Hubble has captured an image of the first-ever predicted supernova explosion. The reappearance of the supernova dubbed "Refsdal" was calculated by different mass models of a galaxy cluster whose immense gravity is warping the supernova's light as the light travels toward Earth. The supernova was previously seen in November 2014 behind the galaxy cluster MACS J1149.5+2223, part of Hubble's Frontier Fields program. Astronomers spotted four separate images of the supernova in a rare arrangement known as an Einstein Cross. This pattern was seen around a galaxy within MACS J1149.5+2223. While the light from the cluster has taken about five billion years to reach us, the supernova itself exploded much earlier, nearly 10 billion light years ago. The detection of Refsdal's reappearance served as a unique opportunity for astronomers to test their models of how mass especially that of mysterious dark matter is distributed within this galaxy cluster.
Just about anything is possible in our remarkable universe, and it often competes with the imaginings of science fiction writers and filmmakers. Hubble's latest contribution is a striking photo of what looks like a double-bladed lightsaber straight out of the Star Wars films. In the center of the image, partially obscured by a dark, Jedi-like cloak of dust, a newborn star shoots twin jets out into space as a sort of birth announcement to the universe. Gas from a surrounding disk rains down onto the dust-obscured protostar and engorges it. The material is superheated and shoots outward from the star in opposite directions along an uncluttered escape route the star's rotation axis. Much more energetic than a science fiction lightsaber, these narrow energetic beams are blasting across space at over 100,000 miles per hour. This celestial lightsaber does not lie in a galaxy far, far away but rather inside our home galaxy, the Milky Way.
A large-scale dynamo and magnetoturbulence in rapidly rotating core-collapse supernovae
Nature 528, 7582 (2015). doi:10.1038/nature15755
Authors: Philipp Mösta, Christian D. Ott, David Radice, Luke F. Roberts, Erik Schnetter & Roland Haas
Magnetohydrodynamic turbulence is important in many high-energy astrophysical systems, where instabilities can amplify the local magnetic field over very short timescales. Specifically, the magnetorotational instability and dynamo action have been suggested as a mechanism for the growth of magnetar-strength magnetic fields (of 1015 gauss and above) and for powering the explosion of a rotating massive star. Such stars are candidate progenitors of type Ic-bl hypernovae, which make up all supernovae that are connected to long γ-ray bursts. The magnetorotational instability has been studied with local high-resolution shearing-box simulations in three dimensions, and with global two-dimensional simulations, but it is not known whether turbulence driven by this instability can result in the creation of a large-scale, ordered and dynamically relevant field. Here we report results from global, three-dimensional, general-relativistic magnetohydrodynamic turbulence simulations. We show that hydromagnetic turbulence in rapidly rotating protoneutron stars produces an inverse cascade of energy. We find a large-scale, ordered toroidal field that is consistent with the formation of bipolar magnetorotationally driven outflows. Our results demonstrate that rapidly rotating massive stars are plausible progenitors for both type Ic-bl supernovae and long γ-ray bursts, and provide a viable mechanism for the formation of magnetars. Moreover, our findings suggest that rapidly rotating massive stars might lie behind potentially magnetar-powered superluminous supernovae.
Astronomy: Galaxies caught in cosmic web
Nature 528, 7582 (2015). doi:10.1038/528310e
Astronomers have discovered eight massive young galaxies within what might be a large web of dark matter.Ordinary matter, including galaxies, is thought to have aggregated along threads of dark matter in the early Universe. But the progenitors of today's galaxies are often shrouded in
Astrophysics: Cosmic boost reveals dim galaxy
Nature 528, 7582 (2015). doi:10.1038/528310b
Astronomers have spied the faintest object ever seen in the early Universe.Leopoldo Infante at the Pontifical Catholic University of Chile in Santiago and his team used NASA's Hubble and Spitzer space telescopes to study distant objects. They examined sections of the sky through a