Posted by A new study proposes a transparent way to decide not only where SETI surveys should search, but also which stars may deserve lower priority.
The “Torlakcik Catalog” applies a rule-based avoidance model to 1.74 million stars from Gaia Data Release 3, filtering targets according to stellar characteristics associated with long-term habitability. The model evaluates seven criteria: stellar mass, age, spectral type, metallicity, multiplicity, photometric variability and activity among M dwarfs. A star meeting any exclusion criterion is flagged along with a machine-readable reason code, allowing astronomers to trace exactly why it was rejected. Applied to 1,742,306 Gaia stars, the system excluded 964,471, or 55.4%, while retaining 777,835 as higher-priority SETI candidates. G- and K-type stars dominate the retained population. Age and metallicity were the strongest filters, each affecting about 29% of the original sample. One important feature is the treatment of uncertain stellar ages. Instead of automatically rejecting every star with an estimated age below three billion years, the method uses Gaia’s upper age limit. This uncertainty-aware approach preserved 355,086 stars that would otherwise have been removed.
The researchers also compared the catalog with Breakthrough Listen targets. Of 405 matched stars from its primary list, 56.5% failed the habitability-based criteria. The authors argue this reflects different strategies: Breakthrough Listen emphasizes nearby, bright stars where signals would be easier to detect, whereas the new catalog prioritizes stars considered more favorable for complex life.
The retained stars have a median distance of 382 parsecs and a sky density of about 19 stars per square degree, making the catalog potentially useful for existing facilities including MeerKAT and the VLA. The software and catalog are publicly available and designed for integration into future SETI scheduling pipelines. While the method might be debatable, it still allows us to look at the SETI problem from the different perspective.
