Table 9.
Key parameters of the Vela X-1 system for future studies.
| Parameter | Current knowledge | See also sections | Robustness, uncertainty |
|---|---|---|---|
| System | |||
| Distance | Sect. 5.1 | 3.1.1, 3.2.3 | Quite robust, known to ∼5% |
| Orbital phase parameters (Tecl or Tπ/2, Porb) | Sect. 5.2, Table 3 | 3.1.3, 7.2, 3.2.1, 3.2.2, 3.2.4 | Very robust, uncertainty < 1% |
| Eccentricity e, longitude of periastron ω | Sect. 5.2, Table 3 | 3.2.1, 4.2.1, 4.5.1, 4.5.2 | Robust, known to ∼1%, |
| Inclination i | Sect. 5.3, Table 4 | 2.2, 4.2.1, Fig. 17 | Within ∼20° wide interval |
| HD 77581 | |||
| Stellar mass Mopt | Sect. 5.3, Table 4 | 3.2.2, 4.6 | Systematics often 10-20% |
| Stellar radius Ropt | Sect. 5.3, Table 4 | 2.1, 4.2.1 | Known to < 10% |
| Eff. temperature T⋆ and surface gravity g⋆ | Sect. 5.5, Table 5 | 2.1, 3.2.3 | Dep. on spectral model codes |
| Mass-loss rate Ṁ | Sect. 5.6, Table 7 | 2.1, 3.3, 4.5.1, 4.6 | Dep. on distance & spectral models |
| Terminal wind velocity v∞ | Sect. 5.6, Table 7 | 2.1, 3.2.3, 3.3 | Known to ∼5%, phase-dependent |
| Neutron star | |||
| Mass MNS | Sect. 5.3, Table 4, Fig. 17 | 2.2, 2.4, 3.2.2, 4.2.1 | Only known to a few 10% |
| Magnetic field B | Sect. 5.8 | 2.3, 2.4, 3.1.5, 4.2.2, 4.4 | ∼10% in CRSF formation zone |
Notes. Because the scatter in the values found in the literature is often significant, we refrain from giving specific values here, but refer to the discussion in the corresponding section(s) and provide a rough assessment of the robustness of the knowledge of the parameters. We also note sections describing system elements, observational diagnostics or modeling, where these parameters are relevant.
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