Speckle interferometry at SOAR
Speckle interferometry attains diffration-limited resolution by
processing short-exposure images taken with high magnification. This
method works on relatively bright stars. The High-Resolution
Camera (HRCAM) at the SOAR 4.1-m telescope is used since 2008 for
speckle interferometry. Presently it is mounted at the SOAR Adaptive
Module (SAM). This is a restricted-use instrument supported by its PI
Andrei Tokovinin.
Brief description. The figure below shows the HRCAM (see also
the
instrument manual ). The data are transmitted by an
extended USB link to a PC and registered as image cubes, typically 400
frames of 200x200 pixels each ( speckle
movie ). The data are procesed by IDL programs to compute power
spectrum and auto-correlation function, ACF. A binary star is detected
by "fringes" in the power spectrum or by symmetric peaks in the ACF. Its
parameters are measured by fitting a model to the data. Details of
the data processing are explained in the paper.
Capabilities. Most observations are made in the
Stroemgren y or Cousins I filters with resolution of
25 mas and 36 mas, respectively. The maximum detectable magnitude
difference can reach 6 mag at 1 arcsecond, it is less at smaller
separations (in the Figure below, asterisks are
detections of simulated binaries, squares are non-detections, and
the curve is the estimated limiting magnitude difference) and in the I
filter. The limiting magnitude strongly depends on the seeing
and is deeper in the I band. Stars as faint as V=12 mag were
observed under good seeing, but V=10 mag is a more realistic limit
under median seeing. Typically, some 100 to 150 stars per night are
observed. The effficiency is determined by the telescope pointing and
target acquisition time, the data cubes are collected for only a few
seconds. The raw data are processed by A. Tokovinin using his
software. The data products are measurements of resolved binary and
triple stars and the detection limits at 0.15 and 1 arcsec separation
for unresolved targets.
In March 2017, the failed Luca-S detector was replaced by the iXon-888
camera, on loan from the UNC (courtecy N. Law). It has a higher quantum
efficiency, so a gain of ~1 magnitude in sensitivity is expected.
Example. HIP 83716 is a 1-arcsec visual binary star known
since 1881. Its secondary component is itself a close pair Ba,Bb
discovered at SOAR in 2009. Further monitoring at SOAR revealed the
fast orbital motion, allowing to compute the orbit of Ba,Bb with a
period of 6.5yr and semi-major axis of 70 mas. See also
the NOAO press
release with animation.
Publications. More than 11000 measurements of binary stars
were made at SOAR by 2017 November, ~200 new multiple systems
were discovered. The list of publications below is in chronological
order. Please, take note of the
study of systematic errors of HRCAM.
Typically they are less then 0.1 deg in angle and 0.2% in scale;
small systematic errors in the published data can be corrected using
this document.
-
Tokovinin A., Cantarutti R. First speckle-interferometry at SOAR
telescope with electron multiplictaion CCD. 2008, PASP, 120, 170-177
[PDF, 338K]
-
Tokovinin A., Mason B.D., Hartkopf W.I. Speckle interferometry at Blanco and SOAR telescopes in 2008 and 2009. AJ, 2010, 139, 743-756.
[PDF, 937K] . Electronic tables (ASCII):
table4 (measurements),
table5 (unresolved stars),
table7 (notes).
-
Mason B.D., Hartkopf W.I., Tokovinin A.
Binary Star Orbits. IV. Orbits for 18 Southern Interferometric Pairs.
2010, AJ, 140, 735-743.
-
Tokovinin A. Cantarutti R., Tighe R., Schurter P., van der
Bliek N., Martinez M., Mondaca E.
High-resolution imaging at the SOAR telescope.
2010, PASP, 122, 1483-1494
[PDF, 421K]
ArXiv: 1010.4176
-
Hartkopf, W.I., Tokovinin, A., Mason, B.D.
Speckle Interferometry at SOAR in 2010 and 2011: Measures, Orbits, and
Rectilinear Fits. 2012, AJ, 143, 42
[PDF, 1.2M]
-
Tokovinin, A. Speckle interferometry and orbits of "fast" visual binaries.
2012, AJ, 144, 56
[PDF, 298K]
ArXiv:1206.1882
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Tokovinin, A. Kappa Fornaci, a triple radio-star. 2013, AJ, 145, 76
[PDF, 250K]
ArXiv:1301.1352
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Tokovinin, A. From binaries to multiples I: Data on F and G dwarfs within 67 pc of the Sun.
