The dwarf planet Eris is a trans-Neptunian object with an orbital eccentricity of 0.44, an inclination of 44 degrees and a surface composition very similar to that of Pluto. It resides at present at 95.7 astronomical units (1 AU is the Earth-Sun distance) from Earth, near its aphelion and more than three times farther than Pluto. Owing to this great distance, measuring its size or detecting a putative atmosphere is difficult. Here we report the observation of a multi-chord stellar occultation by Eris on 6 November 2010 UT. The event is consistent with a spherical shape for Eris, with radius 1,163 ± 6 kilometres, density 2.52 ± 0.05 grams per cm(3) and a high visible geometric albedo, Pv = 0.96(+0.09)(-0.04). No nitrogen, argon or methane atmospheres are detected with surface pressure larger than ∼1 nanobar, about 10,000 times more tenuous than Pluto's present atmosphere. As Pluto's radius is estimated to be between 1,150 and 1,200 kilometres, Eris appears as a Pluto twin, with a bright surface possibly caused by a collapsed atmosphere, owing to its cold environment. We anticipate that this atmosphere may periodically sublimate as Eris approaches its perihelion, at 37.8 astronomical units from the Sun.

Critical illness in COVID-19 is an extreme and clinically homogeneous disease phenotype that we have previously shown1 to be highly efficient for discovery of genetic associations2. Despite the advanced stage of illness at presentation, we have shown that host genetics in patients who are critically ill with COVID-19 can identify immunomodulatory therapies with strong beneficial effects in this group3. Here we analyse 24,202 cases of COVID-19 with critical illness comprising a combination of microarray genotype and whole-genome sequencing data from cases of critical illness in the international GenOMICC (11,440 cases) study, combined with other studies recruiting hospitalized patients with a strong focus on severe and critical disease: ISARIC4C (676 cases) and the SCOURGE consortium (5,934 cases). To put these results in the context of existing work, we conduct a meta-analysis of the new GenOMICC genome-wide association study (GWAS) results with previously published data. We find 49 genome-wide significant associations, of which 16 have not been reported previously. To investigate the therapeutic implications of these findings, we infer the structural consequences of protein-coding variants, and combine our GWAS results with gene expression data using a monocyte transcriptome-wide association study (TWAS) model, as well as gene and protein expression using Mendelian randomization. We identify potentially druggable targets in multiple systems, including inflammatory signalling (JAK1), monocyte–macrophage activation and endothelial permeability (PDE4A), immunometabolism (SLC2A5 and AK5), and host factors required for viral entry and replication (TMPRSS2 and RAB2A).

The bipolar planetary nebula NGC 650-1 has been imaged in Hα, Hβ, [N II] λ6583 Å and [S II] λλ6717+6731 Å. These results are used to map the variation of extinction over the interior regions of the shell, where we find evidence for a gradual increase in A V between the SW and NE limits of the central emission bar. It is argued that this is likely to arise from dust associated with the nebular envelope itself. We have also produced a map of electron densities over this region, and find evidence for marked variations in n e over a scale of ∼5 arcsec, a variation which is probably related to the clumpy emission structure observed in low-excitation images. We finally present contour mapping of mid-infrared Spitzer images of the source at 3.6, 4.5, 5.8 and 8 μm. These show that the central bar has a more or less uniform emission structure, although with evidence for condensations which are similar to, and in most cases coincidental with, comparable low-excitation structures noted in [N II]. There is also evidence for an increase in 8/4.5 μm and 5.8/4.5 μm emission ratios with distance from the nucleus, and for an extension of 8 and 5.8 μm emission beyond the ionized regime; a trend which is attributed to strong polycyclic aromatic hydrocarbon band emission within the nebular photodissociative regime.Key words: ISM: jets and outflows -ISM: lines and bands -planetary nebulae: individual: NGC 650-1 -infrared: ISM. I N T RO D U C T I O NThe planetary nebula NGC 650-1 is a characteristic example of the bipolar outflow phenomenon. The morphology of the source was first described by Curtis (1918), who noted the presence of a bright rectangular structure which he interpreted in terms of a highly tilted ring. Deeper images by Minkowski (1960) subsequently registered the presence of large semicircular appendages on either side of the nucleus, beyond which there is also evidence for larger, more irregular and lower excitation nebular extensions (see e.g. the particularly deep images of this source by Corradi & Schwarz 1995;Manchado et al. 1996).Investigations by Harman & Seaton (1966), Sabbadin, Bianchini & Hamzaoglu (1984, Kaler (1983), Preite-Martinez & Pottasch (1983), Pottasch (1996 and Koorneef & Pottasch (1998) indicate a broad range of values for the Zanstra temperatures of this source, although a mean of the more recent estimates appears to indicate

NGC 7009 is a fascinating example of a high‐excitation, elliptical planetary nebula (PN) containing circumnebular rings, and FLIERs and jets along the major axis. We present visual spectroscopy along multiple position angles through the nucleus, taken with the Observatorio Astronomico Nacional (Mexico); mid‐infrared (MIR) spectroscopy and imaging acquired using the Infrared Space Observatory (ISO) and Spitzer Space Telescope (SST), and narrow‐band imaging obtained using the Hubble Space Telescope (HST). The data show that the mid‐infrared (MIR) continuum is dominated by a broad ≈100 K continuum, and a strong excess attributable to crystalline silicate emission. The primary peaks in this excess are similar to those observed in Forsterite and clino‐ and ortho‐enstatite. The MIR images, by contrast, appear to be dominated by ionic transitions, with the 8.991 μm transition of [Ar iii] being important in the 8.0‐μm band. The morphology and size of the envelope are found to vary with wavelength, with the largest dimensions occurring at 8.0 μm – a trend which is also reflected in an increase in the 8.0 μm/4.5 μm and 5.8 μm/4.5 μm ratios with distance from the nucleus. The visual spectroscopy permits us to map density and temperature throughout the shell, and confirm that the lowest values of ne are located close to the ansae, where densities appear to be of the order of 900–2600 cm−3. We provide mean line intensities for 116 transitions in six regions of the shell, and use mapping to confirm a systematic increase in excitation in the outer portions of the envelope. We finally use the ground‐based spectroscopy, and ratioing of HST images to investigate the presence of shocks in the ansae and interior envelope. It is concluded that line ratios in the ansae may be partially consistent with shock excitation, although these features are primarily dominated by photoionization. We also note evidence for shock excitation at the limits of the interior elliptical shell, and for multiple bow‐shock structures centred upon the ansae. The orientations of the easterly bow‐shocks may have varied over time, indicating precession of the collimating engine at a rate of  deg yr−1, whilst the outward splaying of the westerly ‘jet’ appears consistent with shock refraction modelling. We finally note that HST observations of the halo rings show them to have widths of the order of ∼1–3 arcsec, and steep changes in surface brightness consistent with local shock activity.