TRILEGAL 1.3 help

Introduction This is TRILEGAL 1.3, a code for simulating the stellar photometry of
  • any field of the Galaxy
  • star clusters
  • nearby galaxies
    Presently, it simulates normal stars, white and brown dwarfs, and non-interacting binaries. The photometry can be produced for many different broad- and intermediate-band systems, including non-standard ones.

    TRILEGAL version 1.0 has been described in the paper

    Star counts in the Galaxy. Simulating from very deep to very shallow photometric surveys with the TRILEGAL code, L. Girardi, M.A.T. Groenewegen, E. Hatziminaoglou, L. da Costa, Astronomy & Astrophysics 463, 895 (2005).
    The present version is essentially the same as in the papers, but for many extensions in the input databases, improved accuracy, a moderate code optimization, and the adaptation to be used through a CGI form. New extended versions are expected to be available every few months.

    Warning: Since this service is still under development, some of the potentialities of TRILEGAL have been temporarily hidden to external users: for instance, you are still not allowed to provide your own filter transmission curves, or new SFR, AMR and IMF files, and cannot simulate the population of star clusters and nearby galaxies. We plan to eliminate these limitations as soon as technically feasible.

  • The input form Most of the input parameters are described in the Girardi et al. (2005) paper. The default values correspond to the paper calibration. The parameters one normally wants to change from simulation to simulation are:
  • The pointing parameters: coordinates (Galactic or Equatorial, Epoch 2000) for the field center, and total field area.
  • The photometric system: several pre-defined systems are included. They result from the work started in Girardi et al. (2002) (see the corresponding BC tables and isochrones in
  • The extinction calibration: the best option is likely to use the "calibration at infinity", where one enters the AV value taken from extinction maps, for instance Schlegel, Finkbeiner & Davis (1998) ones (available online at Extinction is always expressed in the mean wavelength of the Johnson V-band, i.e. λ=5550 A, and then inferred for other pass-bands by using the Cardelli, Clayton, & Mathis (1989) extinction curve and filter throughputs for the selected photometric system.
  • The output The main output file contains
  • a series of population and physical parameters of the stars;
  • the apparent photometry in the selected system.
    For the moment, there is no positional information but for the distance modulus. Binaries are presented by single entries containing the physical parameters of the primary plus the photometry for the entire system. Future TRILEGAL versions will improve upon these points.

    Example of output fields:

    #Gc logAge [M/H] m_ini   logL   logTe logg  m-M0   Av   m2/m1 Mbol   U      B      V      ...      
     1   7.11 -0.24  0.13595 -1.779 3.512 4.345  7.7   0.036 0.00 16.917 22.248 20.575 18.916 ... 
  • Gc: the Galactic component: 1=thin disc, 2=thick disc, 3=halo, 4=bulge, 5=additional object;
  • logAge: log10 of age in years;
  • [M/H]: initial metallicity respect to the Sun's;
  • m_ini: initial mass in Msun;
  • logL: log10 of luminosity in Lsun;
  • logTe: log10 of effective temperature in K;
  • logg: log10 of surface gravity in c.g.s. units;
  • m-M0: absolute distance modulus;
  • Av: extinction in the V-band;
  • m2/m1: mass ratio for binaries (=0 for single stars);
  • Mbol: apparent bolometric magnitude;
  • remaining columns: apparent magnitudes in the several pass-bands;
  • Mact: actual mass in Msun.

    Different kinds of stars can be easily recognised by their population and physical parameters, e.g. white dwarfs have logg>7, brown dwarfs have m_ini<0.08, cool giants (M and C-types) have logTe<3.4 && logg<2, etc.

  • This service is mantained by Léo Girardi at the Osservatorio Astronomico di Padova.
    Questions, comments and special requests should be directed to leo.girardi@oapd·inaf·it .
    Last modified: Feb. 27, 2009