************************************************************* ************************************************************* ** THEORETICAL ISOCHRONES IN SEVERAL PHOTOMETRIC SYSTEMS ** ** Second (isoc_photsys.01) release, Dec 2003 ** ** (with the addition of isoc_2mass in July 2004) ** ************************************************************* ************************************************************* The present database (isoc_photsys.01) contains the data files mentioned in "Theoretical isochrones in several photometric systems II. The Sloan Digital Sky Survey UGRIZ system" by L. Girardi, E.K. Grebel, M. Odenkirchen, C. Chiosi, 2004, to appear in Astronomy & Astrophysics. together with links to the previous database (isoc_photsys.00): "Theoretical isochrones in several photometric systems I. Johnson-Cousins-Glass, HST/WFPC2, HST/NICMOS, Washington, and ESO Imaging Survey filter sets" by L. Girardi, G. Bertelli, A. Bressan, C. Chiosi, M.A.T. Groenewegen, P. Marigo, B. Salasnich, and A. Weiss, 2002, Astronomy & Astrophysics, 391, 195. and data files from a related paper: ¨Theoretical isochrones compared to 2MASS observations: Open clusters at nearly solar metallicity¨, by Ch. Bonatto, E. Bica, L. Girardi, 2004, Astronomy & Astrophysics, 415, 571. Please refer to these papers for a complete description of the models. And, when referring to the models, please refer also to the original source of evolutionary data, listed in Table 1 there (see also http://pleiadi.oapd.inaf.it/isoc_photsys.00.html#table ). The present files correspond to the "official" release that accompany the publication of the paper by A&A. They may differ slightly from data informally distributed in precedence. The present files will not be changed, unless for the correction of small typos that may still be present. Any future extension will be _added_ into separate directories, with different names. ************************************************************ MAIN DIRECTORIES / PHOTOMETRIC SYSTEMS ************************************************************ All data files are separated in directories according to the photometric system under consideration: isoc_ubvrijhk --> for Johnson-Cousins-Glass isoc_wfpc2ab --> for HST/WFPC2, ABmag isoc_wfpc2st --> for HST/WFPC2, STmag isoc_wfpc2vega --> for HST/WFPC2, VEGAmag isoc_nicmosab --> for HST/NICMOS, ABmag isoc_nicmosst --> for HST/NICMOS, STmag isoc_nicmosvega --> for HST/NICMOS, VEGAmag isoc_washington --> for Washington isoc_eis --> for EIS WFI + SOFI isoc_emmi --> for EIS EMMI isoc_sloan --> for SDSS, ABmag isoc_2mass --> for 2MASS, VEGAmag Herebelow, these directories will be generically referred to as isoc_. Each one of the isoc_ directories contain: ************************************************************ TABLES OF BOLOMETRIC CORRECTIONS ************************************************************ Bolometric corrections, computed according to Eq. 7, are tabulated for all input spectra (Sect. 3) and filters. The following files are available: isoc_/bctab_m25.dat --> BCs for [M/H]=-2.5 isoc_/bctab_m20.dat --> BCs for [M/H]=-2.0 isoc_/bctab_m15.dat --> BCs for [M/H]=-1.5 isoc_/bctab_m10.dat --> BCs for [M/H]=-1.0 isoc_/bctab_m05.dat --> BCs for [M/H]=-0.5 isoc_/bctab_p00.dat --> BCs for [M/H]= 0.0 isoc_/bctab_p05.dat --> BCs for [M/H]=+0.5 where [M/H] is related to the initial metal mass fraction Z by [M/H] = log10(Z/Zsun) (This is just an aproximation, but is accurate enough for most purposes). Each one of these files contains N columns with: Column (1) n --> sequential number for the spectra; Column (2) Teff --> effective temperature (in K); Column (3) logg --> logarithm of surface gravity (in cgs units); Columns (4) to (N) --> bolometric correction BC for each filter. Given BC for a filter, the corresponding stellar absolute magnitude is M_absolute = M_bolometric - BC A bolometric correction of -999999 means that the input spectra presents null flux (infinite magnitude) in that filter pass-band. This occurs rarely, and just for very cool stars in UV filters. Inside a file, two main blocks of BCs are included: - First, those derived from BDdusty1999 (Allard et al. 1999) + ATLAS9 (Castelli et al. 1997) + blackbody, totalling ~600 spectra in a sequence of increasing Teff and logg; - Second, those derived from the modified Fluks et