An orbiting NASA observatory has picked up signs that several stars exploded as supernovas in the last few million years, and more are coming, making the region a kind of 'supernova factory.'

The Chandra X-Ray Observatory observes the sky in high-energy, X-Ray wavelengths that can't be detected at the surface. It has picked up new data from the Carina Nebula, in the constellation of the same name (it is visible from the southern hemisphere). The nebula is a mix of gas, dust and massive, hot young stars about 7,500 light years away. Most of the stars that form in such a nebula will be much more massive than the sun. When they run out of fuel they explode as supernovas and leave behind neutron stars, which are made of material so dense that a cubic centimeter of it weighs a metric ton.

Chandra has found more than 14,000 stars in this region. It also revealed a diffuse X-ray glow, as well as six possible neutron stars when previous observations had only detected one neutron star in Carina. In addition, when Chandra looked at the star clusters in the nebula, there seemed to be a lack of bright, point X-ray sources.

Junfeng Wang from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., said that makes a case that a large number of stars have already exploded. These stars were likely between 20 and 40 times the mass of the Sun and would have exploded in the last few million years, which is very recent in cosmic terms.

Neutron stars in star-forming regions like Carina are difficult to see because the low-energy X-rays that they give off tend to be absorbed by gas and dust. That means the detected neutron stars probably represent only a small fraction of the whole population, providing more evidence that supernova activity is ramping up. The diffuse X-ray glow is also evidence of past supernovas.

Eta Carinae, the star that marks the nebula in the sky, is likely to be one of the stars that goes supernova soon - meaning in the next few million years. It is a massive, unstable star. When it does explode, it will likely be a spectacular light in the Earth's sky. These latest results suggest Eta Carinae is not alone.

Supernovas play an important role in the evolution of galaxies and planetary systems, because they are the source of most of the chemical elements in the universe heavier than iron. They also seed the rest of space with elements such as carbon, oxygen and nitrogen, and can nudge gas clouds into collapsing to form new star systems.