Recent updates on the Search for Planet Nine

It’s a year since proposed the existence of Planet Nine (1).  Despite the fact that its discovery remains elusive, there have been a great many academic papers written on the subject, and no shortage of serious researchers underpinning the theoretical concepts supporting its existence.  Many have sought evidence in the solar system which indirectly points to the perturbing influence of this mysterious world; others have provided data which have helped to constrain the parameters of its orbit (by effectively demonstrating where it could NOT be).  Throughout 2016, I have been highlighting these developments on the Dark Star Blog.


At the close of 2016, two further papers were published about Planet Nine.  The first of these delves more deeply into the possibility that Planet Nine (Brown’s new name for Planet X, which seems to have caught on among astronomers keen to distance this serious search from, well, the mythological planet Nibiru) has a resonance relationship with some of the objects beyond the Edgeworth-Kuiper Belt which it is perturbing.  These kinds of resonance relationships are not unusual in planetary orbital dynamics, so such a suggestion is not that odd, even given the eccentricities of the bodies involved here.  The new research, from the University of California, Santa Cruz, bolsters the case for this kind of pattern applying to Planet Nine’s orbit:

“We extend these investigations by exploring the suggestion of Malhotra et al. (2016) (2) that Planet Nine is in small integer ratio mean-motion resonances (MMRs) with several of the most distant KBOs. We show that the observed KBO semi-major axes present a set of commensurabilities with an unseen planet at ~654 AU (P~16,725 yr) that has a greater than 98% chance of stemming from a sequence of MMRs rather than from a random distribution.” (3)

Their randomised ‘Monte Carlo’ calculations provide a best fit with a planet of between 6 and 12 Earth masses, whose eccentric orbit is inclined to the ecliptic by about 30 degrees.  They are unable to point to a specific area of the sky to search, but provide a broad-brush region which they favour as most probable.  Dr Millholland has also helpfully provided a 3D manipulable 3D figure of the cluster of extended scattered disk objects allegedly affected by the purported Planet Nine, alongside their extrapolated orbit for it (4).  Read More…

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The Galactic Core Spits out Dark Stars

A new theory about planet formation has posited that stars, placed under inordinate stress, could break apart catastrophically, flinging their smouldering remains out into the void at tumultuous speeds.  It would take quite a force to render stars apart in this way.  The supermassive black hole which lies at the centre of the galaxy creates just such an impression.  Wayward stars drifting inexorably into the depths of its immense gravitational well would not fare well, during what are termed Tidal Disruption Events (1,2).


Researchers from Harvard University (namely, undergraduate Eden Girma and James Guillochon, an Einstein fellow at the Harvard-Smithsonian Center for Astrophysics), have conducted computer simulations to model what happens to this streaming material, and the results are quite extraordinary:

Every few thousand years, an unlucky star wanders too close to the black hole at the center of the Milky Way. The black hole’s powerful gravity rips the star apart, sending a long streamer of gas whipping outward. That would seem to be the end of the story, but it’s not.  New research shows that not only can the gas gather itself into planet-size objects, but those objects then are flung throughout the galaxy in a game of cosmic “spitball.”” (3)

Read More…

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Cryovolcanoes on Ceres 

It’s been a little while since the Dawn probe imaged those mysterious ‘lights’ in the craters of the dwarf planet Ceres (1).  On first impression, these seem to be impact marks where brighter materials lying below the surface were exposed following meteoritic bombardment.  But they are uncommonly bright for an asteroid, so speculation about the nature of the materials involved has been rife in the planetary science community, and what it could mean for how the dwarf planet formed in the first place (2).  The bright spots, now widely thought to be salt deposits, have recently even been given names:

“The two most famous bright spots on Ceres have been given names. These once-mysterious spots are now thought by most scientists to be salt deposits. They’re now called Cerealia Facula (for the brighter of the two spots) and Vinalia Faculae (for the cluster of less reflective spots to the east). Both names are related to ancient Roman festivals.” (3)


