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Unveiling the Unique Star Family Ophion Discovered by Gaia Mission

The European Space Agency’s Gaia mission has unveiled a remarkable discovery: a peculiar family of stars exhibiting unexpected behavior. This revelation highlights the mission’s capacity to identify astronomical phenomena that might have otherwise gone unnoticed.

In brief

Gaia’s latest findings showcase a distinct star family eager to disperse, offering new insights into stellar evolution and the dynamics of our galaxy.

In-depth

Stars in the Milky Way typically form in cohesive groups, emerging simultaneously from similar environments. As these stars mature, they often venture into the galaxy together, although smaller clusters might dissolve over time. Notably, larger familial groups tend to remain relatively intact, moving in unison across vast cosmic distances.

Gaia has been instrumental in cataloging such star families. Its observations have led to discoveries of extensive strings of stars that have persisted for billions of years, and it has helped to uncover the ancient star streams that formed the earliest structures of our galaxy. By examining these stellar families, astronomers can glean insights not just about individual stars, but also about the overall evolution of the Milky Way.

A family like no other

Using data from Gaia, researchers have identified an extraordinary family of over a thousand young stars, aptly named Ophion. This family, while sizable, is expected to completely disperse in an unprecedentedly short timeframe, leaving little to trace its existence.

Dylan Huson, a researcher at Western Washington University and the lead author of the study, remarked, “Ophion contains stars that appear destined to scatter chaotically across the galaxy, which defies expectations for such a large family. This process will occur in a fraction of the typical time it would take for a family of this magnitude.”

A new model

To identify Ophion, Huson and his team crafted a novel model that leverages Gaia’s extensive spectroscopic data, focusing on youthful, low-mass stars located relatively close to the Sun. This model, termed Gaia Net, was applied to the enormous spectrum dataset released in Gaia’s data release 3, ultimately zeroing in on stars younger than 20 million years. That’s when Ophion emerged from the analysis.

“This marks the first application of such a model to young stars, facilitated by Gaia’s vast and high-quality observational data,” noted Johannes Sahlmann, ESA Gaia Project Scientist. “This capability to gather mass measurements of young stars is among Gaia’s groundbreaking contributions to stellar astronomy.”

Furthermore, the open data policy of the Gaia mission fosters innovation in interdisciplinary research. Many members of the Ophion discovery team are computer science students who utilized Gaia’s data to develop new analytical methods that enhance our understanding of the Milky Way’s stellar population.

Solving the mystery

The unusual behavior of Opion raises intriguing questions. Researchers propose several theories regarding the dynamics influencing this star family. Situated about 650 light-years away, Ophion is in proximity to other significant clusters of young stars. Energetic events originating from these stellar neighbors could have played a role in the rapid dispersion of Ophion.

Additionally, evidence suggests past supernova explosions in the vicinity might have expelled material from Ophion, propelling its stars into erratic trajectories.

“The precise factors leading to the peculiar behavior of this star family remain a mystery, as nothing quite like it has been observed previously,” commented Marina Kounkel, co-author of the study from the University of North Florida. “This discovery challenges traditional concepts of star grouping and detection; previously established clustering methods may not have captured Ophion, underscoring the importance of Gaia’s rich datasets and our new analytical approaches.”

As the Gaia mission concluded its observational work in March after more than a decade of mapping the skies, the scientific journey continues. Numerous discoveries are anticipated in the coming years, alongside Gaia’s forthcoming data releases. The next significant release (Data Release 4) is scheduled for late 2026, with a comprehensive Gaia legacy data publication expected no sooner than the end of 2030.

Notes for editors

The paper “Gaia Net: Towards robust spectroscopic parameters of stars of all evolutionary stages” by Dylan Huson et al. has been published in The Astrophysical Journal. For access, visit this link.

Source
www.esa.int