NASA's Chandra rewinds story of great eruption of the 1840s

Astronomers have discovered crucial new information on an eruption from Eta Carinae that was observed on Earth in the middle of the 19th century, thanks to images captured over a 20-year period with NASA's Chandra X-ray Observatory.

Ten years' worth of Chandra data have been merged into a new video with frames from 1999, 2003, 2009, 2014, and 2020 of Eta Carinae. Using information from ESA's (European Space Agency) XMM-Newton and Chandra images, astronomers are able to track the star eruption that occurred 180 years ago as it continues to explode into space at velocities of up to 4.5 million miles per hour. Eta Carinae has provided fresh insights into how various space observatories might collaborate to support our understanding of changes in the cosmos that occur on human timescales.

These findings are published in The Astrophysical Journal in a publication.

Two enormous stars, one around 90 times the mass of the sun and the other estimated to be about 30 times the mass of the sun, are part of the Eta Carinae system. Astronomers have named the massive explosion that occurred in the middle of the 19th century on Eta Carinae the "Great Eruption." Eta Carinae expelled material that was between 10 and 45 times the mass of the sun during this event. On opposite sides of the two stars, this material developed into a dense pair of spherical clouds of gas known as the Homunculus Nebula.

About half a century ago, a brilliant X-ray ring surrounding the Homunculus Nebula was identified and examined in earlier Chandra research. Important clues about the turbulent past of Eta Carinae are revealed by the Chandra's latest movie and a deep image created by combining the data, including the ring's quick growth and a faint shell of X-rays that was previously unidentified.

Leading the study was Michael Corcoran of NASA's Goddard Space Flight Center in Greenbelt, Maryland. "We've interpreted this faint X-ray shell as the blast wave from the Great Eruption in the 1840s," Corcoran said. "It reveals a significant portion of Eta Carinae's past that we would not have known otherwise."

Corcoran and colleagues believe that the Homunculus Nebula and the recently found outer X-ray shell have a common ancestor because to their comparable shapes and orientations.

It is hypothesized that material was expelled from Eta Carinae far in advance of the 1843 Great Eruption, i.e., between 1200 and 1800, based on the mobility of gas clumps previously observed in Hubble Space Telescope data. The brilliant X-ray ring was later formed as the rapid blast wave from the Great Eruption tore through space, meeting with the clumps and scorching them to millions of degrees. Now the blast wave is past the luminous ring.

According to co-author Kenji Hamaguchi, a researcher at NASA Goddard and the University of Maryland, Baltimore County, "the shape of this faint X-ray shell is a plot twist." "It indicates that the bright inner ring, the Homunculus, and the faint shell are probably all products of star system eruptions."

Using XMM-Newton, the scientists observed that Eta Carinae's X-ray brightness has decreased over time, which is consistent with earlier system studies made using NASA's Neutron Star Interior Composition Explorer (NICER) instrument on the International Space Station. The brightness of Eta Carinae in X-rays during the time of the Great Eruption was estimated by the authors using a straightforward model. They then coupled this estimate with the material's speed, which they calculated based on the video, to calculate the rate at which the high-speed gas was expelled.

Based on this data and an approximation of the gas released, the researchers concluded that the Great Eruption was most likely the result of two explosions. The X-ray blast wave was originally created by a brief expulsion of a little quantity of rapid, low-density gas. The slower outflow of dense gas that ultimately resulted in the formation of the Homunculus Nebula came next.

One of the co-authors of the new X-ray research, Nathan Smith of the University of Arizona, leads a team that has previously proposed that the Great Eruption was produced by the merging of two stars in what was formerly a triple system. Since it would result in material being ejected in a flat plane, this would also explain the ring-like shape visible in X-rays.

Smith remarked, "The Eta Carinae story just keeps getting more interesting." "Every piece of evidence points to Eta Carinae surviving a massive explosion that would typically destroy a star. I'm eager to see what further surprises Eta Carinae has in store for us in the upcoming data installment."

Provided by NASA