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We have performed H and K S band observations of the planetary system around HR 8799 using the new AO system at the Large Binocular Telescope and the PISCES Camera. The excellent instrument performance (Strehl ratios up to 80% in H band) enabled the detection of the innermost planet, HR 8799e, at H band for the first time. The H and K S magnitudes of HR 8799e are similar to those of planets c and d, with planet e being slightly brighter. Therefore, HR 8799e is likely slightly more massive than c and d. We also explored possible orbital configurations and their orbital stability. We confirm that the orbits of planets b, c and e are consistent with being circular and coplanar; planet d should have either an orbital eccentricity of about 0.1 or be non-coplanar with respect to b and c. Planet e can not be in circular and coplanar orbit in a 4:2:1 mean motion resonances with c and d, while coplanar and circular orbits are allowed for a 5:2 resonance. The analysis of dynamical stability shows that the system is highly unstable or chaotic when planetary masses of about 5 M J for b and 7 M J for the other planets are adopted. Significant regions of dynamical stability for timescales of tens of Myr are found when adopting planetary masses of about 3.5, 5, 5, and 5 M J for HR 8799b, c, d, and e respectively. These masses are below the current estimates based on the stellar age (30 Myr) and theoretical models of substellar objects.

The stability of the lower troposphere along the east side of the sub-tropical North Atlantic is analyzed and characterized using upper air meteorological long-term records at the Canary Islands (Tenerife), Madeira (Madeira) and Azores (Terceira) archipelagos. The most remarkable characteristic is the strong stratification observed in the lower troposphere, with a strengthening of stability centred at levels near 900 and 800 hPa in a significant percentage of soundings (ranging from 17 % in Azores to 33 % in Güimar, Canary Islands). We show that this double structure is associated with the top of the marine boundary layer (MBL) and the trade-wind inversion (TWI) respectively. The top of the MBL coincides with the base of the first temperature inversion (≈900 hPa) where a sharp change in water vapour mixing ratio is observed. A second temperature inversion is found near 800 hPa, which is characterized by a large directional wind shear just above the inversion layer, tied to the TWI. We find that seasonal and latitudinal variations of the height and strength of both temperature inversions are driven by large-scale subsiding air from the upper troposphere associated with the descent branch of the Hadley cell. Increased general subsidence in summertime enhances stability in the lower troposphere, more markedly in the southern stations, where the inversion-layer heights are found at lower levels enhancing the main features of these two temperature inversions. A simple conceptual model that explains the lower tropospheric inversion enhancement by subsidence is proposed. Electronic supplementary materialThe online version of this article (

We present diffraction-limited Ks band and L ′ adaptive optics images of the edge-on debris disk around the nearby F2 star HD 15115, obtained with a single 8.4 m primary mirror at the Large Binocular Telescope. At Ks band the disk is detected at signal-to-noise per resolution element (SNRE) ∼ 3-8 from ∼ 1-2. ′′ 5 (45-113 AU) on the western side, and from ∼ 1.2-2. ′′ 1 (63-90 AU) on the east. At L ′ the disk is detected at SNRE ∼ 2.5 from ∼ 1-1. ′′ 45 (45-90 AU) on both sides, implying more symmetric disk structure at 3.8 µm. At both wavelengths the disk has a bow-like shape and is offset from the star to the north by a few AU. A surface brightness asymmetry exists between the two sides of the disk at Ks band, but not at L ′ . The surface brightness at Ks band declines inside 1 ′′ (∼ 45 AU), which may be indicative of a gap in the disk near 1 ′′ . The Ks -L ′ disk color, after removal of the stellar color, is mostly grey for both sides of the disk. This suggests that scattered light is coming from large dust grains, with 3-10 µm-sized grains on the east side and 1-10 µm dust grains on the west. This may suggest that the west side is composed of smaller dust grains than the east side, which would support the interpretation that the disk is being dynamically affected by interactions with the local interstellar medium.

The new 8.4m LBT adaptive secondary AO system, with its novel pyramid wavefront sensor, was used to produce very high Strehl ( 75% at 2.16µm) near infrared narrowband (Brγ: 2.16µm and [FeII]: 1.64µm) images of 47 young (∼ 1 Myr) Orion Trapezium θ 1 Ori cluster members. The inner ∼ 41 × 53 ′′ of the 01 The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona university system; cluster was imaged at spatial resolutions of ∼ 0.050 ′′ (at 1.64µm). A combination of high spatial resolution and high S/N yielded relative binary positions to ∼ 0.5 mas accuracies. Including previous speckle data, we analyze a 15 year baseline of high-resolution observations of this cluster. We are now sensitive to relative proper motions of just ∼ 0.3 mas/yr (0.6 km/s at 450 pc) this is a ∼ 7× improvement in orbital velocity accuracy compared to previous efforts. We now detect clear orbital motions in the θ 1 Ori B 2 B 3 system of 4.9 ± 0.3 km/s and 7.2 ± 0.8 km/s in the θ 1 Ori A 1 A 2 system (with correlations of PA vs. time at > 99% confidence). All five members of the θ 1 Ori B system appear likely as a gravitationally bound "mini-cluster". The very lowest mass member of the θ 1 Ori B system (B 4 ; mass ∼ 0.2M ⊙ ) has, for the first time, a clearly detected motion (at 4.3 ± 2.0 km/s; correlation=99.7%) w.r.t B 1 . However, B 4 is most likely in an long-term unstable (non-hierarchical) orbit and may "soon" be ejected from this "mini-cluster". This "ejection" process could play a major role in the formation of low mass stars and brown dwarfs.