clustertools.cluster.cluster module

The StarCluster class and key internal functions

class clustertools.cluster.cluster.StarCluster(tphys=0.0, units=None, origin=None, ctype='snapshot', projected=False, **kwargs)

Bases: object

A class that represents a star cluster population that ooperations and functions can be performed on

Parameters:

tphysfloat

Time (units not necessary) associated with the population (default: 0)

unitsstr

Units of stellar positions and velocties. Options include ‘pckms’,’pcmyr’, ‘kpckms’,’kpcgyr’,’radec’,’nbody’,and ‘galpy’. For ‘pckms’ and ‘kpckms’, stellar velocities are assumed to be km/s. (default: None)

originstr

Origin of coordinate system within which stellar positions and velocities are defined. Options include ‘centre’, ‘cluster’, ‘galaxy’ and ‘sky’. Note that ‘centre’ corresponds to the systems centre of density or mass (as calculated by clustertools) while ‘cluster’ corresponds to the orbital position of the cluster’s initial centre of mass given ‘tphys’. In some cases these two coordinate systems may be the same. (default: None)

ctypestr

Code type used to generate the cluster population. Current options include ‘snapshot’, ‘nbody6’,’nbody6se’,’nemo’,’gyrfalcon’,’snaptrim’, amuse’,’clustertools’,’snapauto’. The parameter informs clustertools how to load the stellar popuation and advance to the next snapshot. (default: ‘snapshot’)

projectedbool

return projected values instead of 3D value. (default: False)

Other Parameters:

sfilestr

file containing single star data

bfilestr

file contain binary star data

ssefilestr

file containing single star evolution data

bsefilestr

file contain binary star evolution data

tfilestr

name of file contain tail star data

ofilestr

orbit file

ofilenamestr

orbit filename if ofile is not given

orbitstr

galpy orbit instance

ounitsstr

{‘pckms’,’pcmyr’,’kpckms’,’kpcgyr’,’radec’,’nbody’,’galpy’} units of orbital information (else assumed equal to StarCluster.units)

rofloat

distance to the Galactic centre (Default: solar_ro)

vofloat

circular velocity at ro (Default: solar_vo)

zofloat

Sun’s distance above the Galactic plane (default: solar_zo)

solarmotionfloat

array representing U,V,W of Sun (default: solar_motion)

nsnapint

if a specific snapshot is to be read in instead of starting from zero

nzfillint

value for zfill when reading and writing snapshots (default: 5)

snapbasestr

string of characters in filename before nsnap (default: ‘’)

snapendstr

string of character in filename after nsnap (default: ‘.dat’)

snapdirstr

string name of directory of snapshots if different than wdir (Default: ‘’)

delimiterstr

choice of delimiter when reading ascii/csv files (default: ‘,’)

wdirstr

working directory of snapshots if not current directory

intializebool

initialize a galpy orbit after reading in orbital information (default: False)

advancebool

set to True if this a snapshot that has been advanced to from an initial one? (default: False)

centre_method: str

{None,’orthographic’,’VandeVen’} method to convert to clustercentric coordinates when units are in radec (Default: None)

givestr

set what parameters are read in from nemo/gyrfalcon (default: ‘mxv’) Currently only accepts ‘mxvpqael’ as an alternative.

History

——-

2018 - Written - Webb (UofT)

add_action(JR, Jphi, Jz, OR=None, Ophi=None, Oz=None, TR=None, Tphi=None, Tz=None)

Add action values to the cluster instance

Parameters:

JR,Jphi,Jzfloat

orbit actions

OR,Ophi,Ozfloat

orbit frequencies

TR,Tphi,Tzfloat

orbit periods

Returns:

None

add_actions(JR, Jphi, Jz, OR=None, Ophi=None, Oz=None, TR=None, Tphi=None, Tz=None)

Add action values to the cluster instance

Parameters:

JR,Jphi,Jzfloat

orbit actions

OR,Ophi,Ozfloat

orbit frequencies

TR,Tphi,Tzfloat

orbit periods

Returns:

None

add_binary_stars(xb1, yb1, zb1, vxb1, vyb1, vzb1, xb2, yb2, zb2, vxb2, vyb2, vzb2, mb1=None, mb2=None, id1=None, id2=None, m01=None, m02=None, npop1=None, npop2=None, set_com=True, return_com=False)

Individually add binary stars to StarCluster.

Parameters:

xb1,yb1,zb1: float

stellar positions of primary. Input is assumed to be in cartesian coordinates unless self.units==’radec’ and self.origin==’sky’, then positions are assumed to be ra,dec,dist (degrees, degrees, kpc)

vxb1,vyb1,vzb1: float

stellar velocities of primary. Input is assumed to be in cartesian coordinates unless self.units==’radec’ and self.origin==’sky’, then positions are assumed to be pmra,pmdec,vlos (mas/yr, mas/yr, km/s)

xb2,yb2,zb2: float

stellar positions of secondary. Input is assumed to be in cartesian coordinates unless self.units==’radec’ and self.origin==’sky’, then positions are assumed to be ra,dec,dist (degrees, degrees, kpc)

vxb2,vyb2,vzb2: float

stellar velocities of secondary. Input is assumed to be in cartesian coordinates unless self.units==’radec’ and self.origin==’sky’, then positions are assumed to be pmra,pmdec,vlos (mas/yr, mas/yr, km/s)

mb1. mb2float

mass of primary and secondary (default: None)

id1,id2: int

primary and secondary star ids (default: None)

m01,m02: float

initial primary and secondary stellar masses (default: None)

npop1,npop2int

population number of primary and secondary star, for use with multiple populations (default: None)

set_combool

set coordinates of binary’s centre of mass in main arrays (default: False)

return_combool

reuturn coordinates of binary’s centre of mass (default: False)

Notes

History:

• 2022 - Written - Webb (UofT)

add_bse(id1, id2, kw1, kw2, kcm, ecc, pb, semi, m1, m2, logl1, logl2, logr1, logr2, ep1=None, ep2=None, ospin1=None, ospin2=None)

Add binary star evolution information to stars

• parameters are common output variables in NBODY6

• values are never adjusted during unit or coordinate changes

Parameters:

id1/id2int

id of star1 and star2

kw1/kw2int

stellar evolution tags (for using with NBODY6)

kcmint

stellar evolution tag for binary star

eccfloat

eccentricity of binary orbit

pb: float

period of binary orbit

semifloat

semi major axis of binary orbit

m1/m2float

masses of binary stars

logl1/logl2float

luminosities of binary stars

logr1/logr2float

radii of binary stars

ep1/ep2float

epochs of binary stars

ospin1/ospin2float

opsin of binary stars

Returns:

