# 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…

Source: https://mysteriesdept.com/mysteries/hd-139139-random-transiter/evidence/EVD0DD2G5H5GJJG/among-619-bright-saturated-k2-c15-stars-only-hd-139139-shows  
Publisher: Mysteries Department  
Licence: CC BY 4.0 (credit Mysteries Department and link the page)  

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[HD 139139, the "Random Transiter"](https://mysteriesdept.com/mysteries/hd-139139-random-transiter)Evidence

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.](https://mysteriesdept.com/mysteries/hd-139139-random-transiter/answers/ANS0D79S1JY7DXT/the-dips-are-an-undiagnosed-instrumental-or-data-processing)

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
```

Key

**EVD** 0DD2G5H5GJJG

Kind

Evidence

Tier

Suggestive

Proposed

[Session 1](https://mysteriesdept.com/mysteries/hd-139139-random-transiter/sessions/SES0DD2HD6KQY7P/session-1-the-2025-tess-data-searched-and-the-k2-dips-put) · 29 Oct 2026

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