This report covers the workings of Commission 26 over the triennial period 2012-2015 and is the last report of the Commission. Included are reports from Working Groups and the Commission 26 Circular; all of which will be continuing in Commission G1 (Binary and Multiple Stars). Also included is a report of the Splinter Meeting of Commissions 26, 42 & G1, submitted observatory reports and a history of Commission 26.

Main Publications:

Abt, H. A. 2008, The Difference Between Metal-Poor and Metal-Rich Binaries, AJ, 135, 722

Abt, H. A. 2009, Stellar Rotation versus Duplicity in Open Cluster Early-Type Stars, PASP, 121, 1307

Abt, H. A. 2010, The Origin of the Exoplanets, PASP, 122, 1015

The business meeting of Commission 26 was held on Friday, 7 August 2009, and consisted mainly of scientific talks. At the end, incoming President J. A. Docobo gave a video presentation with his thoughts regarding future activities of Commission 26, including the comments of members of the OC. He also announced a December 2009 workshop and discussed potential meetings in the coming years.

A continuation of this WG was voted for at the IAU GA 2006 in Prague. The International Celestial Reference Frame (ICRF) is defined by the positions of 212 distant quasars at radio wavelengths. The primary, optical reference frame is the Hipparcos Celestial Reference Frame (HCRF), which is the Hipparcos Catalog without astrometric ‘problem’ stars (in: H. Rickman (ed.) 2001, Proceedings IAU XXIV General Assembly, Transactions IAU XXIVB (San Francisco: ASP), Resolution B1.2). The Tycho-2 catalog with its 2.5 million brightest stars forms the first step in the densification of the optical reference frame. However, the limiting magnitude of about V = 12 of the Tycho-2 catalog is not sufficient for most applications in astronomy and the goal of this IAU Working Group is to further extend the grid of highly accurate positions and motions toward more and fainter stars. The web site of this WG is at <ad.usno.navy.mil/dens_wg/>.

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.

Although we were happy to welcome over 20 new members at the Prague meeting, Commission 26 is still one of the smallest in the IAU. Notwithstanding its size, it continues to carry on an active and diversified program of activities. Our web site, maintained at the US Naval Observatory, contains further information on the Commission. The site includes links to other relevant sites, to databases and catalogues, an archive of our Information Circulars, a list of upcoming meetings of interest, as well as an extensive bibliography of recently published papers on double and multiple stars. The site can be accessed at <ad.usno.navy.mil/wds/dsl.html#iau>.

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 30 2006) of four major double star catalogs maintained at the USNO:

• • Washington Double Star Catalog (WDS),

• • Second Photometric Magnitude Difference Catalog,

• • Fourth Catalog of Interferometric Measurements of Binary Stars, and

• • Sixth Catalog of Orbits of Visual Binary Stars.

Each of these catalogs had seen significant changes during the past six years; for example, the WDS has grown by over 150,000 measures and the number of systems in the Interferometric Catalog has nearly doubled. Other improvements include precise coordinates for the vast majority of systems, as well as new observing lists for tens of thousands of “neglected” doubles.

Also included on this CDROM is a Catalog of Linear Elements for several hundred optical pairs. These elements should prove useful for improving the components' proper motions, as well as providing scale calibration out to several tens of arcseconds.

As was done with its predecessor, the new CDROM is automatically distributed free of charge to members of the double star community and to astronomy libraries. Others may receive a complementary copy upon request.

Changes in the double star database are highlighted, describing various methods of observation (both historically and those of the past few years) and their effectiveness in different regimes of separation space. The various niches for wide- and narrow-field work as they apply to double and multiple stars are examined and the different types of information which each can provide are described. Despite the significant growth of the double star database, much can still be done, such as finding lost pairs, filling in missing parameters so that observing programs can select all stars appropriate to their capabilities, or providing at least gross kinematic descriptions. After more than 20 years of successful work, speckle interferometry and conventional CCD astrometry have replaced filar micrometry and photography as preferred classical techniques. Indeed, most work in filar micrometry is now being done by amateurs. Work on pairs described as neglected in the last major WDS data release (2001) is given as a specific example. Finally, the continued need to publish data in classical double star parameters is also discussed.

