The narrative from the original symposium proposal follows, outlining
the reasoning behind the proposal and the research topics which will be
covered during the meeting.
IAU Colloquium 135, "Complementary Approaches to Double and Multiple
Star Research", was held at Callaway Gardens (near Atlanta, Georgia)
in 1992, and was meant to emphasize the expanding overlap of
observational opportunities offered to binary star researchers by
advances in precise radial velocity techniques, interferometry, etc.
Additional topics included recent advances in our knowledge of
duplicity for young stars and pre-main sequence stars, the latest
theories of binary and multiple star formation, and the tantalizing
first results from HST and Hipparcos. The meeting successfully brought
together nearly one hundred astronomers with a diversity of expertise
until then rarely found at a single meeting on binary stars.
MAJOR ADVANCES IN INSTRUMENTATION AND TECHNIQUES
Much has changed in the ensuing 13 years! HST is now approaching the
end of its life, and its successor is under construction. Hipparcos
results have been published and well-studied, and the next generation
of astrometry satellites now under development promise results orders
of magnitude greater in both precision and quantity. Speckle
interferometry and adaptive optics have replaced visual micrometry as
the routine methods of measuring visual binaries, while long-baseline
interferometry has now produced a significant body of results for
closer binaries with the promise of an outburst of activity in the
resolution of spectroscopic binary systems during the next few years.
Interferometric results from the HST FGS have also become plentiful.
All of these represent dramatic changes in the way we conduct
astrometry of binaries.
Similar tremendous advances continue in other areas as well.
Variability-induced motion and other color-based detection methods are
being used to mine the SDSS database for new binaries, and may be used
with GAIA and SIM data as well. Superior infrared detectors and
techniques, as well as the recent availability of infrared
spectroscopy and imaging from space with the Spitzer Space Telescope
(SST), are revolutionizing the study of pre-main sequence binaries and
binaries with cool star and brown dwarf components. Ever more accurate
radial velocity techniques have yielded long-period orbits that
further blur the distinction between the traditional spectroscopic and
visual separation/period regimes and yield accurate stellar masses
across the spectral range - not to mention the new short-period systems
and 120+ exoplanets discovered over the last decade! Within the next
several years hundreds of additional exoplanets (with diameters as
small as the Earth) are expected to be discovered by the COROT and
Kepler missions.
BINARIES NEAR AND FAR: PRECISE DISTANCES AND ASTROPHYSICAL LABS
Binary systems are now observable in increasing numbers in other
galaxies within our Local Group. For example, several thousand new
eclipsing systems have been already discovered in the Magellanic
Clouds by the MACHO and OGLE programs alone, while additional systems
are being discovered in M31 and M33. Within the next decade hundreds
of thousands new eclipsing systems are expected to be discovered from
automated wide field search programs. Orbital inclinations and
therefore accurate masses will soon be within our grasp even for non-
eclipsing spectroscopic and visual binaries beyond our Milky Way,
providing an unprecedented opportunity to obtain by far the best
determinations of the distances to nearby galaxies. Observations of
these stars (in our Galaxy and in exterior galaxies with large ranges
in metal abundances) will significantly improve our understanding of
stellar atmospheres (effects such as gravity darkening, etc.) by
allowing us to compare the spectral appearance of rapidly-rotating
stars seen equator-on with those of equal-mass binaries seen more pole-
on.
IMPACTS OF NEW PROGRAMS AND POWERFUL TECHNIQUES
Studies of binary and multiple star systems are being strongly
stimulated by high-precision (milli- and micro-magnitude) photometric
observations from MOST and soon from COROT and KEPLER. There are
corresponding exciting developments in theory and in modern methods
such as Doppler tomography and synthetic spectrum libraries that, for
example, are capable of disentangling individual component spectra
even for binaries and multiple systems with heavily blended spectral
lines. Another exciting area is the rapidly developing investigation
of pulsating stars in binary systems. Ultimately, asteroseismology as
well as apsidal motion studies could help to test and improve the
theory of stellar structure and evolution, again contributing to the
improvement of the methodology over a wide range of astrophysical
applications.
ADVANCES IN MODELING AND THEORY
Computer modelling is now possible with detail undreamed of a decade
ago, giving us insights into the formation of binary and multiple star
systems within condensing molecular clouds or the flow of material
between components of an interacting binary. These mass-exchanging
binaries are vital tools to study and improve the theory of accretion
disks, again with far-reaching applications to disks on galactic
scales (such as AGN) and on planetary scales (proto-planetary disks).
ADVANCES IN THE STUDY OF WIDE BINARIES AND MULTIPLE STARS
The study of wide binaries and multiple star systems have not received
much attention since a colloquium held in Brussels in 1987. Yet,
research in this area has seen a similar revolution. For example, high-
precision positions and proper motions from astrometry projects such
as Tycho-2, 2MASS, Super COSMOS, and UCAC are yielding many new faint
common-proper motion pairs, as well as astrometric binaries. Binaries
(both wide and close) are also being searched for in clusters and
associations, even in other galaxies. In the past several years wide
pairs have been used as probes of our Galaxy's dark matter content, in
calibrating the chromospheric activity vs. age relation for late type
main sequence stars, in determining the white-dwarf and main-sequence
luminosity functions, in setting constraints on post-main sequence
mass loss (via orbital expansion), and in assessing the intrinsic
completeness of new deep surveys. Wide binaries, especially if they
have different spectral types, can also be used to test the assumption
of identical initial abundances for binaries and confront theoretical
evolutionary tracks and models.
MULTITUDES OF SUBSTELLAR COMPANIONS: NEW BINARY CLASSES
Not even envisioned a decade ago were the variety and ubiquity of
substellar companions, including L- and T-dwarfs, brown dwarf pairs,
and exoplanets. Following initial discoveries of these objects in the
mid-1990's, an explosion of advancements has occurred in these
fields. We now have two new classes of spectral types, along with
evidence that the frequencies of substellar versus stellar companions
are profoundly different. There are also strong suspicions that the
typical exoplanet has an orbital and cosmogonical history different
than that of our own solar system planets. Both the techniques for
discovery and theoretical origins for these new classes of stellar
systems overlap with the interests of the traditional binary and
multiple star community.
RATIONAL FOR THE SYMPOSIUM: CLOSE AND WIDE BINARY SYSTEMS
We therefore proposed a follow-up to the "Complementary
Approaches" colloquium, this time expanded into a symposium to
highlight the many advances in our field mentioned above and broaden
the cross fertilization theme of the first meeting by including
members of both the "wide" and "close" binary communities. It is
appropriate that such a meeting be held in the Czech Republic at the
General Assembly, since much of the pioneering work on binary and
variable stars has been carried out in Central and Eastern Europe for
over a century.
As this proposal was a merger of two similar efforts, the Scientific
Organizing Committee (SOC) is co-chaired by Prof. Edward F.
Guinan (Villanova University, USA), Dr. Petr Harmanec (Charles
University, Prague, Czech Republic), and Dr. William I Hartkopf (U.S.
Naval Observatory, USA).
SYMPOSIUM FORMAT AND ORGANIZATION
The format for the symposium is a mix of invited oral
review presentations(~30 min) and more narrowly focused topical (~15-
20 min) presentations. There will also be contributed posters, with
some dissertation-related talks by advanced graduate students and
plenty of time for discussion. It is expected that this comprehensive
symposium should attract a large number of astronomers attending the
General Assembly. The topics covered cut across a wide range of interests
and we expect about 250 - 300 to attend and participate.