Encounters
O-Type ○｜encounter｜ENC｜20260908165233-00-•
Following the discovery of Cygnus X–1, the second BHB to be identified was LMC X–3 (Cowley et al. 1983). Both sources are persistently bright in X-rays, and their secondaries are massive O/B-type stars (White et al. 1995). The third identified BHB, A 0620–00, is markedly different (McClintock & Remillard 1986). A 0620–00 was discovered as an X-ray nova in 1975 when it suddenly brightened to an intensity of 50 Crab to become the brightest nonsolar X-ray source ever observed (Elvis et al. 1975). Then, over the course of a year, the X-ray nova decayed back into quiescence to become a feeble (1 Crab) source (McClintock et al. 1995). Similarly, the optical counterpart faded from outburst maximum by mags to in quiescence, thereby revealing the optical spectrum of a K-dwarf secondary.
Source: Remillard & McClintock 2006 ┃ X-Ray Properties… ⚬𓂃
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