Three-dimensional magnetic reconnection in astrophysical plasmas

This research is supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB41000000), the National Natural Science Foundations of China (11773039, 11903050, 11790304, 11790300 and 41704169), the National Key R&D Program of China (2019YFA0405000), Key Programs of the Chinese Academy of Sciences (QYZDJ-SSW-SLH050), the Youth Innovation Promotion Association of CAS (2017078) and NAOC Nebula Talents Program. R.G. is supported by the Incoming Post-Docs in Sciences, Technology, Engineering, Materials and Agrobiotechnology (IPD-STEMA) project from Université de Liège.Magnetic reconnection is a fundamental process in laboratory, magnetospheric, solar and astrophysical plasmas, whereby magnetic energy is converted into heat, bulk kinetic energy and fast particle energy. Its nature in two dimensions is much better understood than that in three dimensions, where its character is completely different and has many diverse aspects that are currently being explored. Here, we focus on the magnetohydrodynamics of three-dimensional reconnection in the plasma environment of the Solar System, especially solar flares. The theory of reconnection at null points, separators and quasi-separators is described, together with accounts of numerical simulations and observations of these three types of reconnection. The distinction between separator and quasi-separator reconnection is a theoretical one that is unimportant for the observations of energy release. A new paradigm for solar flares, in which three-dimensional reconnection plays a central role, is proposed.PostprintPeer reviewe

Tetra­aqua­bis­(2-{[5-(pyridin-4-yl)-1,3,4-oxadiazol-2-yl]sulfan­yl}acetato)­cobalt(II) monohydrate

In the title compound, [Co(C9H6N3O3S)2(H2O)4]·H2O, the two 2-{[5-(pyridin-4-yl)-1,3,4-oxadiazol-2-yl]sulfan­yl}acetate ligands are monodentate. One coordinates the metal atom via the pyridyl N atom whereas the other coordinates via the carboxyl­ate O atom. The CoII atom adopts a slightly distorted octa­hedral coordination geometry with four O atoms of the coordinated water mol­ecules located in the equatorial plane and the N and O atoms of the two POA ligands in axial positions. In the crystal, the components are connected through O—H⋯O and O—H⋯N hydrogen bonds into a three-dimensional framework

Partial wave effects in the heavy quarkonium radiative electromagnetic decays

In a previous paper \cite{Bc}, it was pointed out that the wave functions of all particles are not pure waves, besides the main partial waves, they all contain {other partial waves}. It is very interesting to know what role these different partial waves play in particle transitions. Therefore, by using the Bethe-Salpeter equation method, we study the radiative electromagnetic decays $\psi\rightarrow\gamma\chi_{_{cJ}}$ and $\Upsilon\rightarrow\gamma\chi_{_{bJ}}$ ($J=0,1,2$). We find that for the $S$ and $P$ wave dominated states, like the $\psi(2S)$, $\Upsilon(2S)$, $\chi_{_{cJ}}(1P)$, and $\chi_{_{bJ}}(1P)$ etc., the dominant $S$ and $P$ waves provide main and nonrelativistic contrition to the decays; other partial waves mainly contribute to the relativistic correction. For the states like the $\psi(1D)$, $\Upsilon(2D)$, $\chi_{c2}(1F)$, and $\chi_{b2}(1F)$ etc., they are the $S-P-D$ mixing state dominated by $D$ wave or the $P-D-F$ mixing state dominated by $F$ wave. Large decay widths are found in the transitions $\psi(2D)\to \chi_{c2}(1F)$, $\Upsilon(1D)\to \chi_{bJ}(1P)$, and $\Upsilon(2D)\to \chi_{bJ}(2P)$ etc., which may be helpful to study the missing states $\chi_{c2}(1F)$, $\Upsilon(1D)$, and $\Upsilon(2D)$.Comment: 31 pages, 19 table

The peculiar filamentary HI structure of NGC 6145

In this paper, we report the peculiar HI morphology of the cluster spiral galaxy NGC 6145, which has a 150 kpc HI filament on one side that is nearly parallel to its major axis. This filament is made up of several HI clouds and the diffuse HI gas between them, with no optical counterparts. We compare its HI distribution with other one-sided HI distributions in the literature, and find that the overall HI distribution is very different from the typical tidal and ram-pressure stripped HI shape, and its morphology is inconsistent with being a pure accretion event. Only about 30% of the total HI gas is anchored on the stellar disk, while most of HI gas forms the filament in the west. At a projected distance of 122 kpc, we find a massive elliptical companion (NGC 6146) with extended radio emission, whose axis points to an HI gap in NGC 6145. The velocity of the HI filament shows an overall light-of- sight motion of 80 to 180 km/s with respect to NGC 6145. Using the long-slit spectra of NGC 6145 along its major stellar axis, we find that some outer regions show enhanced star formation, while in contrast, almost no star formation activities are found in its center (less than 2 kpc). Pure accretion, tidal or ram-pressure stripping is not likely to produce the observed HI filament. An alternative explanation is the jet-stripping from NGC 6146, although direct evidence for a jet-cold gas interaction has not been found.Comment: 12 pages, 6 figures; Accepted for publication in A

Bis{N 2,N 6-bis­[(pyridin-3-yl)meth­yl]pyridine-2,6-dicarboxamide-κN}bis­(methanol-κO)bis­(thio­cyanato-κN)cobalt(II)

In the title compound, [Co(NCS)2(C19H17N5O2)2(CH3OH)2], the CoII atom lies on an inversion center and is coordinated by two isothio­cyanate N atoms, two O atoms of methanol mol­ecules and two pyridine N atoms in a slightly distorted octa­hedral environment. Inter­molecular O—H⋯O and N—H⋯N hydrogen bonds join the complex mol­ecules into layers parallel to the bc plane

Study progress on the relationship between obstructive sleep apnea hypopnea syndrome and glaucoma

Glaucoma is a progressive optic neurodegenerative disease with specific characteristics of structural optic nerve head(ONH)and with changes in the inner retinal layer(ganglion cell complex)along with the presence of corresponding functional visual field(VF)changes that are irreversible. Obstructive sleep apnea hypopnea syndrome(OSAHS)is characterized by recurrent complete or partial interruption of normal breathing due to functional occlusion or collapse of upper airway during sleep that leads to apnea or hypopnea and hypoxia. This causes decrease in the arterial oxygen(O2)saturation and a rise in the carbon dioxide saturation during sleep and results in transient hypoxia and increased vascular resistance in body tissues. OSAHS is an independent risk factor for cardiovascular and cerebrovascular, and many reports showed that OSAHS is one of the systemic risk factors for glaucoma which causes irreversible visual field damage, but lacks a systematic analysis of the relationship between the two. Comprehensive glaucoma evaluation should be recommended in patients with OSAHS