If you are attentive enough to the sky and have looked at it during the last nights, you may have noticed the appearance of a new bright point. In truth, it is not new at all, but these days it burns unusually brightly. The star RS Ophiuchus, 4566 light-years away, is erupting. She became as much as seven magnitudes brighter - 4, 8 instead of 12.
RS Ophiuchus is a recurring nova: a star that periodically erupts. Only a dozen of these stars have been found in the Milky Way galaxy. RS Ophiuchus flares up approximately every 15-20 years. The last time it was in 2006.
RS Ophiuchi OUTBURST
Taken by Ernesto Guido, Marco Rocchetto & Adriano Valvasori on August 9, 2021 @ Remotely from Australia through TELESCOPE LIVE network
recurrent nova RS Oph is in Outburst. The last large outburst of RS Oph occurred in Feb. 2006, → pic.twitter.com/FMqDZEQ0Xx
- mizuho kai (@ mizuho73700856) August 9, 2021
The fact is that RS Ophiuchus is a binary system. There, a red giant and a white dwarf spin in an endless gravitational dance. And with an enviable frequency, this dance leads to a cataclysm. The white dwarf constantly draws material from the red giant into its atmosphere. Having reached a critical mass, stellar matter falls onto the surface of the dwarf, which leads to a colossal explosion. This explosion is called a flash of a new one. During this explosion, the brightness of the star increases significantly.