stellaR (version 0.3-4)

makeIso: Construct stellar isochrones from tracks

Description

The function computes by interpolation stellar isochrones of given ages from evolutionary tracks.

Usage

makeIso(age, z=NULL, y=NULL, ml=NULL, afe=NULL, log=FALSE, linear=TRUE,
         tr=NULL, baseURL="ftp://cdsarc.u-strasbg.fr/pub/cats/J/A+A/540/A26/")

Arguments

age

the ages (in Gyr) of the isochrones to construct. A vector of ages is allowed.

z

the initial metallicity of the isochrones to build.

y

the initial helium abundance of the isochrones to build.

ml

the mixing-length of the isochrones to build.

afe

the alpha-enhanchment of the isochrone to build. It can be one of afe = 0 for [alpha/Fe] = 0.0 or afe = 1 for [alpha/Fe] = 0.3.

log

a logical value indicating whether the interpolation of the tracks should be performed on the logarithm of the evolutionary time.

linear

a logical value indicating whether linear interpolation should be performed. Only the option linear=TRUE is currently available.

tr

a set of track to be used for isocrones construction. See Details for further information.

baseURL

the URL of the base directory of the database from where get the models.

Value

The function returns an object of class isoset.

Details

Isochrones are obtained by mean of a standard interpolation procedure on the set of tracks. Let \(S(m)\) be the set of tracks, parametrized by the value of the mass \(m\). Let \(t_i(m)\) be the evolutionary time for the ith point on the track of mass \(m\). Let be \(k\) the point on the track of lower mass of \(S(m)\) for which \(t_k(m)\) is greater of the time required for the isochrone.

For each point \(j >= k\) on \(S(m)\), an interpolation of mass, logarithm of the effective temperature and logarithm of the luminosity is performed among tracks. These points define the required isochrone.

If a set of tracks is supplied by mean of the argument tr, the function interpolates among these tracks. The values of z, y, ml, afe are recovered from the supplied objects and a test of consistency is performed to assure that the tracks are homogeneous in these parameters.

References

M. Dell'Omodarme, G. Valle, S. Degl'Innocenti, and P.G. Prada Moroni (2012). The Pisa Stellar Evolution Data Base for low-mass stars. Astronomy and Astrophysics, 540, A26.

Examples

# NOT RUN {
 ### slow!
 
# }
# NOT RUN {
  isoset <- makeIso(11.2, 0.002, 0.25, 1.7, 0)
# }
# NOT RUN {
  ### get data from local directory /data
  
# }
# NOT RUN {
isoset <- makeIso(c(11.2, 12.4), 0.002, 0.25, 1.7, 0, baseURL="/data/")
# }