Wulff Dieter Heintz, Professor Emeritus of Astronomy at Swarthmore College, passed away at his home on 10 June 2006, following a two-year battle with lung cancer. He had just turned 76 a week earlier. Wulff was one of the leading authorities on visual double stars, and was also a chess master. A prominent educator, researcher, and scholar, Wulff was noted for being both succinct and meticulous in everything he did. Wulff Heintz was born on 3 June 1930 in Würzburg (Bavaria), Germany. Naturally left-handed, the young Wulff's elementary school teachers forced him to learn to write “correctly” using his right hand, and so he became ambidextrous. During the 1930s, Wulff's family saw the rise of Adolph Hitler and lived under the repressive Nazi regime. Conditions were austere, and it was often difficult to find fuel to keep the house warm. As a teenager during World War II, Wulff listened to his family radio for any news from the outside world. He used to say that he loved the blackouts during the bombing runs because it made it much easier to see the stars. One night, an incendiary bomb landed on the roof of his family home, and Wulff climbed up to the roof and extinguished it. The next morning, he saw that his high school had been completely leveled by Allied bombs. As Germany continued to suffer massive losses on the Russian Front, primarily due to unexpectedly severe winters, teenage boys were inducted into the military and sent off to replenish the troops. To avoid an uncertain fate, Wulff hid out in a farmhouse in the countryside outside Munich. When the Allied troops invaded Germany in 1945, the young Wulff volunteered to translate information from the American and British soldiers to the local villagers. During this time, the soldiers taught Wulff how to smoke cigarettes, a habit which he continued until his final days, even after having been diagnosed with lung cancer.

In keeping with its co-sponsorship by members of both the “close” and “wide” binary star communities, IAU Symposium 240 has been jointly dedicated to the honor of Czech astronomer Mirek J. Plavec and the memory of U.S. astronomer Charles E. Worley.

Charles Worley, long-time astronomer at the U.S. Naval Observatory, was born on May 22, 1935, in Iowa City, Iowa, and grew up in Des Moines the son of an M.D., Charles L. Worley, and his wife Iona Cooney Worley, a homemaker. He became interested in astronomy at age nine. His first observational work as an amateur astronomer was plotting and recording more than 10,000 meteors for the American Meteor Society. Continuing his love for astronomy he attended Swarthmore College, where he took part in the parallax program as an Observing Assistant. He also met the other love of his life, his wife, Jane Piper. They were married in 1956 next to Sproul Observatory on the Swarthmore campus. He obtained a B.A. in mathematics from San Jose State College in 1959. He worked for the Lick Observatory in California (1959–1961) as a Senior Assistant and Research Astronomer under a Naval Research grant to observe double stars. After arriving at the U.S. Naval Observatory in 1961, he was the motive force behind an extensive program of double star observation (being himself, a prolific observer), instrumental innovation, and double star cataloging. He quickly gained recognition as one of the world's leading experts in the field of double star astronomy. Charles died on New Year's Eve, 1997, two days before his scheduled retirement.

The new observing and reduction techniques available to astronomers have led to remarkable changes in the field of double and multiple stars. New classes of companions, such as brown dwarfs and exoplanets, have been discovered. Binaries which previously constituted distinct classes are now observable by multiple techniques. With many long-baseline optical interferometers operational or planned, with improvements in other techniques, and with astrometric space-based missions in various states of planning and funding, the situation is likely to become more complicated. The result is greater understanding for the scientist, but greater challenges for the cataloger!

The “problem” is that purveyors of different techniques use different nomenclature, both in terms of root designation and component identifier. It is this latter inconsistency which causes the most confusion and is the topic of this Special Session.

This talk will illustrate some of the many designation ambiguities and summarize efforts made during the past few years to address this problem.

The Washington Multiplicity Catalog (WMC) project is an effort to address the often conflicting nomenclature schemes used by astronomers in different fields of double and multiple star research, by compiling a catalog of all known binary and multiple systems, then assigning a consistent (insofar as possible) component designation to each component. Components are treated in the same manner whether stellar or sub-stellar (e.g., brown dwarf, exosolar planet) in nature. This effort was begun shortly before the 2000 IAU General Assembly in Manchester, UK. A sample version of the planned catalog was presented at IAU Colloquium 191, held in Mérida, México in February 2003, and a modified version of this sample will be presented at the July 2003 GA in Sydney, Australia. Finally, if the nomenclature and catalog format are agreed upon, a full-sky version of the catalog will be created in time for the 2006 GA in Prague.

Advances in instrumentation and reduction methods are blurring the historical distinctions between various classes of double stars. One result of this is increasing confusion in double star nomenclature, as the conventions followed by different observers are sometimes incompatible. The Washington Multiplicity Catalog is presented as a means of developing a single nomenclature scheme for all types of doubles, as well as a comprehensive database for all duplicity information.

Graphite encapsulated nanocrystals produced by a low carbon tungsten arc were analyzed to determine their chemistry, crystallography, and nanostructural morphology. Metallic nanocrystals of Fe, Co, and Ni are in the face-centered cubic (fcc) phase, and no trace of the bulk equilibrium phases of body-centered cubic (Fe) and hexagonal close-packed (Co) were found. Various analytical techniques have revealed that the encased nanocrystals are pure metal (some carbide was found in the case of Fe), ferromagnetic, and generally spherical. The nanocrystals are protected by turbostratic graphite, regardless of the size of the nanocrystals. The turbostratic graphite coating is usually made up of between 2 and 10 layers. No trace of any unwanted elements (e.g., oxygen) was found. The low carbon: metal ratio arc technique is a relatively clean process for the production of graphite encapsulated nanocrystals.