Table of Contents

Name

snapbinary - analyze binaries in a snapshot

Synopsis

snapbinary [parameter=value]

Description

For a given pair of stars, some statistics is computed of what kind of binary it is (ignoring any other stars in the neighborhood). For a bound pair the semi-major axis, period and eccentricity will be given.

The program snapstat(1NEMO) with option debug=1 will report the progression of nearest neighbors, which are good candidates for binaries.

Parameters

The following parameters are recognized in any order if the keyword is also given:
in=
input file name [???]
i1=
First star, where 0 is the first star in the snapshot. A nemoinp(1NEMO) list (e.g. 0:100) can also be given. [0]
i2=
Second star. A nemoinp(1NEMO) list (e.g. 0:100) can also be given, but only stars greater than i1= are used. [1]
bound=t|f
If given, only bound stars are listed. [t]

Examples

In this given snapshot snapstat(1NEMO) is used to report close pairs (but note it will only report pairs closer than the previous one):
% snapstat snap22 exact=t all=t debug=1
### nemo Debug Info: rmin=31.0396 for (0,1) mass (0.00131882,0.000923836)
### nemo Debug Info: rmin=8.34925 for (0,4) mass (0.00131882,0.000368837)
### nemo Debug Info: rmin=5.88091 for (0,5) mass (0.00131882,0.000265256)
### nemo Debug Info: rmin=4.40751 for (0,6) mass (0.00131882,0.000296517)
### nemo Debug Info: rmin=2.86166 for (0,7) mass (0.00131882,0.000534057)
### nemo Debug Info: rmin=2.70097 for (0,28) mass (0.00131882,0.000926514)
### nemo Debug Info: rmin=0.315905 for (1,8) mass (0.000923836,0.00156653)
### nemo Debug Info: rmin=0.0229803 for (8,33) mass (0.00156653,0.000452991)
### nemo Debug Info: rmin=0.00713546 for (23,24) mass (0.000450885,0.000545665)
### nemo Debug Info: rmin=0.00623804 for (23,26) mass (0.000450885,0.000242503)
### nemo Debug Info: rmin=0.00586965 for (41,46) mass (0.0132193,0.0132209)
### nemo Debug Info: rmin=0.00439421 for (45,151) mass (0.00408217,0.00155427)
### nemo Debug Info: rmin=0.00404594 for (51,141) mass (0.00565297,0.00139231)
### nemo Debug Info: rmin=0.00345551 for (61,138) mass (0.00394162,0.00155196)
### nemo Debug Info: rmin=0.00337327 for (61,141) mass (0.00394162,0.00139231)
### nemo Debug Info: rmin=0.00292007 for (64,68) mass (0.00475124,0.00506128)
### nemo Debug Info: rmin=0.00240338 for (70,76) mass (0.00603871,0.0529179)
### nemo Debug Info: rmin=0.00133495 for (70,93) mass (0.00603871,0.0048034)
### nemo Debug Info: rmin=0.00097828 for (145,420) mass (0.00324217,0.00133839)
### nemo Debug Info: rmin=0.000652002 for (188,406) mass (0.00122891,0.000262444)
Star 70 might be part of a triple.
% snapbinary snap22  188 406
  m1,m2,mu: 0.00122891 0.000262444 0.00149135
  pos,vel:  0.000156675 -0.000590395 0.000228021 0.152756 -0.147408 0.406277
  T,W,E:    0.105062 -2.28734 -2.18228 
  H,|H|:    -0.000206252 -2.88217e-05 6.70914e-05 0.000218796
  a,b,p,e:  0.000341696 0.000104729 3.20995e-05 0.951871
  period:   0.00102766
  
% snapbinary snap22  1 8 bound=f
  m1,m2,mu: 0.000923836 0.00156653 0.00249036
  pos,vel:  0.29847 -0.0686271 -0.0774708 -0.113217 -0.010249 -0.0666479
  T,W,E:    0.00868257 -0.00788328 0.000799292 
  H,|H|:    0.00377985 0.0286634 -0.0108288 0.030873
  a,b,p,e:  -1.55786 -0.772167 0.382732 1.1161
  period:   Inf (Not a binary)
  
and here is an example with mk2body:
  % mk2body -  1 | snapbinary - 
  ### nemo Debug Info: U: -1   T: 0.25   T+U: -0.75  T/U: -0.25
  i1,i2:    0 1
  m1,m2,mu: 1 1 2
  pos,vel:  -1 0 0 0 -1 0
  T,W,E:    0.5 -2 -1.5 
  H,|H|:    0 0 1 1
  a,b,p,e:  0.666667 0.57735 0.5 0.5
  period:   2.4184

See Also

kep2kep(1NEMO) , mk2body(1NEMO) , snapstat(1NEMO) , snapshot(5NEMO)

Files

NEMO/src/nbody/reduc/snapbinary.c

Author

Peter Teuben

Update History


3-Mar-2019    V0.1 quick hack        PJT
7-mar-2019    V0.3 i1= and i2= can be a list    PJT


Table of Contents