The new model will help researchers understand how the expanding cloud of gas around the two stars formed. Credit: NASA Goddard Space Flight Center, inset: NASA, ESA, Hubble SM4 ERO Team
An international team of astronomers has created the first high-resolution 3D map of the Homunculus Nebula that surrounds the Eta Carinae binary system.
The model will help researchers understand how the expanding cloud of gas around the two stars formed.
Eta Carinae is the one of the most massive binary systems known to astronomers, but it used to be even bigger.
Between 1838 and 1845 the system underwent an unusual variation, brightening so much that it briefly became the second brightest star in the sky after Canopus.
During this time the star expelled a huge amount of gas, perhaps as much as 40 solar masses.
This gas formed a double lobed dust filled cloud known as the Homunculus Nebula, which is now around a light year long and expanding at more than 2.1 million km/h.
The team were able to calculate the velocity of the gas as it moved away from the nebula, and translate this into a 3D model.
The new model shows several features that previous studies have found, including pronounced holes at the end of each lobe, while finding some new features, such the curious arm-like protrusions emanating from each lobe near the centre and deep trenches curving along each end.
“Our model indicates that this cast shell of gas and dust has a more complex origin than is generally assumed,” said Thomas Madura, a NASA Postdoctoral Program fellow and a member of the study team.
“For the first time, we see evidence suggesting that intense interactions between the stars in the central binary played a significant role in sculpting the nebula we see today.”
Star ships in the night
Every 5.5 years the two stars undergo their closest pass, at around the distance between Mars and the Sun.
As they pass each other the stellar winds from the two stars interact with each other and a relic of such an interaction in the 19th century is imprinted on the Homunculus Nebula.
“Previous efforts to explain its shape have assumed that both lobes were more or less identical and symmetric around their long axis,” says team member Jose Groh from Geneva University in Switzerland.
“The new features strongly suggest that interactions between Eta Carinae’s stars helped mould the Homunculus.”
If you have access to a 3D printer you can get an even closer look at the model as NASA have also converted the data in to a format that can be downloaded and printed at home.
Download the file here.