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Table 1
Main parameters of the sdO stars BD +37° 1977, BD +37° 442, and HD 49798.
| Parameter | Symbol | BD +37° 1977 | BD +37° 442 | HD 49798 | |||
| Value | Reference | Value | Reference | Value | Reference | ||
|
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| Surface gravity | log g | ≃4.0 | 1 | 4.00 ± 0.25 | 4 | 4.35 | 6 |
| Luminosity (L⊙) | L | 25 000 | 1 | 25 000 | 1 | 14 000 | 6 |
| Effective temperature (K) | Teff | 48 000 | 2 | 48 000 | 2 | 46 500 | 6 |
| Magnitudes | U | 8.67 | 3 | 8.57 | 5 | 6.76 | 7 |
| B | 9.93 | 3 | 9.73 | 5 | 8.02 | 7 | |
| V | 10.17 | 3 | 10.01 | 5 | 8.29 | 7 | |
| Distance (kpc) | d | ≃2.7 | 2 | 2.0 |
4 | 0.65 ± 0.10 | 8 |
| Terminal wind velocity (km s-1) | v∞ | 2000 | 2 | 2000 | 2 | 1350 | 9 |
| Mass–loss rate (M⊙ yr-1) | Ṁ | 10-8.2 | 2 | 10-8.5 | 2 | 10-8.5 | 6 |
Reference. 1) Darius et al. (1979); 2) Jeffery & Hamann (2010); 3) Jordi et al. (1991); 4) Bauer & Husfeld (1995); 5) Landolt (1973); 6) Hamann (2010); 7) Landolt & Uomoto (2007); 8) Kudritzki & Simon (1978); 9) Hamann et al. (1981).
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