KIC 8462852 Observations Options

[JRehling]

Kepler found one very, very strange case:

http://www.theatlantic.com/science/archive...-galaxy/410023/

In a nutshell, while Kepler was observing it, the star (larger and brighter than the Sun) exhibited four dimming events that took place at irregular intervals, blocked a lot more light than a Jupiter-sized planet would block, and had a "shape" that varied in all four cases and did not resemble a planet.

This case is attracting some wild speculation… in fact, it is seemingly certain that something wild must be going on; it's just a matter of which wild scenario is the correct one.

If I had to throw my hat in the ring, I'd guess that a distant collision and breakup has placed big swarms of matter into a very long-period orbit. But there's no hypothesis that's been offered that doesn't seem problematic.

[Rittmann]

I was wondering...

How much obscuring could happen in a system like ours of some big body with plenty of water entered the inner system? Something like KIC 12557548.

http://www.space.com/15849-disintegrating-...er-mission.html

If the orbit change was recent and chaotic, could it leave behind a trail big and wide enough as to obscure the star in such a way? I always wondered how massive would be a tail for something like a Pluto if it fell below the ice line due to some disturbance. And in that system there is a second star some 885AU away, so something like a Sedna (936 AU of aphelion) could be disturbed and end up falling onto the main.

Let's make some comparison to see the numbers. Halley comet has a mean diameter of 11km, with dimensions of 15x8 km. I found some old calculations that suggest a mass loss of 1.8x10_8 metric tons per appearance. We are talking of a comet that approaches the Sun 0.58 AU, and with an expected life of around 40 more appearances, so it's pretty unstable in cosmic terms, but still gives a good idea of the survivavility of such body.

In comets outgassing is caused not only in the surface, but also by the heating of its interior as demonstrated by Rosetta and the jets that appeared in the night side of 67P. Still, we can make - for the sake of making some rough numbers - an approximation to relate mass loss and comet surface. With these numbers, for something the size of - to give some known thing - Ceres, we could relate mass losses by that formula. Of course, we are assuming similar compositions, which we know is not true for Ceres and Halley.

A(sphere) = 4πr_2

Halley (5.5 km_2): 380km_2
Ceres: 2.770.000 km_2

So something the size of Ceres could lose 7300 more mass per visit to the inner solar system. Using the equivalences above, that would be a mass loss of 1.3x10_12 tons per transit.

With a mass so significantly higher than a comet, though, such a body could also be a lot more stable over time. Let's calculate how many orbits would be needed to lose 10% of the mass of such a body if its density was 0.5 g/cm3. Ceres has a mass of 9.393x10_20 kg at 2.16g/cm3 density, so at the density of a comet (more valid for the surface conditions than for the inner rocky mantle) of such a body, we would have an equivalent comet four times lighter, at 2.4x10_20 kg. 10% mass loss would then be 2.4x10_16 metric tons.

So for a mass loss of 10%, we get a value of at approx. 20.000 orbits. At 750 days period that would mean 40.000 years to lose that 10% of mass.

Something like Pluto, 15 times more massive than Ceres, would take probably 10-15 times more time to lose 10% of its mass, giving the possible value for a full disintegration somewhere around 4 million years.

Of course, a period of just 2 years is not plausible for such bodies, which should be born beyond the ice lines and have far longer orbital periods. At 80 years of orbital period we are talking of 160 million years for a full disintegration. That could account for the lifetime of this star, and be a remnant of its chaotic birth.

In any case, such a body would create a massive tail that could obscure the inner system. Not only that, after detaching from the main body, the tiny particles could be subject to the gravity well of passing planets, creating clouds of dust trailing them over the centuries. Planetary gravity wells could very well form trails of their own of huge sizes. I have no idea on how long would they survive, and how opaque they could become, but the peaks may indicate clouds born from different tails created by different orbits of the diving massive comet.

Furthermore, we know very little about the companion star. If the companion is in a circular orbit is one thing, but if it is in an elongated orbit like Sedna, the main star would be bombed by all icy objects from its outer regions constantly. The same could be possible for the companion, so a good indicator would be check the magnitude variations of the companion star.

For a star passing by at that distance, the disturbance would probably be self-explained by the massive infalling material from the outer parts of that system.