New Catalog Helps SETI Avoid Wasting Time on Unlikely Stars

Where Not to Look in the Search for ET

When scanning the skies for signs of alien civilizations, astronomers face a practical problem: with up to 400 billion stars in the Milky Way and limited telescope time, which stars should they listen to? Most SETI programs prioritize proximity, pointing dishes at the nearest, brightest stars. But this strategy ignores a fundamental issue: not all stars are equally good candidates for hosting complex life. Some burn too hot and die too quickly, others are too young, and some are chemically impoverished, making planet formation unlikely. Listening to those stars might be a complete waste of time.

A High School Student's Solution

Sahin Torlakcik, a high school student from Ankara, Turkey, decided to tackle this problem. The result, published in a peer-reviewed journal, is the Torlakcik Catalog—a rule-based filtering system applied to nearly 1.75 million stars from the Gaia space telescope's data archive. The goal was not to find the best candidates but to systematically identify the worst ones and set them aside.

Seven Stellar Parameters

Using seven stellar parameters, the model highlights stars unlikely to host complex life and removes them from the search list. The criteria include:

• Mass: Stars more than 1.5 times the mass of our Sun burn through their fuel too fast. Complex life requires at least a few billion years to evolve, so heavyweight stars don't live long enough.
• Age: Stars younger than three billion years face the same problem from the other direction. Life on Earth took roughly that long just to get past single-celled organisms.
• Metallicity: Stars with too little iron and other heavy metals are poor candidates for forming rocky planets.
• Binary systems: Two stars orbiting each other create gravitational environments that can destabilize planetary orbits.
• Photometric variability and chromospheric activity: Red dwarfs that are photometrically variable or chromospherically active (with flares) can blast their planets with radiation, making life unlikely.

Implications for SETI

By filtering out these unlikely stars, the Torlakcik Catalog helps SETI researchers focus their limited telescope time on the most promising targets. This approach could significantly increase the chances of detecting a signal from an extraterrestrial civilization. The catalog is a valuable resource for future SETI observations, allowing astronomers to prioritize stars that are most likely to host complex life.

Conclusion

The Torlakcik Catalog represents a smart, systematic way to narrow the search for extraterrestrial intelligence. By identifying where not to look, it helps us focus on where we might actually find something. As SETI continues to scan the skies, tools like this will be essential for making the most of our resources.

This article is based on reporting by Universe Today. Read the original article.