Binaries are typically excluded from direct imaging exoplanet surveys. However, the recent findings of Kepler and radial velocity programs show that planets can and do form in binary systems. Here, we suggest that visual binaries offer unique advantages for direct imaging. We show that Binary Differential Imaging (BDI), whereby two stars are imaged simultaneously at the same wavelength within the isoplanatic patch at a high Strehl ratio, offers improved point spread function (PSF) subtraction that can result in increased sensitivity to planets close to each star. We demonstrate this by observing a young visual binary separated by 4 '' with MagAO/Clio-2 at 3.9 mu m, where the Strehl ratio is high, the isoplanatic patch is large, and giant planets are bright. Comparing BDI to angular differential imaging (ADI), we find that BDI's 5 sigma contrast is similar to 0.5 mag better than ADI's within similar to 1 '' for the particular binary we observed. Because planets typically reside close to their host stars, BDI is a promising technique for discovering exoplanets in stellar systems that are often ignored. BDI is also 2-4x more efficient than ADI and classical reference PSF subtraction, since planets can be detected around both the target and PSF reference simultaneously. We are currently exploiting this technique in a new MagAO survey for giant planets in 140 young nearby visual binaries. BDI on a space-based telescope would not be limited by isoplanatism effects and would therefore be an even more powerful tool for imaging and discovering planets.

K-Cl is a simple system displaying all four main types of bonding, as it contains (i) metallic potassium, (ii) elemental chlorine made of covalently bonded Cl-2 molecules held together by van der Waals forces, and (iii) an archetypal ionic compound KCl. The charge balance rule, assigning classical charges of "+1" to K and "-1" to Cl, predicts that no compounds other than KCl are possible. However, our quantum-mechanical variable-composition evolutionary simulations predict an extremely complex phase diagram, with new thermodynamically stable compounds K3Cl, K2Cl, K3Cl2, K4Cl3, K5Cl4, K3Cl5, KCl3 and KCl7. Of particular interest are 2D-metallic homologs Kn+1Cln, the presence of positively charged Cl atoms in KCl7, and the predicted stability of KCl3 already at nearly ambient pressures at zero Kelvin. We have synthesized cubic Pm (3) over barn -KCl3 at 40-70 GPa and trigonal P (3) over bar c1 -KCl3 at 20-40 GPa in a laser-heated diamond anvil cell (DAC) at temperature exceeding 2000 K from KCl and Cl-2. These phases were identified using in situ synchrotron X-ray diffraction and Raman spectroscopy. Upon unloading to 10 GPa, P (3) over bar c1 -KCl3 transforms to a yet unknown structure before final decomposition to KCl and Cl-2 at near-ambient conditions.

We have discovered that 2MASS 08355977-3042306 is an accreting K7, double-lined, spectroscopic binary younger than similar to 20 Myr. The age of a dispersed young star can best be determined if it is a member of a known young moving group. However, the three dimensional space velocities (UVW) we calculate using radial velocity measurements, proper motions, and plausible photometric distances make membership in any known young moving group unlikely.

We use fast transient transmission and emission spectroscopies in the pulse laser heated diamond anvil cell to probe the energy-dependent optical properties of hydrogen at pressures of 10-150 GPa and temperatures up to 6000 K. Hydrogen is absorptive at visible to near-infrared wavelengths above a threshold temperature that decreases from 3000 K at 18 GPa to 1700 K at 110 GPa. Transmission spectra at 2400 K and 141 GPa indicate that the absorptive hydrogen is semiconducting or semimetallic in character, definitively ruling out a first-order insulator-metal transition in the studied pressure range.

We spectroscopically investigated the energy gap of the correlated antiferromagnetic insulator LaMnPO1-xFx (x = 0.0 and 0.04) as a function of temperature and pressure, separately, in conjunction with many-body electronic structure calculations. These results show that the electronic structure in all measured regimes is well described by a model that includes both Mott-Hubbard interactions and Hund's rule coupling. Moreover, we find that by applying external pressure, thereby reducing the effective Mott-Hubbard interaction and Hund's coupling, the energy gap in LaMnPO1 xFx can be fully closed, yielding a metallic state.

