Search Publications
Eight per cent leakage of Lyman continuum photons from a compact, star-forming dwarf galaxy
Schaerer, D.; Thuan, T. X.; Izotov, Y. I. +4 more
One of the key questions in observational cosmology is the identification of the sources responsible for ionization of the Universe after the cosmic ‘Dark Ages’, when the baryonic matter was neutral. The currently identified distant galaxies are insufficient to fully reionize the Universe by redshift z ≈ 6 (refs 1, 2, 3), but low-mass, star-formin…
A homogeneous nucleus for comet 67P/Churyumov-Gerasimenko from its gravity field
Jorda, L.; Pätzold, M.; Sierks, H. +13 more
Cometary nuclei consist mostly of dust and water ice. Previous observations have found nuclei to be low-density and highly porous bodies, but have only moderately constrained the range of allowed densities because of the measurement uncertainties. Here we report the precise mass, bulk density, porosity and internal structure of the nucleus of come…
Resolved atomic lines reveal outflows in two ultraluminous X-ray sources
Fabian, Andrew C.; Middleton, Matthew J.; Pinto, Ciro
Ultraluminous X-ray sources are extragalactic, off-nucleus, point sources in galaxies, and have X-ray luminosities in excess of 3 × 1039 ergs per second. They are thought to be powered by accretion onto a compact object. Possible explanations include accretion onto neutron stars with strong magnetic fields, onto stellar-mass black holes…
A combined transmission spectrum of the Earth-sized exoplanets TRAPPIST-1 b and c
Triaud, Amaury H. M. J.; Valenti, Jeff A.; Wakeford, Hannah R. +11 more
Three Earth-sized exoplanets were recently discovered close to the habitable zone of the nearby ultracool dwarf star TRAPPIST-1 (ref. 3). The nature of these planets has yet to be determined, as their masses remain unmeasured and no observational constraint is available for the planetary population surrounding ultracool dwarfs, of which the TRAPPI…
A radio-pulsing white dwarf binary star
Gänsicke, B. T.; Dhillon, V. S.; Pala, A. F. +23 more
White dwarfs are compact stars, similar in size to Earth but approximately 200,000 times more massive. Isolated white dwarfs emit most of their power from ultraviolet to near-infrared wavelengths, but when in close orbits with less dense stars, white dwarfs can strip material from their companions and the resulting mass transfer can generate atomi…
Aggregate dust particles at comet 67P/Churyumov-Gerasimenko
Jessberger, Elmar K.; Torkar, Klaus; Levasseur-Regourd, Anny-Chantal +9 more
Comets are thought to preserve almost pristine dust particles, thus providing a unique sample of the properties of the early solar nebula. The microscopic properties of this dust played a key part in particle aggregation during the formation of the Solar System. Cometary dust was previously considered to comprise irregular, fluffy agglomerates on …
Cold, clumpy accretion onto an active supermassive black hole
Baum, Stefi A.; O'Dea, Christopher P.; McNamara, Brian R. +22 more
Supermassive black holes in galaxy centres can grow by the accretion of gas, liberating energy that might regulate star formation on galaxy-wide scales. The nature of the gaseous fuel reservoirs that power black hole growth is nevertheless largely unconstrained by observations, and is instead routinely simplified as a smooth, spherical inflow of v…
Exposed water ice on the nucleus of comet 67P/Churyumov-Gerasimenko
Langevin, Y.; Bellucci, G.; Jaumann, R. +77 more
Although water vapour is the main species observed in the coma of comet 67P/Churyumov-Gerasimenko and water is the major constituent of cometary nuclei, limited evidence for exposed water-ice regions on the surface of the nucleus has been found so far. The absence of large regions of exposed water ice seems a common finding on the surfaces of many…
High-molecular-weight organic matter in the particles of comet 67P/Churyumov-Gerasimenko
Krüger, Harald; Haerendel, Gerhard; Langevin, Yves +39 more
The presence of solid carbonaceous matter in cometary dust was established by the detection of elements such as carbon, hydrogen, oxygen and nitrogen in particles from comet 1P/Halley. Such matter is generally thought to have originated in the interstellar medium, but it might have formed in the solar nebula—the cloud of gas and dust that was left…
A 17-billion-solar-mass black hole in a group galaxy with a diffuse core
Ma, Chung-Pei; Greene, Jenny E.; Blakeslee, John P. +3 more
Quasars are associated with and powered by the accretion of material onto massive black holes; the detection of highly luminous quasars with redshifts greater than z = 6 suggests that black holes of up to ten billion solar masses already existed 13 billion years ago. Two possible present-day ‘dormant’ descendants of this population of ‘active’ bla…