by Kim Phifer | Aug 28, 2011 | Daily Paper Summaries
How homogenous is the population of Type Ia supernovae?
by Nathan Goldbaum | Aug 27, 2011 | Daily Paper Summaries
Today we will be discussing an exciting discovery – the first observations of an entirely new spectral class of stellar objects!
by Susanna Kohler | Aug 26, 2011 | Daily Paper Summaries
Ever wonder how sunspots are formed? This paper takes a close look at how the magnetic structures that give rise to sunspots make it all the way from the deep solar interior to its surface.
by Ian Czekala | Aug 26, 2011 | Daily Paper Summaries
We know other stars have planets. We know that certain stars have circumstellar disks. We know that before there are planets, there must be a protoplanetary disk; we also know that these two states must be connected through a evolutionary path which includes planet formation.
What if–if we were just so lucky–we found a protoplanetary system that had a disk, that was aligned so perfectly, and that was bright enough, and ….
by Maria Drout | Aug 24, 2011 | Daily Paper Summaries
Three-dimensional Hydrodynamic Core-Collapse Supernova Simulations for a 11.2 M⊙ Star with Spectral Neutrino Transport Tomoya Takiwaki, Kei Kotake, Yudai Suwa First author’s institution: Center for Computational Astrophysics, National Astronomical Observatory of Japan Core-collapse supernovae are some of the most energetic explosions in the universe and astronomers have devoted an incredible amount of both brain power and computational power to unraveling this astrophysical phenomenon. Despite this fact, the problem is far from solved.The ‘standard model’ for these explosions begins when a star with an initial mass greater than ~8 solar masses has progressed through a series of nuclear fusion processes in its core, culminating in the burning of silicon into iron-56. At this stage, fusion can proceed no further and the outward pressure supplied by the energy produced during nuclear burning ceases. If the overlying star is massive enough, the core will be unable to support itself and begins to collapse. In this high energy environment photodisintegration (effectively the reverse of nuclear fusion) and electron capture convert the iron core into free neutrons. When the core reaches approximately nuclear density, pressure exerted by the strong nuclear force and neutron degeneracy cause the collapse to halt. The remaining infalling matter then “bounces” off the proto-neutron star, causing an outward propagating shock wave.Ok, now hang with me. This is where it starts to get complicated… Simulations indicate that this initial shock is NOT what causes the supernova explosions we observe. Rather, additional photodisintegration and neutrino release cause the wave to lose energy and halt after less than a second. This produces a “standing shock” approximately 150 km from the proto-neutron star. In order...
