5 Bolometric magnitudes

Apparent bolometric magnitudes could be computed for 126 Henize S stars by integrating the spectral energy distribution derived from the Geneva U, B and V bands ( $\lambda_{\rm eff} = 3463, 4227$ and 5488 Å, respectively) and from the SAAO J, H, K and L bands ( $\lambda_{\rm eff} = 1.2, 1.6, 2.2$ and 3.4 $\mu$m, respectively). All the photometry was corrected from interstellar reddening as described in Sects. 3.3 and  4. The flux calibration for the SAAO photometry was kindly provided by Dr. I. Glass (1999, priv. comm.); for the Geneva photometry, it is taken from Rufener & Nicolet (1988). No correction has been applied for the contribution of the flux longward of 3.4 $\mu$m which is generally quite small (< 5% of the total energy distribution; Glass & Feast 1973). These apparent bolometric magnitudes are listed in the column $m_{\rm bol}$ in Table 5.

Unfortunately these bolometric magnitudes are only available for 126 stars. A second estimate of the bolometric magnitudes has thus been performed; it is less restrictive but also far less accurate. Multivariate classification has been performed on the 205 S stars of the Henize sample (Sect. 8 and Paper III), resulting in a classification of the stars in 6 well-defined and rather homogeneous groups (Sect. 8 and Paper III). For each group, a bolometric correction in the V band (BC_V) has been derived from the stars that have a reliable apparent bolometric magnitude available from the integration of the UBVJHKL fluxes. Thanks to these average bolometric corrections, apparent bolometric magnitudes could be computed for the 170 stars with a V magnitude available. These apparent bolometric magnitudes are listed in the column $m_{{\rm bol},V}$ of Table 5.