The black hole low-mass X-ray binary V404 Cygni is part of a wide triple.

Evidence suggests that, when compact objects such as black holes and neutron stars form, they may receive a 'natal kick', during which the stellar remnant gains momentum. Observational evidence for neutron star kicks is substantial, yet is limited for black hole natal kicks, and some proposed black hole formation scenarios result in very small kicks. Here we report that the canonical black hole low-mass X-ray binary (LMXB) V404 Cygni is part of a wide hierarchical triple with a tertiary companion at least 3,500 astronomical units (AU) away from the inner binary.

An infrared transient from a star engulfing a planet.

Planets with short orbital periods (roughly under 10 days) are common around stars like the Sun. Stars expand as they evolve and thus we expect their close planetary companions to be engulfed, possibly powering luminous mass ejections from the host star. However, this phase has never been directly observed.

A dense 0.1-solar-mass star in a 51-minute-orbital-period eclipsing binary.

Of more than a thousand known cataclysmic variables (CVs), where a white dwarf is accreting from a hydrogen-rich star, only a dozen have orbital periods below 75 minutes. One way to achieve these short periods requires the donor star to have undergone substantial nuclear evolution before interacting with the white dwarf, and it is expected that these objects will transition to helium accretion. These transitional CVs have been proposed as progenitors of helium CVs.

A 62-minute orbital period black widow binary in a wide hierarchical triple.

Over a dozen millisecond pulsars are ablating low-mass companions in close binary systems. In the original 'black widow', the eight-hour orbital period eclipsing pulsar PSR J1959+2048 (PSR B1957+20), high-energy emission originating from the pulsar is irradiating and may eventually destroy a low-mass companion. These systems are not only physical laboratories that reveal the interesting results of exposing a close companion star to the relativistic energy output of a pulsar, but are also believed to harbour some of the most massive neutron stars, allowing for robust tests of the neutron star equation of state.

A loud quasi-periodic oscillation after a star is disrupted by a massive black hole.

The tidal forces close to massive black holes can rip apart stars that come too close to them. As the resulting stellar debris spirals toward the black hole, the debris heats up and emits x-rays. We report observations of a stable 131-second x-ray quasi-periodic oscillation from the tidal disruption event ASASSN-14li.

and GBM Observations of the First Galactic Ultraluminous X-ray Pulsar Swift J0243.6+6124.

Swift J0243.6+6124 is a newly discovered Galactic Be/X-ray binary, revealed in late September 2017 in a giant outburst with a peak luminosity of 2 × 10(/7 kpc) erg s (0.1-10 keV), with no formerly reported activity.

A debris disk around an isolated young neutron star.

Pulsars are rotating, magnetized neutron stars that are born in supernova explosions following the collapse of the cores of massive stars. If some of the explosion ejecta fails to escape, it may fall back onto the neutron star or it may possess sufficient angular momentum to form a disk. Such 'fallback' is both a general prediction of current supernova models and, if the material pushes the neutron star over its stability limit, a possible mode of black hole formation.

Nuclear-powered millisecond pulsars and the maximum spin frequency of neutron stars.

Millisecond pulsars are neutron stars that are thought to have been spun-up by mass accretion from a stellar companion. It is not known whether there is a natural brake for this process, or if it continues until the centrifugal breakup limit is reached at submillisecond periods. Many neutron stars that are accreting mass from a companion star exhibit thermonuclear X-ray bursts that last tens of seconds, caused by unstable nuclear burning on their surfaces.