Chapter 4: Eta Carinae
Of the estimated three hundred billion stars in our galaxy, Eta Carinae may well be the biggest and brightest of them all. Weighing in at 150 times the mass of our Sun, it is five million times as luminous!
Huge stars like Eta Carinae have very short, turbulent lives. In the 1840s, Eta Carinae became unstable and blew off as much gas as ten Suns. At the same time, it released as much visible light as a supernova, which usually destroys a star. Eta Carinae survived the explosion, but the outburst produced two expanding lobes of hot gas that continues to expand outwards at over two million kilometers (12 million miles) per hour.
Figure 10: Eta Carinae - visible image. This image, by the Hubble Space Telescope, shows two huge billowing lobes of gas and dust expanding in opposite directions at two and eight o'clock. between them is the very active central star which is hidden deep within a dusty shroud. The lobes are surrounded by a less dense cloud of dust and gas depicted with a thin line boundary. Each lobe is bigger than an entire solar system.
Figure 11: Eta Carinae - infrared image. the infrared emission of Eta Carinae originates from dust ejected by the star during several huge outbursts within the past several hundred years. the dust produced by stars can by silicate (like sand) or carbon (like oot). the infrared image is the same scale as the optical image. The highest intensity infrared emission comes from the central region around the equator of the central star, where the dust is thickest and represented as a speckled texture. the diagonal lines within the outermost boundary line denote the coolest layer of infrared emision.
Figure 12: Eta Carinae - radio image. this image is the same scale as the optical and infrared. The highest intensity comes from the region closest to the central star. The radio emission is generated as the intense winds of hot gas leaving the star smash into the surrounding dusty gas.
Figure 13: Eta Carinae - X-ray image. this image, taken by the Chandra Observatory, is zoomed out from the previous three views, all of which fit in the central spot or nebula, a cloud of gas that surrounds this central star. As you touch the image, you can identify a horseshoe-shaped region of ultra-hot gas surrounding the nebula way beyond the dusty lobes imaged by Hubble. This gas, at a temperature of three million degrees Celsius (five million degrees Fahrenheit) and spanning two light years, was ejected by Eta Carinae in a previous explosive outburst.
Eta Carinae will end its life with an immense supernova explosion. It could happen any day! Let's now take a look at two former superstars that have already suffered that fate.