Listening to the Standard Candles: A Survey-Scale Search for Phase-Coded Beacons in Cepheids, RR~Lyrae and β~Cephei Stars
Abstract
Learned et al. (2008) proposed that a civilization could use Cepheids and RR Lyrae stars, the most closely watched clocks in astronomy, as beacons, firing pulsations early with a particle beam to write a message into the timing residuals. The one search to date examined a single Kepler star. We describe Star SETI, an automated pipeline that selects Cepheids, RR Lyrae and β Cephei stars from Gaia DR3, measures per-cycle (TESS, Kepler) or block-averaged (ASAS-SN, ZTF) observed-minus-computed timing residuals, tests them for non-white structure, decodes them as a bit stream under the cumulative (``staircase'') modulation of a one-sided trigger, and matches the words to catalogs of recognizable sequences. A resonant antineutrino beam grazing the base of the driving zone needs hundreds to tens of thousands of times less power than a central beam, and driving an RR Lyrae star takes most of its light. Injections into real light curves show that only RR Lyrae stars are detectable near the amplitude that Learned et al. proposed, with half of the codes recovered at 0.2--0.4 per cent of a period per bit in TESS; the ground-based surveys detect only codes held for tens of cycles per bit and decode none. We time 97,725 light curves of 77,596 stars and vet 38,230 timing anomalies; 6823 have timing structure that the vetting cannot attribute to a known cause, all but eight of them on block-averaged timing to which only part of the vetting applies. The highest-ranked are non-radial modes in first-overtone RR Lyrae stars, Blazhko modulation and mode beating in β Cephei stars, and no decoded word survives a false-discovery correction. We find no beacon. That bounds only beacons: a perfectly compressed message is indistinguishable from noise, so a civilization communicating efficiently rather than advertising could leave residuals that pass all of our tests, in stars that we cannot single out.
Related
- Cepheid Metallicity in the Leavitt Law (C-MetaLL) survey: X First spectroscopic characterization of Galactic Type II Cepheids and calibration of the Period-Wesenheit-Metallicity relations
- H I Absorbers as Beacons of Hidden Structure at z ∼ 3: Multi-Component, Metal-Rich Absorption System near a Protocluster
- VELOcities of CEpheids (VELOCE) III. Reconstructing radial velocity curves of classical Cepheids
- Interstellar extinction of classical Cepheids from neighboring stars. I. Methodology and application to 16 Galactic Cepheids
- Theoretical pulsation properties of RR Lyrae and Type II Cepheids in the JWST and Roman photometric systems
BibTeX
@misc{guillochon2026listening,
title = {{Listening to the Standard Candles: A Survey-Scale Search for Phase-Coded Beacons in Cepheids, RR~Lyrae and $β$~Cephei Stars}},
author = {James Guillochon},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.31860},
eprint = {2610.31860},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.31860},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Listening to the Standard Candles: A Survey-Scale Search for Phase-Coded Beacons in Cepheids, RR~Lyrae and β~Cephei Stars
AU - James Guillochon
PY - 2026
DA - 2026/10/22
PB - arXiv
DO - 10.48550/arxiv.2610.31860
UR - https://arxiv.org/abs/2610.31860
AB - Learned et al. (2008) proposed that a civilization could use Cepheids and RR Lyrae stars, the most closely watched clocks in astronomy, as beacons, firing pulsations early with a particle beam to write a message into the timing residuals. The one search to date examined a single Kepler star. We describe Star SETI, an automated pipeline that selects Cepheids, RR Lyrae and β Cephei stars from Gaia DR3, measures per-cycle (TESS, Kepler) or block-averaged (ASAS-SN, ZTF) observed-minus-computed timing residuals, tests them for non-white structure, decodes them as a bit stream under the cumulative (``staircase'') modulation of a one-sided trigger, and matches the words to catalogs of recognizable sequences. A resonant antineutrino beam grazing the base of the driving zone needs hundreds to tens of thousands of times less power than a central beam, and driving an RR Lyrae star takes most of its light. Injections into real light curves show that only RR Lyrae stars are detectable near the amplitude that Learned et al. proposed, with half of the codes recovered at 0.2--0.4 per cent of a period per bit in TESS; the ground-based surveys detect only codes held for tens of cycles per bit and decode none. We time 97,725 light curves of 77,596 stars and vet 38,230 timing anomalies; 6823 have timing structure that the vetting cannot attribute to a known cause, all but eight of them on block-averaged timing to which only part of the vetting applies. The highest-ranked are non-radial modes in first-overtone RR Lyrae stars, Blazhko modulation and mode beating in β Cephei stars, and no decoded word survives a false-discovery correction. We find no beacon. That bounds only beacons: a perfectly compressed message is indistinguishable from noise, so a civilization communicating efficiently rather than advertising could leave residuals that pass all of our tests, in stars that we cannot single out.
ER -