Dust cloud behind dimming of massive star Betelgeuse, scientists say.

Extract from ABC News

Posted 5hours ago, updated 3hours ago

This graphic illustrates how the southern region of the supergiant star Betelgeuse may have suddenly become fainter.(Supplied: NASA/ESA and E Wheatley)

Astronomers have determined the cause of the dramatic dimming observed last year and earlier this year of one of the brightest stars in the night sky, a colossus called Betelgeuse that appears to be on its way toward a violent death.

Key points:

• If placed at the centre of our solar system, Betelgeuse would extend to the planet Jupiter
• Scientists suspect Betelgeuse is nearing the end of its life cycle
• It is located relatively near our solar system

Based on Hubble Space Telescope observations, scientists said they believe Betelgeuse ejected a huge hot, dense cloud of material into space that cooled to form dust, shielding the star's light and making it appear dimmer from the perspective of viewers on Earth.

Betelgeuse is classified as a red supergiant, the largest type of star. It is more than 10 times the mass of our sun.

If it resided at the centre of our solar system, its surface would extend to the planet Jupiter.

This artist's illustration imagines how Betelgeuse might look up close.(NASA: ESO, L Calcada)

Scientists suspect Betelgeuse — pronounced "beetle juice" — is nearing the end of its life cycle when it will use up its nuclear fuel and explode, relatively soon in cosmic terms, in an event known as a supernova.

"Frankly, we don't know for sure how soon Betelgeuse will go supernova," said astrophysicist Andrea Dupree, director of the Solar Stellar Planetary Sciences Division at the Harvard-Smithsonian Center for Astrophysics and leader of the research published this week in the Astrophysical Journal.

"It is likely not in our lifetimes. But, we do not know how a star behaves the week before, the night before it explodes," Ms Dupree added.

Supergiant Betelgeuse (top left) is one of the brightest stars in the Orion constellation.(Wikipedia: Rogelio Bernal Andreo)

In a supernova, huge stars like Betelgeuse expel large amounts of heavy elements, including carbon, oxygen, calcium and iron, into space that become building blocks of new generations of stars.

Betelgeuse is located relatively near our solar system, about 725 light-years away. A light-year is the distance light travels in a year, 9.5 trillion kilometres.

Its dimming began last October and by mid-February had lost more than two-thirds of its brilliance.

It returned to its usual brilliance by April but may be dimming again, which researchers are working to confirm.

Reuters