A shock flash breaking out of a dusty red supergiant.

Shock-breakout emission is light that arises when a shockwave, generated by the core-collapse explosion of a massive star, passes through its outer envelope. Hitherto, the earliest detection of such a signal was at several hours after the explosion1, although a few others had been reported2-7. The temporal evolution of early light curves should provide insights into the shock propagation, including explosion asymmetry and environment in the vicinity, but this has been hampered by the lack of multiwavelength observations. Here we report the instant multiband observations of a type II supernova (SN 2023ixf) in the galaxy M101 (at a distance of 6.85 ± 0.15 Mpc; ref. 8), beginning at about 1.4 h after the explosion. The exploding star was a red supergiant with a radius of about 440 solar radii. The light curves evolved rapidly, on timescales of 1-2 h, and appeared unusually fainter and redder than predicted by the models9-11 within the first few hours, which we attribute to an optically thick dust shell before it was disrupted by the shockwave. We infer that the breakout and perhaps the distribution of the surrounding dust were not spherically symmetric.

[Genetic analysis of an infant with duplication 9q34 syndrome].

OBJECTIVE: To determine the genetic cause of an infant with multiple congenital anomalies. METHODS: Routine karyotype analysis and chromosome microarray analysis (CMA) were carried out for the infant and her parents. RESULTS: CMA has detected a 9.3 Mb duplication at 9q34.11-q34.3. G-banding analysis suggested that the infant has a 46,XX,der(1)add(1)(p34.1) karyotype, while her father was 46, XY, t(1,9)(p36.3;q34.1). Fluorescence in situ hybridization (FISH) analysis confirmed that the 9q34 duplication has derived from the balanced translocation carried by the father. CONCLUSION: A 9.3 Mb duplication was detected within the 9q34 region in an infant featuring multiple congenital anomalies. CMA and FISH have enabled detection of this duplication and facilitated genetic counseling and prevention of birth of further affected offspring.

Circumstellar material ejected violently by a massive star immediately before its death.

Type II supernovae represent the most common stellar explosions in the Universe, for which the final stage evolution of their hydrogen-rich massive progenitors towards core-collapse explosion are elusive. The recent explosion of SN 2023ixf in a very nearby galaxy, Messier 101, provides a rare opportunity to explore this longstanding issue. With the timely high-cadence flash spectra taken within 1-5 days after the explosion, we can put stringent constraints on the properties of the surrounding circumstellar material around this supernova. Based on the rapid fading of the narrow emission lines and luminosity/profile of Hα emission at very early times, we estimate that the progenitor of SN 2023ixf lost material at a mass-loss rate M≈6×10-4M⊙a-1 over the last 2-3 years before explosion. This close-by material, moving at a velocity vw≈55kms-1, accumulates a compact CSM shell at the radius smaller than 7×1014 cm from the progenitor. Given the high mass-loss rate and relatively large wind velocity presented here, together with the pre-explosion observations made about two decades ago, the progenitor of SN 2023ixf could be a short-lived yellow hypergiant that evolved from a red supergiant shortly before the explosion.