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 flare, 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 heating.

Minutes-duration optical flares with supernova luminosities.

In recent years, certain luminous extragalactic optical transients have been observed to last only a few days. Their short observed duration implies a different powering mechanism from the most common luminous extragalactic transients (supernovae), whose timescale is weeks. Some short-duration transients, most notably AT2018cow (ref.

The nature of an ultra-faint galaxy in the cosmic dark ages seen with JWST.

In the first billion years after the Big Bang, sources of ultraviolet (UV) photons are believed to have ionized intergalactic hydrogen, rendering the Universe transparent to UV radiation. Galaxies brighter than the characteristic luminosity L* (refs. ) do not provide enough ionizing photons to drive this cosmic reionization.

Constraints on the Hubble constant from supernova Refsdal's reappearance.

The gravitationally lensed supernova Refsdal appeared in multiple images produced through gravitational lensing by a massive foreground galaxy cluster. After the supernova appeared in 2014, lens models of the galaxy cluster predicted that an additional image of the supernova would appear in 2015, which was subsequently observed. We use the time delays between the images to perform a blinded measurement of the expansion rate of the Universe, quantified by the Hubble constant ().

A magnified compact galaxy at redshift 9.51 with strong nebular emission lines.

Ultraviolet light from early galaxies is thought to have ionized gas in the intergalactic medium. However, there are few observational constraints on this epoch because of the faintness of those galaxies and the redshift of their optical light into the infrared. We report the observation, in JWST imaging, of a distant galaxy that is magnified by gravitational lensing.

Shock cooling of a red-supergiant supernova at redshift 3 in lensed images.

The core-collapse supernova of a massive star rapidly brightens when a shock, produced following the collapse of its core, reaches the stellar surface. As the shock-heated star subsequently expands and cools, its early-time light curve should have a simple dependence on the size of the progenitor and therefore final evolutionary state. Measurements of the radius of the progenitor from early light curves exist for only a small sample of nearby supernovae, and almost all lack constraining ultraviolet observations within a day of explosion.

A fast radio burst source at a complex magnetized site in a barred galaxy.

Fast radio bursts (FRBs) are highly dispersed, millisecond-duration radio bursts. Recent observations of a Galactic FRB suggest that at least some FRBs originate from magnetars, but the origin of cosmological FRBs is still not settled. Here we report the detection of 1,863 bursts in 82 h over 54 days from the repeating source FRB 20201124A (ref.

A WC/WO star exploding within an expanding carbon-oxygen-neon nebula.

The final fate of massive stars, and the nature of the compact remnants they leave behind (black holes and neutron stars), are open questions in astrophysics. Many massive stars are stripped of their outer hydrogen envelopes as they evolve. Such Wolf-Rayet stars emit strong and rapidly expanding winds with speeds greater than 1,000 kilometres per second.

Unpacking wonder: from curiosity to comprehension.

From the macrocosm of the universe to the microcosm of the human body, our discoveries about ourselves and the natural world continue to spark our experience of awe and wonder. But how exactly does science define and explain the experience of awe and wonder? Social psychologist Michelle Shiota, writer Caspar Henderson, and astrophysicist Alex Filippenko unpack the emerging science behind the emotions of awe and wonder, including their role in our ongoing quest for understanding and knowledge.

A surge of light at the birth of a supernova.

It is difficult to establish the properties of massive stars that explode as supernovae. The electromagnetic emission during the first minutes to hours after the emergence of the shock from the stellar surface conveys important information about the final evolution and structure of the exploding star. However, the unpredictable nature of supernova events hinders the detection of this brief initial phase.

X-ray emission from SN 2012ca: A Type Ia-CSM supernova explosion in a dense surrounding medium.

X-ray emission is one of the signposts of circumstellar interaction in supernovae (SNe), but until now, it has been observed only in core-collapse SNe. The level of thermal X-ray emission is a direct measure of the density of the circumstellar medium (CSM), and the absence of X-ray emission from Type Ia SNe has been interpreted as a sign of a very low density CSM. In this paper, we report late-time (500-800 d after discovery) X-ray detections of SN 2012ca in data.

Energetic eruptions leading to a peculiar hydrogen-rich explosion of a massive star.

