Methane emission from a cool brown dwarf.

Beyond our Solar System, aurorae have been inferred from radio observations of isolated brown dwarfs1,2. Within our Solar System, giant planets have auroral emission with signatures across the electromagnetic spectrum including infrared emission of H3+ and methane. Isolated brown dwarfs with auroral signatures in the radio have been searched for corresponding infrared features, but only null detections have been reported3. CWISEP J193518.59-154620.3. (W1935 for short) is an isolated brown dwarf with a temperature of approximately 482 K. Here we report James Webb Space Telescope observations of strong methane emission from W1935 at 3.326 µm. Atmospheric modelling leads us to conclude that a temperature inversion of approximately 300 K centred at 1-10 mbar replicates the feature. This represents an atmospheric temperature inversion for a Jupiter-like atmosphere without irradiation from a host star. A plausible explanation for the strong inversion is heating by auroral processes, although other internal and external dynamical processes cannot be ruled out. The best-fitting model rules out the contribution of H3+ emission, which is prominent in Solar System gas giants. However, this is consistent with rapid destruction of H3+ at the higher pressure where the W1935 emission originates4.

Near-infrared background anisotropies from diffuse intrahalo light of galaxies.

Unresolved anisotropies of the cosmic near-infrared background radiation are expected to have contributions from the earliest galaxies during the epoch of reionization and from faint, dwarf galaxies at intermediate redshifts. Previous measurements were unable to pinpoint conclusively the dominant origin because they did not sample spatial scales that were sufficiently large to distinguish between these two possibilities. Here we report a measurement of the anisotropy power spectrum from subarcminute to one-degree angular scales, and find the clustering amplitude to be larger than predicted by the models based on the two existing explanations. As the shot-noise level of the power spectrum is consistent with that expected from faint galaxies, a new source population on the sky is not necessary to explain the observations. However, a physical mechanism that increases the clustering amplitude is needed. Motivated by recent results related to the extended stellar light profile in dark-matter haloes, we consider the possibility that the fluctuations originate from intrahalo stars of all galaxies. We find that the measured power spectrum can be explained by an intrahalo light fraction of 0.07 to 0.2 per cent relative to the total luminosity in dark-matter haloes of 10(9) to 10(12) solar masses at redshifts of about 1 to 4.

Reduction of severe wrist injuries in snowboarding by an optimized wrist protection device: a prospective randomized trial.

BACKGROUND: The benefits of sport are well recognized, but many activities carry a sport-specific injury risk. Snowboarding has become an increasingly popular winter sport in Austria in recent years, with an estimated 900,000 participants annually. Roughly 6,000 of these suffer from injury and up to 2,000 sustain moderate or severe wrist injuries (mainly fractures of the distal radius and epiphysiolyses). METHODS: We conducted a prospective, randomized, controlled trial to test the protective effect of a wrist protector, which differs in position, stiffness, length, and fixation from conventional protectors. Seven hundred twenty-one snowboarders were randomized into two groups. The risk factors and the injuries that occurred were registered by questionnaires and, in case of medical treatment, by medical reports. Time until injury (in half-days) was compared by the proportional hazards model. RESULTS: Nine severe wrist injuries were sustained in the unprotected control group and only one in the protected group (hazard ratio, 0.13; 95% confidence limits, 0.02, 1.04). Twelve snowboarders of the protector group secretly discarded their protectors during the trial (including the snowboarder who suffered the one and only severe wrist injury of this group). A per-protocol analysis was therefore performed, which demonstrated a more accentuated result (p = 0.003). There was no statistically significant increase in the incidence of other types of injury. Experience was shown to be a further protective factor. CONCLUSION: We recommend the use of a wrist protector, particularly for novices participating in this sport. As in other domains of medicine, preventive measures can decrease morbidity also in terms of sport injuries.