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Hubble solves the mystery of Monster Star dimming



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Last year, when the bright red superstar Betelguese in the Orion constellation faded sharply but then recovered, astronomers were puzzled. The dimming lasted for several weeks. Now, astronomers have set their sights on a giant star in the neighboring constellation Canis Major.

The red super giant VY Canis Majoris (larger, bigger, and more violent than Betelgeuse) experienced a longer period of dimness, which lasted for several years. New discoveries by NASA’s Hubble Space Telescope indicate that this super giant is undergoing the same process as betel nut, but on a larger scale.

The leader of the study, astrophysicist Roberta Humphreys of the University of Minnesota in Minneapolis, explained: “VY Canis Majoris performs similarly to Betelgeuse on steroids.”

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Like Betelgeuse, Hubble’s data also provides answers to why this larger star is dimming. For Betelgeuse, dimming corresponds to the outflow of gas that may form dust. From our point of view, this temporarily obstructs some of Betelgeuse’s light, resulting in a dimming effect.

Humphries said: “In VY Canis Majoris, we saw something similar, but on a larger scale. A large amount of material ejected corresponds to its very deep fading, which may be due to dust temporarily blocking the light emitted by the star. .”

The huge red supergiant star is 300,000 times brighter than our sun. If it replaces the sun in our own solar system, the swollen monster will stretch hundreds of millions of miles between the orbits of Jupiter and Saturn.

Humphreys explained: “This star is absolutely amazing. It is one of the largest stars we know. It is a very evolved red supergiant star. It has exploded in multiple huge eruptions.”

The huge arc of plasma surrounds the star, and the distance from the star is thousands of times farther than the distance between the earth and the sun. These arcs look like solar radiation from our own sun, but on a larger scale. Moreover, they are not physically connected to the stars, but look like they have been thrown away and are moving away. Some other structures close to the star are still relatively compact, looking like nodules and nebula-like features.

In previous Hubble works, Humphries and her team were able to determine when these large structures ejected from the stars. They found dates in the past few hundred years, and some dates in the last 100 to 200 years.

Now, in a new study with Hubble, researchers have solved the feature of being closer to a star, which may be less than a century old. By using Hubble to determine the speed and movement of hot gas and other characteristic offshore knots, Humphreys and her team were able to more accurately determine the dates of these eruptions. They made a surprising discovery: When VY Canis Majoris faded to one-sixth of its usual brightness, many of the knots were related to multiple episodes in the 19th and 20th centuries.

Unlike Betelgeuse, VY Canis Majoris is now drowsy and cannot be seen with the naked eye. The star was once visible, but it has dimmed so much that it can only be seen with a telescope now.

Superman loses 100 times the weight of betel nut. Some knots are more than twice the mass of Jupiter. Humphries said: “It’s amazing that this star can do this.” “The origin of these high-quality loss events in VY Canis Majoris and Betelgeuse may be due to large-scale surface activity, large convection like the sun. Cells. But on VY Canis Majoris, these cells may be as big as the whole cell. The sun or bigger.”

Humphries continued: “This may be more common among red super giants than scientists think, and VY Canis Majoris is an extreme example.” “It may even be the main mechanism that causes mass loss, which has always been A mystery of the red super giant.”

Although other red supergiants are relatively bright and emit a lot of dust, they are not as complicated as VY Canis Majoris. “So what’s special? VY Canis Majoris may be in a unique evolutionary state that distinguishes it from other stars. This may be an active state for a short period of time (maybe only a few thousand years). We will not I saw a lot of people around,” Humphries said.

The star’s life began with a super-hot, bright, blue supergiant star whose mass may be 35 to 40 times the mass of the sun. After a few million years, as the rate of hydrogen nucleus combustion changes, the star expands into a red supergiant star. Humphreys suspected that the star might briefly return to a warmer state and then expand back to the red supergiant stage.

Humphries explained: “Perhaps what makes VY Canis Majoris so special, so extreme, and so very complex ejection power may be that it is the second stage of the red super giant.” VY Canis Majoris may have been reduced by half. weight. It may not explode directly into a black hole, rather than explode as a supernova.

The team’s findings were published in the Astronomical Journal on February 4, 2021.

The Hubble Space Telescope is an international cooperation project between NASA and the European Space Agency (ESA). The NASA Goddard Space Flight Center in Greenbelt, Maryland manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland conducted the Hubble Science Experiment. STScI is operated for NASA by the Association of Universities for Astronomical Research in Washington, D.C.


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