The Spatial and Emission Properties of the Large [O III] Emission Nebula Near M31

Drechsler et al. (2023) reported the unexpected discovery of a 1.5 degree long [O III] emission nebula 1.2 degrees southeast of the M31 nucleus. Here we present additional images of this large emission structure, called SDSO, along with radial velocity and flux measurements from low-dispersion spectra. Independent sets of [O III] images show SDSO to be composed of broad streaks of diffuse emission aligned NE-SW. Deep H$\alpha$ images reveal no strong coincident emission suggesting a high [O III]/H$\alpha$ ratio. We also find no other [O III] emission nebulosity as bright as SDSO within several degrees of M31 and no filamentary H$\alpha$ emission connected to SDSO. Optical spectra taken along the arc's northern limb reveal [O III] $\lambda\lambda$4959,5007 emissions matching the location and extent seen in our [O III] images. The heliocentric velocity of this [O III] nebulosity is $-9.8 \pm 6.8$ km s$^{-1}$ with a peak surface brightness of $(4\pm2) \times 10^{-18}$ erg s$^{-1}$ cm$^{-2}$ arcsec$^{-2}$ ($\sim$0.55 Rayleigh). We discuss SDSO as a possible unrecognized supernova remnant, a large and unusually nearby planetary nebula, a stellar bow shock nebula, or an interaction of M31's outer halo gas with high-velocity circumgalactic gas. We conclude that galactic origins for SDSO are unlikely and favor instead an extragalactic M31 halo--circumgalactic cloud interaction scenario, despite the nebula's low radial velocity. We then describe new observations that may help resolve the true nature and origin of this large nebulosity so close to M31 in the sky.Comment: 21 pages, 12 figure

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb carbonate geochronology: strategies, progress, and limitations

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U–Pb geochronology of carbonate minerals, calcite in particular, is rapidly gaining popularity as an absolute dating method. The high spatial resolution of LA-ICP-MS U–Pb carbonate geochronology has benefits over traditional isotope dilution methods, particularly for diagenetic and hydrothermal calcite, because uranium and lead are heterogeneously distributed on the sub-millimetre scale. At the same time, this can provide limitations to the method, as locating zones of radiogenic lead can be time-consuming and “hit or miss”. Here, we present strategies for dating carbonates with in situ techniques, through imaging and petrographic techniques to data interpretation; our examples are drawn from the dating of fracture-filling calcite, but our discussion is relevant to all carbonate applications. We review several limitations to the method, including open-system behaviour, variable initial-lead compositions, and U–daughter disequilibrium. We also discuss two approaches to data collection: traditional spot analyses guided by petrographic and elemental imaging and image-based dating that utilises LA-ICP-MS elemental and isotopic map data

MOST detects corotating bright spots on the mid-O type giant {\xi} Persei

We have used the MOST (Microvariability and Oscillations of STars) microsatellite to obtain four weeks of contiguous high-precision broadband visual photometry of the O7.5III(n)((f)) star {\xi} Persei in November 2011. This star is well known from previous work to show prominent DACs (Discrete Absorption Components) on time-scales of about 2 d from UV spectroscopy and NRP (Non Radial Pulsation) with one (l = 3) p-mode oscillation with a period of 3.5 h from optical spectroscopy. Our MOST-orbit (101.4 min) binned photometry fails to reveal any periodic light variations above the 0.1 mmag 3-sigma noise level for periods of hours, while several prominent Fourier peaks emerge at the 1 mmag level in the two-day period range. These longer-period variations are unlikely due to pulsations, including gravity modes. From our simulations based upon a simple spot model, we deduce that we are seeing the photometric modulation of several co-rotating bright spots on the stellar surface. In our model, the starting times (random) and lifetimes (up to several rotations) vary from one spot to another yet all spots rotate at the same period of 4.18 d, the best-estimated rotation period of the star. This is the first convincing reported case of co-rotating bright spots on an O star, with important implications for drivers of the DACs (resulting from CIRs - Corotating Interaction Regions) with possible bright-spot generation via a breakout at the surface of a global magnetic field generated by a subsurface convection zone.Comment: 9 pages, 4 figures, 2 tables, MNRAS in pres

Targeting of Slc25a21 is associated with orofacial defects and otitis media due to disrupted expression of a neighbouring gene.

