beforeitsnews.com/.../supergiant-star-to-explode-in-earths-neighborhood...
Jan 23, 2013 - Multiple arcs are revealed around Betelgeuse, the nearest red supergiant star to Earth, in this new image from ESA's Herschel space ...
Betelgeuse: The Eventual Supernova
Elizabeth Howell, SPACE.com Contributor | July 18, 2013 04:14am ET
|
This cool space wallpaper is a composite color image of
the Herschel PACS 70, 100, 160 micron-wavelength images of Betelgeuse.
Credit: ESA/Herschel/PACS/L. Decin et al
|
Betelgeuse is a star nearing the end of its life. Because it is
creating heavier and heavier elements in its core that could be used for
stars after it dies, a NASA story
once dubbed the red giant a workaholic.
The star is a famous one among amateur astronomers not only for its size and brightness, but also because it is part of
Orion, a bright winter constellation in the Northern Hemisphere.
Professional astronomers also keep a close eye on the star, as it is notoriously variable: its diameter changes from anywhere
between 550 to 920 times the sun's diameter. In 2013, astronomers said Betelgeuse is
likely to crash into a "cosmic wall" of interstellar dust in a few thousand years.
Locating Betelgeuse
Ancient astronomers would have easily spotted Betelgeuse because of its
size and relatively close distance from Earth: it is about 600
light-years away and has a variable brightness generally peaking at 0.4
and falling below 1.2. Some 20th-century observations by the American
Association of Variable Star Observers suggested
peak magnitudes of 0.2 in 1933 and 1942. It is the
12th brightest star in the night sky. The star's location is:
-
Right ascension: 05 hours 55 minutes 10.3 seconds
-
Declination: +07 degrees 24 minutes 25 seconds
It is probable that the name "Betelgeuse" originated in Arabic words,
but the star had other names (for example) in Sanskrit, traditional
Chinese and even in Hawaiian; in the latter, it was known as Kauluakoko.
The coming supernova
When astronomers say Betelgeuse is expected to explode soon, they mean
shortly in astronomical terms: within a million years, according to
several sources. Predicting exactly when it will turn into a supernova
is difficult, however, as it depends on precise calculations of its mass
as well as an understanding of what is going on inside the star.
Betelgeuse is so vast — its size would extend beyond Jupiter's orbit if
it were placed in the sun's position in the solar system — that several
telescopes have captured images of the star and spotted it shedding
mass. Starting in 1993 and continuing for at least 15 years,
its radius shrank by 15 percent, an astonishing amount for so short a time.
"We do not know why the star is shrinking," said Edward Wishnow, a
research physicist at UC Berkeley's Space Sciences Laboratory, in 2009.
"Considering all that we know about galaxies and the distant universe,
there are still lots of things we don't know about stars, including what
happens as red giants near the ends of their lives."
Nearing the wall
As the star prepares for what could be a large explosion, another challenge awaits: it is expected to
crash into a wall of interstellar dust in the next few thousand years.
An infrared Herschel Space Observatory image released in 2013 suggested
it would crash into the dust at a speed of 66,960 miles per hour
(107,761 kilometers per hour.)
The crash would take a while to complete: the solar wind is expected to
touch the line around 5,000 years from now, with the heart of the star
crashing into the bar 12,500 years after that.
end quote from:
-
No comments:
Post a Comment