Vela X-1 | B0.5 Ib | celestial sphere | | | 11000 to 28000 K | 8.96 days | single line spectroscopic binary | determined from proper motion and radial velocity | which depends on luminosity class | 0.2 magnitudes or greater | | | from the point of view of Earth's orbit | | some difficulty in distinguishing between various kinds | from the point of view of Earth | blue-white | or center of gravity | | He I | which is diffused out from the hotter core | | | half the stars in the solar neighborhood are members of star systems | | | | | gravitational contraction and or fusion | which takes place primarily within the core | | star catalog | | X-ray | | | | 7 | hydrogen, helium | of unseen companion 1.7 to 15 Msun, with a probable value of about 2.6 Msun. | - R, S, T, U, V, W, X, Y, or Z and the genitive of the latin constellation name
- RR, RS, RT, RU, RV, RW, RX, RY, or RZ and the genitive of the latin constellation name when the single letter designations are exhausted
- AA...AZ, BB...BZ, etc. (omitting J), which ends with QQ...QZ and the genitive of the latin constellation namewhen the RR...RZ designations are exhausted
- V 335, V 336, etc., when the double letter designations are exhausted
| within a period of decades | 3U 0900-40 | I | 2 |