The magnetic field in the NGC 2024 FIR 5 dense core

We used the Submillimeter Array (SMA) to observe the thermal polarized dust emission from the protostellar source NGC 2024 FIR 5. The polarized emission outlines a partial hourglass morphology for the plane-of-sky component of the core magnetic field. Our data are consistent with previous BIMA maps, and the overall magnetic field geometries obtained with both instruments are similar. We resolve the main core into two components, FIR 5A and FIR 5B. A possible explanation for the asymmetrical field lies in depolarization effects due to the lack of internal heating from FIR 5B source, which may be in a prestellar evolutionary state. The field strength was estimated to be 2.2 mG, in agreement with previous BIMA data. We discuss the influence of a nearby H{\sc ii} region over the field lines at scales of $\sim 0.01$ pc. Although the hot component is probably compressing the molecular gas where the dust core is embedded, it is unlikely that the radiation pressure exceeds the magnetic tension. Finally, a complex outflow morphology is observed in CO (3 $\rightarrow$ 2) maps. Unlike previous maps, several features associated with dust condensations other than FIR 5 are detected.Comment: 48 pages, 12 figures, accepted for publication in The Astrophysical Journa

Optimization and resilience of complex supply-demand networks

Acknowledgments This work was supported by NSF under Grant No. 1441352. SPZ and ZGH were supported by NSF of China under Grants No. 11135001 and No. 11275003. ZGH thanks Prof Liang Huang and Xin-Jian Xu for helpful discussions.Peer reviewedPublisher PD

catena-Poly[[[bis­(4-amino­benzoato-κO)copper(II)]-μ-1,1′-(pentane-1,5-di­yl)diimidazole] trihydrate]

In the title compound, {[Cu(C7H6NO2)2(C11H16N4)]·3H2O}n, each CuII atom is coordinated by two O atoms from two 4-amino­benzoate anions, and two N atoms from two different 1,1′-(pentane-1,5-di­yl)diimidazole (biim-5) ligands, to furnish a distorted square-planar geometry. The biim-5 ligand coordinates to two copper(II) cations, acting as a bridging ligand; as a result the copper(II) cations are connected to form an infinite chain structure. The polymeric chains are linked through a variety of hydrogen bonds to form a three-dimensional structure

1,1′-(4-Oxoheptane-1,7-di­yl)bis­(2-methyl-1H-benzimidazole) penta­hydrate

The title compound, C23H26N4O·5H2O, has noncrystallographic twofold rotation symmetry in the solid state. It crystallizes with five solvent water mol­ecules in the asymmetric unit. Four of these water mol­ecules are connected with each other via hydrogen-bonding inter­actions to form two types of centrosymmetric hexa­meric (H2O)6 rings. Via edge sharing of the hexa­mers, the water clusters thus build infinite chains that stretch parallel to the a axis. The fifth water mol­ecule provides an additional connection between the two hexa­meric (H2O)6 units via hydrogen bonds to both rings. The water mol­ecules in the channels along the a axis are also bonded via O—H⋯N hydrogen bonds to the organic units, and face-to-face π–π inter­actions [with centroid-to-centroid distances of 3.656 (1) Å and average face-to-face distances of 3.431 (5) Å] between the aromatic rings of adjacent mol­ecules complete the inter­molecular inter­actions in this structure