KIC 8462852 Observations |
KIC 8462852 Observations |
Oct 15 2015, 04:45 PM
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#1
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
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. |
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Jan 26 2016, 11:25 PM
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#2
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Junior Member Group: Members Posts: 68 Joined: 27-March 15 Member No.: 7426 |
I wonder if trillions of comets, especially after colliding and reducing themselves to bits, wouldn't make for a uniform debris field around a star, rather than one comprised of distinct clumps of material. The latter is what seems to be present at KIC 8462852.
I also wonder if perturbations of comets by Neptune-mass planets would be great enough over a single century, so as to account for a fairly steady dimming of the star's light by about one fifth. |
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Jan 27 2016, 12:22 AM
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#3
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
During the Kepler era, KIC 8462852's brightness seems quite constant most of the time. If this represents the same luminosity star as it was 100 years ago, perpetually dimmed by some debris between us and it, there has to be a component of debris that is remarkably constant, and therefore fine, and can't be taking the form (most of the time) of large, individually significant chunks.
So, we'd have to have the star partially blocked by something like Saturn's rings (i.e., fine material, translucent, not necessarily shaped like rings), all the time, with bigger episodic events happening from time to time, and those "rings" would have to be pretty far from the star most of the time in order for the IR observations to turn up nothing. That means that the material is either far from the star all the time in a relatively circular orbit (or spherical shell, or a thick belt between a plane and a sphere), or in an elliptical orbit that crosses in front of the star. That seems odd, but the observational constraints don't allow for a lot of other exogenous explanations. I'd like to hear of some endogenous explanations; it may be too much to ask at this time. |
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Jan 27 2016, 05:38 AM
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#4
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Senior Member Group: Members Posts: 1585 Joined: 14-October 05 From: Vermont Member No.: 530 |
I'd like to hear of some endogenous explanations; it may be too much to ask at this time. When I consult google on this, I find that the rotational rate is 0.88 days, and you see a wiggle with that frequency in the light curve. So with the big dramatic dips, if the dip itself doesn't have that 0.88 day period, then it can't be anything like giant starspots or shortlived metal clouds... it couldn't be *anything* constrained to the star's rotational period. So to be endogenous, it would almost have to be the star burping out its own veil. How else would something endogenous be so transient? Or is the star's rotational pole in view, in which case a transient phenomenon at that pole could stay in view? Still, it looks like these dips are super-short. Maybe if it's the magnetic pole, it occasionally sucks in occulting materials. So it's like an opaque aurora viewed pole-on. So some sort of passing cloud of matter gets sucked in, turns into a very short-lived veil over the pole, and then dissipates. Which I guess would be an exogenous trigger.... anyways, I'm only speculating on the geometry of what would be endogenous, not the physics. Because I can't offer a physical explanation. |
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