Is the Kelvin Theorem Valid for High-Reynolds-Number Turbulence?

The Kelvin-Helmholtz theorem on conservation of circulations is supposed to hold for ideal inviscid fluids and is believed to be play a crucial role in turbulent phenomena, such as production of dissipation by vortex line-stretching. However, this expectation does not take into account singularities in turbulent velocity fields at infinite Reynolds number. We present evidence from numerical simulations for the breakdown of the classical Kelvin theorem in the three-dimensional turbulent energy cascade. Although violated in individual realizations, we find that circulations are still conserved in some average sense. For comparison, we show that Kelvin's theorem holds for individual realizations in the two-dimensional enstrophy cascade, in agreement with theory. The turbulent ``cascade of circulations'' is shown to be a classical analogue of phase-slip due to quantized vortices in superfluids and various applications in geophysics and astrophysics are outlined.Comment: 4 pages, 3 figure

Oosporein from Tremella fuciformis

The title compound [systematic name: 3,3′,6,6′-tetra­hydroxy-4,4′-dimethyl-1,1′-bi(cyclo­hexa-3,6-diene)-2,2′,5,5′-tetra­one], C14H10O8, was isolated from Tremella fuciformis. The mol­ecule has 2 symmetry, with the mid-point of the C—C bond linking the cyclo­hexa­dienedione rings located on a twofold rotation axis. In the mol­ecule, the ring is approximately planar, with an r.m.s. deviation of 0.0093 Å, and the two rings make a dihedral angle of 67.89 (5)°. Inter­molecular O—H⋯O hydrogen bonding occurs in the crystal structure

Spatially resolved MaNGA observations of the host galaxy of superluminous supernova 2017egm

Superluminous supernovae (SLSNe) are found predominantly in dwarf galaxies, indicating that their progenitors have a low metallicity. However, the most nearby SLSN to date, SN 2017egm, occurred in the spiral galaxy NGC 3191, which has a relatively high stellar mass and correspondingly high metallicity. In this paper, we present detailed analysis of the nearby environment of SN 2017egm using MaNGA IFU data, which provides spectral data on kiloparsec scales. From the velocity map we find no evidence that SN 2017egm occurred within some intervening satellite galaxy, and at the SN position most metallicity diagnostics yield a solar and above solar metallicity (12 + log (O/H) = 8.8-9.1). Additionally we measure a small H-alpha equivalent width (EW) at the SN position of just 34 Angs, which is one of the lowest EWs measured at any SLSN or Gamma-Ray Burst position, and indicative of the progenitor star being comparatively old. We also compare the observed properties of NGC 3191 with other SLSN host galaxies. The solar-metallicity environment at the position of SN 2017egm presents a challenge to our theoretical understanding, and our spatially resolved spectral analysis provides further constraints on the progenitors of SLSNe.Comment: Accepted version in ApJ Letter. Thank you for useful comment