al. (1994) M-giant spectra (10 spectra), in a sequence of decreasing Teff. Blackbody and M-giant spectra have arbitrarily been given logg=5.0 and logg=0.0, respectively. These tables can be easily interpolated for any value of logg and Teff. For constructing the following isochrones, we adopt bi-linear interpolations in logg and log(Teff). Any time we go out of the available range of logg, the nearest extreme value for that Teff is used. In this way we avoid risky extrapolations of BC values. ************************************************************ TABLES OF ISOCHRONES ************************************************************ For each photometric system, the following isochrone files are available: ------------------------------------------------------------------ FILENAME COMPOSITION REFERENCE ---------extended-set--------------------------------------------- isoc_/isoc_z0.dat [Z=0.0, Y=0.230] Ma01 isoc_/isoc_z0004.dat [Z=0.0001, Y=0.230] Gi01+Gi96 isoc_/isoc_z0004.dat [Z=0.0004, Y=0.230] Gi00+Be94 isoc_/isoc_z001.dat [Z=0.001, Y=0.230] Gi00 isoc_/isoc_z004.dat [Z=0.004, Y=0.240] Gi00+Be94 isoc_/isoc_z008.dat [Z=0.008, Y=0.250] Gi00+Be94 isoc_/isoc_z019.dat [Z=0.019, Y=0.273] Gi00+Be94 isoc_/isoc_z030.dat [Z=0.030, Y=0.300] Gi00 ---------classic-------------------------------------------------- isoc_/isoc_z019nov.dat [Z=0.019, Y=0.273] Gi00 ---------solar-scaled-vs.alpha-enhanced--------------------------- isoc_/isoc_z008s.dat [Z=0.008, Y=0.250] Sa00 isoc_/isoc_z019s.dat [Z=0.019, Y=0.273] Sa00 isoc_/isoc_z040s.dat [Z=0.040, Y=0.320] Sa00 isoc_/isoc_z040s.dat [Z=0.070, Y=0.390] Sa00 isoc_/isoc_z008a.dat [Z=0.008, Y=0.250] Sa00 isoc_/isoc_z019a.dat [Z=0.019, Y=0.273] Sa00 isoc_/isoc_z040a.dat [Z=0.040, Y=0.320] Sa00 isoc_/isoc_z040a.dat [Z=0.070, Y=0.390] Sa00 ---------detailed-TPAGB------------------------------------------- isoc_/isoc_z004m.dat [Z=0.004, Y=0.240] MG01 isoc_/isoc_z008m.dat [Z=0.008, Y=0.250] MG01 isoc_/isoc_z019m.dat [Z=0.019, Y=0.273] MG01 ------------------------------------------------------------------ The above table is an over-simplified version of paper's Table 1, where all basic details and references are found. The user is strongly urged to look at that table (also available at http://pleiadi.oapd.inaf.it/isoc_photsys.00.html#table ) to find the basic differences between isochrone files. Moreover, the user is _strongly_ encouraged to refer to the original papers, listed in the last column above. Those are the places where the real important information is found: the prescriptions for the several physical processes envolved in the calculations. Each file contains a complete series of isochrones with log(age/yr) values at equally spaced intervals of Delta(log age)=0.05 (i.e., two consecutive isochrones differ by only 12 percent in their ages.) Each one of these files contains HEADER LINE: with the exact age and metallicity value of the isochrone; followed by N columns with: Column (1) log(age/yr) --> logarithm of the age (in yr); Column (2) M_ini --> initial mass of the star (in solar units); Column (3) M_act --> actual mass of the star, i.e., the mass obtained considering the previous history of mass-loss; Column (4) logL/Lo --> logarithm of surface luminosity (in solar units), log(L/Lsun); Column (5) logTef --> logarithm of effective temperature (in K), log(Teff/K); Column (6) logG --> logarithm of surface gravity (in cgs units); Column (7) Mbol --> absolute bolometric magnitude; Columns (8) to (N-1) --> absolute magnitude in each pass-band; Column (N) FLUM --> indefinite integral of the Salpeter IMF by number (see Gi00 for more details); From the above quantities, stellar colours can be easily derived. We remark that the initial mass M_ini (and not M_act) is the useful quantity for population synthesis calculations, since together with the initial mass function it determines the relative number of stars in different sections of the isochrones. Also the quantity FLUM can be used for this purpose. ************************************************************ INTEGRATED MAGNITUDES OF SINGLE-BURST STELLAR POPULATIONS ************************************************************ For each isochrone file, there's also a file containing the integrated absolute magnitudes of the corresponding single-burst stellar populations (SSP). The available files