None

add_energies(kin, pot, etot=None)

Add energy information for stars

• total energy and Q for the cluster are also calculated

• values are never adjusted during unit or coordinate changes

Parameters:

kinfloat

kinetic energy

potfloat

potentail energy

etotfloat

total energy - calculated as kin+pot if not given

Returns:

None

add_nbody6(nc=0, rc=0.0, rbar=1.0, rtide=0.0, xc=0.0, yc=0.0, zc=0.0, zmbar=1.0, vbar=1.0, tbar=1.0, rscale=1.0, ns=0.0, nb=0.0, n_p=0.0)

Add additional information to StarCluster

• parameters are common output variables in NBODY6

• values are never adjusted during unit or coordinate changes

Parameters:

ncint

number of stars in core (default:0)

rcint

core radius (default:0)

rbarfloat

scaling factor between NBODY units and pc (default:1.)

rtide

rtide set in the simulation (default:0)

xc,yc,zcfloat

position of cluster centre (default:0)

zmbarfloat

scaling factor between NBODY units and Msun (default:1.)

vbarfloat

scaling factor between NBODY units and km/s (default:1.)

tbarfloat

scaling factor between NBODY units and Myr (default:1.)

rscalefloat

the scale radius of data (default:1.)

nsint

number of single stars (default:0)

nbint

number of binary stars (default:0)

npint

number of particles (default:0)

Returns:

None

add_orbit(xgc, ygc, zgc, vxgc, vygc, vzgc, ounits=None, initialize=False, from_centre=False, tphys=None)

Add orbit properties to StarCluster

Parameters:

xgc,ygc,zgc: float

cluster’s galactocentric position

vxgc,vygc,vzgc: float

cluster’s galactocentric velocity

ounits: str

units of position and velocity. Options include ‘pckms’,’pcmyr’ ‘kpckms’,’kpcgyr’,’radec’,’nbody’,and ‘galpy’. Values will be converted to match self.units

initialize: bool

Initialize a galpy orbit for self.orbit (default: False)

from_centrebool

genrate orbit from cluster’s exact centre instead of its assigned galactocentric coordinates (default: False)

tphysfloat

physical time as per the orbit file

Returns:

None

add_rotation(qrot)

Add a degree of rotation to an already generated StarCluster

Parameters:

clusterclass

StarCluster

qrotfloat

fraction of stars with v_phi < 0 that are switched to vphi > 0

Returns:

x,y,z,vx,vy,vzfloat

stellar positions and velocities (now with rotation)

add_sse(kw, logl, logr, ep=None, ospin=None, arg=None)

Add stellar evolution information to stars

• parameters are common output variables in NBODY6

• values are never adjusted during unit or coordinate changes

Parameters:

kwint

stellar evolution type (based on NBODY6)

loglfloat

log of luminosity

logrfloat

log of stellar radius

epfloat

epoch

ospinfloat

ospin

argint

array address arguments if SSE parameters do not necessarily match position and velocity arrays

Returns:

None

add_stars(x, y, z, vx, vy, vz, m=None, id=None, m0=None, npop=None, nb=0, sortstars=False, analyze=True)

Add stars to StarCluster.

Parameters:

x,y,z: float

stellar positions. Input is assumed to be in cartesian coordinates unless self.units==’radec’ and self.origin==’sky’, then positions are assumed to be ra,dec,dist (degrees, degrees, kpc)

vx,vy,vz: float

atellar velocities. Input is assumed to be in cartesian coordinates unless self.units==’radec’ and self.origin==’sky’, then positions are assumed to be pmra,pmdec,vlos (mas/yr, mas/yr, km/s)

m: float int

stellar mass

id: int

star id

m0: float int

initial stellar mass

npopint

population number, for use with multiple populations

nb: int

number of binary stars, which are assumed to be the first 2*nb stars in the array (default:0)

sortstars: bool

order stars by radius (default: False)

analyzebool

perform analysis on cluster after stars are added

Notes

History:

• 2018 - Written - Webb (UofT)

analyse(sortstars=True, projected=True)

Call analyze with alternative spelling

Parameters:

sortstarsbool

sort star by radius after coordinate change (default: True)

projectedbool

sort projected radii as well, but do not change self.projected (default: True)

Returns:

None

analyze(sortstars=True, projected=True)

Calculate properties related to mass, radius, and velocity

Parameters:

sortstarsbool

sort star by radius after coordinate change (default: True)

projectedbool

sort projected radii as well, but do not change self.projected (default: True)

Returns:

None

ckin(mmin=None, mmax=None, nmass=10, rmin=None, rmax=None, vmin=None, vmax=None, emin=None, emax=None, kwmin=0, kwmax=1, indx=None, projected=False)

NAME: Find the kinematic concentration parameter ck

• see Bianchini et al. 2018, MNRAS, 475, 96

Parameters:

clusterclass

StarCluster instance

mmin/mmaxfloat

specific mass range

nmass

number of mass bins used to calculate alpha

rmin/rmax

specific radial range

vmin/vmaxfloat

specific velocity range

emin/emaxfloat

specific energy range

kwmin/kwmaxint

specific stellar evolution type range

npopint

population number

indxbool

specific subset of stars

projectedbool

use projected values (default: False)

Returns:

ckfloat

kinematic concentration

Other Parameters:

kwargsstr

key words for plotting

closest_star(projected=None, argmument=False)

Find distance to closest star for each star - uses numba

Parameters:

clusterclass

positions of stars within the StarCluster

projectedbool

use projected values (default: False)

argumentbool

return argument of closest star as well (default: False)

Returns:

minimum_distancefloat

distance to closest star for each star

if argument:

argint

argument of closest star for each star

core_relaxation_time(coulomb=0.4, projected=None)

Calculate the core relaxation time (Stone & Ostriker 2015) of the cluster

• Stone, N.C. & Ostriker, J.P. 2015, ApJ, 806, 28

Parameters

clusterclass

StarCluster

coulombfloat

Coulomb parameter (default: 0.4)

projectedbool

use projected values (default: False)

methodstr

choose between Stone & Ostriker 2015 and other methods (in development)

Returns

trc

energies(specific=True, ids=None, projected=None, softening=0.0, full=True, parallel=False, **kwargs)

