It will be visible to the naked eye only for a few days . The white dwarf RS Ophiuchi will be visible because it has just experienced a huge thermonuclear explosion that has transformed it into a nova, an event that takes place every 15 years and that multiplies its brightness by seven (hence the reason why it is visible to the eye naked despite being 4,566 light years distant from our planet).
An epic eruption, seen from Earth
Located in the constellation Ophiuchus (the snake hunter), the star’s eruption has caused it to go from being a magnitude 12 object to a magnitude 4.8 on the scale used by astronomers to determine how visible something will be. being observed from Earth . The naked eye limit for humans is magnitude 6.5, but this can vary based on light pollution levels. This erupting star, RS Ophiuchi, is a rare type of stellar phenomenon, as we have so far only discovered 10 in the Milky Way, out of the 100 billion stars in our galaxy.
Why every 15 years?
It is a recurring nova. The regular and repeating novae are the result of the fact that RS Ophiuchi is a binary star, a white dwarf in a close orbit with a red giant. When this time passes, the mass of the white dwarf increases so much that the pressure and temperature in a hydrogen layer on the surface of the white dwarf, cause a thermonuclear explosion, which violently expels all the excess of absorbed material, producing a nova. The most recent nova of this system (RS Oph) was in 2006, but known bursts of the star date back to 1898.
According to spectroscopic observations of the star, the brightness is consistent with a nova, so violent that matter is being ejected into space at speeds of around 2,600 kilometers per second.
If the white dwarf accumulates so much mass that it exceeds a vital mass threshold known as the Chandrasekhar limit , it will become unstable and explode in a Type Ia supernova, but it is not something that will happen anytime soon. It will take about 100,000 years, when the red dwarf accumulates enough mass to reach a critical mass.
How do I find it?
The constellation Ophiuchus is currently in the south after sunset , above the better-known constellation Sagittarius and its familiar Teapot asterism, which is closer to the horizon. If you look over Teapot Peak and cross the cloudy strip of the Milky Way, you will reach the region of the sky where RS Oph is located. Seeing it with the naked eye will likely require us to be in an area of low light pollution, with dark skies, and it will be visible to the south after sunrise for a few weeks, astronomers say.
It will be another 15 to 20 years before it accumulates enough material for another explosion of nova, that is, in the mid-2030s.