Every supernova so far observed has been considered to be the terminal explosion of a star. Moreover, all supernovae with absorption lines in their spectra show those lines decreasing in velocity over time, as the ejecta expand and thin, revealing slower-moving material that was previously hidden. In addition, every supernova that exhibits the absorption lines of hydrogen has one main light-curve peak, or a plateau in luminosity, lasting approximately 100 days before declining.

USE OF VIBRIO CHOLERAE SURFACE STRUCTURES FOR SPECIFIC PROPHY- LAXIS AND DIAGNOSTICS OF CHOLERA.

The need for efficient and cost-effective cholera vaccine hasn't lost its actuality in view of the emergence of new strains leading to severe clinical forms of cholera and capable to replace strains of the seventh.cholera pandemic, and in connection with the threat of cholera spreading beyond the borders of endemic countries. In this review data from literature sources are presented about the use of outer membrane proteins, vesicles, cell ghosts of the cholera causative agent in specific prophylaxis and diagnostics of the disease.

[SOME ASPECTS OF NON-SPECIFIC PROPHYLAXIS AND THERAPY OF ESPECIALLY DANGEROUS INFECTIONS].

Recently, due to spread of dangerous and especially dangerous infections much attention is given to development of complex approaches to their prophylaxis and therapy. Data on use of immune modulators, cytokines, probiotics, preparations of plant origin for non-specific prophylaxis of especially dangerous infections are analyzed in the review, and expediency of their combined use with specific and emergency prophlaxis of these diseases is evaluated.

No signature of ejecta interaction with a stellar companion in three type Ia supernovae.

Type Ia supernovae are thought to be the result of a thermonuclear runaway in carbon/oxygen white dwarfs, but it is uncertain whether the explosion is triggered by accretion from a non-degenerate companion star or by a merger with another white dwarf. Observations of a supernova immediately following the explosion provide unique information on the distribution of ejected material and the progenitor system. Models predict that the interaction of supernova ejecta with a companion star or circumstellar debris lead to a sudden brightening lasting from hours to days.

Distances with <4% precision from type Ia supernovae in young star-forming environments.

The luminosities of type Ia supernovae (SNe), the thermonuclear explosions of white-dwarf stars, vary systematically with their intrinsic color and the rate at which they fade. From images taken with the Galaxy Evolution Explorer (GALEX), we identified SNe Ia that erupted in environments that have high ultraviolet surface brightness and star-formation surface density. When we apply a steep model extinction law, we calibrate these SNe using their broadband optical light curves to within ~0.

Astrophysics. Multiple images of a highly magnified supernova formed by an early-type cluster galaxy lens.

In 1964, Refsdal hypothesized that a supernova whose light traversed multiple paths around a strong gravitational lens could be used to measure the rate of cosmic expansion. We report the discovery of such a system. In Hubble Space Telescope imaging, we have found four images of a single supernova forming an Einstein cross configuration around a redshift z = 0.

Evidence for two distinct populations of type Ia supernovae.

Type Ia supernovae (SNe Ia) have been used as excellent standardizable candles for measuring cosmic expansion, but their progenitors are still elusive. Here, we report that the spectral diversity of SNe Ia is tied to their birthplace environments. We found that those with high-velocity ejecta are substantially more concentrated in the inner and brighter regions of their host galaxies than are normal-velocity SNe Ia.

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).

PTF 11kx: a type Ia supernova with a symbiotic nova progenitor.

There is a consensus that type Ia supernovae (SNe Ia) arise from the thermonuclear explosion of white dwarf stars that accrete matter from a binary companion. However, direct observation of SN Ia progenitors is lacking, and the precise nature of the binary companion remains uncertain. A temporal series of high-resolution optical spectra of the SN Ia PTF 11kx reveals a complex circumstellar environment that provides an unprecedentedly detailed view of the progenitor system.

Exclusion of a luminous red giant as a companion star to the progenitor of supernova SN 2011fe.

Type Ia supernovae are thought to result from a thermonuclear explosion of an accreting white dwarf in a binary system, but little is known of the precise nature of the companion star and the physical properties of the progenitor system. There are two classes of models: double-degenerate (involving two white dwarfs in a close binary system) and single-degenerate models. In the latter, the primary white dwarf accretes material from a secondary companion until conditions are such that carbon ignites, at a mass of 1.