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.

[ngunn]

Accepting the idea of eclipsing objects of some kind, why do they have to be in orbit around the star? Couldn't they be anywhere in the line of sight? So far there is no evidence of periodicity that would arise from regular orbits, only a sequence of apparently one-off events. If the objects are in a much closer but very faint system that just happens to be aligned with the star then they wouldn't have to be so big to produce the observed degree of obscuration - and of course they'd only pass once.

[HSchirmer]

Accepting the idea of eclipsing objects of some kind, why do they have to be in orbit around the star?
Couldn't they be anywhere in the line of sight?

I was thinking that same thing, perhaps we're seeing something closer?

This WTF star is estimated to be around 1480 LY from earth, in the Cygnus constellation.
It's just up and right from a star cluster NGC 6866 (arrow below)


First, that's looking towards the galactic center, the densest area for stars, and molecular clouds and other dark stuff, e.g. steppenwolf planets and brown dwarfs. So, perhaps it's a transit by something closer, a brown dwarf with planet(s) or a brown dwarf with comet belts.

Second, turns out that there is a nearby (~14 LY) triple star system V1581 Cygni in the same area as WTF (1450 LY).
So, let's assume the triple system has ejected something, planets or shredded comets. They would be 100 times closer, and thus could be 100 times smaller to cause the occultation. Instead of hypothetical object(s) ~50 Jupiter diameters across, object(s) 1/2 the diameter of Jupiter ( a normal ice-giant planet) could be the explanation.

[JRehling]

Interesting thoughts, nprev and HSchirmer. The first thing to grapple with is the probability of an object in one system transiting a coincidentally-aligned more distant star. The next thing to grapple with is the probability of four such events happening in a short time. In addition, the shapes of the events are still weird. And, finally, in such a paradigm, it becomes a little odd that no such event completely eclipsed the distant star, reducing its observed brightness to zero.

The last two might be addressed if we imagine that these are comet-like. Then, in fact, the star may be getting completely covered in terms of area, but by a translucent object. And the first objection may be addressed by a "Birthday Theorem" of sorts: Given enough object pairs, some really precise alignments may occur.

It's the second objection that seems thorniest: How can the closer system have so many objects that transit the more distant star? It would require either that the closer system have a dense halo of large objects or that the closer system has a lot of large objects orbiting in the same plane that coincidentally contains the farther star.

I don't know. Something weird is happening. The closer-and-farther system case seems to handle one weird aspect of the data – the size of the objects – but adds another weird thing – the coincidental perfect alignment – and maintains several of the weird things from the single-system hypothesis. I don't know which, if either, of those two explanations is more likely.

[HSchirmer]

I don't know. Something weird is happening.
The closer-and-farther system case seems to handle one weird aspect of the data – the size of the objects – but adds another weird thing – the coincidental perfect alignment – and maintains several of the weird things from the single-system hypothesis.
I don't know which, if either, of those two explanations is more likely.

Basically, I'm following an old saying "if you see hoof prints, think horses, not unicorns"
Better to go with something known-but-extremely-unlikely rather than something entirely-unprecedented.

Basically, it's a "devil you know" situation- which is more unlikely? What is the least bizarre explanation?

A - A nearby star with multiple opaque objects in a tight orbital plane, that all happen to occult a distant star?
B - A distant star with multiple opaque objects in a tight plane, that all happen to be several Jupiters across?

So, how certain are we about the WTF star? IRC, the classification is F-type, 6k-7k kelvin, located about 1,400 LY away.
Ok, what if it's not a "normal" distant F star, but a variant of procyon, (F star and white dwarf) but with a white dwarf that has a 6k-7k temperature. So, what would a near by white dwarf pulling material from a brown dwarf look like? Could it be something with the temperature and H2 lines that resemble a F class star? The luminous star would be roughly earth sized, and thus the observed occultations could be a result of "standard" rocky planets or dwarf planets.

[JRehling]

Comet Hale-Bopp's tail had a maximum length of over 60 million km. Comets can easily exceed Jupiter in size, and then some. However, one comet like Hale-Bopp wouldn't obscure a star; the tail is translucent. So this phenomenon couldn't be explained by one Hale-Bopp. But if a larger body, or set of bodies traveling together, were outgassing as much as Hale-Bopp did, we might have an explanation for this which isn't too crazy.

[JRehling]

Another thought: A comet seen transiting its star would be, most likely, pointing its tail directly away from the star and directly towards us. This would reduce its size, but increase its opacity. We have never observed a comet in this solar system from that geometry.

From Keplerian considerations, the transiting objects, if orbiting KIC 8462852, is more than 3 AU distant. Because this star is much brighter than the Sun, that may correspond to high levels of cometary outgassing.