Exploring the Great Eruption of Eta Carinae with NASA's Chandra X-Ray Observatory
Key Highlights :
Since the mid-19th century, astronomers have been captivated by the stellar eruption of Eta Carinae, a binary system containing two massive stars. Now, with the help of NASA's Chandra X-Ray Observatory, astronomers have been able to take snapshots of the system over the past 20 years and learn important new details about the eruption.
Combining data from Chandra and the European Space Agency's XMM-Newton, astronomers have created a movie of Eta Carinae from 1999, 2003, 2009, 2014, and 2020. This movie has revealed that the stellar eruption from 180 years ago continues to expand into space at speeds of up to 4.5 million miles per hour.
The observations have also revealed a bright ring of X-rays around the Homunculus Nebula, which was discovered about 50 years ago and studied in previous Chandra work. The movie and a deep image generated from the data have shown hints about Eta Carinae's volatile history, including rapid expansion of the ring and a previously unknown faint shell of X-rays outside it.
The faint X-ray shell is believed to be the blast wave from the Great Eruption in the 1840s. The shape of the shell is similar to the Homunculus Nebula, suggesting that both structures have a common origin. The idea is that material was blasted away from Eta Carinae sometime between 1200 and 1800, and then the fast blast wave from the Great Eruption tore through space, colliding with and heating the clumps to millions of degrees to create the bright X-ray ring.
The researchers also found that the X-ray brightness of Eta Carinae has faded with time, and applied a simple model to estimate how bright Eta Carinae was in X-rays at the time of the Great Eruption. Combining this information with an estimate of how much gas was ejected, the researchers determined that the Great Eruption likely consisted of two explosions. There was a first, quick ejection of a small amount of fast, low-density gas which produced the X-ray blast wave, followed by the slower ejection of dense gas that eventually formed the Homunculus Nebula.
The new insights gleaned from Eta Carinae show how different space observatories can work together to help us understand changes in the universe that unfold on human timescales. The researchers hope that the next episode of data will reveal even more surprises about Eta Carinae.
