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Appendix A: Line ratio analysis

Fig. A.1 Locus of the binary components in several equivalent width diagnostic plots. These plots are the Na 22076 μm + Ca 2.2634 μm versus CO(4–2) + CO(2–0) (upper right), Al 2.1169 μm versus Mg 2.1066 μm (upper left), Mg 2.2814/Ca 2.2634 μm versus Mg 2.1066/Al 2.1169 μm (lower left), and Si 2.1885/Ti 21903 μm versus Mg 2.1066/Al 2.1169 μm (lower right). The ONC binary components (in black) are labeled, as well as the spectral type of the dwarf (red), giant (turquoise), and intermediate-gravity (blue) spectral type templates.

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Appendix B: Comparative samples of T Tauri binaries

We used several samples of T Tauri binaries to study the dependency of the properties of T Tauri binaries on the environment. In order to minimize potential biases introduced by relative extinction and veiling, we prefer to use systems with a significant amount of observational data especially including spectroscopy and/or visual photometry. The considered samples are those from WG01 (20 systems) and HK03 (19 systems) in Tau-Aur, from P03 in Oph (8 systems), and from D12 in ONC (7 systems). We used the spectral types and luminosities reported in these studies to derive the component mass and age from

the B98, PS99, and S00 PMS tracks. For those 9 systems from WG01 found in HK03 we used the stellar parameters derived in HK03. Errors in spectral type were assumed to be ±1 subclass for WG01, HK03, and P03 and those reported in the case of D12. For HK03 systems uncertainties in log L were assumed to be 0.2 dex. The T Tauri types (C for CTTS and W for WTTS) were assigned from resolved IR-excess measurements, notably the K − L measurements from McCabe et al. (2006). For the D12 sample, we made use of criteria such as r_K, H − K color excess, and Brγ emission. The component masses and ages are reported in Table B.1 and the system mass ratios and relative ages are shown in Table B.2.

© ESO, 2013