CHARA's Program of Binary Star Speckle Interferometry
The "resolution" of a telescope is its ability to see fine detail in
images, and the basic resolution limit is determined by
the diameter of a telescope's light collecting lens or mirror. For
example, a 100-inch telescope has ten times of the resolution of a
10-inch telescope. Under most circumstances, atmospheric turbulence
restricts the resolution of all telescopes to one having an aperture of
only 10-inches. These turbulence effects are caused by heat flowing
through the atmosphere and are analogous to what one sees when looking
across a hot parking lot and seeing the boiling view beyond it.
 In 1970, the French astronomer Antoine Labeyrie described a method whereby atmospherically induced blurring can be thwarted to obtain resolved detail down to the theoretical diffraction limit. Labeyrie's technique of "speckle
interferometry" uses high-magnification, short-exposure snapshots to
freeze out the instantaneous effects of turbulence and then applies
mathematical techniques to remove these effects. The method works best
when the object being observed is simple in appearance and not too
extended in size. Its limitations superbly match the needs for studying
binary star systems, pairs of stars bound by their mutual gravitational
attraction into elliptical orbits about a common center of mass. A brief gallery of illustrations of the speckle process, including raw and reduced observations as well as a photo of Antoine Labeyrie, can be found here.
From 1977 until 1998, CHARA astronomers carried out the most scientifically productive
program in the world in astronomical speckle interferometry applied to
the study of binary stars. These measurements yielded newly
determined stellar masses, distances, and luminosities through the
determination of orbits with an order of magnitude increase in accuracy
over classical visual results. The resolution of speckle
interferometry often permits the direct resolution of spectroscopic
binaries and provides a sensitivity to detection of duplicity in a
realm of orbital periods and semimajor axes inaccessible to other
existing methods. The development of instrumentation and algorithms to
extend the power of speckle methods continues to be of high priority
within CHARA. This research was supported continuously by the
National Science Foundation for more than 20 years. CHARA published thousands of accurate measurements of binaries, including more than 300 systems that had never been previously resolved, from data obtained with our instrumentation at 4-m class telescopes in Arizona, California, Chile and Hawaii.
The CHARA speckle observing program incorporated nearly 10,000 stars. In addition to visual and
spectroscopic binaries, program objects included composite spectrum
stars, occultation binaries, plus stars with suspected variable radial
velocity or other indication of possible duplicity such as excess
luminosity or abnormal colors. Surveys for duplicity among the bright
stars, the high velocity stars, Cepheid variables, and young stellar
associations were conducted as observing time permitted.
The success of this program laid the groundwork for CHARA's entry into the field of long-baseline, multiple-telescope interferometry and provided CHARA with the credibility that has ultimately led to the CHARA Array. With a switch in emphasis to the much higher resolution available from Arrays, the CHARA speckle program was retired in 1998. But we are pleased that a synoptic program of binary star speckle interferometry continues at the U.S. Naval Observatory in Washington under the direction of Dr. Brian Mason (who received his PhD at Georgia State University) and Dr. Bill Hartkopf (who managed the day-to-day efforts of the CHARA speckle program for many years).
Popular accounts of this program have been described in SKY AND TELESCOPE magazine articles published in May 1977 and November 1996. CHARA's catalogue of interferometric measurements of binary stars was transferred to the U.S. Naval Observatory where it is available as a component of the
Double Star Library along with many other valuable resources.
Bibliography of GSU/CHARA Speckle Publication
(Click here for reprints of these papers.)
Photographic Speckle Series:
ApJ 215, 159, 1977
ApJ 255, 932, 1978
ApJ 228, 493, 1979
ApJ 230, 497, 1979
ApJS 43, 327, 1980
ApJS 48, 273, 1982
ApJS 49, 267, 1982
ApJS 51, 309, 1982
ApJS 54, 251, 1984
ICCD Speckle Series:
AJ 93, 183, 1987 C1 = CFHT
AJ 93, 688, 1987 C2 = KPNO
AJ 94, 1318, 1987 C3 = KPNO
AJ 97, 510, 1989 C4 = KPNO
AJ 99, 965, 1990 C5 = KPNO+CTIO
AJ 104, 810, 1992 C6 = KPNO
AJ 105, 220, 1993 C7 = Hyades
AJ 106, 352, 1993 C8 = CTIO
AJ 106, 637, 1993 C9 = clusters
AJ 106, 1639, 1993 C10 = Bright Stars
AJ 108, 2299, 1994 C11 = KPNO
AJ 111, 393, 1996 C12 = Lowell Obs.
