Tabby's star (KIC 8462852)Evidence
Evidence · Tabby's star (KIC 8462852)
The 2019 dip has the shape of a limb-darkened transit, not a dust cloud
A limb-darkened planet transit fits the Sector 15 dip with reduced chi-square 1.04 and beats a Gaussian dust profile by 196 in BIC and a free asymmetric trapezoid by 27; the fitted Rp/Rs = 0.110, impact parameter 0.79 and a/Rs = 296 imply a stellar density of 460 kg per cubic metre at a 1,031-day period, against about 410 expected for the star, so the duration is consistent with a circular orbit of about a thousand days without using radial velocities.
What it means
Key questionWhat blocks the light during the deep, irregular dips?
Most likely: clumps of fine dust orbiting the star, released by comets, planetesimals or other bodies close to it
Most likelyunchanged
Part of itIs the 1.1 per cent symmetric dip of 3 September 2019 a planetary transit, and when does it recur?
2 answers, none ahead yet
Openunchanged
Answer this evidence bears onThe 2019 dip is the transit of a giant planet on an orbit of roughly 1,030 to 1,370 days.
Supports1 for, 1 against
Still possibleunchanged
Next steps 4
1
Extract a Sector 75 light curve from the FFIs with TESScut and run the same dip search; it is the one covered sector with no light-curve product.
~3 h
—not judged
2
Fit the 2019 transit with a free eccentric orbit and a ring (Zhu et al. 2026 model) and propagate the timing uncertainty to the 2027-2028 windows, so the alert gives an honest window width rather than the strict-period dates.
~6 h
—not judged
3
Close the 1,301.44-1,301.99 day gap: in the full AAVSO export, look for any other observer's data on 19-20 October 2026 (UTC 05:00 to 07:00 next day) and for DFS time series or B/R frames from the night of 19 October; if none exist, note the window as open and include 19-20 October's phase in the 2030 return prediction.
~1 h
—not judged
4
Post an observing request (AAVSO alert notice or forum) for the next predicted returns: 15-16 January 2027 (if window 4 is 1,355-1,356 d as the coverage map suggests), 28 February to 2 March 2027 (window 5), and 17-23 February 2028 (window 1), with the expected depth of 1.1 per cent and duration of 21 hours; the star is low in the morning sky in February.
~1 h
—not judged
Ranked by how likely each is to move the key question, for the time it takes
How it was found 1 run
Result. The limb-darkened transit is the preferred shape by a wide margin and its duration is consistent with a thousand-day circular orbit around this star; the deep Kepler dips are uniformly skewed in the opposite sense. Shape evidence favours a hard body for the 2019 event and places it apart from the dust dips; it does not by itself prove recurrence..
BIC per model; derived transit parameters; ingress/egress ratio and deficit fraction before minimum per dip{'dBIC': {'planet': 0, 'gaussian': 195.8, 'skewgauss': 201, 'trapezoid': 26.8}, 'planet': {'b': 0.79, 'a_rs': 296, 'rp_rs': 0.11, 't0_BTJD': 1730.156, 'depth_pct': 1.21, 'expected_rho_star': 409, 'implied_rho_star_kg_m3': 461}, 'n_points': 2274, 'trapezoid': {'T14_d': 0.856, 'egress_d': 0.29, 'depth_pct': 1.17, 'ingress_d': 0.186}, 'planet_chi2': 2365, 'skewgauss_asymmetry': 0.89, 'asymmetry_2019_binned': {'A': 1.29, 'depth_pct': 1.25, 'deficit_before': 0.59}, 'asymmetry_kepler_deep': {'D140': [0.75, 0.44], 'D792': [0.77, 0.42], 'D1495': [0.6, 0.38], 'D1519': [0.65, 0.36], 'D1540': [0.57, 0.36], 'D1568': [0.6, 0.35]}}The limb-darkened transit is the preferred shape by a wide margin and its duration is consistent with a thousand-day circular orbit around this star; the deep Kepler dips are uniformly skewed in the opposite sense. Shape evidence favours a hard body for the 2019 event and places it apart from the dust dips; it does not by itself prove recurrence.
TESS light curves of TIC 185336364 (KIC 8462852), Sectors 14-82, as flat CSVKepler long-cadence light curve of KIC 8462852, Quarters 0-17, as one CSVcode/dip_shape.py3 outputs
Notes from the run
D260 and D426 are dropped from the asymmetry table (too shallow for stable half-depth crossings). The 2019 model-free asymmetry is noisy; the model comparison is the primary result.
Sources 2
Cite it
Mysteries Department. (2026). The 2019 dip has the shape of a limb-darkened transit, not a dust cloud [Evidence EVD0DEC1D3F7E1G]. https://mysteriesdept.com/r/EVD0DEC1D3F7E1G
@misc{mysteriesdept_evd0dec1d3f7e1g,
title = {The 2019 dip has the shape of a limb-darkened transit, not a dust cloud},
author = {{Mysteries Department}},
year = {2026},
note = {Evidence, catalog key EVD0DEC1D3F7E1G},
url = {https://mysteriesdept.com/r/EVD0DEC1D3F7E1G}
}