Calculate kinetic and potential energy of every star

Parameters:

clusterclass

StarCluster instance

specificbool

find specific energies (default: True)

ids: boolean array or integer array

if given, find the energues of a subset of stars defined either by an array of star ids, or a boolean array that can be used to slice the cluster (default: None)

projectedbool

use projected values (default: False)

softeningfloat

Plummer softening length in cluster.units (default: 0.0)

fullbool

calculate distance of full array of stars at once with numbra (default: True)

parallelbool

calculate distances in parallel (default: False)

Returns:

kin,potfloat

kinetic and potential energy of every star if the i_d argument is not used. If i_d argument is used, return an arrays with potential and kinetic energy in the same shape of i_d

History

2019 - Written - Webb (UofT) 2022 - Updated with support for multiple ids or an idexing array - Gillis (UofT)

eta_function(mmin=None, mmax=None, nmass=10, rmin=None, rmax=None, vmin=None, vmax=None, emin=None, emax=None, kwmin=0, kwmax=1, indx=None, projected=False, plot=False, **kwargs)

NAME: Find power slope of velocity dispersion versus mass

• mass bins are set up so that there are an equal number of stars in each bin

Parameters:

clusterclass

StarCluster instance

mmin/mmaxfloat

specific mass range

nmass

number of mass bins used to calculate alpha

rmin/rmax

specific radial range

vmin/vmaxfloat

specific velocity range

emin/emaxfloat

specific energy range

kwmin/kwmaxint

specific stellar evolution type range

npopint

population number

indxbool

specific subset of stars

projectedbool

use projected values (default: False)

plotbool

plot the mass function

Returns:

m_meanfloat

mean mass in each bin

sigvmfloat

velocity dispersion of stars in each bin

etafloat

power-law slope of (sigvm ~ m^eta)

eetafloat

error in eta

yetafloat

y-intercept of fit to log(sigvm) vs log(m)

eetafloat

error in yeta

Other Parameters:

kwargsstr

key words for plotting

find_centre(xstart=0.0, ystart=0.0, zstart=0.0, vxstart=0.0, vystart=0.0, vzstart=0.0, indx=None, nsigma=1.0, nsphere=100, density=True, rmin=0.1, rmax=None, nmax=100, method='harfst', nneighbour=6, reset_centre=False)

Find the cluster’s centre

• The default assumes the cluster’s centre is the centre of density, calculated via the find_centre_of_density function.

• For density=False, the routine first works to identify a sphere of nsphere stars around the centre in which to perform a centre of mass calculation (similar to NBODY6). Stars beyond nsigma standard deviations are removed from the calculation until only nsphere stars remain. This step prevents long tidal tails from affecting the calculation

Parameters:

clusterclass

StarCluster

xstart,ystart,zstartfloat

starting position for centre (default: 0,0,0)

vxstart,vystart,vzstartfloat

starting velocity for centre (default: 0,0,0)

indx: bool

subset of stars to perform centre of density calculation on (default: None)

nsphereint

number of stars in centre sphere (default:100)

rminfloat

minimum radius of sphere around which to estimate density centre (default: 0.1 cluster.units)

rmaxfloat

maxmimum radius of sphere around which to estimate density centre (default: None cluster.units, uses maximum r)

nmaxfloat

maximum number of iterations (default:100)

methodstr

method for finding the centre of density (‘harfst’ (default), ‘casertano’)

if method==’casertano’

nneighbourint

number of neighbours for calculation local densities

reset_centrebool

forcibly reset cluster’s centre of mass (default: False)

Returns:

xc,yc,zc,vxc,vyc,vzc - coordinates of centre of mass

find_centre_of_density(xstart=0.0, ystart=0.0, zstart=0.0, vxstart=0.0, vystart=0.0, vzstart=0.0, indx=None, nsphere=100, rmin=0.1, rmax=None, nmax=100, method='harfst', nneighbour=6, reset_centre=False)

Find cluster’s centre of density

• Find cluster’s centre of density:

  if method==’harfst’ use (Harfst, S., Gualandris, A., Merritt, D., et al. 2007, NewA, 12, 357) courtesy of Yohai Meiron if method==’casertano’ use (Casertano, S., Hut, P. 1985, ApJ, 298, 80)

Parameters:

clusterclass

StarCluster

xstart,ystart,zstartfloat

starting position for centre (default: 0,0,0)

vxstart,vystart,vzstartfloat

starting velocity for centre (default: 0,0,0)

indx: bool

subset of stars to perform centre of density calculation on (default: None)

nsphereint

number of stars in centre sphere (default:100)

rminfloat

minimum radius of sphere around which to estimate density centre (default: 0.1 cluster.units)

rmaxfloat

maxmimum radius of sphere around which to estimate density centre (default: None cluster.units, uses maximum r)

nmaxfloat

maximum number of iterations (default:100)

methodstr

method for finding the centre of density (‘harfst’ (default), ‘casertano’)

if method==’casertano’

nneighbourint

number of neighbours for calculation local densities

reset_centrebool

forcibly reset cluster’s centre of mass (default: False)

Returns:

xc,yc,zc,vxc,vyc,vzcfloat

coordinates of centre of mass

find_centre_of_mass(reset_centre=False)

Find the centre of mass of the cluster

Parameters:

clusterclass

StarCluster

Returns:

xc,yc,zc,vxc,vyc,vzcfloat

coordinates of centre of mass

half_mass_relaxation_time(coulomb=0.4, projected=None)

Calculate the half-mass relaxation time (Spitzer 1987) of the cluster - Spitzer, L. 1987, Dynamical evolution of globular clusters - Need to adjust amplitude for different input units

Parameters:

clusterclass

StarCluster

coulombfloat

Coulomb parameter (default: 0.4)

projectedbool

use projected values (default: False)

Returns:

trhfloat

half-mass relaxation time within radius rad

initialize_orbit(from_centre=False, ro=None, vo=None, zo=None, solarmotion=None)

Initialize a galpy orbit instance for the cluster

Parameters:

clusterclass

StarCluster

from_centrebool

intialize orbits from cluster’s exact centre instead of cluster’s position in galaxy (default :False)

rofloat

galpy distance scale (default: None)

vofloat

galpy velocity scale (default: None)

zofloat

Sun’s distance above the Galactic plane (default: None)

solarmotionfloat

array representing U,V,W of Sun (default: None)

Returns:

orbitclass

GALPY orbit

initialize_orbits(ro=None, vo=None, zo=None, solarmotion=None)

