A strange dim and fast supernova

An article published in the journal “Science” describes the study of a supernova cataloged as iPTF 14gqr which had a very short duration emitting a relatively dim light and ejecting a limited amount of materials. A team of researchers studied this out-of-the-ordinary supernova using observations from the Palomar Observatory and other telescopes concluding that probably the fault is of a companion, a neutron star that attracted many layers of the dying star, limiting its explosion. The supernova probably produced another neutron star forming a binary system of which in the distant future we might see the merger.

Generally supernovae are extremely energetic because they’re stars much more massive than the Sun that went through a number of violent phases of their agony up to an explosion that among other things ejects a considerable amount of materials. However, about 920 million light years from Earth, at the edges of a spiral galaxy, something strange happened that was sighted on Earth in 2014. It was a supernova in which there was a core collapse but not in the usual way.

The supernova iPTF 14gqr, also cataloged as SN 2014ft, was classified as type Ic, which means that the exploded star lost its outer layers of hydrogen and helium due to an external agent, which in a binary system is typically its companion. In some cases, the amount of stripped materials is so great as to leave a relatively small mass in what is called an ultra-stripped supernova.

The image (courtesy SDSS/Caltech/Keck) shows three views of the galaxy in which there was the iPTF 14gqr supernova shortly before, during and immediately after that event. The area of ​​iPTF 14gqr is indicated in circles and the light coming from the supernova is visible only in the central panel. The event was discovered at the Palomar Observatory during a survey called the intermediate Palomar Transient Factory (iPTF), which allowed it to be detected a few hours after its light started reaching the Earth.

The evolution of the supernova was subsequently observed also with other telescopes that are part of the Global Relay of Observatories Watching Transients Happen (GROWTH) network. This allowed to study it continuously and to detect its anomalous characteristics in order to understand its nature. Its total duration was about two weeks, very short for a supernova.

In the past some cases of this type have already been sighted, but the supernova iPTF 14gqr is the first of its type identified shortly after the explosion. One more hour of data, especially regarding the event’s initial phase, can help researchers to understand their mechanisms. This time the analysis of the collected data suggests that the supernova left a neutron star as a remnant and that its companion is also a neutron star. They’re close so they’re likely to end up merging but at least for the moment it’s impossible to say when: perhaps it already happened and the electromagnetic and gravitational waves emitted after that event are traveling towards the Earth.

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