Homozygosity for Slc25a21(tm1a(KOMP)Wtsi) results in mice exhibiting orofacial abnormalities, alterations in carpal and rugae structures, hearing impairment and inflammation in the middle ear. In humans it has been hypothesised that the 2-oxoadipate mitochondrial carrier coded by SLC25A21 may be involved in the disease 2-oxoadipate acidaemia. Unexpectedly, no 2-oxoadipate acidaemia-like symptoms were observed in animals homozygous for Slc25a21(tm1a(KOMP)Wtsi) despite confirmation that this allele reduces Slc25a21 expression by 71.3%. To study the complete knockout, an allelic series was generated using the loxP and FRT sites typical of a Knockout Mouse Project allele. After removal of the critical exon and neomycin selection cassette, Slc25a21 knockout mice homozygous for the Slc25a21(tm1b(KOMP)Wtsi) and Slc25a21(tm1d(KOMP)Wtsi) alleles were phenotypically indistinguishable from wild-type. This led us to explore the genomic environment of Slc25a21 and to discover that expression of Pax9, located 3' of the target gene, was reduced in homozygous Slc25a21(tm1a(KOMP)Wtsi) mice. We hypothesize that the presence of the selection cassette is the cause of the down regulation of Pax9 observed. The phenotypes we observed in homozygous Slc25a21(tm1a(KOMP)Wtsi) mice were broadly consistent with a hypomorphic Pax9 allele with the exception of otitis media and hearing impairment which may be a novel consequence of Pax9 down regulation. We explore the ramifications associated with this particular targeted mutation and emphasise the need to interpret phenotypes taking into consideration all potential underlying genetic mechanisms

Impact of the COVID-19 Pandemic on the Welfare of Animals in Australia

We report on the various responses in Australia during 2020 to minimize negative impacts of the COVID-19 pandemic on the welfare of animals. Most organizations and individuals with animals under their care had emergency preparedness plans in place for various scenarios; however, the restrictions on human movement to contain the spread of COVID-19, coupled with the economic impact and the health effects of COVID-19 on the skilled workforce, constituted a new threat to animal welfare for which there was no blueprint. The spontaneous formation of a national, multisectoral response group on animal welfare, consisting of more than 34 organizations with animals under their care, facilitated information flow during the crisis, which helped to mitigate some of the shocks to different organizations and to ensure continuity of care for animals during the pandemic. We conclude that animal welfare is a shared responsibility, and accordingly, a multisectoral approach to animal welfare during a crisis is required. Our experience demonstrates that to safeguard animal welfare during crises, nations should consider the following: a national risk assessment, clear communication channels, contingency plans for animal welfare, a crisis response group, and support systems for animal care providers. Our findings and recommendations from the Australian context may inform other countries to ensure that animal welfare is not compromised during the course of unpredictable events

Synthesis and controlled growth of osmium nanoparticles by electron irradiation

YesWe have synthesised osmium nanoparticles of defined size (1.5–50 nm) on a B- and S-doped turbostratic graphitic structure by electron-beam irradiation of an organometallic osmium complex encapsulated in self-spreading polymer micelles, and characterised them by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and atomic force microscopy (AFM) on the same grid. Oxidation of the osmium nanoparticles after exposure to air was detected by X-ray photoelectron spectroscopy (XPS).We thank the Leverhulme Trust (Early Career Fellowship No. ECF-2013-414 to NPEB), the University of Warwick (Grant No. RD14102 to NPEB), the ERC (Grant No. 247450 to PJS), and the EPSRC (EP/F034210/1 to PJS). L.M.A.P., J.L., and G.C. acknowledge financial support from the EU through the ERC Consolidator Grant “VISUAL-MS”

Recognizing detachment-mode seafloor spreading in the deep geological past.

Large-offset oceanic detachment faults are a characteristic of slow- and ultraslow-spreading ridges, leading to the formation of oceanic core complexes (OCCs) that expose upper mantle and lower crustal rocks on the seafloor. The lithospheric extension accommodated by these structures is now recognized as a fundamentally distinct “detachment-mode” of seafloor spreading compared to classical magmatic accretion. Here we demonstrate a paleomagnetic methodology that allows unequivocal recognition of detachment-mode seafloor spreading in ancient ophiolites and apply this to a potential Jurassic detachment fault system in the Mirdita ophiolite (Albania). We show that footwall and hanging wall blocks either side of an inferred detachment have significantly different magnetizations that can only be explained by relative rotation during seafloor spreading. The style of rotation is shown to be identical to rolling hinge footwall rotation documented recently in OCCs in the Atlantic, confirming that detachment-mode spreading operated at least as far back as the Jurassic