Search Publications
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 shared accretion instability for black holes and neutron stars
Altamirano, D.; Belloni, T.; Degenaar, N. +20 more
Accretion disks around compact objects are expected to enter an unstable phase at high luminosity1. One instability may occur when the radiation pressure generated by accretion modifies the disk viscosity, resulting in the cyclic depletion and refilling of the inner disk on short timescales2. Such a scenario, however, has onl…
An evolutionary continuum from nucleated dwarf galaxies to star clusters
Zhang, Hongxin; Liu, Chengze; Cuillandre, Jean-Charles +21 more
Systematic studies1-4 have revealed hundreds of ultra-compact dwarf galaxies (UCDs5) in the nearby Universe. With half-light radii rh of approximately 10-100 parsecs and stellar masses M* ≈ 106-108 solar masses, UCDs are among the densest known stellar systems6. Although …
Minutes-duration optical flares with supernova luminosities
Filippenko, Alexei V.; de Boer, Thomas; Magnier, Eugene A. +74 more
In recent years, certain luminous extragalactic optical transients have been observed to last only a few days1. Their short observed duration implies a different powering mechanism from the most common luminous extragalactic transients (supernovae), whose timescale is weeks2. Some short-duration transients, most notably AT201…
A high-mass X-ray binary descended from an ultra-stripped supernova
Gies, Douglas R.; Richardson, Noel D.; Younes, George +6 more
Ultra-stripped supernovae are different from other terminal explosions of massive stars, as they show little or no ejecta from the actual supernova event1,2. They are thought to occur in massive binary systems after the exploding star has lost its surface through interactions with its companion2. Such supernovae produce littl…
A rotating white dwarf shows different compositions on its opposite faces
Kulkarni, S. R.; Vennes, Stéphane; Hermes, J. J. +35 more
White dwarfs, the extremely dense remnants left behind by most stars after their death, are characterized by a mass comparable to that of the Sun compressed into the size of an Earth-like planet. In the resulting strong gravity, heavy elements sink towards the centre and the upper layer of the atmosphere contains only the lightest element present,…
A planetary collision afterglow and transit of the resultant debris cloud
Mamajek, Eric; Kirkpatrick, J. Davy; Sainio, Arttu +19 more
Planets grow in rotating disks of dust and gas around forming stars, some of which can subsequently collide in giant impacts after the gas component is removed from the disk1-3. Monitoring programmes with the warm Spitzer mission have recorded substantial and rapid changes in mid-infrared output for several stars, interpreted as variati…
The high optical brightness of the BlueWalker 3 satellite
Bannister, Michele T.; Bassa, Cees; Damke, Guillermo +37 more
Large constellations of bright artificial satellites in low Earth orbit pose significant challenges to ground-based astronomy1. Current orbiting constellation satellites have brightnesses between apparent magnitudes 4 and 6, whereas in the near-infrared Ks band, they can reach magnitude 2 (ref. 2). Satellite operators, astron…
Compact [C II] emitters around a C IV absorption complex at redshift 5.7
Simcoe, Robert A.; Kashino, Daichi; Eilers, Anna-Christina +4 more
The physical conditions of the circumgalactic medium are investigated by means of intervening absorption-line systems in the spectrum of background quasi-stellar objects (QSOs) out to the epoch of cosmic reionization1-4. A correlation between the ionization state of the absorbing gas and the nature of the nearby galaxies has been sugges…
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…