This article will explore the potential for life to develop in the outer planetary systems of red giant stars. It will then discuss the death-throes of red giant stars, and whether the subsequent outward thrust of stellar material might provide another mechanism for free-floating planets in interstellar space.
Exoplanets have already been found orbiting extremely old stars, one some 11 billion years old (1). This star, named Kepler-444, makes our own Sun, at a mere 4.6 billion years old, seem like an infant in comparison. The implication of this is that life could readily have got going early on in the history of the universe, long before the birth of our Sun. Furthermore, if these exoplanets were to benefit from a relatively stable stellar environment during that long timescale, then the chances of life evolving into higher forms are statistically more probable. Scale this up across trillions of stars, and the possibilities become clear.
Our own Sun has a shorter lifespan than this. Its main sequence life is expected to last another 5 billion years, by which point it will have burned up all of its hydrogen fuel. Then it will swell into a red giant star, before collapsing down into a white dwarf. For Earth, this post-main sequence (post-MS) phase of the Sun’s life will be pretty disastrous. The Sun’s expansion to a red giant will swallow the Earth up. However, a less catastrophic outcome might be expected for planets in the outer solar system, beyond, say, Jupiter. In fact, their climates might significantly improve – for a while, at least. The habitable zone of the solar system will expand outwards, along with the expanding star. Saturn’s largest moon Titan, for instance, might benefit greatly from a far milder climate – as long as it can hang onto its balmy atmosphere in the red heat of the dying Sun.
The expansion of habitable zones, as late main sequence stars become hydrogen-starved, offers the potential for life to make a new start in previously frigid environments. The burning question here is how long these outer planets have to get life going before the red giant then withdraws into its cold white shell. A study published last year by scientists at the Cornell University’s Carl Sagan Institute attempted to answer this question (2), choosing to examine yellow dwarf stars whose sizes range from half that of the Sun, to approximately twice its mass. They argue that the larger stars along this sequence could well have larger rocky terrestrial planets in their outer planetary systems than our Sun does (at least, insofar as we know it does!) This is because the density of materials in their initial proto-planetary disks should be that much greater for larger stars (3). Larger Earth-like planets in outer regions mean more potential for stable atmospheric conditions during the post-MS period under consideration. In other words, the growing red giant (which is shedding its mass pretty wildly at this point) would not necessarily blast away an outer planet’s atmosphere if that rocky planet had sufficient gravity to hold onto it.
For some time, astrophysicists have argued over how many Dark Stars there might be in the galaxy, with varying opinions. (Note that astronomers use several different names for these objects: sub-brown dwarfs, Y Dwarfs, ‘planemos’). In this short article, I argue that new evidence presented about the stellar populations of open star clusters point towards there being more Dark Stars than stars in our galaxy.
When I use the term ‘Dark Star’ in my book (1) and internet articles, I’m generally referring to gas giant planets/ultra-cool dwarf stars which are several times more massive than Jupiter, up to perhaps ~13 times as massive (at this point, the gas giant begins to burn deuterium and is reclassified as a brown dwarf). Most examples of these objects (perhaps more than a few million years old) are essentially dark. By contrast, very young examples light up more brightly, because they still retain some heat from their formation. It’s a curious quirk of nature that these sub-brown dwarfs are actually smaller in size than Jupiter, despite being heavier. Because these objects are so small, and so dim, they are extraordinarily difficult to observe. Some have been found, but they are usually either extremely young (and therefore still burning brightly), or are exoplanets discovered orbiting parent stars (and so detectable through gravitational ‘wobble’ effects, or other means of finding massive exoplanets).
It has been my contention for some time that the populations of these objects are significantly underestimated. It is recognised generally that these ultra-cool dwarf stars may be free-floating objects in inter-stellar space, often as a result of having been ejected from young star systems as the fledgling planets in those systems jostle for position. Opinions about their numbers vary greatly among astrophysicists. There may be twice as many of these objects as stars, according to studies involving gravitational microlensing surveys of the galactic bulge (2). Other studies conflict with this conclusion, arguing that there may be as few as 1 object of 5-15 MJup size per 20-50 stars in a cluster (3). This discrepancy is important because the difference is perhaps as high as two orders of magnitude, and this ultimately affects our understanding of how many free-floating Dark Stars we can expect to find out there.