The detectability of planetesimal impacts on imaged exoplanets can be measured using Jupiter during the 1994 comet Shoemaker-Levy 9 events as a proxy. By integrating the whole planet flux with and without impact spots, the effect of the impacts at wavelengths from 2 to 4 is revealed. Jupiter's reflected light spectrum in the near-infrared is dominated by its methane opacity including a deep band at 2.3 mu m. After the impact, sunlight that would have normally been absorbed by the large amount of methane in Jupiter's atmosphere was instead reflected by the cometary material from the impacts. As a result, at 2.3 mu m, where the planet would normally have low reflectivity, it brightened substantially and stayed brighter for at least a month. (C) 2015 Elsevier Inc. All rights reserved.

The conduction of heat through minerals and melts at extreme pressures and temperatures is of central importance to the evolution and dynamics of planets. In the cooling Earth's core, the thermal conductivity of iron alloys defines the adiabatic heat flux and therefore the thermal and compositional energy available to support the production of Earth's magnetic field via dynamo action(1-3). Attempts to describe thermal transport in Earth's core have been problematic, with predictions of high thermal conductivity(4-7) at odds with traditional geophysical models and direct evidence for a primordial magnetic field in the rock record(8-10). Measurements of core heat transport are needed to resolve this difference. Here we present direct measurements of the thermal conductivity of solid iron at pressure and temperature conditions relevant to the cores of Mercury-sized to Earth-sized planets, using a dynamically laser-heated diamond-anvil cell(11,12). Our measurements place the thermal conductivity of Earth's core near the low end of previous estimates, at 18-44 watts per metre per kelvin. The result is in agreement with palaeomagnetic measurements(10) indicating that Earth's geodynamo has persisted since the beginning of Earth's history, and allows for a solid inner core as old as the dynamo.

Exoplanet detections have revolutionized astronomy, offering new insights into solar system architecture and planet demographics. While nearly 1,900 exoplanets have now been discovered and confirmed(1), none are still in the process of formation. Transition disks, protoplanetary disks with inner clearings(2-4) best explained by the influence of accreting planets(5), are natural laboratories for the study of planet formation. Some transition disks show evidence for the presence of young planets in the form of disk asymmetries(6,7) or infrared sources detected within their clearings, as in the case of LkCa 15 (refs 8, 9). Attempts to observe directly signatures of accretion onto protoplanets have hitherto proven unsuccessful(10). Here we report adaptive optics observations of LkCa 15 that probe within the disk clearing. With accurate source positions over multiple epochs spanning 2009-2015, we infer the presence of multiple companions on Keplerian orbits. We directly detect Ha emission from the innermost companion, LkCa 15 b, evincing hot (about 10,000 kelvin) gas falling deep into the potential well of an accreting protoplanet.

The only known compound of sodium and hydrogen is archetypal ionic NaH. Application of high pressure is known to promote states with higher atomic coordination, but extensive searches for polyhydrides with unusual stoichiometry have had only limited success in spite of several theoretical predictions. Here we report the first observation of the formation of polyhydrides of Na (NaH3 and NaH7) above 40GPa and 2,000 K. We combine synchrotron X-ray diffraction and Raman spectroscopy in a laser-heated diamond anvil cell and theoretical random structure searching, which both agree on the stable structures and compositions. Our results support the formation of multicenter bonding in a material with unusual stoichiometry. These results are applicable to the design of new energetic solids and high-temperature superconductors based on hydrogen-rich materials.

We report the discovery of a scattering component around the HD 141569 A circumstellar debris system, interior to the previously known inner ring. The discovered inner disk component, obtained in broadband optical light with Hubble Space Telescope/Space Telescope Imaging Spectrograph coronagraphy, was imaged with an inner working angle of 0 25, and can be traced from 0 ''.4 (similar to 46 AU) to 1 ''.0 (similar to 116 AU) after deprojection using i = 55 degrees. The inner disk component is seen to forward scatter in a manner similar to the previously known rings, has a pericenter offset of similar to 6 AU, and break points where the slope of the surface brightness changes. It also has a spiral arm trailing in the same sense as other spiral arms and arcs seen at larger stellocentric distances. The inner disk spatially overlaps with the previously reported warm gas disk seen in thermal emission. We detect no point sources within 2 ''(similar to 232 AU), in particular in the gap between the inner disk component and the inner ring. Our upper limit of 9 +/- 3 M-J is augmented by a new dynamical limit on single planetary mass bodies in the gap between the inner disk component and the inner ring of 1 M-J, which is broadly consistent with previous estimates.