They discover two stars almost touching each other in a planetary nebula

An international team of astronomers, led by the researcher of the Instituto de Astrofísica of Canarias (IAC) and University of La Laguna (ULL) David Jones and with the completion of several observation campaigns in Chile, discovered a binary system with an orbital period of a little over three hours

The discovery, which required several years of observation, is not only surprising because it 's about binary stars with one of the shortest orbital periods ever observed in a planetary nebula, but it also reveals the possibility that, due to its proximity the system undergoes an explosion of nova before the nebula dissipates.

The planetary nebulae are approx. Scenes of gas and dust that expel stars similar to our Sun at the end of their lives. "In many cases, we see that this ejection stems from an interaction between the progenitor star and a close companion, which is why they form nebulae with such elaborate structures," Jones explains.

In the survey, whose results were published in the scientific journal Monthly Notices of the Royal Astronomical Society (MNRAS) studied the planetary nebula M3- 1, a firm candidate to have been created by a binary system because of its jets of material, very common in the interactions between two nearby stars.

According to Brent Miszalski, researcher of the SALT telescope in South Africa and co-author of the study, "was to be a binary star, so we decided to observe it for try to understand the relationship between the stars and the nebula they formed. "

Observations immediately confirmed the suspicions. "When we started to observe it, we immediately saw that it was a binary system and that its brightness was changing rapidly. it had a very short orbital period, "says Henri Boffin, a researcher at the Southern European Observatory (ESO). acronyms in English) in Germany. In fact, the calculated spacing between the two stars is about 160,000 kilometers, less than half the distance between the Earth and the Moon.

After several campaigns of observations in in Chile with telescopes Very Large Telescope (VLT) and New Technology Telescope (NTT) researchers were able to collect enough of data to begin to understand the properties of stars, such as their mbad, temperature, and size.

"To our surprise, we discovered that the stars were large and that, so close to each other, it is highly likely that a few thousand years from now, we could see another one. kind of binary interaction in the form of an explosion of nova, "he adds. Paulina Sowicka, student at the Nicolaus Copernicus Center in Poland

The result of the observations contradicts current theories of the binary evolution according to which z formed the planetary nebula, the stars stay apart for a long time before they can interact again. When this happens, the nebula should have already dispersed to not be observed. However, a nova explosion observed in 2007, known as Nova Vul 2007 in another planetary nebula, challenged the model.

"In the case of M3-1, we see another candidate, who may experience a similar evolution, as the stars almost touch each other, it will not take long for interactions to recur and, perhaps, that we're producing a nova in a planetary nebula, "Jones concludes.