A stable-frequency transmitter with relative radial acceleration to a receiver will show a change in received frequency over time, known as a ‘drift rate.’ For a transmission from an exoplanet, astronomers must account for multiple components of drift rate: the exoplanet’s orbit and rotation, the Earth’s orbit and rotation, and other contributions. Understanding the drift rate distribution produced by exoplanets relative to Earth, can help scientists constrain the range of drift rates to check in a Search for Extraterrestrial Intelligence (SETI) project to detect radio technosignatures, and help them decide validity of signals-of-interest, as they can compare drifting signals with expected drift rates from the target star. In a new study, University of California, Los Angeles astronomer Megan Grace Li and colleagues modeled the drift rate distribution for over 5,300 confirmed exoplanets, using parameters from the NASA Exoplanet Archive.
“Our work gives deeper insight into what extraterrestrially transmitted signals may look like if they come from exoplanets, informing not only the parameter space of technosignature searches but also possible interpretations of detected signals,” Li said.
In the study, Li and co-authors focused on exoplanets from the NASA Exoplanet Archive (NEA).
They calculated the orbital drift rate distributions for over 5,300 known exoplanets, in the process, creating a tool with which researchers can quickly calculate expected drift rates from any exoplanetary system.
They found that 99% of the total drift rate distribution fell within 53 nHz.
In a previous paper, the researchers discovered that exoplanetary systems showed drift rates up to 200 nHz in the most extreme cases and recommended this as a threshold.
The new work builds upon this foundation by considering not only the maximum drift rates from extreme systems but also the average or most likely drift rates from all known systems.
“These results imply that, in many…
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