Is Nemesis Really the Second Sun in Our Solar System?

Fact about Nemesis in solar system
Several years ago, a scientific theory was propagated about the existence of an evil twin of the Sun which visited the Earth every 26 million years to cause widespread extinction through comets and impacts. Is this second sun theory real? Is there a black mass coming up fast to cause extinction? Investigate further with Buzzle and find out the truth behind Nemesis: the Second Sun in our Solar System.
Did Nemesis Kill Dinosaurs?
There is a theoretical hypothesis that dinosaurs might have become extinct due to the cosmic impact of Oort cloud, a comet emitting from a 'disk of dark matter' known as Nemesis.
Nemesis or the Death Star is the hypothetical second sun in our solar system. It's a dwarf red or brown-sized star that is named after the Greek Goddess of Vengeance and Destruction. It orbits the Sun at a distance of about 95,000 AU (1.5 light-years).

It is said to be beyond the Oort cloud, and follows a highly elliptical orbit that periodically disturbs comets in the dense Oort cloud, hurling a large number of comets into the inner Solar System. It is theoretically stated that these impacts take place periodically, every 26 million years, and cause mass extinction on Earth.

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The Nemesis Theory and its Effects
☀ In the early 1980s, prominent scientists noticed a periodic pattern in the extinctions that occurred on Earth. They observed a 26-million-year cycle between every extinction which urged them to investigate the astronomical charts for further explanations.
☀ In the year 1984, Richard Muller, a Physics professor at the University of California, Berkeley came up with the theory that there was a dwarf-sized star, brown or red in color which produced dim light making it difficult to spot. It stood 1.5 light years away from the sun. He proposed that this star could very well be the cause of these periodic mass extinctions.
☀ Scientists formulated that this star would disturb the Oort cloud which is made up of icy rocks and lies beyond the planet Pluto. The Oort cloud moves in elliptical orbits around the sun. Scientists theorized that as the 'death star' comes closer to this Oort cloud, the icy rocks in this region will begin to melt and change into comets.
☀ If that happened, Nemesis would hurl extra comets out of the sphere sending them towards the inner solar system and the Earth. The impact would be so great that this would trigger mass extinctions. This would occur every 26 million years during the time when Nemesis would pass through the Oort cloud.
☀ The Kuiper belt is a doughnut-shaped ring or a disk of debris that lies just beyond Neptune's orbit and could be formed by a companion star. Space research has found that there could be other cosmic systems that could be affected by a companion star that results in the shaping of debris disks.
☀ The presence of the dwarf planet, Sedna, that orbits up to 12,000 years away from the sun, has surprised many astronomers. Scientists have speculated that a massive object such as a dim star could be responsible for keeping Sedna so far away from the sun.
☀ The theory appears debatable with some scientists applauding it while others feel it is baseless without evidence; however, a study of fossil records suggest that mass extinctions are more likely to happen around the 26 million cycle; whereas, other studies of craters show that such a pattern does not exist.
☀ The theory seemed to get a boost in 1984, when paleontologists David Raup and Jack Sepkoski published a research paper claiming that they had identified a statistical periodicity in the extinction rates over the last 250 million years by using various forms of time series analysis. This research was based on the extinction intensity variation for fossil families of marine vertebrates, invertebrates, and protozoans. It identified about 12 such extinction events over a speculated time period.
☀ Astronomers have still argue that it's not possible for the Nemesis star to travel far out from the sun without affecting the stellar orbits in the galaxy resulting in variations in the periodic timetable.
☀ Astronomers have since studied the sky for over four years in three infrared wavelengths using the Two Micron All Sky Survey (2MASS). This instrument discovered 173 brown dwarfs farther away from our solar system but none can be termed as Nemesis: The Death Star.
☀ NASA sent out the Wide-field Infrared Survey Explorer on a 1.25-year mission which discovered a number of brown dwarfs within 20 light-years with none of them resembling the Nemesis.
☀ Due to the lack of exact knowledge and evidence from the two sensitive instruments used by the scientists, it was concluded that the Sun is a single star in our solar system, and it does not have a companion.
One of the pages of NASA's "Ask an Astrobiologist" has David Morrison, Astrobiology Senior Scientist, October 17, 2012 rightly stating―
"(T)he Sun is not part of a binary star system. There has never been any evidence to suggest a companion. The idea has been disproved by several infrared sky surveys, most recently the WISE mission. If there were a brown dwarf companion, these sensitive infrared telescopes would have detected it."

We hope we have provided you with enough information and managed to clear the confusion regarding Nemesis―the Death Star.