- #281
stefan r
Science Advisor
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Same reason you see Polaris as the north star.Vanadium 50 said:Why?
Same reason you see Polaris as the north star.Vanadium 50 said:Why?
stefan r said:Same reason you see Polaris as the north star.
sorry,Vanadium 50 said:That didn't clarify anything. Why would a ringed system necessarily show the same face to us every orbit?
JMz said:To clarify (I hope): The rings would always appear face-on, whether or not they were between the Sun and that star (though they wouldn't be visible when they weren't occulting the Sun). They don't change orientation relative to the star as they orbit the Sun, just as the Earth's axis doesn't change orientation relative to Polaris or any other star over the course of a year.
It isVanadium 50 said:Right, but suppose your aliens lived on Regulus rather than Polaris. They would see Earth or Saturn - or better still, Uranus - transit the sun - why is the ring orientation necessarily constant?
The more tilted the rings are, the less they will occult. This hypothesis is already aiming for substantially more coverage than even Saturn's unusually large and dense rings can provide, even if they were oriented like Uranus's.stefan r said:When Galileo first looked at Saturn he noticed that Saturn had ears. If the rings had been face on it would have looked like another sphere. Rings viewed off of axis might be better for explaining strange light curves.
Am I missing something here? Or are you? (I question myself because I know you're super smart.)Vanadium 50 said:That didn't clarify anything. Why would a ringed system necessarily show the same face to us every orbit?
We don't know if Saturn's rings are unusually large. J1407b probably has a ring system with 200 times the diameter of Saturn's rings. Easily large enough to obscure the whole star, leading to a massive (>90%) dip in brightness.JMz said:The more tilted the rings are, the less they will occult. This hypothesis is already aiming for substantially more coverage than even Saturn's unusually large and dense rings can provide, even if they were oriented like Uranus's.
A good point. For rings in the Solar System, big planets have rings -- but they're all insignificant (in blocking sunlight for distant observers) except for Saturn. My unstated hypothesis was that large, dense ring systems are very rare, and that the few we know of are known just because of a very strong observational selection effect.mfb said:We don't know if Saturn's rings are unusually large. J1407b probably has a ring system with 200 times the diameter of Saturn's rings. Easily large enough to obscure the whole star, leading to a massive (>90%) dip in brightness.
The duration and frequency of the dips in KIC 8462852 rule out a similar explanation there.
Got it -- sort of like Neptune's. My impression is that such rings would not be both large/dense and incomplete, except for a brief interval soon after formation. (And this star is not newly born.) But whether or not that's typical, we are dealing with an atypical system: All explanations so far are either poor fits to the data or improbable scenarios.Vanadium 50 said:I now see what you're saying, and my problem is I wrote what I wrote, not what I meant. What I was imaging was a set of irregular rings, darker/thicker in spots, partially obscured by the planet. This would give you a kind of irregular periodicty.
Birrabenzina said:This star is pretty interesting.
Has someone any link to some paper which analyzes this star in detail? Maybe it's a double system with a type Y or T brown dwarf