That was said by Elias Aydi, an astronomer at Michigan State University in East Lansing, who led a team from 40 international institutions to observe the brightening of a nova. To do so, they had the help of NASA’s Fermi and NuSTAR space telescopes, and the Canadian BRITE-Toronto satellite, and reviewed stellar explosions.
Each year, scientists discover about ten novae. They are unobtrusive stars living a conventional life in a binary system when suddenly, an inside stream of hydrogen from their companion is expelled towards the unobtrusive star creating an explosion. And this is when the ugly duck becomes the nova-swan that takes everyone’s breath away. The eruption has an energy 10,000 to 100,000 times energy our Sun outputs in a year.
The nova outburst was captured by the satellites in 2018. It occurred some 13,000 light-years away, in the constellation Carina. The nova was named V906 Carinae. The novelty his nova brought is that scientists finally figured out that it is the shock waves that are responsible for the explosion’s visible light.
Shock waves from stellar explosions
“We were able to gather the best-ever visible and gamma-ray observations of a nova to date. The exceptional quality of our data allowed us to distinguish contemporary flares in both optical and gamma-ray light, which provides smoking-gun evidence that shock waves play a major role in powering some stellar explosions,” was Aydi’s complete statement.
Since 2010, when Fermi Telescope first detected a nova, shock waves were observed in the debris, but the conclusion that the shock waves generate gamma rays responsible for the visible light is new. Novae weren’t considered to be that strong as to produce the kind of acceleration required.
Aydi and his team’s conclusion confirm a former theory that was saying that shock waves are responsible for a more significant part of the eruption’s light than the stellar explosions themselves. The method belongs to Kwon-Lok Li at Michigan State and dates back in 2017.