The NASA/ESA Hubble Space Telescope turned 31 this year, and for the occasion, the Hubble team has just released a beautiful image of the luminous blue variable star AG Carinae. AG Carinae is located approximately 20,000 light-years away in the constellation of Carinae. The star is a few million years old and its expected lifetime is between 5 and 6 million years. AG Carinae is surrounded by an expanding shell of gas and dust that is shaped by the powerful winds of the star. This nebula is about 5 light-years wide, which equals the distance from here to our nearest star, Alpha Centauri. The huge structure was created from one or more giant eruptions several thousand years ago. AG Carinae’s outer layers were blown into space, the expelled material amounting to roughly 10 times the mass of our Sun. These outbursts are typical in the life of a rare type of star called a Luminous Blue Variable (LBV).
This Hubble image shows AG Carinae, a luminous blue variable star some 20,000 light-years away in the constellation of Carinae. The color image was made from separate exposures taken in the visible and ultraviolet regions of the spectrum with Hubble’s Wide Field Camera 3 (WFC3) instrument. Four filters were used to sample various wavelengths. The color results from assigning different hues to each monochromatic image associated with an individual filter. Image credit: NASA / ESA / STScI.
These stars have a dual personality. They appear to spend years in semi-quiescent bliss and then they erupt in a petulant outburst, during which their luminosity increases — sometimes by several orders of magnitude. AG Carinae is estimated to be up to 70 times more massive than our Sun and shines with the blinding brilliance of one million suns. Major outbursts such as the one that produced the nebula featured in this image occur a few times during a LBV’s lifetime. LBV stars are rare: fewer than 50 are known among the galaxies in our local group of neighboring galaxies. These stars spend tens of thousands of years in this phase, a blink of an eye in cosmic time. Some are expected to end their lives in titanic supernova blasts, which enrich the Universe with the heavier elements beyond iron.