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A surge of light at the birth of a supernova

2018; Nature Portfolio; Volume: 554; Issue: 7693 Linguagem: Inglês

10.1038/nature25151

1476-4687

Melina C. Bersten, G. Folatelli, Federico García, Schuyler D. Van Dyk, O. G. Benvenuto, M. Orellana, V. A. Buso, José Luis Sánchez, Masaomi Tanaka, Keiichi Maeda, A. V. Filippenko, WeiKang Zheng, Thomas G. Brink, S. B. Cenko, Thomas de Jaeger, S. Kumar, Takashi J. Moriya, K. Nomoto, D. A. Perley, I. Shivvers, Nathan Smith,

Pulsars and Gravitational Waves Research

The discovery of a newly born type IIb supernova reveals a rapid brightening at optical wavelengths that corresponds to the shock-breakout phase of the explosion. Supernovae do not provide warning signs that they are about to explode—at least not that we have been able to recognize. With rare exceptions (such as the supernova SN 1987A), supernovae are caught some undetermined time after their explosion. Melina Bersten et al. report observations of the supernova SN 2016gkg in the galaxy NGC 613. The explosion of this star was caught serendipitously by an amateur astronomer who was testing a new camera with 20-second exposures, so the timing of the beginning of the event is tightly constrained. The brightness of the supernova increased very rapidly, at a rate of about 40 magnitudes per day. It is difficult to establish the properties of massive stars that explode as supernovae1,2. 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 star3,4,5,6. However, the unpredictable nature of supernova events hinders the detection of this brief initial phase7,8,9. Here we report the serendipitous discovery of a newly born, normal type IIb supernova (SN 2016gkg)10, which reveals a rapid brightening at optical wavelengths of about 40 magnitudes per day. The very frequent sampling of the observations allowed us to study in detail the outermost structure of the progenitor of the supernova and the physics of the emergence of the shock. We develop hydrodynamical models of the explosion that naturally account for the complete evolution of the supernova over distinct phases regulated by different physical processes. This result suggests that it is appropriate to decouple the treatment of the shock propagation from the unknown mechanism that triggers the explosion.