Evidence · HD 139139, the "Random Transiter"

Among 619 bright saturated K2 C15 stars, only HD 139139 shows random multi-hour dips

Run on 619 K2 Campaign 15 stars of similar brightness (Tmag 8.6–9.7, all saturated), the same search finds HD 139139 among the top five for excess events of 1.5 hours or longer. It is the only quiet star whose excess is random, multi-hour, ~200 ppm dips. The four above it are two periodic eclipsing binaries, a star whose dips are about half periodic, and an active M dwarf.

Suggestive0

What it bears on 1 answer

The dips are an undiagnosed instrumental or data-processing effect in the K2 Campaign 15 data.

Still possible

AGAINST

Found by 1 run

Run	Measured	Result	Against	Decision	Date
Run	Excess = dips - sign-flipped bumps at >=5.5 sigma, events >=1.5 h, K2SFF	{'rank': 5, 'n_stars': 619, 'HD139139': 15, 'population_quantiles_50_90_99': [0, 1, 9.6]}	The same statistic across 619 stars of Tmag 8.6-9.7 in C15	HD 139139 is the only quiet star with an excess of random, multi-hour dips; the four ranked above it are periodic or active stars. Not a generic saturated-star artefact.

Cite it

Mysteries Department. (2026). Among 619 bright saturated K2 C15 stars, only HD 139139 shows random multi-hour dips [Evidence EVD0DD2G5H5GJJG]. https://mysteriesdept.com/r/EVD0DD2G5H5GJJG

@misc{mysteriesdept_evd0dd2g5h5gjjg,
  title     = {Among 619 bright saturated K2 C15 stars, only HD 139139 shows random multi-hour dips},
  author    = {{Mysteries Department}},
  year      = {2026},
  note      = {Evidence, catalog key EVD0DD2G5H5GJJG},
  url       = {https://mysteriesdept.com/r/EVD0DD2G5H5GJJG}
}