"Kepler" discovered a strange supernova: quickly caught fire, quickly went out
Despite the fact that the orientation system in the space of the Kepler telescope runs out of fuel , the device continues to work. Usually a telescope captures the passage of exoplanets across the disk of its star, but it is also able to record events like supernova explosions. The other day it became known about the next discovery, which was made with the help of "Kepler": astronomers discovered a very unusual supernova, which behaved completely different from its "relatives".
Initially, the supernova in question was not assigned to a particular class. The problem is that it ignited very quickly and disappeared no less quickly - about eight times faster than usual. The information transmitted by the telescope, the authors of the discovery handed over to colleagues, so that other experts could take up the analysis of the situation.
The event in question received the identifier KSN 2015K. Data on this object has already fallen into the hands of scientists, but no one has ever classified it as a system at the initial stage of supernova development. The flash itself was as bright as other flashes that appear during a supernova explosion. But all this happened according to a somewhat accelerated scenario.
The KSN 2015K reached its peak brightness in just a couple of days. Then, within a week, the “supernova” gradually faded, and after three weeks the object completely disappeared. For comparison, another supernova reached its maximum brightness in two weeks, not days. As mentioned above, the KSN 2015K achieved maximum brightness eight times faster than a “normal” supernova, if this adjective is applicable to supernovae.
The process of the emergence of a “fast supernova”, if it is, of course, a supernova, got its own name, FELT (fast evolving luminous transient).
Previously, FELTs were recorded by telescopes, but very rarely and in random order, since it is impossible to predict their appearance in a certain area of the sky. Accordingly, it was impossible to study the evolutionary stages of “fast supernovae” because of their scarcity. But the information provided by the Kepler telescope of a different kind - although it “spotted” the flash in random order, but thanks to the frequency of observations of the same sky (every half hour), scientists were able to trace the development stages of KSN 2015K.
Presumably, such a fast supernova, a representative of a new class of “kilon” stars, appears when two neutron stars or a neutron star merge with a black hole. In some cases, a very large star turns into a "kilo" one. True, such stars are not yet known to astronomers - the star must be truly gigantic. It may well be that the explosion of Eta Kiel, which occurred in the 1800s, is just a kilon. Then for several days it was the brightest star in the horizon of the Earth. After the explosion, the star left a huge gas and dust cloud.
The term kilo was proposed by Brian Metzger in 2010. It is intended to show that the energy radiated by an object can be approximately 1000 times higher than the energy radiated by ordinary new ones. Kilon, among other things, is also a powerful source of gravitational waves and strong electromagnetic radiation. There is speculation that kilo - the main supplier of elements heavier than iron.
The first kilon observations were made in 2013 thanks to the Hubble telescope. Then he was able to registershort gamma-ray burst 130603B. Kilon gravitational waves were first recorded on August 17, 2017 by the LIGO and Virgo observatories (GW170817). In the same region of the sky, gamma radiation (GRB 170817A, SSS17a) was detected with the Fermi (GLAST Fermi) and INTEGRAL space telescopes. Kilonova appeared in the galaxy NGC 4993 in the constellation Hydra. Scientists have observed an outbreak for several weeks, build a light curve, obtain spectra, find out what elements formed during the explosion.
To date, the exact reason for the appearance of the kilon is unknown, and even more so, of such “fast” ones as the KSN 2015K object, there are only the assumptions mentioned above. Scientists continue to analyze the information received, so that other discoveries can wait for us. The results of the study of the object were published in the publication Nature Astronomy.
DOI: 10.1038 / s41550-018-0423-2