Rapid optical fluctuations in the black hole binary V4641 Sagittarii. Konus-Wind observation of Galactic transient V404 Cyg in outburst. TAOS early optical observations of V404 Cyg. MAXI/GSC detection of a new outburst from the Galactic black hole candidate GS 2023+338 (V* V404 Cyg). The first accurate parallax distance to a black hole. Near-infrared spectroscopy of low-mass X-ray binaries: accretion disk contamination and compact object mass determination in V404 Cyg and Cen X-4. Discovery of fast optical activity in the X-ray source GX 339−4. The remarkable rapid X-ray, ultraviolet, optical and infrared variability in the black hole XTE J1118+480. A model-independent analysis of the variability of GRS 1915+105. GRS 1915+105 and the disc-jet coupling in accreting black hole systems. On different types of instabilities in black hole accretion discs: implications for X-ray binaries and active galactic nuclei. The lack of sustained accretion-not the actual rate-would then be the critical factor causing large-amplitude oscillations in long-period systems. Instead, we propose that a long orbital period is a key condition for these large-amplitude oscillations, because the outer part of the large disk in binaries with long orbital periods will have surface densities too low to maintain sustained mass accretion to the inner part of the disk. This suggests that the accretion rate is not the critical parameter for inducing inner-disk instabilities. Our data show that optical oscillations on timescales of 100 seconds to 2.5 hours can occur at mass-accretion rates more than ten times lower than previously thought 1. Here we report an extensive multi-colour optical photometric data set of V404 Cygni, an X-ray transient source 6 containing a black hole of nine solar masses 7 (and a companion star) at a distance of 2.4 kiloparsecs (ref. These large-amplitude, relatively slow timescale, phenomena are thought to have physical origins distinct from those of X-ray or optical variations with small amplitudes and fast timescales (less than about 10 seconds) often observed in other black-hole binaries-for example, XTE J1118+480 (ref. In fact, such oscillations have been observed only in sources with a high mass-accretion rate, such as GRS 1915+105 (refs 2, 3). When this rate approaches the critical rate (the Eddington limit), thermal instability is supposed to occur in the inner disk, causing repetitive patterns of large-amplitude X-ray variability (oscillations) on timescales of minutes to hours 1. It is generally believed that matter is absorbed into black holes via accretion disks, the state of which depends primarily on the mass-accretion rate. How black holes accrete surrounding matter is a fundamental yet unsolved question in astrophysics. Nature volume 529, pages 54–58 ( 2016) Cite this article Repetitive patterns in rapid optical variations in the nearby black-hole binary V404 Cygni