540, HD36955, HD37479, HD61045, HD89069, HD144334, HD164258, HD349321, HD343872, HD184471, HD196691) and 2 triple systems (HD37140, HD338226) were for the first time resolved by the astrometric method.