Is science sometimes in danger of getting tunnel vision? Recently published ebook author, Ian Miller, looks at other possible theories arising from data that we think we understand. Can looking problems in a different light give scientists a different perspective?

Predictions For The Oldest Planet So Far?

One of the most intriguing announcements recently regarding exoplanets is that two planets have been found around the red dwarf Kapteyn's star, which happens to be about rather close to us, at about 13 light years distance. Even more intriguing is its proper motion; it was about 11 light years distant about 11,000 years ago. The reason for this is that it is orbiting the galaxy in the opposite direction to us! Galaxies grow by accreting galaxies, and our galaxy has apparently swallowed a small galaxy, some of which may be known now as the Omega Centauri cluster. Another interesting feature of this star is that it was formed about two billion years after the big bang. Not surprisingly, the star is rather short of heavy elements, as these have to be made in supernovae.
 
The planets have been found using the Doppler method, which measures small variations in velocity of the star as it wobbles due to the planets. This star has a mass of about 0.28 times that of the sun, and a surface temperature of about 3,500 degrees C, and such low stellar masses make the detection of planets somewhat easier, because small stars wobble more through the gravitational effects of the same sized planet. The two planets are (b) at 0.168 A.U. from the star, and at least about 4.5 times Earth's mass, and (c) at 0.311 A.U. from the star, and at least about 7 times Earth's mass. (The "at least" is because what is measured is msini, i.e. the actual tug that we see is the component in our directions, and the angle of the orbital plane is unknown.) The reason this hit the news is that (b) is at a distance from the star where water could be liquid, so it is in the so-called habitable zone. With over 11 billion years for life to evolve, would it? If it would, with an extra 6.5 billion years, why hasn't its technology led to space travel to us?
 
If you accept my theory of planetary formation, the answer is, life there is highly unlikely. In this theory, certain types of planet form at specific temperatures in the accretion disk. The temperature depends on the power generated at a point, which in turn depends on the gravitational potential and the rate of the starwards component of matter flowing through the point. The first, from Newton, is proportional to stellar mass, the second, from observation, is very roughly proportional to stellar mass squared. Accordingly, the radial distance for equal temperatures will vary between accretion disks proportional to stellar mass cubed. Now, this is an extremely rough approximation, not the least because we have left heat radiation out of the calculation and assumed it to be proportionally the same for all disks. However, heat is radiated by dust, which depends on metallicity (which, to astronomers, means elements heavier than helium) and this is an extremely low metallicity star. If we assume my approximate relationship, then the Jupiter equivalent should be at 0.12 A.U. and the Saturn at 0.20 A.U., both plus or minus quite a lot.
 
Notwithstanding the inherent errors, I am reasonably confident we do not have rocky planets there, because while my estimates have a large potential error, there is a huge difference between the melting point of ice and the melting point of iron (needed to get iron lumps as in meteorites). Further, the error is reasonably consistent, being out by a factor of 1.4 for the Jupiter equivalent, and 1.55 for the Saturn equivalent, if those are what they are. That is reasonable for less heat loss due to lower metallicity. In my theory of planetary formation, these two planets would be interpreted as the cores of the Jupiter equivalent (formed like a snowball by ice sticking together near its melting point following collisions) and a Saturn equivalent (formed by melt fusion of methanol/ammonia/water near that eutectic temperature, the energy of the collision providing the heat, the melt then fusing the ice.) The reason they would not develop to full gas giants would be simply a lack of material to grow that big. Of course such dust as was available would also be incorporated, and the resultant planets would be like a giant Ganymede and a giant Titan. Thus I would expect (b) to have little atmosphere but maybe be a waterworld on the face tidally locked to the star, and (c) to have a nitrogen atmosphere, and maybe methane. Why maybe? Because methane is photochemically degraded, and presumably has to be regenerated on Titan. On Kapteyn c, with 11 billion years photochemistry, the methane may not have lasted. There would be no life on (b), nor for that matter in any Europa under-ice ocean, because of a general deficiency of nitrogen, and also a probable difficulty in forming phosphate esters.
 
So, that is my prediction. Unfortunately, I guess I shall never know whether it is right.
 
Finally, a small commercial break! Four of my fictional ebooks are on special at Amazon from the solstice for a few days, including the one that was actually the cause of my developing my alternative theory of planetary formation. The fiction required an unusual discovery on Mars, I invented one, and an editor had the cheek to say it was unbelievable. Now editors in publishing houses have a right to criticize grammar, but not science, so I ended up determined to do something about this. Details of the special are at http://wp.me/p2IwTC-5r
Posted by Ian Miller on Jun 16, 2014 12:55 AM Europe/London

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