The shard-like asteroid from deep space which shot through the solar system last years, known as ‘Oumuamua, set many an astronomer’s heart racing. The peculiar body was determined to be the first confirmed interstellar asteroid to have been observed (1). It’s possible, though, that other comets which pursue so-called hyperbolic orbits (moving fast enough to escape the solar system) also have an interstellar origin, rather than having originated from the Oort Cloud. A team of Spanish astrophysicists, who have more than a passing interest in the topic of Planet X, have performed powerful computer simulations to build up a picture of the trajectories and spatial origins of various hyperbolic comets (2). The objects they chose to consider have inbound velocities greater than 1km/s
Following adjustment for the Sun’s own movement through space towards the Solar Apex, interstellar visitors would likely have a more or less random distribution to their radiants (the position in the sky from which they came, rather like meteor showers striking the Earth’s atmosphere). The Spanish team carried out statistical analysis on the emerging sky maps of these radiants, and looked for patterns or clusters of these origin points. Statistically significant patterns did indeed emerge from the data. A particularly large source was located in the zodiacal constellation Gemini. Such a clustering might indicate a number of possibilities, which the astrophysicists explore in their paper.
One possibility is a close flyby of a star in the past which could have disrupted the outer edges of the distant Oort Cloud, sending comets in-bound towards the Sun. Looking at the tracking of candidate flybys in the (by Cosmic standards) relatively recent past, Carlos de la Fuente Marcos, Raul de la Fuente Marcos & S. J. Aarseth argue that there is a possible correlation between this cluster of hyperbolic orbit radiants in Gemini, and a close flyby of a neighbouring binary red dwarf system known as Scholz’s star some 70,000 years ago (2). At a current distance of about 20 light years, Scholz’s star may be a close neighbour to the Sun relatively speaking, but even so it took a while for it to be discovered. This was probably because of a combination of factors: Its proximity to the Galactic plane, its relative dimness, and its slow relative movement across the sky (3). Its distance was less than a light year 70,000 years ago, and its rapid movement away from us in the intervening time helps to explain why it was difficult to detect as a neighbouring binary star: Its retreating motion is mostly along our line of sight, making it difficult to differentiate from background stars. Read More…
Dr Konstantin Batygin and Dr Mike Brown argue in their latest paper that the retrograde Kuiper Belt Objects Niku and Drac could have once been extended scattered disk objects (1). If you have been following these blogs during 2016, it will come as no surprise to you to hear that the influence which perturbed them into their anomalous current orbits was Planet Nine, the 10+Earth-mass planet lurking several hundred-plus Astronomical Units away, whose gravitational influence seems to be influencing the objects in and beyond the Kuiper Belt beyond Neptune (2):
“Adopting the same parameters for Planet Nine as those previously invoked to explain the clustering of distant Kuiper belt orbits in physical space, we carry out a series of numerical experiments which elucidate the physical process though which highly inclined Kuiper belt objects with semi-major axes smaller than a < 100 AU are generated. The identified dynamical pathway demonstrates that enigmatic members of the Kuiper belt such as Drac and Niku are derived from the extended scattered disk of the solar system.” (1) Read More…
We seem to be getting very close now to a discovery of a massive Planet X in the outer solar system. I heard this report on the evening BBC news, a slot which indicates the seriousness with which this subject is now being taken by the scientific community:
“American astronomers say they have strong evidence that there is a ninth planet in our Solar System orbiting far beyond even the dwarf world Pluto. The team, from the California Institute of Technology (Caltech), has no direct observations to confirm its presence just yet. Rather, the scientists make the claim based on the way other far-flung objects are seen to move. But if correct, the putative planet would have 10 times the mass of Earth.