AJ, 2014, 147, 86 [PDF, 371K]
The electronic tables are available here.
ArXiv:1401.6825
- Tokovinin, A., Mason, B. D., Hartkopf, W. I. Speckle
interferometry at SOAR in 2012 and 2013. 2014, AJ, 147, 123.
ArXiv:1403.4970
- Tokovinin, A. Gorynya, N.A., Morrell, N.I.
The quadruple system ADS 1652. 2014, MNRAS, 443 (2): 3082-3089
[PDF, 192K]
- Tokovinin, A. Imaging survey of subsystems in secondary
components to nearby southern dwarfs. 2014, AJ, 148, 72
[PDF, 228K] ,
ArXiv:1407.6045
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Tokovinin, A., Latham, D. W., Mason, B. D. The unusual quadruple system HD 91962
with a "planetary" architecture. 2015, AJ, 149, 195
[PDF, 184K]
ArXiv: 1504.06535
- Tokovinin, A., Mason, B.D., Hartkopf, W.I., Mendez, R.A., Horch, E.P.
Speckle interferometry at SOAR in 2014. 2015, AJ, 150, 50
[PDF, 338K] ,
ArXiv: 1506.05718
-
Schmitt, J. R., Tokovinin, A., Wang, Ji, Fischer, D. A.,
Kristiansen, M. R., LaCourse, D. M., Gagliano, R., Tan, A. J. V.,
Schwengeler, H. M., Omohundro, M. R., Venner, A., Terentev, I., Schmitt, A. R.,
Jacobs, T. L., Winarski, T., Sejpka, J., Jek, K., Boyajian, T. S.,
Brewer, J. M., Ishikawa, S. T., Lintott, C., Lynn, S., & Weiksna, A.
Planet hunters X: searching for nearby neighbors of 75 planet and eclipsing
binary candidates from the K2 Kepler extended mission.
2016, AJ, 151, 159
- Tokovinin, A., Mason, B.D., Hartkopf, W.I., Mendez, R.A., Horch, E.P.
Speckle interferometry at SOAR in 2015. 2016, AJ, 151, 153
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Tokovinin, A. Orbits of subsystems in four hierarchical multiple stars.
2016, AJ, 152, 10
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Tokovinin, A. Orbits of four young triple-lined multiple systems.
2016, AJ, 152, 11
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Tokovinin, A. New orbits based on speckle interferometry at SOAR.
2016, AJ, 152, 138
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Tokovinin, A. The triple system Zeta Aquarii.
2016, ApJ, 831, 151
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Gomez, J., Docobo, J. A., Campo, P. P., Mendez, R. A
Orbits of 12 Southern Binaries Based on Soar Speckle Observations.
2016, AJ, 152, 216
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Tokovinin, A. & Latham, D. W. Relative orbit orientation in several resolved multiple systems. 2017, ApJ, 838, 54
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Tokovinin, A. New orbits based on speckle interferometry at SOAR. II. 2017, AJ, 154, 110
- Mendez, R. A., Claveria, R. M., Orchad, M. E., Silva, J. F.
Orbits for eighteen visual binaries and two double-line spectroscopic binaries observed with HRCAM on the SOAR 4m telescope, using a new Bayesian orbit code based on Markov chain Monte Carlo. 2017, AJ, 154, 187.
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Briceno, C. & Tokovinin, A. New binaries in the \epsilon Cha association.
2017, AJ, 154, 195
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Tokovinin, A. Ten years of speckle interferometry at SOAR. 2018, PASP, 130, 5002
[PDF, 446K]
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Tokovinin, A. Dancing twins: stellar hierarchies that formed sequentially? 2018, AJ, 155, 160
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Tokovinin, A., Mason, B.D., Hartkopf, W.I., Mendez, R.A., Horch, E.P.
Speckle interferometry at SOAR in 2016 and 2017. 2018, AJ, 155, 235
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Tokovinin, A. Spectroscopic orbits of subsystems in multiple stars. III. 2018, AJ, 156, 48
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Tokovinin, A. & Briceno, C. Yes, multi-periodic dwarfs in Upper Scorpius are binaries. Submitted to AJ 2018-07-06.
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Tokovinin, A.Spectroscopic orbits of subsystems in multiple stars. IV. Double-lined pairs. Submitted to AJ 2018-07-18.
Updated: Jul 23, 2018 A. Tokovinin