The Eta Carinae system is one of the most massive and luminous stellar systems in the Milky Way, located approximately 7,500 light-years away within the Carina Nebula. It consists of at least two stars: a highly unstable luminous blue variable (LBV) primary star with an estimated mass exceeding 100 times that of the Sun, and a hot, luminous companion star of roughly 30 solar masses. The companion orbits the primary every 5.5 years along a highly eccentric path. Together, the system radiates more than five million times the energy output of our Sun, making it the most luminous stellar system within 10,000 light-years.

Eta Carinae is renowned for its extreme instability and violent outbursts. During the mid-19th century, it underwent the historic “Great Eruption,” becoming the second-brightest star in the night sky between 1843 and 1845, despite its vast distance from Earth. In this event, the primary star expelled at least 30 solar masses of gas and dust, forming the massive, expanding, bipolar Homunculus Nebula that now surrounds the system and obscures it from direct optical observation. Much of the starlight is absorbed by dense dust and re-emitted at infrared wavelengths, making Eta Carinae the brightest object in the mid-infrared night sky.

Astronomers study Eta Carinae across the electromagnetic spectrum—from radio waves to X-rays and gamma rays—to better understand the physics of extreme stellar environments. The powerful stellar winds from both stars collide at millions of miles per hour, heating surrounding material to millions of degrees and producing intense, variable X-ray emissions tied to their orbital cycle. Although its exact fate remains uncertain, Eta Carinae’s immense mass and instability suggest it will eventually end its life in a supernova or possibly a hypernova, leaving behind a black hole and creating a spectacular astronomical event visible from Earth.