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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Tabby's Star | 4/5 | https://en.wikipedia.org/wiki/Tabby's_Star | reference | science, encyclopedia | 2026-05-05T13:18:12.474605+00:00 | kb-cron |
One proposed explanation for the reduction in light is that it is due to a cloud of disintegrating comets orbiting the star elliptically. This scenario would assume that a planetary system around Tabby's Star has something similar to the Oort cloud and that gravity from a nearby star caused comets from said cloud to fall closer into the system, thereby obstructing the spectra of Tabby's Star. Evidence supporting this hypothesis includes an M-type red dwarf within 132 billion kilometers (885 AU) of Tabby's Star. The notion that disturbed comets from such a cloud could exist in high enough numbers to obscure 22% of the star's observed luminosity has been doubted. The smooth shallow ingress and sharp egress of some dimming events, as well as some symmetric triple dips, are difficult to explain with the comet scenario. Instead, a few asteroid-like bodies embedded in a dust cloud may better explain the star's light curve. Submillimetre-wavelength observations searching for farther-out cold dust in an asteroid belt akin to the Sun's Kuiper Belt suggest that a distant "catastrophic" planetary disruption explanation is unlikely; the possibility of a disrupted asteroid belt scattering comets into the inner system is still to be determined.
=== Younger star with coalescing material around it ===
Astronomer Jason T. Wright and others who have studied Tabby's Star have suggested that if the star is younger than its position and speed would suggest, then it may still have coalescing material around it. A 0.8–4.2-micrometer spectroscopic study of the system using the NASA Infrared Telescope Facility (NASA IRTF) found no evidence for coalescing material within a few astronomical units of the mature central star.
=== Planetary debris field ===
High-resolution spectroscopy and imaging observations have also been made, as well as spectral energy distribution analyses using the Nordic Optical Telescope in Spain. A massive collision scenario would create warm dust that glows in infrared wavelengths, but there is no observed excess infrared energy, ruling out massive planetary collision debris. Other researchers think the planetary debris field explanation is unlikely, given the very low probability that Kepler would ever witness such an event due to the rarity of collisions of such size. As with the possibility of coalescing material around the star, spectroscopic studies using the NASA IRTF found no evidence for hot close-in dust or circumstellar matter from an evaporating or exploding planet within a few astronomical units of the central star. Similarly, a study of past infrared data from NASA's Spitzer Space Telescope and Wide-field Infrared Survey Explorer found no evidence for an excess of infrared emission from the star, which would have been an indicator of warm dust grains that could have come from catastrophic collisions of meteors or planets in the system. This absence of emission supports the hypothesis that a swarm of cold comets on an unusually eccentric orbit could be responsible for the star's unique light curve, but more studies are needed.
=== Consumption of a planet === In December 2016, a team of researchers proposed that Tabby's Star swallowed a planet, causing a temporary and unobserved increase in brightness due to the release of gravitational energy. As the planet fell into its star, it could have been ripped apart or had its moons stripped away, leaving clouds of debris orbiting the star in eccentric orbits. Planetary debris still in orbit around the star would then explain its observed drops in intensity. Additionally, the researchers suggest that the consumed planet could have caused the star to increase in brightness up to 10,000 years ago, and its stellar flux is now returning to the normal state.
=== Large planet with oscillating rings === Sucerquia et al. (2017) suggested that a large planet with oscillating rings may help explain the unusual dimmings associated with Tabby's Star.
=== Large ringed planet followed by Trojan swarms === Ballesteros et al. (2017) proposed a large, ringed planet trailed by a swarm of Trojan asteroids in its L5 Lagrangian point, and estimated an orbit that predicts another event in early 2021 due to the leading Trojans followed by another transit of the hypothetical planet in 2023. The model suggests a planet with a radius of 4.7 Jupiter radii, large for a planet (unless very young). An early red dwarf of about 0.5 R☉ would be easily seen in infrared. The current radial velocity observations available (four runs at σv ≈ 400 m/s) hardly constrain the model, but new radial velocity measurements would greatly reduce the uncertainty. The model predicts a discrete and short-lived event for the May 2017 dimming episode, corresponding to the secondary eclipse of the planet passing behind KIC 8246852, with about a 3% decrease in the stellar flux with a transit time of about 2 days. If this is the cause of the May 2017 event, the planet's orbital period is more precisely estimated as 12.41 years with a semi-major axis of 5.9 AU.