Stars, we see them in the night sky.They glitter like tiny particles.Are they really sort of single particle..?? NO, most of the stars, studied till today, are actually star systems which has two or more stars.They are called BINARY star systems.Like our nearest star system,4.3 light year far, ALPHA CENTAURI, is made up of three stars. Then why we are alone,why we have only one star in our solar system......??
Alpha Centauri star system
Now-a-days scientists are thinking of a companion of sun named NEMESIS. It is not discovered yet, but there are some reasonable evidences for this sun's sibling.
From the course of history it is observed that in every 26 million years period mass extinction of species happen.Extinction of dinosaurs was part of these extinctions. It is some kind of mystery, why 26 million periodic extinction? A guy named Richard Muller, professor of physics, University of California, Berkeley and faculty senior scientist at Lawrence Berkeley National Laboratory, has come with a solutions. He forwarded a theory,suggests a sibling of sun, which is supposed to be 1 to 3 light-year from the sun. Sun is much more massive than his brother. Nemesis creates anarchy in the OART CLOUD which leads some comets to rush towards inner solar system. Some comets get engaged with earth and create catastrophes in earth which leads to mass extinction. I should mention here about oart cloud. Oart cloud is thick layer of icy comets covering outer solar system and when Nemesis passes through it, anarchy is being made and after story you know. .
Mass Extinction
Oart Cloud
It is supposed to be very less massive than sun. It together with sun, revolve around their common barycenter. It is less massive so it follow a long path around barycenter.
Here question comes, why it couldn't be seen till now..?? Richard answer that it can be a red dim dwarf star, after-all it has low mass (relative to sun) and red dwarfs are very common in the universe. It is being thought that today it is very far from sun and has very slow velocity relative to sun, means should be looked like a common star. We have a broad area to see and we don't know where to look for it. you can think like, we are able to see very far red dwarfs but why we didn't see it till now?....we don't know where to look.
NASA had a explorer named Wide-field Infrared Survey Explorer (WISE) in the space but it was unable to find Nemesis.but some kind of disturbance had been observed in the oart cloud. Later a planet hypothesized named TYCHE, nemesis's "good sister".It is supposed to be 4 times more massive than Jupiter and has about 500 times big orbit than Neptune.Can it be cause of mass extinctions......hmm......NO. Because first it has very lass mass to create such kind of rush in oart cloud and second its orbital time period is 1.8 million years and extinction happens in every 26 million years.
n 2003,a planet named SEDENA was discovered. It is almost 30 times most distant than where neptune is form the sun. Actually it has very eccentric orbit around sun,Aphelion is 937 AU ( AU=astronomical unit, 1 AU= distance between earth and sun ) and Aphelion is 79 AU. It is where no planet was supposed to be discovered. Some scientists say that it could be nemesis's gravity which attracted sedana that far.
SEDENA-Hubble's Image
n Sumerian civilisation planet named "NIBIRU (Planet of the crossing) " has been told, which is now being thought as nemesis..or tyche maybe. Above them all, should we worry for the nemesis right now. I guess..actually Richard Muller guess...NO. Because he calculated that nemesis will revisit oart cloud after 10 million yIears and who knows where will we be at that time.
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