Binary Star Combined Solution Package
Donald Gudehus
The software program "binary" allows one to combine astrometric, speckle, and radial velocity data in order to simultaneously solve for the orbital elements and ratio of semimajor axes, system radial velocity, proper motion, and parallax, if possible, of a binary or multiple star system, by means of the nonlinear least squares routine, "nonlinfit". The source code for OpenVMS and Unix, and executables for VAX, Linux, and Mac OS X are freely available. Some features of the program are:
- 1) Up to 10000 data points can be considered
- 2) Any data point can be ignored by setting its sigma in the file to
a key value
- 3) The weights for a file can be scaled at run time
- 4) Points can be excluded from the solution based upon their phase
- 5) Apsidal motion for the main components can be solved for
- 6) Each spectroscopic component is allowed to have up to five spectroscopic
subcomponents, present in the parent's file and/or in separate files,
for a maximum of twelve objects
- 7) Optional allowance for the light travel time across the orbit for the
spectroscopic data, including subcomponents, can be made
- 8) When possible, the mass(es) and mean error(s) are calculated
- 9) The reduced chi squared is calculated for each data dimension
- 10) The errors of each parameter are calculated
- 11) Any parameter or combination of parameters can be held constant in the
solution
- 12) The solution can be rerun with points which deviate beyond some factor
times the sigma, excluded
- 13) The data and the solution can be plotted over the entire time span
or over one cycle, with and without the subcomponents, and with the
subcomponents alone
- 14) The residuals of the visual data can be written to a file in standard
format for further analysis
- 15) The program can be run with input parameters contained in a "save"
file and with some of them optionally specified on the command line
- 16) The program can also solve for the orbits of planets around stars.
A companion program "editbinary" allows one to edit values in the standard data files. Arithmetic operations are performed on one or more columns simultaneously. Some of the operations are:
- 1) Adding or multiplying the data values by a constant
- 2) Precessing the coordinates of the data
- 3) Smoothing the data by averaging over specified intervals
- 4) Manual entering of visual, spectroscopic, and 1-D interferometric data points
- 5) Converting weights to sigmas
- 6) Creating artificial visual, spectroscopic, and 1-D interferometric data from user supplied
elements
The program "one2two" fits a cosine curve to 1-D interferometric data consisting of projected baseline angle, and projected binary separation, and derives the two-dimensional data point, position angle and separation which can then be used in the above "binary" program.
Also included with the package are four demonstration programs, nl_demo_1.exe, nl_demo_2.exe, nl_demo_3.exe, and nl_demo_4.exe which utilize the nonlinear least squares subroutine, nonlinfit, which is used by binary, and the plot package programs plotcom.exe and xyplot_ascii.exe which are used for directing a plot file to any supported plot device, and for plotting data from one or more ASCII files on any supported plot device, respectively.
The program "binary" is also available in the MIIPS (Multipurpose Interactive Image Processing System) package.
