Brian D. Mason

SPECKLE INTERFEROMETRY AT THE BLANCO AND SOAR TELESCOPES IN 2008 AND 2009

The results of speckle interferometric measurements of binary and multiple stars conducted in 2008 and 2009 at the Blanco and SOAR 4 m 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. Typical internal measurement precision is 0.3 mas in both coordinates, typical companion detection capability is Δm ~ 4.2 at 015 separation. These data were obtained with a new electron-multiplication CCD camera; data processing is described in detail, including estimation of magnitude difference, observational errors, detection limits, and analysis of artifacts. We comment on some newly discovered pairs and objects of special interest.

A Multiplicity Survey of Chromospherically Active and Inactive Stars

Surveys of three samples of solar-type stars, segregated by chromospheric emission level, were made to determine their multiplicity fractions and to investigate the evolution of multiplicity with age. In total, 245 stars were searched for companions with ΔV ≤ 3.0 and separations of 0035 to 108 using optical speckle interferometry. By incorporating the visual micrometer survey for duplicity of the LamontHussey Observatory, the angular coverage was extended to 50 with no change in the ΔV limit. This magnitude difference allows mass ratios of 0.63 and larger to be detected throughout a search region of 2–127 AU for the stars observed. The 84 primaries observed in the chromospherically active sample are presumably part of a young population and are found to have a multiplicity fraction of 17.9% ± 4.6%. The sample of 118 inactive, presumably older, primaries were selected and observed using identical methods and are found to have a multiplicity fraction of only 8.5% ± 2.7%. Given the known link between chromospheric activity and age, these results tentatively imply a decreasing stellar multiplicity fraction from 1 to 4 Gyr, the approximate ages of the two samples. Finally, only two of the 14 very active primaries observed were found to have a companion meeting the survey detection parameters. In this case, many of the systems are either very young, or close, RS CVn type multiples that are unresolvable using the techniques employed here.

BINARY STAR ORBITS. IV. ORBITS OF 18 SOUTHERN INTERFEROMETRIC PAIRS

First orbits are presented for 3 interferometric pairs and revised solutions for 15 others, based in part on first results from a recently initiated program of speckle interferometric observations of neglected southern binaries. Eight of these systems contain additional components, with multiplicity ranging up to 6.

Multiple Stars in the Field

When examining the statistics of multiple stars in the field, especially coming from visual binary star point of view, several problems present themselves. First, and most importantly, is distinguishing between physical multiples and optical pairs. Establishing physicality is not a simple ”binary” response as there are degrees of certainty. We discuss some of the reasons for caring about non-physical pairs, as well as the tools for establishing or more correctly identifying apparent kinematic properties which hopefully result in dynamic solutions. The Washington Double Star Catalog, the Visual Orbit Catalog, and the US Naval Observatory speckle program are used as examples in many of these cases. The magnum opus for a global characterization of these systems is the Washington Multiplicity Catalog (WMC). Selected as a catalog and a method to ”develop a simple, unambiguous, flexible, and computer friendly designation scheme for stellar companions (including planets)” at a multi-commission meeting in Manchester (GA24). This was re-affirmed at Special Session 3 in Sydney (GA25) by Commissions 5, 8, 26, 42, 45 and the Working Group on Interferometry when a sample (1/2 hour band) WMC was produced. An all-sky WMC is in progress the binary sources utilized in its construction and the implications resulting from it with regards to multiple stars in the field are discussed.

DIVISION IV / COMMISSION 26 / WORKING GROUP BINARY AND MULTIPLE SYSTEM NOMENCLATURE

Abstract : The Working Group on Binary and Multiple System Nomenclature was formed within Commission 26 following Special Session 3 held during the 2003 Sydney General Assembly. Its purpose is to create the Washington Multiplicity Catalog, a comprehensive database first introduced at a multi-commission meeting at the IAU XXIV General Assembly in Manchester, 2000. Data are being compiled from the US Naval Observatory visual binary catalogs and supplemented with binary and multiple star information from other sources to include but not limited to spectroscopy, photometry, eclipsing and interacting system, as well as extra-solar planets and substellar companions. The goal being creation of a comprehensive hierarchical database and to reduce confusion from multiple nomenclature schemes used by disparate techniques.

U.S. Naval Observatory Double Star CD 2006.5

The U.S. Naval Observatory has produced its second CDROM of double star catalogs. This successor to the 2001.0 CDROM includes the latest versions (June 3

Speckle Interferometry with Small Telescopes

Speckle interferometry is a mature technique first utilized by Antoine Labeyrie over a quarter century ago. Unlike conventional interferometry, speckle is filled-aperture interferometry utilizing the turbulence cells of the atmosphere over the telescope to constructively interfere and produce diffraction limited information. Despite an initial flurry of activity, however, work at the present time is limited to a few groups, typically utilizing telescopes of 0.7 to 4.0 meters. Although actual images have been difficult to obtain and are rather expensive (both in computer and telescope time) to produce, speckle interferometry is well suited to simple morphologies, such as relative astrometry of binary and multiple stars. The vast bulk of work done in speckle interferometry is observations of binary stars. These observations can be used to: determine stellar masses (although this is also dependent on the availability of other data, e.g., spectroscopic or parallactic), provide an independent check on proper motions determined for close doubles by other techniques, provide verification or confirmation of close binaries found by other techniques (e.g., Hipparcos), or, due to the rapid operation of most speckle observing, provide information as to the multiplicity characteristics of a large sample of stars over a large regime of p-Δm space. Speckle investigation can also aid in the study of stars in planetary searches by culling from targeted searches stars unlikely to have life harboring planets, or to ensure that “planets” detected spectroscopically are not (due to the sin i dependence) pole-on binary stars. Many of these known binaries in need of investigation can be observed with moderate or smaller sized telescopes.