Dwarf Star Heading For Solar System — Will It Be Our Nemesis?
According to a study set for publication shortly, there is a 90 percent chance that a dwarf star similar to the theorized Nemesis star will pass through the outer boundaries of our solar system between a quarter and half million years from now. This Nemesis-like dwarf star has the potential for disturbing the perhaps trillions of comets circling in the Oort cloud beyond the primary planets and sending many plummeting into the inner solar system. Comets, composed of rock, dust, and even some organic material, are thought to have impacted the Earth many times though its history.
The paper containing the study has been accepted for publication in Astronomy & Astrophysics and was authored by Coryn Bailer-Jones, an astrophysicist at the Max Planck Institute for Astronomy in Heidelberg, Germany. In this study, Bailer-Jones analyzed the movement of 50,000 stars and their projected movement in the future to determine the possible risks to the solar system. The data for these stars was taken from the European Space Agency’s Hipparcos spacecraft, and was evaluated to see which stars might have the greatest risk of approaching our solar system. From this, he determined that 14 stars were projected to come close enough to influence the Oort cloud.
Of the 14 stars, a star designated as Hip 85605 would come the closest. Hip 85605 has a 90 percent chance of passing between 0.13 and 0.65 light years away. Another is GL 710, which has a similar chance of approaching our solar system at a distance of 0.32 and 1.44 light years.
The significance of these distances is that the Oort cloud extends out to a distance of almost one light year, and so the passage of a body as large as a dwarf star would have a significant chance of disturbing the orbits of the now-quiet potential comets in the cloud, similar to the way that the proposed Nemesis star would.
The existence of the Nemesis star was proposed as a way to explain the seeming regular periodic extinctions of life on Earth. With mass extinctions occurring roughly every 27 million years, it was proposed that the sun had a twin that orbited the sun and came close enough on a regular basis to disturb the Oort cloud. Once disturbed, comets in a stable orbit in the Oort cloud would change orbit and fall into the solar system in paths crossing the Earth’s orbit.
This isn’t something the average person needs to worry about today. However, one quarter to one half million years is well within the time that upright ancestors of present day humans wandered the Earth, and is likely to be within the reasonable future reign of humans. However, if a dwarf star does enter the solar system and causes a Nemesis-like effect in the Oort cloud, it would be reasonable to expect that an incoming planet-killing comet could be dealt with by that time, as long as humans have not done something to cause a few remaining survivors to be living in caves.
[Image credit: NASA/JPL-Caltech]
