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Millihertz oscillations near the innermost orbit of a supermassive black hole
Ingram, Adam; Fabian, Andrew C.; Remillard, Ronald A. +22 more
Recent discoveries from time-domain surveys are defying our expectations for how matter accretes onto supermassive black holes (SMBHs). The increased rate of short-timescale, repetitive events around SMBHs, including the recently discovered quasi-periodic eruptions1, 2, 3, 4–5, are garnering further interest in stellar-mass companions a…
Hydrogen escaping from a pair of exoplanets smaller than Neptune
Schreyer, Ethan; Owen, James E.; Loyd, R. O. Parke +18 more
Exoplanet surveys have shown a class of abundant exoplanets smaller than Neptune on close, <100-day orbits1, 2, 3–4. These planets form two populations separated by a natural division at about 1.8 R⊕ termed the radius valley. It is uncertain whether these populations arose from separate dry versus water-rich formation chan…
A lanthanide-rich kilonova in the aftermath of a long gamma-ray burst
Kilpatrick, Charles D.; Lee, Chung-Uk; Im, Myungshin +24 more
Observationally, kilonovae are astrophysical transients powered by the radioactive decay of nuclei heavier than iron, thought to be synthesized in the merger of two compact objects1-4. Over the first few days, the kilonova evolution is dominated by a large number of radioactive isotopes contributing to the heating rate2,5. On…
SO2, silicate clouds, but no CH4 detected in a warm Neptune
Henning, Thomas; Östlin, Göran; Güdel, Manuel +43 more
WASP-107b is a warm (approximately 740 K) transiting planet with a Neptune-like mass of roughly 30.5 M⊕ and Jupiter-like radius of about 0.94 RJ (refs. 1,2), whose extended atmosphere is eroding3. Previous observations showed evidence for water vapour and a thick, high-altitude condensate layer in the at…
A magnetar giant flare in the nearby starburst galaxy M82
Thuillot, William; Mereghetti, Sandro; Esposito, Paolo +32 more
Magnetar giant flares are rare explosive events releasing up to 1047 erg in gamma rays in less than 1 second from young neutron stars with magnetic fields up to 1015−16 G (refs. 1,2). Only three such flares have been seen from magnetars in our Galaxy3,4 and in the Large Magellanic Cloud5 in ro…
Lense-Thirring precession after a supermassive black hole disrupts a star
Loewenstein, Michael; Pasham, Dheeraj R.; Guolo, Muryel +8 more
An accretion disk formed around a supermassive black hole after it disrupts a star is expected to be initially misaligned with respect to the equatorial plane of the black hole. This misalignment induces relativistic torques (the Lense-Thirring effect) on the disk, causing the disk to precess at early times, whereas at late times the disk aligns w…
A long-period radio transient active for three decades
de Martino, D.; Heywood, I.; Rea, N. +22 more
Several long-period radio transients have recently been discovered, with strongly polarized coherent radio pulses appearing on timescales between tens to thousands of seconds1,2. In some cases, the radio pulses have been interpreted as coming from rotating neutron stars with extremely strong magnetic fields, known as magnetars; the orig…
X-ray polarization evidence for a 200-year-old flare of Sgr A*
Ingram, Adam; Kaaret, Philip; Wu, Kinwah +101 more
The centre of the Milky Way Galaxy hosts a black hole with a solar mass of about 4 million (Sagittarius A* (Sgr A)) that is very quiescent at present with a luminosity many orders of magnitude below those of active galactic nuclei1. Reflection of X-rays from Sgr A* by dense gas in the Galactic Centre region offers …
A helium-burning white dwarf binary as a supersoft X-ray source
Burgess, J. M.; Werner, K.; Haberl, F. +12 more
Type Ia supernovae are cosmic distance indicators1,2, and the main source of iron in the Universe3,4, but their formation paths are still debated. Several dozen supersoft X-ray sources, in which a white dwarf accretes hydrogen-rich matter from a non-degenerate donor star, have been observed5 and suggested as Type I…
A highly magnified star at redshift 6.2
Mahler, Guillaume; Anderson, Jay; Broadhurst, Tom +26 more
Galaxy clusters magnify background objects through strong gravitational lensing. Typical magnifications for lensed galaxies are factors of a few but can also be as high as tens or hundreds, stretching galaxies into giant arcs1,2. Individual stars can attain even higher magnifications given fortuitous alignment with the lensing cluster. …