The complex circumstellar environment of supernova 2023ixf

The early evolution of a supernova (SN) can reveal information about the environment and the progenitor star. When a star explodes in vacuum, the first photons to escape from its surface appear as a brief, hours-long shock-breakout flare1,2, followed by a cooling phase of emission. However, for stars exploding within a distribution of dense, optically thick circumstellar material (CSM), the first photons escape from the material beyond the stellar edge and the duration of the initial flare can extend to several days, during which the escaping emission indicates photospheric heating3. Early serendipitous observations2,4 that lacked ultraviolet (UV) data were unable to determine whether the early emission is heating or cooling and hence the nature of the early explosion event. Here we report UV spectra of the nearby SN 2023ixf in the galaxy Messier 101 (M101). Using the UV data as well as a comprehensive set of further multiwavelength observations, we temporally resolve the emergence of the explosion shock from a thick medium heated by the SN emission. We derive a reliable bolometric light curve that indicates that the shock breaks out from a dense layer with a radius substantially larger than typical supergiants.

Illuminating gravitational waves: A concordant picture of photons from a neutron star merger

Merging neutron stars offer an excellent laboratory for simultaneously studying strong-field gravity and matter in extreme environments. We establish the physical association of an electromagnetic counterpart (EM170817) with gravitational waves (GW170817) detected from merging neutron stars. By synthesizing a panchromatic data set, we demonstrate that merging neutron stars are a long-sought production site forging heavy elements by r-process nucleosynthesis. The weak gamma rays seen in EM170817 are dissimilar to classical short gamma-ray bursts with ultrarelativistic jets. Instead, we suggest that breakout of a wide-angle, mildly relativistic cocoon engulfing the jet explains the low-luminosity gamma rays, the high-luminosity ultraviolet-optical-infrared, and the delayed radio and x-ray emission. We posit that all neutron star mergers may lead to a wide-angle cocoon breakout, sometimes accompanied by a successful jet and sometimes by a choked jet.

An outburst from a massive star 40 days before a supernova explosion

Some observations suggest that very massive stars experience extreme mass-loss episodes shortly before they explode as supernovae, as do several models. Establishing a causal connection between these mass-loss episodes and the final explosion would provide a novel way to study pre-supernova massive-star evolution. Here we report observations of a mass-loss event detected 40 days before the explosion of the type IIn supernova SN 2010mc (also known as PTF 10tel). Our photometric and spectroscopic data suggest that this event is a result of an energetic outburst, radiating at least 6 × 10(47) erg of energy and releasing about 10(-2) solar masses of material at typical velocities of 2,000 km s(-1). The temporal proximity of the mass-loss outburst and the supernova explosion implies a causal connection between them. Moreover, we find that the outburst luminosity and velocity are consistent with the predictions of the wave-driven pulsation model, and disfavour alternative suggestions.

An infrared flash contemporaneous with the γ-rays of GRB 041219a

The explosion that results in a cosmic gamma-ray burst (GRB) is thought to produce emission from two physical processes: the central engine gives rise to the high-energy emission of the burst through internal shocking, and the subsequent interaction of the flow with the external environment produces long-wavelength afterglows. Although observations of afterglows continue to refine our understanding of GRB progenitors and relativistic shocks, gamma-ray observations alone have not yielded a clear picture of the origin of the prompt emission nor details of the central engine. Only one concurrent visible-light transient has been found and it was associated with emission from an external shock. Here we report the discovery of infrared emission contemporaneous with a GRB, beginning 7.2 minutes after the onset of GRB 041219a (ref. 8). We acquired 21 images during the active phase of the burst, yielding early multi-colour observations. Our analysis of the initial infrared pulse suggests an origin consistent with internal shocks.

The Radio Afterglow and the Host Galaxy of the X-Ray-rich GRB 981226

We report the discovery of a radio transient VLA 232937.2-235553, coincident with the proposed X-ray afterglow for the gamma-ray burst GRB 981226. This gamma-ray burst (GRB) has the highest ratio of X-ray to gamma-ray fluence of all the GRBs detected by BeppoSAX so far, and yet no corresponding optical transient was detected. The radio light curve of VLA 232937.2-235553 is qualitatively similar to that of several other radio afterglows. At the subarcsecond position provided by the radio detection, optical imaging reveals an extended R=24.9 mag object, which we identify as the host galaxy of GRB 981226. Afterglow models that invoke a jetlike geometry for the outflow or that require an ambient medium with a radial density dependence, such as that produced by a wind from a massive star, are both consistent with the radio data. Furthermore, we show that the observed properties of the radio afterglow can explain the absence of an optical transient without the need for large extinction local to the GRB.

Detecting elder abuse: a guide for physicians

Abuse and neglect of the elderly is not a new phenomenom, however, it recently has become recognized as a social problem throughout the United States. Much like child abuse, detection of elder abuse is contingent upon physicians' awareness of this problem and an understanding of the risk factors that often appear before a crisis occurs. Understanding elder abuse detection and risk factors will enable the practicing physician to identify and treat abuse. The purpose of this article is to provide physicians with detection and intervention strategies, with the hope that physicians will utilize their unique relationship with their patients to further the investigation of this growing social problem.

Increased utilization of influenza and pneumococcal vaccines in an elderly hospitalized population

This study compared three interventions designed to increase acceptance of influenza and pneumococcal vaccines among elderly hospitalized patients. All individuals 65 and older able to give informed consent (73 patients) who were admitted to one medical floor of an acute care hospital were randomized to one of three groups. All groups received informational pamphlets explaining influenza and pneumococcal disease, their respective vaccines, and indications for their use. The first group received pamphlets only, the second received nursing follow-up, and the third received trained volunteer follow-up. Patients on another medical floor served as controls. The results showed a significant improvement in vaccine acceptance in all three study groups compared to controls for both influenza (78% vs 0%) and pneumococcal (75% vs 0%) vaccines. The differences among the three groups were not significant. No significant differences were found among patients accepting or refusing vaccination with regard to diagnosis, age, length of stay, sex, or having a private physician. We conclude that a simple educational program followed by offering vaccination before hospital discharge can be easily implemented, and dramatically increase immunization rates in this high risk group.