There is no infrared excess—that is the weirdest part of the whole thing. It means that there isn’t a large system-spanning amount of material heated by the star and radiating in the infrared, that we are just seeing a small fraction of as it happens to pass in front of the star from our angle. Instead, there must be only a small amount of material that we are seeing a reasonable fraction of each time it occults the star. An infrared excess does not depend on the type of material, merely its surface area.
This and the irregular deep nature of the occultation is very strange—large deep occultations mean the matter has to be diffuse rather than something like a planet, irregularity means theres probably multiple clumps, but the lack of infrared excess means we have to be seeing a pretty good fraction of it. The brightness of the star also wiggles a little bit on timecales of ~20 days for part of the dataset, in a manner they don’t know how to interpret.
The leading theories are:
1 - Dust clumps generated from a giant impact between two planets, spread around the orbital range of that planet. Should be some infrared excess in that case though, and the odds of happening to see that in a system that isn’t actively forming are ridiculously tiny.
2 - Exocomet storm in which large, icy dusty objects rain down practically on top of the star and poof into dust, then zoom back out into the outer system, possibly with one large ancestral object breaking up into multiple ones that share an orbit and pass next to the star at irregular intervals like our own solar system’s Kreutz sungrazers. In this case large amounts of dust would be irregularly generated in close proximity to the star where we are much more likely to see them pass in front. When they went back and looked at the star with other instruments, they found a passing red dwarf star only about 1,000 AUs out which could definitely disturb the far outer system and an Oort cloud equivalent.
3 - Something new, some kind of semi-stable clumpy low mass dust belt or a new form of chaotic variable star. Or the astrometry that ruled out certain classes of explanation being wrong.
I’ve read the original paper. http://arxiv.org/pdf/1509.03622v1.pdf
There is no infrared excess—that is the weirdest part of the whole thing. It means that there isn’t a large system-spanning amount of material heated by the star and radiating in the infrared, that we are just seeing a small fraction of as it happens to pass in front of the star from our angle. Instead, there must be only a small amount of material that we are seeing a reasonable fraction of each time it occults the star. An infrared excess does not depend on the type of material, merely its surface area.
This and the irregular deep nature of the occultation is very strange—large deep occultations mean the matter has to be diffuse rather than something like a planet, irregularity means theres probably multiple clumps, but the lack of infrared excess means we have to be seeing a pretty good fraction of it. The brightness of the star also wiggles a little bit on timecales of ~20 days for part of the dataset, in a manner they don’t know how to interpret.
The leading theories are:
1 - Dust clumps generated from a giant impact between two planets, spread around the orbital range of that planet. Should be some infrared excess in that case though, and the odds of happening to see that in a system that isn’t actively forming are ridiculously tiny.
2 - Exocomet storm in which large, icy dusty objects rain down practically on top of the star and poof into dust, then zoom back out into the outer system, possibly with one large ancestral object breaking up into multiple ones that share an orbit and pass next to the star at irregular intervals like our own solar system’s Kreutz sungrazers. In this case large amounts of dust would be irregularly generated in close proximity to the star where we are much more likely to see them pass in front. When they went back and looked at the star with other instruments, they found a passing red dwarf star only about 1,000 AUs out which could definitely disturb the far outer system and an Oort cloud equivalent.
3 - Something new, some kind of semi-stable clumpy low mass dust belt or a new form of chaotic variable star. Or the astrometry that ruled out certain classes of explanation being wrong.