But that’s not the only mystery on Ceres.  There is a growing consensus that there may be geophysical processes going on that are relatively recent (at least in terms of geological time periods): Read More…

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Down a Dusty Lane

Picking up on the mystery of how a massive Planet X could form beyond the outer confines of the Sun’s magnetic environment, as per my previous posts on the accretion of dust beyond the heliopause (1,2) and an exploratory scientific paper I published earlier in the year (3).  I’m searching for evidence, or at least some educated guesswork, about whether interstellar medium beyond the heliosphere of stars might be sufficient over time to build up substantial, gaseous planets loosely bound to their parent star systems.  Such planets might, I suggest, accumulate dust clouds and rings around them, undisrupted by the action of the solar wind trapped within the inner magnetic sphere of the solar system.


Even though this kind of accumulation could be gradually taking place over billions of years, creating a meaningful adjustment to the mass of a substantial planet over these kinds of time periods, it doesn’t seem likely that this kind of effect could take place if our current interstellar environment is anything to go by (although the unexpected presence of interstellar ‘fluff’ beyond the heliopause, described by NASA (4), and the intrusion of large grain particles into the outer solar system (5) do offer some evidence of what could be ‘out there’).

Last month, I looked at evidence of massive stars being aided in their development by the dumping of immense quantities of neighbouring nebula material onto them (6).  I wondered whether a similar mechanism might also be happening in interstellar space at the planetary level, based upon globular frameworks of nebula materials (like gigantic molecular clouds, and the like).

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Niku, Drac and L91 Perturbed by Planet Nine…or Something Else?

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…

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New Trans-Neptunian Object may add to Planet Nine Cluster

Astronomers have announced the discovery of the third most distant object in the solar system, designated 2014 UZ224 (1).  At a distance of 91.6AU, it is pipped to the title of ‘most distant solar system object’ by V774104 at 103AU (2), followed by the binary dwarf planet Eris at 96.2AU(3).  The new scattered disk object lies approximately three times the distance of Pluto away, and may be over 1000km in diameter – potentially putting it into the dwarf planet range.  Its 1140 year orbit is notably eccentric, which is becoming more expected than otherwise with this category of trans-Neptunian object.

The find is a fortunate byproduct of the Dark Energy Survey, which seems to be rather good at picking out these dark, distant solar system objects.  It was first spotted in 2014, with follow-up observations which have firmed up its orbital properties, but clearly delayed the announcement of its existence until now.  These follow-up observations were rather scatty over time, and so the Dark Energy team, led by David Gerdes  of the University of Michigan, developed software to establish its orbital properties: Read More…

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Sub-Brown Dwarfs Hiding in Plain Sight

Not so long ago, brown dwarfs (failed stars caught in an awkward in-betweener zone between stars and planets) were hypothetical bodies.  Their low stellar masses allow for only a very short period of light-emission in their early years, after which they cool and darken considerably.

[A] brown dwarf has too little mass to ignite the thermonuclear reactions by which ordinary stars shine.  However, it emits heat released by its slow gravitational contraction and shines with a reddish colour, albeit much less brightly than a star.” (1)

It was recognised early on that if they existed at all, they would be very difficult to spot – and so it proved.  In recent years, the ability to detect these objects has improved considerably, including more effective infra-red sky surveys.  As they have become more common, the frontier of sub-stellar bodies has dropped in mass into the ultra-cool stellar bodies known as sub-brown dwarfs – many of which would equally properly be designated as rogue gas giant planets.  These objects tend to have masses below 13 times that of Jupiter (13Mj) (2).  These objects have always interested me greatly, and very early on in my own research efforts I was advocating the potential importance of sub-brown dwarfs in the hunt for additional planets orbiting our own Sun at great distances (3).  I used the term ‘Dark Star’ to describe these ultra-cool objects; a term suggested by a friend of mine.  Some can be found orbiting stars (usually beyond 50AU) while others are free-floating entities in their own right.

