The first time a non-feeding stellar-mass black hole has been found! ^
There's a new study out on moon formation around gas giants. They find that moon formation happens quickly in a circumplanetary disk, so several generations of moons are formed and fall into the planet before the final generation is kept simply because there's no more circumplanetary material to facilitate inward migration. The mass of the moon system around Jupiter appears to be less massive than the "typical" gas giant moon system, and planetary mass moons seem likely.
More massive moons around gas giants would be great for exobiology!Satellites Form Fast & Late: a Population Synthesis for the Galilean Moons
Kepler/K2 has discovered two small transiting planets around the bright (V=9) rapidly rotating F-type star HD 106315. Radial velocity follow-up also finds a third, long-period, more massive planet but it's properties aren't yet well constrained.
Ever since the discovery of hot Jupiters in misaligned orbits (e.g., orbiting their star in polar, retrograde, or anywhere in between kind of orbit), an outstanding theoretical question has been the origin of these systems. The proposed explanations broadly fall into two categories: planet formation is a neat process and stellar equators aren't necessarily always aligned with their protoplanetary disks (having a rotation state similar to Uranus), or stars are aligned with the protoplanetary disks and chaotic planet formation involving scattering of planets into crazy orbits produces the observed population of misaligned planets.
Having a bright multi-planet transiting system with a rapidly rotating host star makes HD 106315 a perfect laboratory for exploring this problem. A co-planar multi-planet system is a hallmark of neat, orderly planet formation without violent scattering. Few such systems have been found around stars bright enough to pursue these sorts of investigations, making HD 106315 rather valuable. If the planets orbiting HD 106315 are misaligned with the stellar equator, it would suggest some stars can start out with equators misaligned with the protoplanetary disk, but ultimately the question will need to be investigated using a large sample of multi-planet systems of the kind the TESS mission (scheduled for launch in March 2018) is likely to find. The rapid stellar rotation makes the projected alignment between the stellar spin axis and planet orbit axis measurable via the Rossiter-McLaughlin effect.A Multi-Planet System Transiting the V = 9 Rapidly Rotating F-Star HD 106315Two Small Transiting Planets and a Third Body Orbiting HD 106315
CPU: AMD FX-8350 8 core processor 4GHz / GPU: GeForce GT 730 @ 1920x1080, 60Hz with 1GB adapter RAM / RAM: Patriot Signature 4GB 1600MHz 240-Pin DDR3 (only 2GB work, don't buy it) / Motherboard: MSI 970 Gaming MS-7693