AJ 111, 936, 1996 C13 = CTIO
AJ 112, 1169, 1996 C14 = white dwarfs
AJ 112, 2260, 1996 C15 = occultation stars
AJ 114, 1623, 1997 C16 = Lowell Obs.
AJ 114, 1639, 1997 C17 = Mount Wilson Obs.
AJ 114, 2112, 1997 C18 = Be stars
AJ 115, 821, 1998 C19 = O stars
AJ C20 = in the works!
AJ C21 = ditto!
AJ 118, 509, 1999 C22 = Wolf-Rayet stars
AJ 119, 3084, 2000 C23 = results from 6 telescopes
Studies of Individual Systems:
Eta Ori PASP 88, 957, 1976
51 Tau AJ 212, 450, 1977
12 Per ApJ 223, 526, 1978
17 Cep ApJ 236, 522, 1980
Chi Dra AJ 85, 1265, 1980
Alpha Aur AJ 86, 795, 1981
Tau Per AJ 86, 1397, 1981
Phi Cyg AJ 87, 563, 1982
Gamma Per AJ 87, 563, 1982
94 Aqr PASP 94, 832, 1982
Alpha Aur PASP 95, 992, 1983
R Aqr ApJ 289, L765, 1985
Gamma Per AJ 94, 700, 1987
Alpha Aur AJ 96, 1056, 1988
Beta CrB AJ 100, 239, 1990
ADS 784 AJ 103, 1357, 1992
Eta Vir AJ 103, 1976, 1992
HR 1071 AJ 104, 1961, 1992
15 Mon AJ 106, 2072, 1993
HR 6469 AJ 107, 1529, 1994
Xi UMa AJ 109, 332, 1995
Delta Sge AJ 109, 1856, 1995
HR 6697 AJ 110, 366, 1995
Fin 347 AJ 112, 276, 1996
ADS 14839 AJ 113, 1095, 1997
HR 233, 36 Tau, 73 Leo AJ 114, 1607, 1997
Unresolved Binaries:
PASP 90, 288, 1978
PASP 93, 221, 1981
PASP 96, 105, 1984
Miscellaneous:
Resolving Spectroscopic binaries PASP 88, 317, 1976
Extra-solar planet detection Icarus, 30, 789, 1977
Popular description Sky & Telescope, 53, 346, 1977
Measurement accuracy Applied Optics, 18, 1034, 1979
KPNO speckle camera IAU Colloquium No. 50, 1980
Binary star interferometry Applied Optics, 18, 1034, 1979
Extra-solar planet detection NASA Conf. Pub. 2124, 1980
Summary of results IAU Colloquium No. 62, 1981
GSU ICCD speckle camera Proc. SPIE 331, 113, 1982
Standard stars PASP 95, 777, 1983
First Catalog CHARA Cont. No. 1, 1984
Speckle astrometry IAU Symposium No. 109, 1984
(2 papers)
Calibration in interferometry IAU Symposium No. 111, 1985
Review Article Ann. Rev. Astr. Ap. 23, 59, 1985
Review Article Vistas in Astr. 30, 27, 1987
Space Telescope Guide Stars PASP 99, 223, 1987
Summary of results IAU Colloq. No. 100, 1987
Scientific Potential NOAO/ESO Conference, 1988
Review Article American Scientist, Mar-Apr, 1988
Second Catalog CHARA Cont. No. 2, 1988
Imaging Algorithm Optics Lett. 13, 907, 1988
28 Orbits AJ 98, 1014, 1989
Absolute quadrants AJ 103, 1399, 1992
Various speckle topics IAU Colloq. 135, 1992
(editors, + 7 papers)
Trumpler 14 Cluster PASP 105, 588, 1993
Occultation Catalog CHARA Cont. No. 3, 1994
Asteroids AJ 110, 2463, 1995
Third Catalog CHARA Cont. No. 4, 1995
37 Orbits AJ 111, 370, 1996
Adaptive Optics Photometry AJ 112, 1180, 1996
O Star Duplicity Survey ASP Conf. Series 90, 40, 1996
Popular Description Sky & Telescope, 92, 28, 1996
15 Mon Nears Periastron ApJ 475, L49, 1997
55 UMa = CHARA 133 ApJ 485, 350, 1997
Orbits of 12 Occult. Systems AJ 114, 808, 1997
Orbits of 8 Systems IAU Comm. 26 Inf. Circ. 134, 1998
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