RESUMO
Transient astronomical sources are typically powered by compact objects and usually signify highly explosive or dynamic events. Although high-time-resolution observations are often possible in radio astronomy, they are usually limited to quite narrow fields of view. The dynamic radio sky is therefore poorly sampled, in contrast to the situation in the X-ray and gamma-ray bands in which wide-field instruments routinely detect transient sources. Here we report a transient radio source, GCRT J1745-3009, which was detected during a moderately wide-field monitoring programme of the Galactic Centre region at 0.33 GHz. The characteristics of its bursts are unlike those known for any other class of radio transient. If located in or near the Galactic Centre, its brightness temperature (approximately 10(16) K) and the implied energy density within GCRT J1745-3009 vastly exceed those observed in most other classes of radio astronomical sources, and are consistent with coherent emission processes that are rarely observed. We conclude that it represents a hitherto unknown class of transient radio sources, the first of possibly many new classes that may be discovered by emerging wide-field radio telescopes.
RESUMO
A supernova explosion, the final death throe of a massive star, creates an expanding bubble of hot gas that overruns up the surrounding medium. When a supernova remnant encounters a dense interstellar cloud, the compression may trigger gravitational collapse and the formation of a new generation of stars. This event can be detected through intense stimulated emission in the 1720-megahertz transition of the hydroxyl radical, OH, which yields unique insights into the physical processes and conditions occurring during the interaction.
