Eta Carinae is a binary pair of stars, located roughly 7,500 light-years away from our own Sun. As they orbit around each other, they cause matter near their center to radiate in X-rays. The most massive of these stars is the largest within 10,000 light-years.
Computer engineers at NASA's Goddard Space Flight Center have now produced a 3D model of the binary star system, which could answer questions about how the X-ray peaks are produced.
Every five-and-a-half years, the two stellar bodies approach as close as 140 million miles from each other, roughly the distance between Mars and our own local star. When this occurs, the process creates a spike in X-ray emissions, which can be recorded from the Earth.
The Homunculus Nebula was created during an outburst seen on Earth 170 years ago. Astronomers first noticed the system was growing brighter in 1820. Within seven years, the binary system was producing so much light, it was seen as the second-brightest star in the sky. Even today, astronomers are uncertain why this event and a similar earlier occurrence took place.
Hubble Space Telescope images, as well as observations from other instruments, were collected to produce the most detailed model ever developed of the stellar system. The new model reveals how the system interacts with itself and the surrounding nebula.
"We are coming to understand the present state and complex environment of this remarkable object, but we have a long way to go to explain Eta Carinae's past eruptions or to predict its future behavior," Ted Gull, an astrophysicist at Goddard who spent a decade studying the system, said.
The primary star in the system is cooler and brighter than its companion, roughly 90 times as massive as our sun, and 5 million times more luminous. Statistics are less certain for the other star in the system, but it may have a mass around 30 times that of our parent star, and radiate 1 million times as much light. Both stars produce vast numbers of charged particles, similar to the solar wind from the sun. Clouds of gas are racing away from the larger stars at up to 1 million miles an hour.
As the smaller star races around its larger companion, the motion creates a spiral cavity in the particles racing from the more massive star. Computer models and physical re-creating, produced on a 3D printer, revealed the long tendrils at the edge of the cavity.
"We used past observations to construct a computer simulation, which helped us predict what we would see during the next cycle, and then we feed new observations back into the model to further refine it," Thomas Madura, an astrophysicist working on the program at Goddard, said.