Besançon Galaxy Model

Besançon model of stellar population synthesis of the Galaxy

Here are summarized the model changes since the version released on November 25, 2003 (version described in A. C. Robin, C. Reylé, S. Derrière and S. Picaud. A synthetic view on structure and evolution of the Milky Way, 2003, Astron. Astrophys., 409:523 [ADS] and erratum: 2004, Astron. Astrophys., 416:157)

  • 2022 September 20:
  • 2022 August 24:
    • The photometric errors were not associated to the proper band indicated in the form. The error is now corrected. The field errband_X (where X is the band) now contains the photometric errors rather that the sigma value.
  • 2022 July 1st:
    • The extinction map of Marshall et al was never used. The error is now corrected.
  • 2021 September 15:
    • Simulation results are now downloaded throug a "https://..." link (instead of ftp previously)
  • 2020 Oct 1, 15h02 (CEST):
    • In the header file, when choosing to simulate a sky zone, the indicated solid angle was not recomputed, hence was wrong. This is now properly computed and written. This bug did not impact anything in the simulations
  • 2019 Aug 12, 10h33 (CEST):
    • There was a wrong density of low mass stars in the bar population (at ~Mv = 12.6) which has been corrected today. The change is noticeable only for star count simulations in the bulge region at apparent magnitude fainter than about 24.5 in I. Notice that there are still no stars at mass<0.15 Msun for the bar population (Pop=10) due to lack of low mass Padova isochrones.
  • 2019 May 10:
    • Simulations are now limited to 2 million stars
  • 2019 January 18:
    • The web site has been moved to https (secured connection)
  • 2019 January 16:
  • 2018 September 21:
    • new photometric systems are available : Gaia G, Spitzer, SDSS, GALEX and UVIT bands
    • The kinematics is from the fit to radial velocities from RAVE and proper motions from Gaia-DR1 presented in Robin et al, 2017
    • The outer disc scale length, warp and flare parameters are from Amores et al, 2017
  • 2017 October 26:
    • commissioning of the version based on IVOA UWS web service"
  • 2016 May 24:
    • issue of version 1603 of the model (see more details in the model "Description")
  • 2013 April 30:
    • corrected spectral types for M dwarfs
    • corrected kinematics of the bulge
    • new thick disc fitted to SDSS and 2MASS data
  • 2013 February 12:
    • the distribution in distance inside each volume element has been revised for a smoother distribution. Nowadays the distribution is smooth and can be studied at scales smaller than the distance step used (generally 20pc in the plane and 50 pc far from the plane).
    • White dwarfs: for simulation in the UV for Galex and UVIT satellites, white dwarfs distribution have been refined. Now the model generates two sequences, DA and DB, using Bergeron et al white dwarf models.
    • Halo blue horizontal branch: also for improving simulation in the UV halo BHB have been revised. We now use Basti models for simulating the blue horizontal branch for halo stars. The rest of the isochrones still come from Bergbusch and Vandernberg (1992) ADS.
  • 2009 Octobre 21st: added Galex-UVIT and Megacam+Wircam+Spitzer photometric systems
  • 2006 December 7th: This new version 0611 is an update of the Galaxy model from recent  results, concerning the IMF at low masses (see Schultheis et al, Astron. Astrophys, 447:185, 2006 ADS). It also implements a few new features:

    • An option is proposed for the new extinction model (Marshall et al., Astron. Astrophys., 453:635, 2006 ADS), valuable in the plane: -90<l<90, -10<b<10.
    • A new photometric system composed of the visible bands of the megacam camera at CFHT (u* g' r' i' z') and the NIR bands of the Wircam instrument (J H K) is now available. 
    • The SDSS photometric system is also implemented but just as a color transformed from the CFHTLS system. The color equations are from Nicolas Regnault (private communication) from a detailed analysis of the SNLS (Supernovae Legacy Survey) conducted at CFHT. Available bands are g,r,i,z,J,H,K. J, H, K are close to the 2MASS system.
    • "On the fly" star count computations are possible for obtaining row counts  without photometric errors.
    • White dwarf models have been improved in the Megacam photometric  system.
    • Stellar radius is added in the catalogue simulations for each star.
    • A small error on the coordinate transformation between equatorial to galactic system has been corrected. In some region on the sky (near the Galactic plane) it  implies a small change in the counts, when done in the equatorial system (up to 10% at the very maximum, smaller than a few % in general).
  • 2005 Feb. 22: radial velocities are explicitely constrained within range -999, +999 km/s
  • 2004 Dec. 6: Added use of CFHT-Megacam photometric system. More informations are available here.
Observatoire Aquitain des Sciences de l'Univers
Observatoire des Sciences de l'Univers THETA de Franche-Comté-Bourgogne
Observatoire astronomique de Strasbourg
Laboratoire d'Astrophysique de Bordeaux
Institut UTINAM