For nearly a century, we thought red giant stars had 'heartbeats' caused by hidden planets, but new data shows we were likely wrong.
April 14, 2026
Original Paper
Gaia astrometry disfavors a binary origin for long secondary periods
arXiv · 2604.09767
The Takeaway
Astronomers used to explain the long-period pulses of these stars by assuming they had orbiting companions like brown dwarfs. Gaia spacecraft data now shows these companions don't exist, forcing scientists to search for a completely new internal mechanism to explain the stellar pulses.
From the abstract
Approximately one-third of luminous pulsating red giant stars exhibit long secondary periods (LSPs): stable photometric variability with periods of several months to years in addition to their much shorter primary pulsation cycles. Now nearly a century after their discovery, the physical origin of LSPs remains unresolved. A leading explanation invokes binarity, in which the LSP corresponds to the orbital period of a low-mass companion responsible for both the photometric variability and the radi