Search Publications
Large heterogeneities in comet 67P as revealed by active pits from sinkhole collapse
Bertaux, Jean-Loup; Naletto, Giampiero; Debei, Stefano +64 more
Pits have been observed on many cometary nuclei mapped by spacecraft. It has been argued that cometary pits are a signature of endogenic activity, rather than impact craters such as those on planetary and asteroid surfaces. Impact experiments and models cannot reproduce the shapes of most of the observed cometary pits, and the predicted collision …
The diurnal cycle of water ice on comet 67P/Churyumov-Gerasimenko
Langevin, Y.; Bellucci, G.; Jaumann, R. +77 more
Observations of cometary nuclei have revealed a very limited amount of surface water ice, which is insufficient to explain the observed water outgassing. This was clearly demonstrated on comet 9P/Tempel 1, where the dust jets (driven by volatiles) were only partially correlated with the exposed ice regions. The observations of 67P/Churyumov-Gerasi…
Relativistic boost as the cause of periodicity in a massive black-hole binary candidate
Haiman, Zoltán; Schiminovich, David; D'Orazio, Daniel J.
Because most large galaxies contain a central black hole, and galaxies often merge, black-hole binaries are expected to be common in galactic nuclei. Although they cannot be imaged, periodicities in the light curves of quasars have been interpreted as evidence for binaries, most recently in PG 1302-102, which has a short rest-frame optical period …
Warm-hot baryons comprise 5-10 per cent of filaments in the cosmic web
Richard, Johan; Massey, Richard; Kneib, Jean-Paul +8 more
Observations of the cosmic microwave background indicate that baryons account for 5 per cent of the Universe’s total energy content. In the local Universe, the census of all observed baryons falls short of this estimate by a factor of two. Cosmological simulations indicate that the missing baryons have not condensed into virialized haloes, but res…
Comet 67P/Churyumov-Gerasimenko sheds dust coat accumulated over the past four years
Langevin, Yves; Fischer, Henning; Briois, Christelle +22 more
Comets are composed of dust and frozen gases. The ices are mixed with the refractory material either as an icy conglomerate, or as an aggregate of pre-solar grains (grains that existed prior to the formation of the Solar System), mantled by an ice layer. The presence of water-ice grains in periodic comets is now well established. Modelling of infr…
Two independent and primitive envelopes of the bilobate nucleus of comet 67P
Bertaux, Jean-Loup; Naletto, Giampiero; Debei, Stefano +56 more
The factors shaping cometary nuclei are still largely unknown, but could be the result of concurrent effects of evolutionary and primordial processes. The peculiar bilobed shape of comet 67P/Churyumov-Gerasimenko may be the result of the fusion of two objects that were once separate or the result of a localized excavation by outgassing at the inte…
Fast-moving features in the debris disk around AU Microscopii
Henning, Thomas; Schneider, Glenn; Boccaletti, Anthony +36 more
In the 1980s, excess infrared emission was discovered around main-sequence stars; subsequent direct-imaging observations revealed orbiting disks of cold dust to be the source. These `debris disks' were thought to be by-products of planet formation because they often exhibited morphological and brightness asymmetries that may result from gravitatio…
Dense cloud cores revealed by CO in the low metallicity dwarf galaxy WLM
Brinks, Elias; Elmegreen, Bruce G.; Rubio, Monica +3 more
Understanding stellar birth requires observations of the clouds in which they form. These clouds are dense and self-gravitating, and in all existing observations they are molecular, with H2 the dominant species and carbon monoxide (CO) the best available tracer. When the abundances of carbon and oxygen are low compared with that of hydr…
Resonant interactions and chaotic rotation of Pluto's small moons
Hamilton, D. P.; Showalter, M. R.
Four small moons--Styx, Nix, Kerberos and Hydra--follow near-circular, near-equatorial orbits around the central `binary planet' comprising Pluto and its large moon, Charon. New observational details of the system have emerged following the discoveries of Kerberos and Styx. Here we report that Styx, Nix and Hydra are tied together by a three-body …
Extended hard-X-ray emission in the inner few parsecs of the Galaxy
Hailey, Charles J.; Mori, Kaya; Bauer, Franz E. +19 more
The Galactic Centre hosts a puzzling stellar population in its inner few parsecs, with a high abundance of surprisingly young, relatively massive stars bound within the deep potential well of the central supermassive black hole, Sagittarius A* (ref. 1). Previous studies suggest that the population of objects emitting soft X-rays (less than 10 kilo…