Their mass, lying between that of Jupiter and the deuterium-burning limit at about 13 MJup (4) seems to single Dark Stars out as rather special objects:
“An abrupt change in the mass function at about a Jupiter mass favours the idea that their formation process is different from that of stars and brown dwarfs. They may have formed in proto-planetary disks and subsequently scattered into unbound or very distant orbits.” (2)
Therefore, if the number of free-floating sub-brown dwarfs (also sometimes known as “planemos”) is on the high end of expectation, then it means that there are also likely to be far more of these objects in wide, distant orbits around their parent stars. This, in turn, increases the likelihood of there being a similar Dark Star object (or more) in our own immediate solar neighbourhood. Read More…
NASA made a big announcement this week about new exoplanets found orbiting the dwarf star TRAPPIST-1 some 39 light years away. I’ve discussed this particular dwarf star system before (1), as it was already known to have three terrestrial planets in attendance orbiting very close to this cool, fairly dim star (2,3). The dwarf star is approximately one tenth the size of the Sun, and it’s mass places it on the border between a brown dwarf and a red dwarf star. Unusually for a star this small, TRAPPIST-1 has a high metallicity, which actually exceeds that of the Sun (4).
Now, an international team of astronomers, using the Belgian TRAPPIST telescope in Chile and the Spitzer infra-red space telescope, have released details about a further four terrestrial planets in this mini-star system, three of which (e, f and g) are located within it’s habitable zone, where temperatures favour the presence of liquid water (5):
“Researchers led by Michaël Gillon, of the University of Liège in Belgium, have been studying the infrared light emitted by this miniature star and have detected drops in luminosity characteristic of transits, i.e. the passage of astronomical bodies moving across its face. As early as 2015, the first three planets (dubbed b, c and d) had been identified. Tracking the system using TRAPPIST and the space telescope Spitzer, the team was then able to identify four others planets (e, f, g and h) in 2016. Based on the frequency of these transits and the degree of reduction in luminosity of the star, they have demonstrated that these seven planets are all comparable in size to Earth (to within 15%), and orbit very close to their star.” (6)
Subtitled “Legends, Mysteries, and the Alien Connection to Eternal Life”
New Page Books, 2017
Is it so ridiculous to imagine that our ancestors were visited by hyper-advanced beings from space? It would be entirely natural for them to consider such beings to be gods. It’s not just the ‘magical’ technology on view, their level of knowledge, or their awe-inspiring presence. Perhaps these visitors were indeed effectively immortal. In the last decade or so, futurists have begun to seriously consider a world where aging is eradicated – or at least seriously curtailed. Gene therapy, cloning, stem cell research, advances in medicine – potentially a potent brew of treatments which might, together, offer a fabled fountain of youth to Humanity.
As Nick Redfern argues in his latest book about the ancient gods and their alien connection, if interstellar space-farers were just a few centuries more advanced technologically than us, then it is quite reasonable to imagine that they had already cracked aging. Indeed, one might even add that extending lifetimes considerably would be a mandatory requirement to interstellar exploration, given the timescales involved. In other words, the very presence of spacecraft in our ancient skies millennia ago implies that the pilots are effectively immortal.
But … we’re jumping ahead of ourselves. Firstly, what of the evidence for such a contentious claim?
I was recently sent an excerpt from some ancient Irish Celtic folktales about Deirdre of Ulster. Deirdre was a woman of legendary beauty who occupied a tragic position in the old Celtic pagan mythology, similar to that of Helen of Troy. There are other connections with Near East paganism to explore here, too, in the form of Bel or Baal. From her birth, prophecies were told that the beautiful Deirdre would be the cause of great strife and war. In this context, my friend Mickey noticed in his reading of the old poem that Deirdre was likened to a ‘red star of ruin’:
“O Deirdre, terrible child,
For thee, red star of our ruin,
Great weeping shall be in Eri-
Woe, woe, and a breach in Ulla.”
Druid song of Cathvah“ (1)
Where does the concept of this portent come from? Comets were often associated with catastrophe in ancient times, but not red stars. Perhaps it denoted the planet Mars, with its long-held association with gods of war? That would be within context. However, the translation is specifically a star, rather than a planet or ‘wandering star’. Perhaps they are denoting the prominent Taurean red star Aldebaran, which has been associated by some with the ancient Celtic festival of Beltaine (2).
Whether this association with Aldebaran is correct or not (and I suspect it isn’t), the connection with Beltaine itself is interesting because its meaning is ‘the two fires of Bile’. The festival marks the end of winter, and a ritual of purification which takes place between two fires. If we have a red star as one of these ‘fires’, then might we assume that the Sun is the other? Read More…
I recently reviewed a book about Carl Sagan’s interest in ancient aliens, written by Donald Zygutis (1). Early on in his illustrious career, Sagan expressed scepticism about seeking E.T. life using radio telescopes, instead advocating a search through historical accounts and myths to determine whether our planet had been visited (2). He argued that in a standard galaxy there are so many stars/planets etc, that all you’d need to do is point the radio receiver at any given galactic source beyond the Milky Way, and alien radio signals should come screaming out at you.
They generally don’t, of course, which led Sagan to the early logical conclusion that SETI’s search with radio telescopes was bound to fail. However, this approach became the only game in town, with serious funding at its disposal, and Sagan fell into line behind it – supporting this doomed search for E.T. radio signals ostensibly from stars within out galactic neighbourhood.
