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July 25th 2017
Sunspot activity is at a minimum at the moment
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Recent news items suggest that this giant star betelgeuse is going to explode quite soon, but don't panic it is over 600 light years away so even if it does it will not affect the Earth at all.
Betelgeuse: The incredible shrinking star?
Pinned prominently on Orion’s shoulder, the bright red star Betelgeuse hardly seems like a wallflower. But a new study suggests the giant star has been shrinking for more than a decade.
Betelgeuse is nearing the end of its life as a red super giant. The bright, bloated star is 15 to 20 times more massive than the sun. If it were placed at the centre of the solar system, the star would extend out to the orbit of Jupiter.
But the star’s reach seems to be waning. New observations indicate the giant star has shrunk by more than 15 per cent since 1993. This could be a sign of a long-term oscillation in its size or the star’s first death knells. Or it may just be an artefact of the star’s bumpy surface, which may appear to change in size as the star rotates.
Betelgeuse is enshrouded by vast clouds of gas and dust, so measuring its size is difficult. To cut through this cocoon, Charles Townes of the University of California, Berkeley, and colleagues used a set of telescopes that are sensitive to a particular wavelength of the star’s infrared light.
The cause for this reduction is unknown, as it is unclear how red super giants behave near the end of their lives.
“Maybe there’s some instability in the star and it’s going to collapse or at least go way down in size or blow off some material, but who knows,” Townes, who shared a 1964 Nobel Prize for the invention of the laser, told reporters on Tuesday at a meeting of the American Astronomical Society in Pasadena, California.The shrinking size could also be evidence of an as-yet-unidentified pulsation in the star, says Graham Harper of the University of Colorado in Boulder, who was not affiliated with the study.
The surface of Betelgeuse is known to wobble in and out, fed in part by the roiling energy of convection beneath its surface. Two such pulsations are already known – one seems to start anew each year, the other every 6 years. Since this observation shows a progressive decrease in the size of the star over 15 years with a consistent set of measurements, Harper says: “I think this is a very nice indication that [Betelgeuse] is getting smaller.”
The team used these instruments to measure the size of Betelgeuse’s disc on the sky. Over a span of 15 years, the star’s diameter seems to have declined from 11.2 to 9.6 AU (1 AU, or astronomical unit, is the distance from the Bumpy surface
But he notes the change in size could be an illusion. Simulations suggest temperature differences in red super-giants can make their surfaces extraordinarily bumpy, causing the star to appear to be a different size when viewed from different angles.
“Often if you look at the simulations, the star is not spherical. It looks like a bad potato,” Harper told New Scientist. Betelgeuse is thought to rotate every 18 years or so, which might suggest an especially narrow part of the star recently rotated into view.
Another possibility, Harper says, is that the team is not measuring the surface of the star but a layer of dense molecular gas that some astronomers suspect may hover above it.
The team hopes to get higher-resolution pictures of the star at a variety of wavelengths to determine the origin of the light they are seeing.
Journal reference: the astrophysical Journal, volume 697page 0127
are some basic initial thoughts on this subject of solar-flares
Our Sun is a very large and very active body, it is in fact a giant nuclear fusion reactor, and although it is 93,000,000 miles away we feel the sun’s heat very easily, most of the time we enjoy its warming rays and if we overdo it we get sunburned, the rays we get from the Sun are usually very stable and apart from local cloud conditions, constant.
However the surface of the Sun is constantly being disrupted by bursts of energy which explode in all directions from the Suns surface, occasionally these bursts of energy are directed straight towards the earth, these anomalies have been known to damage satellites and can knockout power grids by overloading the circuits with strong bursts of energy, astronauts on the space station are warned and have to be protected from these energy bursts, humans on the surface are in no danger as we are well protected by our atmosphere.
The spectacular visual effects that can be seen over the poles are known as aurora, these are continuous effects but they do vary in strength depending on the strength of the solar wind, solar wind it is the name given to the continuous stream of particles coming from the sun in all directions, these visual effects over the poles are quite beautiful and are well documented.
Aurora effects are caused by particles from the sun interacting with molecules suspended in our atmosphere causing the visual effects, the particles from the sun traveling on the solar wind do not travel at the speed of light, the light that we see coming from the sun takes just over 8 minutes to reach us here on earth, the solar wind travels at a much slower pace and it may take several days for the effects to be felt here, this is fortunate as it gives us time to prepare and take the necessary precautions.
Fortunately with modern communication systems these dangerous situations can be monitored easily and warnings issued by local government, civil defense, police, local radio and television..