NASA's Hubble Just Captured the Last Violent Gasps of a Doomed Star

'The star is waging a tug-of-war between gravity and radiation pressure to avoid self-destruction.'
Brad Bergan
A gigantic nebula in two stages of decay.ESA / Hubble and NASA, A. Noa, C Britt  

If you're going out, you might as well do it not with one bang, but several.

Earlier in 2021, NASA celebrated Hubble's 31st anniversary by releasing an unprecedented image of the wildly unstable star AG Carinae. But now, researchers have taken another look at the star to reveal different views from 2020 and 2014, revealing an unprecedented window into the last gasps of a dying star, according to a recent blog post on NASA's official website.

And it's absolutely magnificent.

A dying star will endure continued outbursts until it exhausts its fuel

The initial view of the star revealed the ionized hydrogen and nitrogen pushed out by the star, which coheres into a shell surrounding the hot core. This shell has continued to expand while the gasses are released into space. The left side of the image above depicts ionized hydrogen and nitrogen emissions in this shell, while the second image (on the right) is in blue, showing how the dust reflects starlight. Astronomers suspect the visible dust bubbles and stretched-out filament were shaped by potent stellar winds flaring out from the star. Roughly five light-years wide, the nebula's size is roughly the same distance between Earth and the nearest star beyond the solar system, Proxima Centauri.

Technically classified as a Luminous Blue Variable star, AG Carinae is a very hot star. And, because of its colossal size, it's also rare. Luminous Blue Variable stars continually lose mass in the final stages of their lives. And this star is caught in "a tug-of-war between gravity and radiation pressure to avoid self-destruction," according to the NASA post. But, eventually, as it exhausts its supply of fuel, the radiation pressure will drop, and gravity will start to pull stellar material inward, where it will become hotter and hotter until it's ejected in an unthinkably large explosion, flooding into interstellar space. This violent end will continue until the dying star has lost enough mass to achieve a stable state.

The nebula's rings were pushed out of the center at roughly 124 miles per second

The astounding nebula surrounding AG Carinae is comprised of material blasted out of the star throughout many outbursts of the nebula's 10,000 years. The gas we can see is moving at roughly 43 miles (70 km) per second. And the ring or halo of gas formed as a result of an interior stellar wind that cleared the center by pushing out at roughly 124 miles (200 km) per second. That is very, very fast. The doubled effect of the rings could be caused by the collision of some outburst waves with other, earlier ones. Scientists who examined the star and its surrounding nebula also studied the non-spherical structure, which exhibits bipolar symmetry. This shape might point to a mechanism creating the outburst, caused by a disk in the center, or a companion star, called a binary.

AG Carinae could also simply rotate at unspeakably fast speeds, causing irregular, non-spherical shapes to form as gases are blasted outward by the solar wind. The universe is a beautiful place, but it's also a terrifying, violent one. Not every star dies in the relative obscurity of its local neighborhood, like our star will as its outer layers are eventually released into the surrounding space, long after the Earth is obliterated. Some, like AG Carinae, endure a long, eventful end that stands out in the universe as an extremely unique example of stellar death.

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