Initialize a galpy orbit for every star in the cluster

Parameters:

clusterclass

StarCluster

rofloat

galpy distance scale (default: None)

vofloat

galpy velocity scale (default: None)

zofloat

Sun’s distance above the Galactic plane (default: None)

solarmotionfloat

array representing U,V,W of Sun (default: None)

Returns:

orbitclass

GALPY orbit

interpolate_orbit(pot=None, tfinal=None, nt=1000, from_centre=False, ro=None, vo=None, zo=None, solarmotion=None)

Interpolate past or future position of cluster and escaped stars

Parameters:

clusterclass

StarCluster

cluster_potclass

Galpy potential for host cluster that orbit is to be integrated in if None, assume a Plumme Potential

potclass

galpy Potential that orbit is to be integrate in (default: None)

tfinalfloat

final time (in cluster.units) to integrate orbit to (default: 12 Gyr)

ntint

number of timesteps

from_centrebool

intialize orbits from cluster’s exact centre instead of cluster’s position in galaxy (default :False)

ro :float

galpy distance scale (Default: None)

vofloat

galpy velocity scale (Default: None)

zofloat

Sun’s distance above the Galactic plane (default: None)

solarmotionfloat

array representing U,V,W of Sun (default: None)

Returns:

x,y,zfloat

interpolated positions of each star

vx,vy,vzfloat

interpolated velocities of each star

interpolate_orbits(pot=None, tfinal=None, nt=1000, ro=None, vo=None, zo=None, solarmotion=None)

Interpolate past or future position of stars within the cluster

Parameters:

clusterclass

StarCluster

potclass

Galpy potential for host cluster that orbit is to be integrated in if None, assume a Plumme Potential

tfinalfloat

final time (in cluster.units) to integrate orbit to (default: 12 Gyr)

ntint

number of timesteps

ro :float

galpy distance scale (Default: None)

vofloat

galpy velocity scale (Default: None)

zofloat

Sun’s distance above the Galactic plane (default: None)

solarmotionfloat

array representing U,V,W of Sun (default: None)

Returns:

x,y,zfloat

interpolated positions of each star

vx,vy,vzfloat

interpolated velocities of each star

key_params(do_order=True, projected=True)

Call analyze with key_params for backwards compatibility

Parameters:

do_orderbool

sort star by radius after coordinate change (default: True)

projectedbool

sort projected radii as well, but do not change self.projected (default: True)

Returns:

None

mass_function(mmin=None, mmax=None, nmass=10, rmin=None, rmax=None, vmin=None, vmax=None, emin=None, emax=None, kwmin=0, kwmax=1, indx=None, mcorr=None, projected=False, plot=False, **kwargs)

Find mass function over a given mass range

• mass bins are set up so that there are an equal number of stars in each bin

Parameters:

clusterclass

StarCluster instance

mmin/mmaxfloat

specific mass range

nmass

number of mass bins used to calculate alpha

rmin/rmax

specific radial range

vmin/vmaxfloat

specific velocity range

emin/emaxfloat

specific energy range

kwmin/kwmaxint

specific stellar evolution type range

npopint

population number

indxbool

specific subset of stars

projectedbool

use projected values (default: False)

mcorrfloat

completeness correction for masses

plotbool

plot the mass function

Returns:

m_meanfloat

mean mass in each bin

m_histfloat

number of stars in each bin

dmfloat

dN/dm of each bin

alphafloat

power-law slope of the mass function (dN/dm ~ m^alpha)

ealphafloat

error in alpha

yalphafloat

y-intercept of fit to log(dN/dm) vs log(m)

eyalphafloat

error in yalpha

Other Parameters:

kwargsstr

key words for plotting

meq_function(mmin=None, mmax=None, nmass=10, rmin=None, rmax=None, vmin=None, vmax=None, emin=None, emax=None, kwmin=0, kwmax=1, indx=None, projected=False, plot=False, **kwargs)

NAME: Find meq from velocity dispersion versus mass

• mass bins are set up so that there are an equal number of stars in each bin

• As per Bianchini, P. et al. 2016, MNRAS, 458, 3644, velocity dispersion versus mass is fit with the following: sigma(m)= sigma e^(-1/2 m/meq) if m<= meq

  = sigma0 e^(-1/2) (m/meq)^-1/2 if m > meq

Parameters:

clusterclass

StarCluster instance

mmin/mmaxfloat

specific mass range

nmass

number of mass bins used to calculate alpha

rmin/rmax

specific radial range

vmin/vmaxfloat

specific velocity range

emin/emaxfloat

specific energy range

kwmin/kwmaxint

specific stellar evolution type range

npopint

population number

indxbool

specific subset of stars

projectedbool

use projected values (default: False)

plotbool

plot the mass function

Returns:

m_meanfloat

mean mass in each bin

sigvmfloat

velocity dispersion of stars in each bin

meqfloat

Bianchini fit to sigvm vs m

emeqfloat

error in Bianchini fit to sigvm vs m

sigma0float

Bianchini fit to sigvm vs m

esigma0float

error in Bianchini fit to sigvm vs m

Other Parameters:

kwargsstr

key words for plotting

orbit_interpolate(pot=None, tfinal=None, nt=1000, from_centre=False, ro=None, vo=None, zo=None, solarmotion=None)

Interpolate past or future position of cluster and escaped stars

• same as interpolate_orbit, but included for legacy purposes

Parameters:

clusterclass

StarCluster

cluster_potclass

Galpy potential for host cluster that orbit is to be integrated in if None, assume a Plumme Potential

potclass

galpy Potential that orbit is to be integrate in (default: None)

tfinalfloat

final time (in cluster.units) to integrate orbit to (default: 12 Gyr)

ntint

number of timesteps

from_centrebool

intialize orbits from cluster’s exact centre instead of cluster’s position in galaxy (default :False)

ro :float

galpy distance scale (Default: None)

vofloat

galpy velocity scale (Default: None)

zofloat

Sun’s distance above the Galactic plane (default: None)

solarmotionfloat

array representing U,V,W of Sun (default: None)

Returns:

x,y,zfloat

interpolated positions of each star

vx,vy,vzfloat

interpolated velocities of each star

orbital_path(tfinal=0.1, nt=1000, pot=None, from_centre=False, skypath=False, initialize=False, ro=None, vo=None, zo=None, solarmotion=None, plot=False, **kwargs)

