It had to a light echo, giving the illusion of moving through time because each flash was reaching Earth at a different time after bouncing off dusty clouds. Comparison with historical records showed it was a remnant from Eta Carinae's Great Eruption.
The color image at left shows the Carina Nebula, a star-forming region located 7,500 light-years from Earth. (Eta Carinae is near the top.)
The three black-and-white images pictured here show light from the eruption illuminating dust clouds as it moves through them. The images were taken over an eight-year span by the U.S. National Optical Astronomy Observatory's Blanco 4-meter telescope at the CTIO.
This new study has already found some intriguing anomalies in Eta Carinae's behavior compared to its fellow luminous blue variables, using spectroscopy, which gives a detailed "fingerprint" of stars telling astronomers the temperature and speed of ejected material.
For instance, the temperature of its outflow is much cooler that usual, around 8500 degrees Fahrenheit (5,000 Kelvin). Rest and his colleagues are revisiting their models for such stars to determine how this behavior might have occurred. They will continue to monitor Eta Carinae, and expect to see more brightening in six months or so, matching a similar period outburst in 1844.