Nemesis ,the name of our Sun's possible evil twin! Yes, our very own sun could have a twin brother who might have been the reason for major destructions, even the demise of our beloved Dinosaurs. So who is this 'Nemesis'?
According to the research done by Sarah et al. on Embedded binaries and Their dense cores which is a planetary model on how stars are formed and after countless investigations done on dust clouds in the Perseus constellation they've concluded that all stars are born with a companion. To explain further, we need to know what Star system is. Star system or stellar system is a small number of stars that orbit each other bound by gravitational attraction. A star system of two stars is know as Binary star and so on (Triple system, quaternary,etc,.)
For many years, astronomers have wondered if the large number of binary and triple systems of stars in our galaxy are created so close to each other or if they just fall together after they're formed. From many previous researches it was vaguely clear that almost all the stars are born as multiples that often spin away on their own. But this new analysis fixates the claim of born-together hypothesis. Stahler, an astronomer working with Sarah quotes " Our work is a step forward in understanding both how binaries form and also the role that binaries play in early stellar evolution". As a part of the VANDAM survey (The VLA nascent disk and Multiplicity survey) done out of a dense cocoon of dust about 600 light years away that contained a whole nursery of young stars it was clear that all stars are born as binaries. To know more about VANDAM click here
Even if our sun's theoretical sibling cease to exist we cannot see it in our neighbourhood, not until now at least. But their is another hypothesis where some believe that Nemesis pay us a visit every now and then. This could explain the 27-million year cycle of extinctions on earth. So that explains the death of dinosaurs. If not asteroids it has to be this estranged twin !
Richard Muller, another astronomer who studied a red dwarf star about 1.5 light years away found that when this star travels through the icy outer limits of our solar system, it stirs up all the planetary bodies within it's gravity !
Could this be it? On contrary it could just be a dying star manifesting its rage. It's not uncommon for a passing by star to mess things up in a planetary system.  However there is still a fair amount of time for the next cycle of extinction to pop in. We shouldn't overlook the possibilities of an indignant Nemesis destroying life as we know it.. hope not !