A star that exploded almost 200 years ago can now be examined in magnificent detail at different wavelengths. In a new video, a team of scientists modeled the Homunculus Nebula around the star Eta Carinae in three dimensions, providing insight into this incredible event.
The binary system Eta Carina began erupting in the late 1830s and by the early 1840s had become one of the brightest stars in the night sky. The gas and dust thrown out by this eruption into the space around the double star is known as the Homunculus Nebula, the gradual expansion of which obscured the star so that it could not be seen at all with the naked eye.
The amazing double-lobed shape of the Homunculus Nebula could help us better understand the eruptions of massive binary stars and how such nebulae propagate through space. At only 7500 light-years away, this is one of the closest examples of this type of system, so we’ve studied it a lot.
The new models are a continuation of these studies of the giant structure. The Hubble and Chandra observations revealed details in the visible, ultraviolet, and X-rays, while the Spitzer Space Telescope provided infrared wavelengths of the wider Carina Nebula for a holistic reconstruction.
“The team has done such an amazing job representing the volumetric layers that viewers can immediately and intuitively understand the complex structure around Eta Car,” said astronomer Frank Summers, chief imaging officer at the Space Telescope Science Institute (STScI).
“We can not only tell the story of the Great Eruption, but also show the resulting nebula in 3D.”
Due to the fact that this region is very dusty, it is difficult to get very detailed information about the stars themselves. We know that there are at least two stars, both blue giants. The mass of one is about 100 times the mass of the Sun, the other is 30–80 times the mass of the Sun. They revolve around each other every 5.5 years.
Such stars are rather short-lived and will periodically flare up during their short lives. But the Great Eruption of the 1840s was more like a supernova, which led astronomers to believe that the system was originally a triple, and perhaps the flare was the result of the collision and merger of two of the three stars. This could explain several unresolved questions, including how one of the stars could be so much more massive than the other.
Eta Carinae is now visible to the naked eye again (depending on the level of light pollution). Astronomers believe it could end its life in a massive supernova, which in turn could witness the formation of a stellar-mass black hole.
However, given that we know little about the stars themselves, the future of the binary system is difficult to predict. In addition, stars in close stellar binary systems can destabilize each other and disrupt the normal course of events.
This means that Eta Carinae could not only help us understand massive stars, but also open a window into the weirdness of massive, close binary systems. Researchers can also use the data to create physical ways to study the nebula. It’s not just a learning tool; sometimes the accessibility of cosmic phenomena to our other senses, such as hearing or touch, can lead to new discoveries.
“We can take these models, such as the model for Eta Car, and use them in 3D printing and augmented reality programs,” said imaging specialist Kim Arcand from the Chandra X-ray center. “This means that more people can access the data – literally and virtually – and this leads to better learning and engagement.”
You can explore Eta Carinae in more detail on the Universe Unplugged website.