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A close nuclear black-hole pair in the spiral galaxy NGC3393
Elvis, M.; Fabbiano, G.; Wang, Junfeng +1 more
The current picture of galaxy evolution advocates co-evolution of galaxies and their nuclear massive black holes, through accretion and galactic merging. Pairs of quasars, each with a massive black hole at the centre of its galaxy, have separations of 6,000 to 300,000 light years (refs 2 and 3; 1parsec = 3.26light years) and exemplify the first st…
A giant thunderstorm on Saturn
Gurnett, D. A.; Kurth, W. S.; Delcroix, M. +8 more
Lightning discharges in Saturn's atmosphere emit radio waves with intensities about 10,000 times stronger than those of their terrestrial counterparts. These radio waves are the characteristic features of lightning from thunderstorms on Saturn, which last for days to months. Convective storms about 2,000 kilometres in size have been observed in re…
Deep winds beneath Saturn's upper clouds from a seasonal long-lived planetary-scale storm
Phillips, J.; Hueso, R.; Sánchez-Lavega, A. +40 more
Convective storms occur regularly in Saturn's atmosphere. Huge storms known as Great White Spots, which are ten times larger than the regular storms, are rarer and occur about once per Saturnian year (29.5 Earth years). Current models propose that the outbreak of a Great White Spot is due to moist convection induced by water. However, the generati…
The auroral footprint of Enceladus on Saturn
Dougherty, Michele K.; Zhou, Xiaoyan; Saur, Joachim +26 more
Although there are substantial differences between the magnetospheres of Jupiter and Saturn, it has been suggested that cryovolcanic activity at Enceladus could lead to electrodynamic coupling between Enceladus and Saturn like that which links Jupiter with Io, Europa and Ganymede. Powerful field-aligned electron beams associated with the Io-Jupite…
X-ray illumination of the ejecta of supernova 1987A
Panagia, N.; Larsson, J.; Sollerman, J. +25 more
When a massive star explodes as a supernova, substantial amounts of radioactive elements--primarily 56Ni, 57Ni and 44Ti--are produced. After the initial flash of light from shock heating, the fading light emitted by the supernova is due to the decay of these elements. However, after decades, the energy powering a s…
Black hole growth in the early Universe is self-regulated and largely hidden from view
Schawinski, Kevin; Gawiser, Eric; Volonteri, Marta +2 more
The formation of the first massive objects in the infant Universe remains impossible to observe directly and yet it sets the stage for the subsequent evolution of galaxies. Although some black holes with masses more than 109 times that of the Sun have been detected in luminous quasars less than one billion years after the Big Bang, thes…
A distortion of very-high-redshift galaxy number counts by gravitational lensing
Yan, Haojing; Windhorst, Rogier A.; Mao, Shude +1 more
The observed number counts of high-redshift galaxy candidates have been used to build up a statistical description of star-forming activity at redshift z>~7, when galaxies reionized the Universe. Standard models predict that a high incidence of gravitational lensing will probably distort measurements of flux and number of these earliest galaxie…
The unusual gamma-ray burst GRB 101225A explained as a minor body falling onto a neutron star
Covino, S.; D'Avanzo, P.; Campana, S. +17 more
The tidal disruption of a solar-mass star around a supermassive black hole has been extensively studied analytically and numerically. In these events, the star develops into an elongated banana-shaped structure. After completing an eccentric orbit, the bound debris falls into the black hole, forming an accretion disk and emitting radiation. The sa…
Saturn: Storm-clouds brooding on towering heights
Read, Peter
Springtime on Saturn came in with a bang last December, when a massive storm erupted in its north temperate zone. This rare event has been observed in unprecedented detail from the ground and from space. See Letters p.71 & p.75
High molecular gas fractions in normal massive star-forming galaxies in the young Universe
Lutz, D.; Förster Schreiber, N. M.; Genzel, R. +19 more
Stars form from cold molecular interstellar gas. As this is relatively rare in the local Universe, galaxies like the Milky Way form only a few new stars per year. Typical massive galaxies in the distant Universe formed stars an order of magnitude more rapidly. Unless star formation was significantly more efficient, this difference suggests that yo…