Category Astronomy/Space

Representation of the interior of Enceladus with icy crust, ocean and solid core. ROB researchers think that Dione may also have a subsurface ocean. Credit: NASA/JPL-Caltech/Space Science Institute

A subsurface ocean lies deep within Saturn’s moon Dione, according to new data from the Cassini mission to Saturn. Two other moons of Saturn, Titan and Enceladus, are already known to hide global oceans beneath their icy crusts, but a new study suggests an ocean exists on Dione as well. The researchers of the Royal Observatory of Belgium show gravity data from recent Cassini flybys can be explained if Dione’s crust floats on an ocean 100 kilometers below the surface. The ocean is several tens of kilometers deep and surrounds a large rocky core...

Planetary disk around the star known as TW Hydrae. Credit: S. Andrews (Harvard-Smithsonian CfA); B. Saxton (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO)

The dusty disk surrounding star TW Hydrae exhibits circular features that may signal the formation of protoplanets. An astrophysicist argues, however, that the innermost actually points to the impending dispersal of the disk. When the maps appeared at the end of March, experts were electrified. The images revealed an orange-red disk pitted with circular gaps: a detailed portrait of a protoplanetary disk, made up of gas and dust grains, associated with a young star – the kind of structure out of which planets could be expected to form...

Hubble Space Telescope image of supernova 1994D in galaxy NGC 4526 © NASA/ESA

A new math model details a way that dead stars called white dwarfs could detonate, producing a type of explosion that is instrumental to measuring the extreme distances in our universe. The mechanism, described in the Monthly Notices of the Royal Astronomical Society, could improve our understanding of how Type Ia supernovae form. “Type Ia supernovae are extremely important objects in physics, best known for their role in revealing that the expansion of the universe is accelerating,” said Prof. Saavik Ford. “The problem is that people do not agree on exactly how Type Ia supernovae come to be.”

Current research indicates that Type Ia supernova explosions originate from binary star systems – two stars orbiting one...

(a) The trajectory of the electron #1 in the 3D velocity space. (b) A conceptual model of the noncrossing electron orbits. A noncrossing Speiser orbit (solid line) and a noncrossing regular orbit (red). They are computed in a configuration similar to the traditional Speiser orbit (dashed line) in Figure 1. (c) The velocity-space trajectory of the noncrossing Speiser orbit for y < 0 and z < 1.5.

Phenomena like solar flares and auroras are consequences of magnetic reconnection in the near-Earth space. These “magnetic reconnection” events are akin to magnetic explosions that accelerate particles as they rapidly change the topology of the magnetic field lines...