In today’s paper, Rezzolla and Kumar present a solution to the x-ray afterglow problem for the short gamma ray burst model. They show that x-rays can glow steadily for hours after the initial gamma ray emission due to the interactions of a slow and a fast wind.
In this paper the authors present simulations of a model to explain rapidly-fading supernovae, a class of transients whose lightcurves decline quickly without substantial radioactive tails. They posits a standard core-collapse explosion of a standard Type Ib/Ic supernova progenitor, but one that produces very little radioactivity and instead exhibits a light curve governed by oxygen recombination.
Astronomers don’t stop after discovering planets in systems near and far from our own solar system. The next big step is to characterize the planets. We want to understand what they’re made of, what their atmospheres look like, whether they have clouds, how massive they are, how old they are, etc. As it turns out characterizing exoplanets is really, really challenging for both observers and modelers. The challenges encountered are well illustrated by the saga of WASP-12b.
Astronomers have started trying to understand how to organize classes of exoplanets based on their physical characteristics. As it has turned out over the last ten years, exoplanets are considerably more complicated to classify than stars. The evolution of star is based (almost) exclusively on how massive it is at birth. Instead, this paper classifies hot exoplanets by their level of irradiation from their host star and their chemical composition.
Mars is observed to have sedimentary rocks, which provide proof that liquid water once existed on the Martian surface. However, the surface of Mars would have been too cold to have permanent rivers and lakes; the authors of this paper suggest seasonal snowmelt could create enough liquid water to form these rocks.
To characterize the newly-discovered population of small planets, this team from UC Santa Cruz investigated how planets lose mass over their lifetimes, and determined how this loss will affect planet populations. This paper suggests that we can understand the population of small planets using mass loss models, and we make predictions using these models for the masses of irradiated super-Earths.