Bidirectional outflows as evidence of magnetic reconnection leading to a solar microflare

Magnetic reconnection is a rapid energy release process that is believed to be responsible for flares on the Sun and stars. Nevertheless, such flare-related reconnection is mostly detected to occur in the corona, while there have been few studies concerning the reconnection in the chromosphere or photosphere. Here we present both spectroscopic and imaging observations of magnetic reconnection in the chromosphere leading to a microflare. During the flare peak time, chromospheric line profiles show significant blueshifted/redshifted components on the two sides of the flaring site, corresponding to upflows and downflows with velocities of $\pm$(70--80) km s$^{-1}$, comparable with the local Alfv\'{e}n speed as expected by the reconnection in the chromosphere. The three-dimensional nonlinear force-free field configuration further discloses twisted field lines (a flux rope) at a low altitude, cospatial with the dark threads in He I 10830 \r{A} images. The instability of the flux rope may initiate the flare-related reconnection. These observations provide clear evidence of magnetic reconnection in the chromosphere and show the similar mechanisms of a microflare to those of major flares.Comment: 16 pages, 5 figures, accepted for publication in ApJ

Diaqua­[3,5-bis­(4-pyrid­yl)-1H-1,2,4-triazole-κN 3](pyridine-2,6-dicarboxyl­ato-κ3 O 2,N,O 6)nickel(II)

In the title compound, [Ni(C7H3NO4)(C12H9N5)(H2O)2], the NiII atom is coordinated in a distorted octa­hedral geometry by one N and two O atoms from a pyridine-2,6-dicarboxyl­ate ligand, one N atom from a 3,5-bis­(4-pyrid­yl)-1H-1,2,4-triazole ligand in equatorial positions and two water mol­ecules in axial positions. The crystal packing is consolidated by inter­molecular O—H⋯O, O—H⋯N and N—H⋯O hydrogen bonds

9-[4-Hydr­oxy-3-(hydroxy­meth­yl)but­yl]guanine monohydrate

In the mol­ecular structure of the title compound, also named penciclovir monohydrate, C10H15N5O3·H2O, the 4-hydr­oxy-3-hydroxy­methyl­but-1-yl group is connected to guanine through an N atom of the imidazole ring. Water mol­ecules stabilize the mol­ecular packing by forming O—H⋯O hydrogen bonds. A three-dimensional network is generated via inter­molecular N—H⋯N, N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonding

Dark Matter Annihilation via Breit-Wigner Enhancement with Heavier Mediator

We propose a new scenario that both the dark matter freeze-out in the early Universe and its possible annihilation for indirect detection around a supermassive black hole are enhanced by a Breit-Wigner resonance. With the mediator mass larger than the total initial dark matter mass, this annihilation is almost forbidden at late times. Thus, the stringent cosmic microwave background and indirect detection constraints do not apply. However, a supermassive black hole can accelerate the dark matter particles to reactivate this resonant annihilation whose subsequent decay to photons leaves a unique signal. The running Fermi-LAT and the future COSI satellites can test this scenario.Comment: 6 pages, 3 figure