Calculate the cluster’s orbital path

Parameters:

clusterclass

StarCluster

tfinalfloat

final time (in cluster.units) to integrate orbit to (default: 0.1 Gyr)

ntint

number of timesteps

potclass

galpy Potential that orbit is to be integrate in (default: None)

from_centrebool

genrate orbit from cluster’s exact centre instead of its assigned galactocentric coordinates (default: False)

skypathbool

return sky coordinates instead of cartesian coordinates (default: False)

initializebool

Initialize and return Orbit (default: False)

ro :float

galpy distance scale (Default: None)

vofloat

galpy velocity scale (Default: None)

zofloat

Sun’s distance above the Galactic plane (default: None)

solarmotionfloat

array representing U,V,W of Sun (default: None)

plotbool

plot a snapshot of the cluster in galactocentric coordinates with the orbital path (defualt: False)

Returns:

tfloat

times for which path is provided

x,y,zfloat

orbit positions

vx,vy,vzfloat

orbit velocity

oclass

galpy orbit (if initialize==True)

History

2018 - Written - Webb (UofT)

orbital_path_match(tfinal=0.1, nt=1000, pot=None, path=None, from_centre=False, skypath=False, to_path=False, do_full=False, ro=None, vo=None, zo=None, solarmotion=None, plot=False, projected=False, **kwargs)

Match stars to a position along the orbital path of the cluster

Parameters:

clusterclass

StarCluster

tfinalfloat

final time (in cluster.units) to integrate orbit to (default: 0.1 Gyr)

ntint

number of timesteps

potclass

galpy Potential that orbit is to be integrate in (default: None)

patharray

array of (t,x,y,x,vx,vy,vz) corresponding to the tail path. If none path is calculated (default: None)

from_centrebool

genrate orbit from cluster’s exact centre instead of its assigned galactocentric coordinates (default: False)

skypathbool

return sky coordinates instead of cartesian coordinates (default: False) if True, projected is set to True

to_pathbool

measure distance to the path itself instead of distance to central point along the path (default: False)

do_fullbool

calculate dpath all at once in a single numpy array (can be memory intensive) (default:False)

ro :float

galpy distance scale (Default: None)

vofloat

galpy velocity scale (Default: None)

zofloat

Sun’s distance above the Galactic plane (default: None)

solarmotionfloat

array representing U,V,W of Sun (default: None)

plotbool

plot a snapshot of the cluster in galactocentric coordinates with the orbital path (defualt: False)

projectedbool

match to projected orbital path, which means matching just x and y coordinates or Ra and Dec coordinates (not z, or dist) (default:False)

Returns:

tstarfloat

orbital time associated with star

dprogfloat

distance along the orbit to the progenitor

dpath

distance to centre of the orbital path bin (Default) or the orbit path (to_path = True)

orbits_interpolate(pot=None, tfinal=None, nt=1000, ro=None, vo=None, zo=None, solarmotion=None)

Interpolate past or future position of stars within the cluster

• same as interpolate_orbits, but kept for legacy purposes

Parameters:

clusterclass

StarCluster

potclass

Galpy potential for host cluster that orbit is to be integrated in if None, assume a Plumme Potential

tfinalfloat

final time (in cluster.units) to integrate orbit to (default: 12 Gyr)

ntint

number of timesteps

ro :float

galpy distance scale (Default: None)

vofloat

galpy velocity scale (Default: None)

zofloat

Sun’s distance above the Galactic plane (default: None)

solarmotionfloat

array representing U,V,W of Sun (default: None)

Returns:

x,y,zfloat

interpolated positions of each star

vx,vy,vzfloat

interpolated velocities of each star

rcore(method='casertano', nneighbour=6, mfrac=0.1, projected=False, plot=False, **kwargs)

Calculate core radius of the cluster – The default method (method=’casertano’) follows Casertano, S., Hut, P. 1985, ApJ, 298, 80 to find the core – An alternative metrhod (method==’isothermal’) assumes the cluster is an isothermal sphere the core radius is where density drops to 1/3 central value — For projected core radius, the core radius is where the surface density profile drops to 1/2 the central value — Note that the inner mass fraction of stars used to calculate central density is set by mfrac (default 0.1 = 10%)

Parameters:

clusterclass

StarCluster instance

methodstring

method of calculating the core radius of a star cluster (default ‘casertano’)

if method ==’casertano’:

nneighbourint

number of neighbours for calculation local densities

if method==’isothermal’:

mfracfloat

inner mass fraction to be used to establish the central density

projectedbool

use projected values (default: False)

plotbool

plot the density profile and mark the core radius of the cluster (default: False)

Returns

——-

rcfloat

core radius

Other Parameters:

None

relaxation_time(rad=None, coulomb=0.4, projected=None, method='spitzer')

Calculate the relaxation time (Spitzer & Hart 1971) within a given radius of the cluster

• Spitzer, L. Jr, Hart, M.H. 1971, ApJ, 164, 399 (Equation 5)

• Need to adjust amplitude for different input units

Parameters

clusterclass

StarCluster

radfloat

radius within which to calculate the relaxation time (defult: cluster.rm)

coulombfloat

Coulomb parameter (default: 0.4)

projectedbool

use projected values (default: False)

methodstr

choose between Spitzer & Hart 1971 and other methods (in development)

Returns:

trelaxfloat

relaxation time within radius rad

reset_nbody_scale(mass=True, radii=True, rvirial=True, projected=None, **kwargs)

Assign new conversions for real mass, size, and velocity to Nbody units

• kwargs are passed to the virial_radius function. See the virial_radius documenation in functions.py

Parameters:

clusterclass

StarCluster instance

massbool

find new mass conversion (default: True)

radiibool

find new radius conversion (default: True)

rvirialbool (default: True)

use virial radius to set conversion rate for radii as opposed to the approximation that rbar=4/3 rm

projectedbool

use projected values to calculate radius conversion (default: False)

Returns:

zmbarfloat

mass conversion

rbarfloat

radius conversion

vbarfloat

velocity conversion

tbarfloat

time conversion

History:

2018 - Written - Webb (UofT)

return_cluster(units0=None, origin0=None, rorder0=None, rorder_origin0=None, sortstars=False)

return cluster to a specific combination of units and origin

Parameters:

clusterclass

StarCluster

units0str

units that StarCluster will be changed to

origin0str

origin that StarCluster will be changed to

sortstarsbool

sort star by radius after coordinate change (default: False)

Returns:

None

History:

2018 - Written - Webb (UofT)

rlagrange(nlagrange=10, projected=None)

Calculate lagrange radii of the cluster by mass

Parameters:

clusterclass

StarCluster

nlagrangeint

number of lagrange radii bins (default: 10)

mfracfloat

Exact masss fraction to calculate radius. Will supersede nlagrange if not None (default : None)

projectedbool

calculate projected lagrange radii (default: False)

Returns:

rnfloat

lagrange radii

rlimiting(pot=None, rgc=None, nrad=20, projected=False, plot=False, from_centre=False, verbose=False, **kwargs)

Calculate limiting radius of the cluster

• The limiting radius is defined to be where the cluster’s density reaches the local background density of the host galaxy

• for cases where the cluster’s orbital parameters are not set, it is possible to manually set rgc which is assumed to be in kpc.