Read More…

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Three New Objects Extend Hunt for Planet X

The two scientists, Scott Sheppard and Chad Trujillo, who first recognised the clustering of objects thought to reveal the presence of ‘Planet Nine’ (1), have announced the discovery of three new objects.  All three are highly distant objects (2).  Two of them are extended scattered disk objects beyond the traditional Kuiper Belt, and fit reasonably well into the afore-mentioned cluster.  The third, perhaps even more amazingly, is an object whose elongated orbit reaches way out into the distant Oort Cloud of comets, but which also never comes closer than the planet Neptune.   So, this is the first outer Oort cloud object with a perihelion beyond Neptune, designated 2014 FE72.

Here’s how the announcement of these three new objects has been described in a press release from the Carnegie Institution for Science (3), where Scott Sheppard works:

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Complex Brown Dwarf Systems ‘Baffle’ Astronomers

A couple of brown dwarfs have been discovered in a close binary system some 240 light years away, whose two stars circle each other at a distance of about 19AU, similar to that of Uranus around the Sun.   The two new exoplanets orbit close to the primary Sun-like star HD 87646 (1).  These two sub-stellar companions are HD 87646b, which is a minimum 12MJupiter sub-brown dwarf (a ‘hot Jupiter’-type exoplanet) orbiting every 13 days just 0.117AU from the star (2); and  HD 87646c, which is a 57MJupiter brown dwarf circling the star every 673 days (1).  The orbital eccentricity of the brown dwarf is greater than that of the inner sub-brown dwarf, which is in keeping with other observations of brown dwarfs orbiting stars.


Image Credit: Janella Williams, Penn State University

The international team that discovered this remarkable system is perplexed as to how it might have come about:

“Given the fact that HD 87646 is the first known system to have two massive substellar objects orbiting a star in a close binary and the masses of the two objects are close to the minimum masses for burning deuterium and hydrogen, these peculiarities raise questions about the system’s formation and evolution.

“”The large masses of these two substellar objects suggest that they could be formed as stars with their binary hosts: a large molecular cloud collapsed and fragmented into four pieces; the larger two successfully became stars and formed the HD 87646 binary, and the other smaller ones failed to form stars and became the substellar objects in this system. This scenario might be relevant for the binary stars but seems problematic for the two substellar objects on orbits within one AU because it is unclear whether fragmentation on such a small scale can occur,” the paper reads (1)

“Other hypothesis offered by the scientists is that the two newly discovered giant objects were formed like giant planet in a protoplanetary disk around HD 87646A. However, they added that such massive disks are rare in close binaries, and further investigation is needed to confirm this explanation.” (3)

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On Proxima b

August 2016 saw the announcement of the discovery of an Earth-like planet orbiting our nearest neighbourhood star – the red dwarf Proxima Centauri.  The official press release was preceded by a leak to the German media from within the team of astronomers.  Here, I tell the story of the rumours of the announcement, and the wider implications of the discovery itself:

Rumours of an Earth-like Planet Orbiting Proxima Centauri

The German magazine Der Spiegel has reported that a major announcement is imminent:  there is an Earth-like planet orbiting the red dwarf star Proxima Centauri; the Sun’s closest stellar neighbour at 4.24 light years distance.

The magazine claims that the discovery was made by the European Southern Observatory (ESO) using the La Silla Observatory’s reflecting telescope in Chile, based upon a leak from an astrophysicist who has been working with the La Silla team (1).  This alleged discovery is in keeping with the current work being carried out at La Silla, as described in January earlier this year:

“What good news that the Pale Red Dot project is now planning a two-month observing campaign to search for potential Earth-analogs around Proxima Centauri using HARPS, the High Accuracy Radial velocity Planet Searcher spectrograph at the ESO La Silla 3.6m telescope. Nightly monitoring began on January 18th.” (2)

Read More…

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