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Subsurface water and clay mineral formation during the early history of Mars
Murchie, Scott L.; Ehlmann, Bethany L.; Mustard, John F. +4 more
Clay minerals, recently discovered to be widespread in Mars's Noachian terrains, indicate long-duration interaction between water and rock over 3.7 billion years ago. Analysis of how they formed should indicate what environmental conditions prevailed on early Mars. If clays formed near the surface by weathering, as is common on Earth, their presen…
Relativistic jet activity from the tidal disruption of a star by a massive black hole
Troja, E.; Im, M.; Sakamoto, T. +55 more
Supermassive black holes have powerful gravitational fields with strong gradients that can destroy stars that get too close, producing a bright flare in ultraviolet and X-ray spectral regions from stellar debris that forms an accretion disk around the black hole. The aftermath of this process may have been seen several times over the past two deca…
Birth of a relativistic outflow in the unusual γ-ray transient Swift J164449.3+573451
Berger, E.; Frail, D. A.; Kulkarni, S. R. +24 more
Active galactic nuclei, which are powered by long-term accretion onto central supermassive black holes, produce relativistic jets with lifetimes of at least one million years, and the observation of the birth of such a jet is therefore unlikely. Transient accretion onto a supermassive black hole, for example through the tidal disruption of a stray…
A salt-water reservoir as the source of a compositionally stratified plume on Enceladus
Kempf, S.; Postberg, F.; Srama, R. +2 more
The discovery of a plume of water vapour and ice particles emerging from warm fractures (`tiger stripes') in Saturn's small, icy moon Enceladus raised the question of whether the plume emerges from a subsurface liquid source or from the decomposition of ice. Previous compositional analyses of particles injected by the plume into Saturn's diffuse E…
Ocean-like water in the Jupiter-family comet 103P/Hartley 2
Hartogh, Paul; Bergin, Edwin A.; Blake, Geoffrey A. +10 more
For decades, the source of Earth's volatiles, especially water with a deuterium-to-hydrogen ratio (D/H) of (1.558+/-0.001)×10-4, has been a subject of debate. The similarity of Earth's bulk composition to that of meteorites known as enstatite chondrites suggests a dry proto-Earth with subsequent delivery of volatiles by local accretion …
Exclusion of a luminous red giant as a companion star to the progenitor of supernova SN 2011fe
Kulkarni, S. R.; Filippenko, Alexei V.; Cenko, S. Bradley +26 more
Type Ia supernovae are thought to result from a thermonuclear explosion of an accreting white dwarf in a binary system, but little is known of the precise nature of the companion star and the physical properties of the progenitor system. There are two classes of models: double-degenerate (involving two white dwarfs in a close binary system) and si…
A candidate redshift z~10 galaxy and rapid changes in that population at an age of 500Myr
Trenti, M.; Oesch, P. A.; Carollo, C. M. +9 more
Searches for very-high-redshift galaxies over the past decade have yielded a large sample of more than 6,000 galaxies existing just 900-2,000million years (Myr) after the Big Bang (redshifts 6>z>3 ref. 1). The Hubble Ultra Deep Field (HUDF09) data have yielded the first reliable detections of z~8 galaxies that, together with reports of a γ-r…
An actively accreting massive black hole in the dwarf starburst galaxy Henize2-10
Johnson, Kelsey E.; Reines, Amy E.; Sivakoff, Gregory R. +1 more
Supermassive black holes are now thought to lie at the heart of every giant galaxy with a spheroidal component, including our own Milky Way. The birth and growth of the first `seed' black holes in the earlier Universe, however, is observationally unconstrained and we are only beginning to piece together a scenario for their subsequent evolution. H…
Magneto-thermal convection in solar prominences
Shibata, Kazunari; Testa, Paola; Boerner, Paul +6 more
Coronal cavities are large low-density regions formed by hemispheric-scale magnetic flux ropes suspended in the Sun's outer atmosphere. They evolve over time, eventually erupting as the dark cores of coronal mass ejections. Although coronal mass ejections are common and can significantly affect planetary magnetospheres, the mechanisms by which cav…
The unusual γ-ray burst GRB 101225A from a helium star/neutron star merger at redshift 0.33
Im, M.; Fryer, C. L.; Choi, C. +31 more
Long γ-ray bursts (GRBs) are the most dramatic examples of massive stellar deaths, often associated with supernovae. They release ultra-relativistic jets, which produce non-thermal emission through synchrotron radiation as they interact with the surrounding medium. Here we report observations of the unusual GRB 101225A. Its γ-ray emission was exce…