Parameters:

clusterclass

StarCluster

potclass

GALPY potential used to calculate actions

rgc

Manually set galactocentric distance in kpc at which the tidal radius is to be evaluated (default: None)

zgcfloat

For non-spherically symmetric potentials, manually set distance in kpc above disk at which the tidal radius is to be evaluated. When set, rgc becomes radius in cylindrical coordinates (default: None)

nradint

number of radial bins used to calculate density profile (Default: 20)

projectedbool

use projected values (default: False)

plotbool

plot the density profile and mark the limiting radius of the cluster (default: False)

from_centrebool

calculate tidal radius based on location of cluster’s exact centre instead of its assigned galactocentric coordinates (default: False)

verbosebool

Returns

——-

rlfloat

limiting radius

Other Parameters:

kwargsstr

key words for plotting

rtidal(pot=None, rtiterate=0, rtconverge=0.9, indx=None, rgc=None, from_centre=False, plot=False, verbose=False, **kwargs)

Calculate tidal radius of the cluster - The calculation uses Galpy (Bovy 2015_, which takes the formalism of Bertin & Varri 2008 to calculate the tidal radius – Bertin, G. & Varri, A.L. 2008, ApJ, 689, 1005 – Bovy J., 2015, ApJS, 216, 29 - riterate = 0 corresponds to a single calculation of the tidal radius based on the cluster’s mass (np.sum(cluster.m)) – Additional iterations take the mass within the previous iteration’s calculation of the tidal radius and calculates the tidal

radius again using the new mass until the change is less than 90%

• for cases where the cluster’s orbital parameters are not set, it is possible to manually set rgc which is assumed to be in kpc.

Parameters:

clusterclass

StarCluster instance

potclass

GALPY potential used to calculate tidal radius (default: None)

rtiterateint

how many times to iterate on the calculation of r_t (default: 0)

rtconvergefloat

criteria for tidal radius convergence within iterations (default 0.9)

indxbool

subset of stars to use when calculate the tidal radius (default: None)

rgcfloat

Manually set galactocentric distance in kpc at which the tidal radius is to be evaluated (default: None)

zgcfloat

For non-spherically symmetric potentials, manually set distance in kpc above disk at which the tidal radius is to be evaluated. When set, rgc becomes radius in cylindrical coordinates (default: None)

from_centrebool

calculate tidal radius based on location of cluster’s exact centre instead of its assigned galactocentric coordinates (default: False)

plotbool

plot the x and y coordinates of stars and mark the tidal radius of the cluster (default: False)

verbosebool

Print information about iterative calculation of rt

Returns:

rtfloat

tidal radius

Other Parameters:

kwargsstr

key words for plotting

save_cluster()

Save cluster’s units and origin

Parameters:

clusterclass

StarCluster

Returns:

cluster.units, cluster.originstr

units and origin of StarCluster

History:

2018 - Written - Webb (UofT)

sortstars(projected=True)

sort stars based on radius

Parameters:

projectedbool

sort projected radii as well, but do not change self.projected (default: True)

Returns:

None

subset(**kwargs)

Generate a boolean array that corresponds to subset of star cluster members that meet a certain criteria

Parameters:

rmin/rmaxfloat

minimum and maximum stellar radii

mmin/mmaxfloat

minimum and maximum stellar mass

vmin/vmaxfloat

minimum and maximum stellar velocity

emin/emaxfloat

minimum and maximum stellar energy

kwmin/kwmaxint

minimum and maximum stellar type (kw)

npopint

population number

indxbool

user defined boolean array from which to extract the subset

projectedbool

use projected values and constraints (default:False)

Returns:

indxbool

boolean array that is True for stars that meet the criteria

tail_path(dt=0.1, no=1000, nt=100, ntail=100, pot=None, dmax=None, bintype='fix', from_centre=False, skypath=False, to_path=False, do_full=False, ro=None, vo=None, zo=None, solarmotion=None, plot=False, **kwargs)

Calculate tail path +/- dt Gyr around the cluster

Parameters:

clusterclass

StarCluster

dtfloat

timestep that StarCluster is to be moved to

noint

number of timesteps for orbit integration (default:1000)

ntint

number of points along the tail to set the tail spacing (default: 100)

ntailint

number of points along the tail with roaming average (default: 1000)

potclass

galpy Potential that orbit is to be integrate in (default: None)

dmaxfloat

maximum distance (assumed to be same units as cluster) from orbital path to be included in generating tail path (default: None)

bintypestr

type of binning for tail stars (default : ‘fix’)

from_centrebool

genrate orbit from cluster’s exact centre instead of its assigned galactocentric coordinates (default: False)

skypathbool

return sky coordinates instead of cartesian coordinates (default: False)

to_pathbool

measure distance to the path itself instead of distance to central point along the path (default: False)

do_fullbool

calculate dpath all at once in a single numpy array (can be memory intensive) (default:False)

ro :float

galpy distance scale (Default: None)

vofloat

galpy velocity scale (Default: None)

zofloat

Sun’s distance above the Galactic plane (default: None)

solarmotionfloat

array representing U,V,W of Sun (default: None)

plotbool

plot a snapshot of the cluster in galactocentric coordinates with the orbital path (defualt: False)

projectedbool

match to projected orbital path, which means matching just x and y coordinates or Ra and Dec coordinates (not z, or dist) (default:False)

Returns:

tfloat

times for which path is provided

x,y,zfloat

tail path positions

vx,vy,vzfloat

tail path velocities

History

2018 - Written - Webb (UofT)

2019 - Implemented numpy array preallocation to minimize runtime - Nathaniel Starkman (UofT)

tail_path_match(dt=0.1, no=1000, nt=100, ntail=100, pot=None, dmax=None, from_centre=False, to_path=False, do_full=False, ro=None, vo=None, zo=None, solarmotion=None, plot=False, **kwargs)

