Credit: ESA/Hubble, NASA, A. Nota and C. Britt
Two images show puffing dust bubbles, and an erupting gaz shell-the last acts of a monster star’s life.
These views show the dual nature and beauty of star AG Carinae which was the subject of the NASA/ESA Hubble Space Telescope 31st anniversary image in 2021. This new perspective is the result Hubble's observations in 2020 and 2014. It also includes other images taken by the telescope's Wide Field Planetary Camera 2 (in 1994).
The first image shows details of ionized nitrogen and hydrogen emissions from the expanding shell (shown in red). The second image shows the distribution of dust in the reflected starlight. Astronomers believe that the filaments and dust bubbles were formed by powerful stellar winds from the star. The nebula measures approximately five light-years across, which is roughly the distance between here and the nearest star beyond Sun, Proxima Centauri.
AG Carinae, a luminous-blue variable, is officially classified because it is a bright star with varying brightness and hot emission. These stars are rare as they are very few in number. In the last stages of their lives, luminescent blue variable stars lose mass continuously. To avoid self-destruction, the star is engaged in a tug of war between radiation pressure and gravity. The star's radiation pressure begins to decrease as gravity takes hold. Gravitation forces the material to fall inward. It then heats up and explodes into interstellar space. The process continues until the star loses enough mass and is stable.
Credit: ESA/Hubble, NASA, A. Nota and C. Britt
AG Carinae's spectacular nebula was formed from material that the star ejected during its previous outbursts. The gas velocity is 43 miles per second and is approximately 10,000 years old. Although it looks like a ring of gas, the nebula is actually a hollow shell that was emptied of dust and gas by a strong stellar wind at 124 miles per seconds. These images show the gas, which is mainly composed of ionized nitrogen and hydrogen, as a thick red ring. This may be due to multiple outbursts colliding with each other. This blue-colored dust was formed by the stellar winds in clumps.
Scientists who have observed the star and the surrounding nebula noted that the ring may not be perfectly spherical. It seems to exhibit bipolar symmetry. This could indicate that the mechanism causing the outburst might be caused by a disk in its center or that the star may have an accompanying star (known as a binary Star). Alternate theories suggest that AG Carinae, like many large stars, may spin very quickly.
Continue reading Hubble captures a giant star at the edge of disaster
