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Hubble captures a giant star on the brink of destruction. To celebrate the 31st anniversary of the launch of NASA’s Hubble Space Telescope, astronomers pointed the famous observatory at a spectacular “famous star”, one of the brightest stars seen in our galaxy, made up of gas and dust surrounded by a halo resplendent.

The price for Monster Star opulence is “living on the edge.” The star, AG Carinae, is a tug of war between gravity and radiation to prevent self-destruction.

To celebrate the 31st anniversary of the launch of NASA’s Hubble Space Telescope, astronomers pointed the famous observatory at a spectacular “famous star,” one of the brightest stars seen in our galaxy, made up of gas and dust, surrounded by a glowing halo.

The extended layer of gas and dust that surrounds the star is about five light-years wide, which is equal to the distance from here to the closest star beyond the Sun, Proxima Centauri.

The massive structure was formed about 10,000 years ago by one or more massive eruptions. The outer layers of the star flew into space, like a boiling kettle spilling from its lid. The ejected material is about 10 times the mass of our Sun.

These bursts are typical of a rare race of stars called the bright blue variable, a brief convulsive phase in the short life of an ultra-bright, glamorous star that quickly lives and dies young. These stars are among the most massive and brightest stars known.

They only live for a few million years, compared to our Sun’s lifespan of roughly 10 billion years. AG Carinae is a few million years old and resides 20,000 light-years away within our Milky Way galaxy.

The bright blue variables show a dual personality:

They seem to spend years in silent bliss and then erupt into a hilarious bang. These giants are extreme stars, very different from ordinary stars like our Sun. In fact, AG Carinae is estimated to be 70 times more massive than our Sun and shines with the luminosity of a million suns.

“I love studying stars like this because I am fascinated by their instability. They are doing something strange,” said Kerstin Weiss, a specialist in bright blue variables at the Ruhr University in Bochum, Germany.

These images are a combination of separate exposures obtained by the WFC3 / UVIS instrument on the Hubble Space Telescope. Various filters were used to sample narrow wavelength ranges. Color results from assigning a different hue (hue) to each monochrome (grayscale) image attached to a different filter.

Large explosions, such as nebulae, occur once or twice during the life of a bright blue variable. A bright blue variable star emits material only when it is in danger of self-destruction in the form of a supernova.

Due to their massive shapes and ultra-hot temperatures, bright blue variable stars like AG Carinae are in a constant battle to maintain stability.

It is a pulse competition between the radiation pressure from inside the star pushing it outward and the gravitational pressure inward. This cosmic union results in the expansion and contraction of the star.

External pressure sometimes wins the battle, and the star expands to such an enormous size that it is shed from its outer layers, like an erupting volcano.

But this burst occurs only when the star is about to collapse. After the star expels material, it shrinks to its normal size, settles down again, and cools down for a time.

Like many other bright blue variables, AG Carinae remains unstable. It has experienced fewer explosions that are not as powerful as those of the current nebula maker.

On April 24, 1990, in celebration of the 31st anniversary of the launch of NASA’s Hubble Space Telescope, astronomers aimed the famous observatory at a spectacular “famous star”, one of the brightest stars observed in our galaxy, surrounded by a glowing halo of gas. and dust.

Hubble Project Lead Scientist Dr. Jennifer Wiseman takes us on a tour of this amazing new image, describes the current health of the telescope, and summarizes some of Hubble’s contributions to astronomy over the past year.

Although AG Carinae is now silent, as a superhot star, it constantly ejects radiation and a powerful stellar wind (stream of charged particles). This outflow continues to shape the ancient nebula, creating complex structures as the outflow gas strikes the slow-moving outer nebula.

The wind travels at a speed of up to 670,000 mph (one million km / h), which is about 10 times faster than in the expanding nebula. Over time, the hot air captures the material ejected from the cooler, churns it, and moves it away from the star. This “snowplow” effect has cleared a cavity around the star.

The red substance is incandescent hydrogen gas which consists of nitrogen gas. Protruding red material in the upper left indicates where air has passed through a weak area of ​​material and thrown it into space. The most prominent features, highlighted in blue, are tadpoles and unilateral bubble-shaped filamentous structures.

These structures are masses of dust that are illuminated by the reflected light from the star. The tadpole-shaped features, most prominent on the left and below, are dense clumps of dust that have been sculpted by the stellar wind. Hubble’s keen view reveals these delicate-looking structures in great detail.

The image was taken with visible and ultraviolet light. Ultraviolet light offers a slightly clearer view of the filamentary dust structures that extend up to the star. Hubble is ideal for ultraviolet light observations because this wavelength range can only be observed from space.

Massive stars, like AG Carinae, are important to astronomers because of their far-reaching effects on their surroundings. The largest program in Hubble’s history, the Young Stars Ultraviolet Legacy Library as Essential Standards, is studying ultraviolet light from young stars and how their surroundings form.

Bright blue variable stars are rare: fewer than 50 are known among the Local Group galaxies of our neighboring galaxies. These stars spend thousands of years in this phase, in the blink of an eye in cosmic time. Many are expected to end their lives in titanic supernova explosions, which enrich the universe with elements heavier than iron.

Launched on April 24, 1990, NASA’s Hubble Space Telescope has made more than 1.5 million observations of nearly 48,000 celestial objects. During its 31 years of life, the telescope has orbited more than 181,000 orbits around our planet, totaling more than 4.5 billion miles.

The Hubble observations have produced more than 169 terabytes of data, available to current and future generations of researchers. Astronomers using Hubble data have published more than 18,000 scientific papers, of which more than 900 were published in 2020.

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