Match stars to a position along the tail path of the cluster

Parameters:

clusterclass

StarCluster

dtfloat

timestep that StarCluster is to be moved to

noint

number of timesteps for orbit integration (default:1000)

ntint

number of points along the tail to set the tail spacing (default: 100)

ntailint

number of points along the tail with roaming average (default: 1000)

potclass

galpy Potential that orbit is to be integrate in (default: None)

patharray

array of (t,x,y,x,vx,vy,vz) corresponding to the tail path. If none path is calculated (default: None)

from_centrebool

genrate orbit from cluster’s exact centre instead of its assigned galactocentric coordinates (default: False)

skypathbool

return sky coordinates instead of cartesian coordinates (default: False) if True, projected is set to True

to_pathbool

measure distance to the path itself instead of distance to central point along the path (default: False)

do_fullbool

calculate dpath all at once in a single numpy array (can be memory intensive) (default:False)

ro :float

galpy distance scale (Default: None)

vofloat

galpy velocity scale (Default: None)

zofloat

Sun’s distance above the Galactic plane (default: None)

solarmotionfloat

array representing U,V,W of Sun (default: None)

plotbool

plot a snapshot of the cluster in galactocentric coordinates with the orbital path (defualt: False)

projectedbool

match to projected orbital path, which means matching just x and y coordinates or Ra and Dec coordinates (not z, or dist) (default:False)

Returns:

tstarfloat

orbital time associated with star

dprogfloat

distance along the path to the progenitor

dpath

distance to centre of the tail path bin (default) or the tail path (to_path = True)

tapered_mass_function(mmin=None, mmax=None, nmass=10, rmin=None, rmax=None, vmin=None, vmax=None, emin=None, emax=None, kwmin=0, kwmax=1, npop=None, indx=None, projected=False, mcorr=None, plot=False, **kwargs)

Find a tapered mass function over a given mass range

• mass bins are set up so that there are an equal number of stars in each bin

• functional form of the tapered mass function is taken from De Marchi, Paresce & Portegies Zwart 2010

Parameters

clusterclass

StarCluster instance

mmin/mmaxfloat

specific mass range

nmass

number of mass bins used to calculate alpha

rmin/rmax

specific radial range

vmin/vmaxfloat

specific velocity range

emin/emaxfloat

specific energy range

kwmin/kwmaxint

specific stellar evolution type range

npopint

population number

indxbool

specific subset of stars

projectedbool

use projected values (default: False)

mcorrfloat

completeness correction for masses

plotbool

plot the mass function

Returns:

m_meanfloat

mean mass in each bin

m_histfloat

number of stars in each bin

dmfloat

dN/dm of each bin

alphafloat

power-law slope of the mass function (dN/dm ~ m^alpha)

ealphafloat

error in alpha

yalphafloat

y-intercept of fit to log(dN/dm) vs log(m)

eyalphafloat

error in yalpha

Other Parameters:

kwargsstr

key words for plotting

to_WDunits(analyze=True)

Convert stellar positions/velocities, centre of mass, and orbital position and velocity to Walter Dehnen Units

Parameters:

clusterclass

StarCluster

analyzebool

run analysis function (default: True)

Returns:

None

History:

2022 - Written - Webb (UofT)

to_amuse(analyze=True)

Convert stellar positions/velocities, centre of mass, and orbital position and velocity to AMUSE Vector and Scalar Quantities

Parameters:

clusterclass

StarCluster

analyzebool

run analysis function (default: True)

Returns:

None

History:

2022 - Written - Webb (UofT)

to_audays()

Convert binary star semi-major axis and periods to solar radii and days

Parameters:

clusterclass

StarCluster

Returns:

None

to_center(sortstars=True, centre_method=None)

Shift coordinates such that origin is the centre of mass

• this is the same to to_centre, but allows for alternate spelling

Parameters:

clusterclass

StarCluster

sortstarsbool

sort star by radius after coordinate change (default: False)

centre_methodstr

method for shifting coordinates to clustercentric coordinates (see to_cluster). (default: None)

Returns:

None

History:

2018 - Written - Webb (UofT)

to_centre(sortstars=True, centre_method=None)

Shift coordinates such that origin is the centre of mass

Parameters:

clusterclass

StarCluster

sortstarsbool

sort star by radius after coordinate change (default: False)

centre_methodstr

method for shifting coordinates to clustercentric coordinates (see to_cluster). (default: None)

Returns:

None

History:

2018 - Written - Webb (UofT)

to_cluster(sortstars=True, centre_method=None)

Shift coordinates to clustercentric reference frame

• When units=’radec’ and origin=’sky’, the cluster will be shifted to clustercentric coordinates using either:

–centre_method=None: angular distance between each star’s RA/DEC and the RA/DEC of the cluster’s centre with proper motions directly subtracted off –centre_method=’orthographic’ , positions and velocities changed to orthnormal coordinates (Helmi et al. 2018) – centre_method=’VandeVen’ , positions and velocities changed to clustercentric coordinates using method outlined by Van de Ven et al. 2005

• Note the the line of site positions and velocities will just have the galactocentric coordinates of the cluster

subtracted off. Be sure to set projected=True when making any calculations to use only x and y coordinates

Parameters:

clusterclass

StarCluster

sortstarsbool

sort star by radius after coordinate change (default: False)

centre_methodstr

method for shifting coordinates to clustercentric coordinates. (default: None)

Returns:

None

History:

2018 - Written - Webb (UofT)

to_galaxy(sortstars=True)

Shift coordinates to galactocentric reference frame

Parameters:

clusterclass

StarCluster

sortstarsbool

sort star by radius after coordinate change (default: False)

Returns:

None

History:

2018 - Written - Webb (UofT)

to_galpy(analyze=True)

Convert stellar positions/velocities, centre of mass, and orbital position and velocity to galpy units

Parameters:

clusterclass

StarCluster

analyzebool

run analysis function (default: True)

Returns:

None

History:

2018 - Written - Webb (UofT)

to_kpcgyr(analyze=True)

Convert stellar positions/velocities, centre of mass, and orbital position and velocity to kpc and kpc/Gyr

Parameters:

clusterclass

StarCluster

analyzebool

run analysis function (default: True)

Returns:

None

History:

2022 - Written - Webb (UofT)

to_kpckms(analyze=True)

Convert stellar positions/velocities, centre of mass, and orbital position and velocity to kpc and km/s

Parameters:

clusterclass

StarCluster

analyzebool

run analysis function (default: True)

Returns:

None

History:

2018 - Written - Webb (UofT)

to_nbody(analyze=True)

Convert stellar positions/velocities, centre of mass, and orbital position and velocity to Nbody units