are: ------------------------------------------------------------------ FILENAME COMPOSITION REFERENCE ---------extended-set--------------------------------------------- isoc_/sspmag_z0.dat [Z=0.0, Y=0.230] Ma01 isoc_/sspmag_z0004.dat [Z=0.0001, Y=0.230] Gi01+Gi96 isoc_/sspmag_z0004.dat [Z=0.0004, Y=0.230] Gi00+Be94 isoc_/sspmag_z001.dat [Z=0.001, Y=0.230] Gi00 isoc_/sspmag_z004.dat [Z=0.004, Y=0.240] Gi00+Be94 isoc_/sspmag_z008.dat [Z=0.008, Y=0.250] Gi00+Be94 isoc_/sspmag_z019.dat [Z=0.019, Y=0.273] Gi00+Be94 isoc_/sspmag_z030.dat [Z=0.030, Y=0.300] Gi00 ---------classic-------------------------------------------------- isoc_/sspmag_019nov.dat [Z=0.019, Y=0.273] Gi00 ---------solar-scaled-vs.alpha-enhanced--------------------------- isoc_/sspmag_z008s.dat [Z=0.008, Y=0.250] Sa00 isoc_/sspmag_z019s.dat [Z=0.019, Y=0.273] Sa00 isoc_/sspmag_z040s.dat [Z=0.040, Y=0.320] Sa00 isoc_/sspmag_z040s.dat [Z=0.070, Y=0.390] Sa00 isoc_/sspmag_z008a.dat [Z=0.008, Y=0.250] Sa00 isoc_/sspmag_z019a.dat [Z=0.019, Y=0.273] Sa00 isoc_/sspmag_z040a.dat [Z=0.040, Y=0.320] Sa00 isoc_/sspmag_z040a.dat [Z=0.070, Y=0.390] Sa00 ---------detiailed-TPAGB------------------------------------------- isoc_/sspmag_z004m.dat [Z=0.004, Y=0.240] MG01 isoc_/sspmag_z008m.dat [Z=0.008, Y=0.250] MG01 isoc_/sspmag_z019m.dat [Z=0.019, Y=0.273] MG01 ------------------------------------------------------------------ Again, a look at the complete Table 1 (available at http://pleiadi.oapd.inaf.it/isoc_photsys.00.html#table ) is necessary for a better description of the different sources of data. Each one of these files contains N columns with: Column (1) Z --> mass fraction of metals Z; Column (2) Age --> age in yr; Column (3) Mbol --> integrated absolute bolometric magnitude; Columns (4) to (N) --> integrated absolute magnitude in each pass-band; Integrated magnitudes are computed assuming - The Kroupa (2001) initial mass function (IMF) in its corrected version (his eq. 6); it has a nearly-Salpeter slope (alpha=2.30 instead of 2.35) for all masses higher than 1 Msun. - A total SSP initial mass equal to 1.0 Msun; in other words, the magnitudes are given per unit Msun of a SSP. This means that, for a SSP of initial mass M_T (in Msun), its integrated magnitude is given by the number in the table plus the quantity -2.5*log10(M_T) . Anyway, the user should keep in mind that the absolute value of this integrated magnitude depends heavily on the assumed IMF. This because, for any typical IMF, a substantial fraction of the initial mass goes into light stars (lighter than say 1 Msun), whose contribution to the integrated light is generally negligible (except for very large ages). The same comment applies to any mass-to-light ratio eventually derived from our tables. In the case of Kroupa's IMF, the fraction of stars heavier than 1 Msun is equal to Fh_KroupaIMF=0.387. If one wants to adopt a different IMF for the stars with M < 1 Msun, this fraction can be used to roughly estimate the new integrated magnitudes per unit initial mass: they are given by adding the quantity -2.5*log10[Fh_newIMF/Fh_KroupaIMF] to the numbers in our tables. On the other hand, integrated colours depend just little on the details of the IMF. ************************************************************ REFERENCES ************************************************************ A more complete list can be found in the papers. Allard F., Hauschildt P.H., Alexander D.R., Tamanai A., Ferguson J.W., 2000a, in proceed. of "From giant planets to cool stars", ASP Conf. Series v. 212, (eds.) C.A. Griffith & M.S. Marley, p. 127 (at ftp://ftp.ens-Lyon.fr/pub/users/CRAL/fallard/BCdusty1999 ) Bertelli G., Bressan A., Chiosi C., Fagotto F., Nasi E., 1994, A&AS 106, 275 (Be94) Castelli F., Gratton R.G., Kurucz R.L., 1997, A&A 318, 841 (NOVER models at http://cfaku5.harvard.edu/grids.html ) Fluks M.A, Plez B., The P.S., et al., 1994, A&AS 105, 311 Girardi L., Bressan A., Chiosi C., Bertelli G., Nasi E., 1996, A&AS 117, 113 (Gi96) Girardi L., Bressan A., Bertelli G., Chiosi C., 2000, A&AS 141, 371 (Gi00) Girardi L., 2001, unpublished tracks (Gi01) Kroupa P., 2001, MNRAS 322, 231 Marigo P., Girardi L., Chiosi C., Wood P.R., 2001, A&A 371, 152 (Ma01) Marigo P., Girardi L., 2001, A&A 377, 132 (MG01) Salasnich B., Girardi L., Weiss A., Chiosi C., 2000, A&A 361, 1023 (Sa00)