Nearby supernova factory ramps up
The new Chandra survey revealed the presence of six possible neutron stars, providing strong evidence that the supernova activity is ramping up in the Carina Nebula.
May 25, 2011
A local supernova factory has recently started production, according to a wealth of new data from NASA’s Chandra X-ray Observatory on the Carina Nebula. This discovery may help astronomers better understand how some of the galaxy’s heaviest and youngest stars race through their lives and release newly forged elements into their surroundings.
A new Chandra image shows the famous Carina Nebula with 14,000 stars and a diffuse X-ray glow. Chandra X-ray Center
Located in the Sagittarius-Carina Arm of the Milky Way, a mere 7,500 light-years from Earth, the Carina Nebula has long been a favorite target for astronomers using telescopes tuned to a wide range of wavelengths. Chandra’s extraordinarily sharp X-ray vision has detected more than 14,000 stars in this region, revealed a diffuse X-ray glow, and provided strong evidence that supernovae have already occurred in this massive complex of young stars.
“The Carina Nebula is one of the best places we know to study how young, massive stars live and die,” said Leisa Townsley from Penn State University in University Park, Pennsylvania. “Now, we have a compelling case that a supernova show in Carina has already begun.”
One important piece of evidence is an observed deficit of bright X-ray sources in Trumpler 15, one of 10 star clusters in the Carina complex.
“This suggests that some of the massive stars in Trumpler 15 have already been destroyed in supernova explosions,” said Junfeng Wang from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. “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.”
The new Chandra survey also revealed the presence of six possible neutron stars — the dense cores often left behind after stars explode in supernovae — when previous observations had only detected one neutron star in Carina.
Neutron stars in star-forming regions are difficult to spot because low-energy X-rays that are easily absorbed by dust and gas characterize them. Therefore, the detected neutron stars probably represent only a small fraction of the complete population, providing strong evidence that the supernova activity is ramping up.
The diffuse emission observed by Chandra also supports the idea that supernovae have already erupted in Carina. Some of the diffuse X-ray emission almost certainly comes from the winds of massive stars, but some may also come from the remains of supernova explosions.
Another outcome from the new Chandra survey of Carina, which represents about 300 hours of observing time spread over 9 months, is a new population of young, massive stars. These stars had not been seen before because of obscuration or because they are located outside well-studied clusters.
“We may have doubled the number of known young, massive stars in Carina by looking this long with Chandra,” said Matthew Povich from Penn State. “Nearly all of these stars are destined to self-destruct in supernova explosions.”
Undoubtedly, the most famous constituent of the Carina Nebula is Eta Carinae, a massive, unstable star that may be on the verge of exploding as a supernova. When it does explode, it will likely be a spectacular — yet still safe — light in the Earth’s sky. These latest results suggest Eta Carinae is not alone in its volatility.
“Supernovas aren’t just eye-catching events, but they release newly-forged elements like carbon, oxygen, and iron into their surroundings so they can join in the formation of new objects like stars and planets,” said Townsley.