The Pleiades star cluster, also referred to as the Seven Sisters and Messier 45, is an open star cluster situated around 440 light-years away from Earth in the Taurus constellation. It forms the central core of a larger network that includes several known star clusters scattered over 600 parsecs (1,950 light-years). This network is known as the Greater Pleiades Complex and comprises at least 3,091 stars.
Pleiades star cluster. Image credit: NASA / ESA / AURA / California Institute of Technology / Palomar Observatory.
Stars originate from clouds of dust and gas. Clumps of this material come together and eventually collapse under their gravity, creating the hot core that becomes a star.
Star formation typically occurs in bursts, with numerous stars being born in rapid succession.
A collection of stars that form from the same molecular cloud is known as a star cluster.
These stars remain gravitationally bound to one another for thousands of years.
Over tens to hundreds of millions of years, the materials that birthed them are expelled by cosmic winds, radiation, and various astrophysical phenomena.
As this occurs, individual stars can merge into their host galaxies, making it complex to ascertain their relationships and trace their origins, especially after more than 100 million years have elapsed.
In a recent study, Dr. Luke Buuma from the Carnegie Institution for Science Observatory and his colleagues concentrated on the Pleiades star cluster.
Utilizing data from NASA’s TESS mission, ESA’s Gaia spacecraft, and the Sloan Digital Sky Survey (SDSS), they discovered that this cluster is the core of a broader structure of related stars spanning over 1,950 light-years.
“We refer to this as the Greater Pleiades Complex,” Dr. Bouma stated.
“It includes at least three known groups of stars, and likely two additional ones.”
“We confirmed that most members of this structure have origins in the same gigantic stellar nursery.”
A key aspect of their methodology is that a star’s rotation rate decreases with age.
The study utilized a combination of TESS’s stellar rotation data (made to detect exoplanets) and Gaia’s stellar motion observations (designed for mapping the Milky Way).
With this information, they developed a new method based on rotation to identify stars that share common origins.
“For the first time, by amalgamating data from Gaia, TESS, and SDSS, we confidently identified a new member of the Pleiades cluster,” reported Dr. Buma.
“Data from each mission alone was not enough to reveal the full scope of the structure.”
“However, when we integrated stellar motions from Gaia, rotations from TESS, and chemical data from SDSS, a coherent picture took shape.”
“It’s akin to piecing together a jigsaw puzzle, where every dataset provides a different piece of a larger whole.”
Besides their comparable ages, the authors highlighted that the stars in the Greater Pleiades cluster share similar chemical compositions and were once much closer to one another.
The fifth generation of SDSS data was employed for the chemical abundance analysis.
“The Pleiades star cluster has been pivotal in human observations of stars since ancient times,” Dr. Buma remarked.
“This research marks a significant advancement in understanding the changes in the Pleiades star cluster since its formation 100 million years ago.”
The researchers believe their findings carry broad implications.
The Pleiades is not merely an astrophysical benchmark for young stars and exoplanets but also a significant cultural symbol, referenced in the Old Testament and Talmud, celebrated as Matariki in New Zealand, and represented on the Subaru logo in Japan.
Professor Andrew Mann of the University of North Carolina at Chapel Hill stated, “We are starting to understand that many stars near the Sun belong to extensive star clusters with intricate structures.”
“Our study provides a novel method to uncover these hidden connections.”
A paper detailing the survey results has been published this week in the Astrophysical Journal.
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Andrew W. Boyle et al. 2025. Missing Sister Found: TESS and Gaia Reveal Dissolving Pleiades Complex. APJ 994, 24; doi: 10.3847/1538-4357/ae0724
Source: www.sci.news
