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Planets don’t influence solar activity

The planets can affect the solar activity on the sun by exerting tides but these effects are extremely tiny, just a few millimeters, in comparison to all other dynamical forces, a new research has claimed.

The sun is a magnetically active star. Its activity manifests itself as dark sunspots and bright faculae on its visible surface, as well as violent mass ejections and the acceleration of high-energy particles resulting from the release of magnetic energy in its outer atmosphere.

The frequency with which these phenomena occur varies in a somewhat irregular activity cycle of about 11 years, during which the global magnetic field of the Sun reverses. The solar magnetic field and the activity cycle originate in a self-excited dynamo mechanism based upon convective flows and rotation in the outer third of the solar radius. Analysis of radioactive isotopes in tree rings and in polar ice sheets show that other such grand minima of solar activity have occurred over the past millennium, and also revealed a number of quasi-periods in the activity variations, ranging from 80 to about 2,000 years.

Before the magnetic nature of sunspots and other phenomena were discovered, a popular theory associated the activity cycle with the planetary orbital periods, primarily motivated by the similarity between the approximately 11-yr solar cycle and the 11.87 orbital period of Jupiter.

R. Cameron and M. Schussler compared the quasi-periods found in this data set between 40 and 600 years with periods in the tidal torque exerted on a thin shell in the solar interior, which they assumed to be ellipsoidally deformed. Abreu et al. found seemingly striking similarities between the solar and the planetary periods in 5 period bands.

Astronomers probing how black holes shape galaxies

Astronomers have used a worldwide network of radio telescopes to find evidence that a powerful jet of material that is propelled at almost the speed of light by a galaxy’s central black hole is blowing massive amounts of gas out of the galaxy.

The researchers said that this process is limiting the growth of the black hole and the rate of star formation in the galaxy, and thus is a key to understanding how galaxies develop. Scientists proposed two major mechanisms that would slow or halt the process of mass growth and star formation -- violent stellar winds from bursts of star formation and pushback from the jets powered by the galaxy’s central, supermassive black hole.
The scientists studied a galaxy called 4C12.50, nearly 1.5 billion light-years from Earth.

They chose this galaxy because it is at a stage where the black-hole ‘engine’ that produces the jets is just turning on. As the black hole, a concentration of mass so dense that not even light can escape, pulls material toward it, the material forms a swirling disk surrounding the black hole.

Processes in the disk tap the tremendous gravitational energy of the black hole to propel material outward from the poles of the disk.

At the ends of both jets, the researchers found clumps of hydrogen gas moving outward from the galaxy at 1,000 kilometers per second.

One of the clouds has much as 16,000 times the mass of the Sun, while the other contains 140,000 times the mass of the Sun. The larger cloud, the scientists said, is roughly 160 by 190 light-years in size.

Protein may help combat Alzheimer’s disease

Two neurology researchers have come up with a theory that may help unify scientists’ thinking about several neurodegenerative diseases and suggest therapeutic strategies to combat them.

Mathias Jucker, research professor at Yerkes National Primate Research Center, Emory University, and Lary Walker, head of the Department of Cellular Neurology at the Hertie Institute for Clinical Brain Research at the University of Tubingen and the German Center for Neurodegenerative Diseases, outline the emerging concept that many of the brain diseases associated with aging, like Alzheimer’s and Parkinson’s, are caused by specific proteins that misfold and aggregate into harmful seeds.

These seeds behave very much like the pathogenic agents known as prions, which cause mad cow disease, chronic wasting disease in deer, scrapie in sheep, and Creutzfeldt-Jakob disease in humans.

Unlike prion diseases, which can be infectious, Alzheimer’s, Parkinson’s, and other neurodegenerative diseases can not be passed from person to person under normal circumstances.

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