Decades on, and SETI has come up with little of any merit. The odd interesting blip, sure, but nothing demonstrably repetitive, or intelligent. Other searches have also come up empty-handed, including an extensive search for highly advanced galactic civilisations using infra-red (3), based upon the theories of the physicist Freeman Dyson. Looking for an infra-red signature from other galaxies seems like a bit of a stretch to me. Sagan’s initial premise about radio waves emanating from other distant galaxies is more plausible. By staring at the tiny amount of our sky that any given distant galaxy occupies, radio telescopes can cover a lot of possible stars in a very small space. If any of them contain radio-emitting alien species, shouting for attention, then we should pick them up one would have thought. Read More…
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…
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)
One of the accusations levelled at the late Zecharia Sitchin was that he was not able to read and translate the cuneiform scripts of the Sumerians, Akkadians, Babylonians and other ancient Mesopotamian cultures. There aren’t that many people who can read cuneiform, and Sitchin was not a recognised linguistic scholar of ancient languages. As a result, it’s easy for scholars to question his ability to read, transliterate and interpret the ancient Mesopotamian writings.
I came across this issue first-hand in 2003 when appearing in a short university project documentary alongside some noted British Sumerologists and astronomers, discussing Planet X (1). The Sumerologists, curators from the British Museum in London, were sceptical of Sitchin’s knowledge of cuneiform, and his expertise with the ancient languages that used this script:
Christopher Walker (Deputy Keeper, Cuneiform Collection, British Museum): “It’s basically a very subjective interpretation of individual pictures, individual ideas. But he [Sitchin] doesn’t actually sit down and work with the texts. And people think this is a nice idea, this is a nice story, let’s have the next chapter of the story…It’s like Harry Potter.” (2)
Dr Irving Finkel (Assistant Keeper, Cuneiform Collections, British Museum): It is very easy to use Sumerian and the Sumerian culture as your explanation for things because hardly anyone in the world can read Sumerian, and if you can give the impression you can read these texts you can say what you like. And I do think this is a factor. The number of people who can read Sumerian reliably and properly you could fit into this room. I think it would be a bit of a squeeze, you would have to move the furniture, but you could get everyone in the world onto this room.” (2)
There’s a general disillusionment with experts these days. Sometimes, experts get it horribly wrong: Economists failing to see a looming crash, or bursting of an economic bubble; environmental scientists cooking the books to solidify their stance on climate change; politicians expounding doom and gloom if a particular decision is made, only to see markets lift when it comes to pass. This may be a similar situation. Read More…
I’ve spent many years extolling the virtues of life on a cold brown dwarf moon. Similar to the Galilean moons of Jupiter, a moon orbiting a sub-brown dwarf would be warmed internally by the tidal forces generated by its proximity to such a powerful gravitational force. Additionally, the sub-brown dwarf itself might provide some local heating, or at least an abundance of charged-particle strewn local magnetic fields to energise the sub-stellar environment. So, a habitable environment on a moon seems a likely scenario. If a cold, dark sub-brown dwarf were to be found orbiting the Sun at a great distance, then it neatly provides the grounding for extraterrestrial life on our doorstep (1).
This seems to me to be the simplest scenario for life in a sub-brown dwarf system. There are complexities – tidally-locked moons (2), lack of light, and so on. But the basics are there.
Another exotic possibility is that the sub-brown dwarf itself might harbour life. The complex cloud systems in these failed stars can contain layers which are at room temperature, and abundant in water and other chemical goodies which could form the building blocks of life. A team of astronomers from Edinburgh University have been considering this very point, wondering whether very simple life might be able to get going in the clouds of a cold brown dwarf (3). This life might arise in two ways – either somehow evolving from scratch in the cloud environment, or originally being seeded into it by an impacting asteroid or comet. Either way, conditions for life might be good, except for the lack of a solid surface to dwell on:
“Floating out by themselves in the Milky Way galaxy are perhaps a billion cold brown dwarfs, objects many times as massive as Jupiter but not big enough to ignite as a star. According to a new study, layers of their upper atmospheres sit at temperatures and pressures resembling those on Earth, and could host microbes that surf on thermal updrafts...Observations of cold brown dwarf atmospheres reveal most of the ingredients Earth life depends on: carbon, hydrogen, nitrogen, and oxygen, though perhaps not phosphorous.“ (4)
These ideas build upon work done by the late, great Carl Sagan (with his Cornell colleague E. E. Salpeter) on the potential for life in the clouds of the gas giant Jupiter, first considered back in the 1970s (5). They envisioned giant ‘floaters’ filled with hydrogen bobbing through the Jovian atmosphere, tiny ‘sinkers’ and self-propelled ‘hunters’ which had evolved from the lazy floaters (6). All very speculative, but presented in Dr Sagan’s inimitably compelling fashion. Read More…