• requires that cluster.zmbar, cluster.rbar, cluster.vbar are set (defaults are 1)

Parameters:

clusterclass

StarCluster

analyzebool

run analysis function (default: True)

Returns:

None

History:

2018 - Written - Webb (UofT)

to_origin(origin, sortstars=True, centre_method=None)

Shift cluster to origin as defined by keyword

Parameters:

clusterclass

StarCluster

originstr

origin of coordinate system to be shifted to (centre, cluster, galaxy, sky)

sortstarsbool

sort star by radius after coordinate change (default: False)

centre_methodstr

method for shifting coordinates to clustercentric coordinates (see to_cluster). (default: None)

Returns:

None

History:

2018 - Written - Webb (UofT)

to_pckms(analyze=True)

Convert stellar positions/velocities, centre of mass, and orbital position and velocity to pc and km/s

Parameters:

clusterclass

StarCluster

analyzebool

run analysis function (default: True)

Returns:

None

to_pcmyr(analyze=True)

Convert stellar positions/velocities, centre of mass, and orbital position and velocity to pc and pc/Myr

Parameters:

clusterclass

StarCluster

analyzebool

run analysis function (default: True)

Returns:

None

History:

2022 - Written - Webb (UofT)

to_radec(sortstars=True, centre_method=None, analyze=True)

Convert to on-sky position, proper motion, and radial velocity of cluster

Parameters:

clusterclass

StarCluster

sortstarsbool

sort star by radius after coordinate change (default: False)

centre_methodstr

method for shifting coordinates to clustercentric coordinates (see to_cluster). (default: None)

analyzebool

run analysis function (default: True)

Returns:

None

History:

2018 - Written - Webb (UofT)

to_sky(sortstars=True, centre_method=None)

Calculate on-sky position, proper motion, and radial velocity of cluster

• Also changes units to radec

Parameters:

clusterclass

StarCluster

sortstarsbool

sort star by radius after coordinate change (default: False)

centre_methodstr

method for shifting coordinates to clustercentric coordinates. (default: None)

Returns:

None

History:

2018 - Written - Webb (UofT)

to_sudays()

Convert binary star semi-major axis and periods to solar radii and days

Note: Masses will be converted to solar masses

Parameters:

clusterclass

StarCluster

Returns:

None

to_tail()

Calculate positions and velocities of stars when rotated such that clusters velocity vector

points along x-axis

• no change to coordinates in StarCluster

Parameters:

clusterclass

StarCluster

Returns:

x_tail,y_tail,z_tail,vx_tail,vy_tail,vz_tailfloat

rotated coordinates with cluster’s velocity vector point along x-axis

History:

2018 - Written - Webb (UofT)

to_units(units)

Convert stellar positions/velocities, centre of mass, and orbital position and velocity to user defined units

Parameters:

clusterclass

StarCluster

unitsstr

units to be converted to (nbody,galpy,pckms,kpckms,radec)

Returns:

None

History:

2018 - Written - Webb (UofT)

virial_radius(method='inverse_distance', full=True, H=70.0, Om=0.3, overdens=200.0, nrad=20, projected=None, plot=False, **kwargs)

Calculate virial radius of the cluster - Virial radius is calculated using either: – the average inverse distance between particles, weighted by their masses (default) – the radius at which the density is equal to the critical density of the Universe at the redshift of the system, multiplied by an overdensity constant Parameters ———- cluster : class

StarCluster

methodstr

method for calculating virial radius (default: ‘inverse_distance’, alternative: ‘critical_density’)

Returns:

rvfloat

virial radius

Other Parameters:

fullbool

Use Numba to calculate average inverse distance between stars (default:True)

Hfloat

Hubble constant

Omfloat

density of matter

overdensfloat

overdensity constant

projectedbool

calculate projected virial radius (default: False)

plotbool

plot cluster density profile and illustrate virial radius calculation

kwargsstr

key word arguments for plotting function

virialize(qvir=0.5, specific=True, full=True, projected=None, softening=0.0)

Adjust stellar velocities so cluster is in virial equilibrium

Parameters:

clusterclass

StarCluster

qvirfloat

value you wish to virial parameter to be (default: 0.5)

specificbool

find specific energies (default: True)

full: bool

do full array of stars at once with numba (default: full_default)

projectedbool

use projected values when calculating energies (default: False)

softeningfloat

Plummer softening length in cluster.units (default: 0.0)

Returns

——-

qvfloat

scaling factor used to adjust velocities

clustertools.cluster.cluster.overlap_cluster(cluster1, cluster2, tol=0.1, projected=False, return_cluster=True)

Extract a sub population of stars from cluster1 that spatially overlaps with cluster2

Parameters:

cluster1StarCluster

cluster from which stars are to be extracted

cluster2StarCluster

cluster from which overlap region is defined

tol: float

tolerance parameter for how much regions need to overlap (default: 0.1)

projectedbool

use projected values and constraints (default:False)

return_cluster: bool

returns a sub_cluster if True, otherwise return the boolean array (default:True)

Returns:

StarCluster

clustertools.cluster.cluster.sub_cluster(cluster, rmin=None, rmax=None, mmin=None, mmax=None, vmin=None, vmax=None, emin=None, emax=None, kwmin=0, kwmax=15, npop=None, indx=[None], projected=False, sortstars=True, reset_centre=False, reset_nbody=False, reset_nbody_mass=False, reset_nbody_radii=False, reset_rvirial=False, reset_projected=False, **kwargs)

Extract a sub population of stars from a StarCluster

• automatically moves cluster to centre of mass, so all constraints are in clustercentric coordinates and current StarCluster.units

Parameters:

rmin/rmaxfloat

minimum and maximum stellar radii

mmin/mmaxfloat

minimum and maximum stellar mass

vmin/vmaxfloat

minimum and maximum stellar velocity

emin/emaxfloat

minimum and maximum stellar energy

kwmin/kwmaxint

minimum and maximum stellar type (kw)

npopint

population number

indxbool

user defined boolean array from which to extract the subset

projectedbool

use projected values and constraints (default:False)

sortstars: bool

order stars by radius (default: True)

reset_centrebool

re-calculate cluster centre after extraction (default:False)

reset_nbodybool

reset nbody scaling factors (default:False)

reset_nbody_massbool

find new nbody scaling mass (default:False)

reset_nbody_radiibool

find new nbody scaling radius (default:False)

reset_rvirialbool

use virial radius to find nbody scaling radius (default: True)

reset_projectedbool

use projected radii to find nbody scaling radius (default: False)

Returns:

StarCluster