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Home / Science / Hubble Finds the Cause of Betelgeuse’s mysterious haze – Is the aging red Supergiant about to become a Supernova?

Hubble Finds the Cause of Betelgeuse’s mysterious haze – Is the aging red Supergiant about to become a Supernova?



Betelgeuse South is developing

This four-panel image illustrates how the southern region of the bright, fast-growing red supergiant Betelgeuse could suddenly become dimmer for a few months in late 2019 and early 2020. In the first two panels, as seen in the Hubble Space Telescope’s ultraviolet rays, a hot, bright plasma mass is emitted from the appearance of a giant convection cell on the star’s surface. In the third panel, the exhausted gases rapidly expand to the outside. It cools to form a giant cloud that conceals dust particles. The final panel shows a giant dust cloud blocking light (as seen from Earth) from a quarter of the star’s surface. Imaging providers: NASA, ESA and E. Wheatley (STScI)

Hubble discovered that Betelgeuse’s mysterious blurring was due to an outbreak of trauma

Observed by NASA‘S The Hubble Space Telescope is suggesting that the sudden dimming of the supergiant Betelgeuse is most likely due to a large amount of hot matter released into space, forming a cloud of dust that prevents the star’s light from emitting from the surface. by Betelgeuse.

Hubble researchers believe that dust clouds form in metaphysics plasma radiated from a large layer of convection cells on the star’s surface passing through a hot atmosphere to the colder outer layers, where it cools and forms dust particles. The resulting dust cloud blocked light from about a quarter of the star’s surface, starting in late 2019. By April 2020, the star would return to normal brightness.

Betelgeuse is a red, old, supergiant star that has swelled in size due to complex changes, growing in a nuclear fusion furnace at its core. The star is now so large that if it replaced the Sun at the center of the solar system, its outer surface would extend beyond its orbit. Jupiter.

An unprecedented phenomenon for Betelgeuse’s large opacity, which is finally noticeable even with the naked eye, began in October 2019. By mid-February 2020, the monster star had lost more than two-thirds. its brightness.

This sudden dimming has puzzled astronomers, who have been trying to develop some theory for the sudden change. One idea is that a large, cool, dark “star spot” covers a wide area of ​​the visible surface. But Hubble’s observations, led by Andrea Dupree, deputy director of the Center for Astrophysics | Harvard & Smithsonian (CfA), Cambridge, Massachusetts, suggests a cloud of dust covers part of the star.

Hubble’s few months of observations of the Hubble ultraviolet light spectrum for Betelgeuse, which began in January 2019, yielded a timeframe for darkness. These observations provide important new clues about the mechanism behind blurring.

Hubble recorded signs of hot, dense matter moving through the star’s atmosphere in September, October, and November 2019. Then, in December, some of the telescopes were on the ground has observed a dimly lit star in its southern hemisphere.

“With Hubble, we see matter as it leaves the visible surface of the star and moves out into the atmosphere, before the dust forms, making the star appear to fade,” said Dupree. “We can see the effect of a hot, dense region southeast of the star moving outward.

“This material is two to four times brighter than a star’s normal luminosity,” she continued. “And then, for about a month, the southern part of Betelgeuse blurred conspicuously as the star faded. We think it is possible that a dark cloud is the result of a stream that Hubble detected. Only Hubble provided us with evidence that led to blurring.

The group’s article will appear online today (August 13, 2020) in Journal of Astrophysics.

Supergiants like Betelgeuse are important because they push heavy elements like carbon out into space, which become the foundation of new generations of stars. Carbon is also a fundamental component of life as we know it.

Look for a traumatic outbreak

Dupree’s team began using Hubble early last year to analyze the giant star. Their observations are part of a three-year Hubble study to track variations in the star’s outer atmosphere. Betelgeuse is an expansive and contracting variable star, bright and dim at a period of 420 days.

Hubble’s ultraviolet light sensitivity allows researchers to probe layers above the star’s surface, where it’s very hot – more than 20,000 degrees. degrees Fahrenheit – they cannot be detected at visible wavelengths. These layers are partially heated by the star’s turbulent convection cells that bubbles up to the surface.

The Hubble spectroscopy, taken in early and late 2019, and in 2020, probed the star’s outer atmosphere by measuring the magnesium II lines (single ionized magnesium). In September to November 2019, the measured researchers moved the document about 200,000 miles per hour away from the star’s surface into its outer atmosphere.

This hot, dense material continues to go beyond the visible surface of Betelgeuse, reaching millions of miles from the boiling star. At that distance, the material cools enough to form dust, researchers say.

This interpretation is consistent with Hubble’s ultraviolet light observations in February 2020, which show that the activity of the atmosphere outside the star returns to normal, despite the visible light images. shows it’s still blurred.

Although Dupree did not know the cause of the explosion, she assumed it was aided by the star’s pulse cycle, which continued to normal despite the event, as recorded by visual light observations. see. The paper’s co-author, Klaus Strassmeier, of the Leibniz Potsdam Institute for Astrophysics, used the institute’s automated telescope, the STELLar Activity (STELLA), to measure changes in the velocity of the gas on the surface. the star’s face as it rises and falls during cycling impulses. The star is expanding in its cycle at the same time as the convection cell forms. The outgoing ripple impulse from Betelgeuse may have helped push the plasma out into the atmosphere.

Dupree estimates that about twice the amount of normal matter from the southern hemisphere was lost in the three months of the blast. Betelgeuse, like all stars, always loses mass, in this case at speeds 30 million times higher than that of the Sun.

Betelgeuse is so close to Earth and so large that Hubble was able to analyze surface features – making it the only star like that, except for our Sun, where surface details are visible.

A Hubble image taken by Dupree in 1995 for the first time showed a speckled surface of giant convective cells that contracted and swelled, causing them to darken and light up.

Supernova precursor?

The red supergiant is destined to end its life in a supernova explosion. Some astronomers think that the sudden dimming could be a pre-supernova event. The relatively close star, about 725 light years away from us, means that dimming will occur around 1300. But its light is only now reaching Earth.

“Nobody knows what a star does right before it forms a supernova, because it has never been observed,” Dupree explained. “Astronomers have sampled stars maybe a year before they become supernovae, but not in the days or weeks before it happens. But the likelihood that the star will soon become a supernova at any time is quite small. “

Dupree will have another chance to observe the star with Hubble in late August or early September. Currently, Betelgeuse is in the daytime sky, too close to the Sun to be observable via Hubble. But NASA’s Solar Ground Relations Observatory (STEREO) has captured an image of the monster star from its position in space. These observations suggest that Betelgeuse faded again from mid-May to mid-July, though not as dramatically as it was earlier this year.

Dupree hopes to use STEREO for follow-up observations to track Betelgeuse’s brightness. Her plan is to observe Betelgeuse again next year with STEREO as the star expands outward during its cycle to see if it will cause another petulant explosion.

References: “Spatially resolved ultraviolet spectroscopy of Betelgeuse great opacity” by Andrea K. Dupree, Klaus G. Strassmeier, Lynn D. Matthews, Han Uitenbroek, Thomas Calderwood, Thomas Granzer, Edward F Guinan, Reimar Leike, Miguel Montargès, Anita MS Richards, Richard Wasatonic and Michael Weber, August 13, 2020, Journal of Astrophysics.
DOI: 10.3847 / 1538-4357 / aba516




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