Introduction Overview to Symposium 240: Binary Stars as Critical Tools and Tests in Contemporary Astrophysics

摘要

An overview is presented of the many new and exciting developments in binaryand multiple star studies that were discussed at IAU Symposium 240. Impacts on binary andmultiple star studies from new technologies, techniques, instruments, missions and theory arehighlighted. It is crucial to study binary and multiple stars because the vast majority of stars(>60%) in our Galaxy and in other galaxies consist, not of single stars, but of double andmultiple star systems. To understand galaxies we need to understand stars, but since most aremembers of binary and multiple star systems, we need to study and understand binary stars.The major advances in technology, instrumentation, computers, and theory have revolutionizedwhat we know (and also don't know) about binary and multiple star systems. Data now availablefrom interferometry (with milliarcsecond [mas] and sub-mas precisions), high-precision radialvelocities (~1-2 m/s) and high precision photometry (<1-2 milli-mag) as well as the wealth ofnew data that are pouring in from panoramic optical and infrared surveys (e.g., >10,000 newbinaries found since 1995), have led to a renaissance in binary star and multiple star studies. Forexample, advances have lead to the discovery of new classes of binary systems with planet andbrown dwarf components (over 200 systems). Also, extremely valuable data about binary starsare available across the entire electromagnetic spectrumfrom gamma-ray to IR space missionsand from the ground using increasingly more powerful and plentiful optical and radio telescopesas well as robotic telescopes. In the immediate future, spectral coverage could even be extendedbeyond the radio to the first detection of gravity waves from interacting close binaries. Also,both the quality and quantity of data now available on binary and multiple stars are making itpossible to gain unprecedented new insights into the structure, and formation and evolution ofbinary stars, as well as providing valuable astrophysical information (like precise stellar masses,radii, ages, luminosities and distances) to test and constrain current astrophysical theory. Thesemajor advances permit tests of current theories and ideas in stellar astrophysics and provide thefoundations for the next steps in modeling and improvements in theory to be taken.