Search Publications
Anisotropic winds in a Wolf-Rayet binary identify a potential gamma-ray burst progenitor
Callingham, J. R.; Crowther, P. A.; Tuthill, P. G. +5 more
The massive evolved Wolf-Rayet stars sometimes occur in colliding-wind binary systems in which dust plumes are formed as a result of the collision of stellar winds1. These structures are known to encode the parameters of the binary orbit and winds2-4. Here we report observations of a previously undiscovered Wolf-Rayet system,…
The brightening of the pulsar wind nebula of PSR B0540-69 after its spin-down-rate transition
Wang, Q. D.; Zhang, S. N.; Ge, M. Y. +6 more
It is believed that an isolated pulsar loses its rotational energy mainly through a relativistic wind consisting of electrons, positrons and possibly Poynting flux1-3. As it expands, this wind may eventually be terminated by a shock, where particles can be accelerated to energies of X-ray synchrotron emission, and a pulsar wind nebula (…
Observations of a pre-merger shock in colliding clusters of galaxies
Gu, Liyi; Mao, Junjie; Kaastra, Jelle S. +10 more
Clusters of galaxies are the largest known gravitationally bound structures in the Universe. When clusters collide, they create merger shocks on cosmological scales, which transform most of the kinetic energy carried by the cluster gaseous halos into heat1-3. Observations of merger shocks provide key information on the merger dynamics, …
A three-dimensional map of the hot Local Bubble using diffuse interstellar bands
Javadi, Atefeh; van Loon, Jacco Th.; Khosroshahi, Habib G. +2 more
The Solar System is located within a low-density cavity known as the Local Bubble1-3, which appears to be filled with an X-ray-emitting gas at a temperature of 106 K (ref. 4). Such conditions are too harsh for typical interstellar atoms and molecules to survive2,3. The diffuse interstellar bands (DIBs), …
Extended main sequence turn-off originating from a broad range of stellar rotational velocities
Lim, Beomdu; Park, Byeong-Gon; Nazé, Yaël +3 more
Star clusters have long been considered to comprise a simple stellar population, but this paradigm is being challenged, since in addition to multiple populations in Galactic globular clusters1, a number of younger star clusters exhibit a significant colour spread at the main sequence turn-off2-9. A sequential evolution of mul…
Accurate mass and radius determinations of a cool subdwarf in an eclipsing binary
Rebassa-Mansergas, Alberto; Parsons, Steven G.; Torres, Santiago +4 more
Cool subdwarfs are metal-poor low-mass stars that formed during the early stages of the evolution of our Galaxy. Because they are relatively rare in the vicinity of the Sun, we know of few cool subdwarfs in the solar neighbourhood, and none for which both the mass and the radius are accurately determined. This hampers our understanding of stars at…
A high-mass planetary nebula in a Galactic open cluster
Zijlstra, A. A.; Parker, Q. A.; Fragkou, V. +2 more
Planetary nebulae are the ionized ejected envelopes surrounding the remnant cores of dying stars. Theory predicts that main-sequence stars of one to about eight solar masses may eventually form planetary nebulae. Until now, this has not been confirmed at the higher end of the mass range. Here we report that the planetary nebula BMP J1613-5406 is a…
Mapping of shadows cast on a protoplanetary disk by a close binary system
van der Plas, G.; Avenhaus, H.; Girard, J. +47 more
For a comprehensive understanding of planetary formation and evolution, we need to investigate the environment in which planets form: circumstellar disks. Here we present high-contrast imaging observations of V4046 Sagittarii, a 20-Myr-old close binary known to host a circumbinary disk. We have discovered the presence of rotating shadows in the di…
Direct measurement of stellar angular diameters by the VERITAS Cherenkov telescopes
Benbow, W.; Bird, R.; Brose, R. +54 more
The angular size of a star is a critical factor in determining its basic properties1. Direct measurement of stellar angular diameters is difficult: at interstellar distances stars are generally too small to resolve by any individual imaging telescope. This fundamental limitation can be overcome by studying the diffraction pattern in the…