by Susanna Kohler | Oct 7, 2011 | Daily Paper Summaries
Messier 87 (M87) is a giant elliptical galaxy that is best known for its spectacular, 5000-ly-long jet. In this paper, the authors develop models of M87 based on general relativistic numerical simulations and make predictions for the future direct observations of the black hole event horizon that may be possible.
by Courtney Dressing | Sep 15, 2011 | Daily Paper Summaries
Wolfgang & Laughlin combine observations from the HARPS radial velocity survey and the Kepler transit survey to investigate the mass-radius-period distribution of exoplanets. They find that most small planets are rocky.
by Dan Gifford | Sep 4, 2011 | Career Navigation
It’s that time of year! For those of you thinking about grad school, check out how you might prepare yourself for the application process and narrow down your list of schools.
by Courtney Dressing | Sep 1, 2011 | Daily Paper Summaries
How do the planet candidates discovered by Kepler compare to the planets detected by radial velocity surveys? Can we combine the Kepler radii with the RV masses to determine whether small planets are rocky Super-Earths or gaseous mini-Neptunes?
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...
by Courtney Dressing | Aug 3, 2011 | Daily Paper Summaries
McLean et al. observe a new sample of late-M and L dwarfs with the Very large Array to search for a relation between rotation rate and radio activity for ultracool dwarfs.
